Commit 5e12ca9fe3c77ce1d2a3ea1c22c4bcb6d9b2bb0c | zig

author	Matthew Lugg <mlugg@mlugg.co.uk> 2024-04-28 21:44:57+01:00
committer	Matthew Lugg <mlugg@mlugg.co.uk> 2024-09-01 18:30:31+01:00
log	5e12ca9fe3c77ce1d2a3ea1c22c4bcb6d9b2bb0c
tree	a4badc5eab3da4901e1c0c3f3239b07628fc339f
parent	5fb4a7df38deb705f77088d7788f0acc09da613d
signature	Commit is signed but in an unrecognized format.

compiler: implement labeled switch/continue

22 files changed, 1602 insertions(+), 382 deletions(-)

lib
- std
  - zig
    Ast.zig
    AstGen.zig
    Parse.zig
    Zir.zig
src
- Air.zig
- Air
  - types_resolved.zig
- Liveness.zig
- Liveness
  - Verify.zig
- Sema.zig
- Value.zig
- arch
  - aarch64
    CodeGen.zig
  - arm
    CodeGen.zig
  - riscv64
    CodeGen.zig
  - sparc64
    CodeGen.zig
  - wasm
    CodeGen.zig
  - x86_64
    CodeGen.zig
- codegen
  - c.zig
  - llvm.zig
- print_air.zig
- print_zir.zig
test
- behavior.zig
- behavior
  - switch_loop.zig

lib/std/zig/Ast.zig+45-9

...	...	@@ -1184,14 +1184,7 @@ pub fn lastToken(tree: Ast, node: Node.Index) TokenIndex {
1184	1184	n = extra.sentinel;
1185	1185	},
1186	1186
1187		.@"continue" => {
1188		if (datas[n].lhs != 0) {
1189		return datas[n].lhs + end_offset;
1190		} else {
1191		return main_tokens[n] + end_offset;
1192		}
1193		},
1194		.@"break" => {
	1187	.@"continue", .@"break" => {
1195	1188	if (datas[n].rhs != 0) {
1196	1189	n = datas[n].rhs;
1197	1190	} else if (datas[n].lhs != 0) {
...	...	@@ -1895,6 +1888,15 @@ pub fn taggedUnionEnumTag(tree: Ast, node: Node.Index) full.ContainerDecl {
1895	1888	});
1896	1889	}
1897	1890
	1891	pub fn switchFull(tree: Ast, node: Node.Index) full.Switch {
	1892	const data = &tree.nodes.items(.data)[node];
	1893	return tree.fullSwitchComponents(.{
	1894	.switch_token = tree.nodes.items(.main_token)[node],
	1895	.condition = data.lhs,
	1896	.sub_range = data.rhs,
	1897	});
	1898	}
	1899
1898	1900	pub fn switchCaseOne(tree: Ast, node: Node.Index) full.SwitchCase {
1899	1901	const data = &tree.nodes.items(.data)[node];
1900	1902	const values: *[1]Node.Index = &data.lhs;
...	...	@@ -2206,6 +2208,21 @@ fn fullContainerDeclComponents(tree: Ast, info: full.ContainerDecl.Components) f
2206	2208	return result;
2207	2209	}
2208	2210
	2211	fn fullSwitchComponents(tree: Ast, info: full.Switch.Components) full.Switch {
	2212	const token_tags = tree.tokens.items(.tag);
	2213	const tok_i = info.switch_token -\| 1;
	2214	var result: full.Switch = .{
	2215	.ast = info,
	2216	.label_token = null,
	2217	};
	2218	if (token_tags[tok_i] == .colon and
	2219	token_tags[tok_i -\| 1] == .identifier)
	2220	{
	2221	result.label_token = tok_i - 1;
	2222	}
	2223	return result;
	2224	}
	2225
2209	2226	fn fullSwitchCaseComponents(tree: Ast, info: full.SwitchCase.Components, node: Node.Index) full.SwitchCase {
2210	2227	const token_tags = tree.tokens.items(.tag);
2211	2228	const node_tags = tree.nodes.items(.tag);
...	...	@@ -2477,6 +2494,13 @@ pub fn fullContainerDecl(tree: Ast, buffer: *[2]Ast.Node.Index, node: Node.Index
2477	2494	};
2478	2495	}
2479	2496
	2497	pub fn fullSwitch(tree: Ast, node: Node.Index) ?full.Switch {
	2498	return switch (tree.nodes.items(.tag)[node]) {
	2499	.@"switch", .switch_comma => tree.switchFull(node),
	2500	else => null,
	2501	};
	2502	}
	2503
2480	2504	pub fn fullSwitchCase(tree: Ast, node: Node.Index) ?full.SwitchCase {
2481	2505	return switch (tree.nodes.items(.tag)[node]) {
2482	2506	.switch_case_one, .switch_case_inline_one => tree.switchCaseOne(node),
...	...	@@ -2829,6 +2853,17 @@ pub const full = struct {
2829	2853	};
2830	2854	};
2831	2855
	2856	pub const Switch = struct {
	2857	ast: Components,
	2858	label_token: ?TokenIndex,
	2859
	2860	pub const Components = struct {
	2861	switch_token: TokenIndex,
	2862	condition: Node.Index,
	2863	sub_range: Node.Index,
	2864	};
	2865	};
	2866
2832	2867	pub const SwitchCase = struct {
2833	2868	inline_token: ?TokenIndex,
2834	2869	/// Points to the first token after the `\|`. Will either be an identifier or
...	...	@@ -3287,7 +3322,8 @@ pub const Node = struct {
3287	3322	@"suspend",
3288	3323	/// `resume lhs`. rhs is unused.
3289	3324	@"resume",
3290		/// `continue`. lhs is token index of label if any. rhs is unused.
	3325	/// `continue :lhs rhs`
	3326	/// both lhs and rhs may be omitted.
3291	3327	@"continue",
3292	3328	/// `break :lhs rhs`
3293	3329	/// both lhs and rhs may be omitted.

lib/std/zig/AstGen.zig+97-16

...	...	@@ -1144,7 +1144,7 @@ fn expr(gz: GenZir, scope: Scope, ri: ResultInfo, node: Ast.Node.Index) InnerE
1144	1144	.error_set_decl => return errorSetDecl(gz, ri, node),
1145	1145	.array_access => return arrayAccess(gz, scope, ri, node),
1146	1146	.@"comptime" => return comptimeExprAst(gz, scope, ri, node),
1147		.@"switch", .switch_comma => return switchExpr(gz, scope, ri.br(), node),
	1147	.@"switch", .switch_comma => return switchExpr(gz, scope, ri.br(), node, tree.fullSwitch(node).?),
1148	1148
1149	1149	.@"nosuspend" => return nosuspendExpr(gz, scope, ri, node),
1150	1150	.@"suspend" => return suspendExpr(gz, scope, node),
...	...	@@ -2160,6 +2160,11 @@ fn breakExpr(parent_gz: GenZir, parent_scope: Scope, node: Ast.Node.Index) Inn
2160	2160	if (break_label != 0) {
2161	2161	if (block_gz.label) \|*label\| {
2162	2162	if (try astgen.tokenIdentEql(label.token, break_label)) {
	2163	const maybe_switch_tag = astgen.instructions.items(.tag)[@intFromEnum(label.block_inst)];
	2164	switch (maybe_switch_tag) {
	2165	.switch_block, .switch_block_ref => return astgen.failNode(node, "cannot break from switch", .{}),
	2166	else => {},
	2167	}
2163	2168	label.used = true;
2164	2169	break :blk label.block_inst;
2165	2170	}
...	...	@@ -2234,6 +2239,11 @@ fn continueExpr(parent_gz: GenZir, parent_scope: Scope, node: Ast.Node.Index)
2234	2239	const tree = astgen.tree;
2235	2240	const node_datas = tree.nodes.items(.data);
2236	2241	const break_label = node_datas[node].lhs;
	2242	const rhs = node_datas[node].rhs;
	2243
	2244	if (break_label == 0 and rhs != 0) {
	2245	return astgen.failNode(node, "cannot continue with operand without label", .{});
	2246	}
2237	2247
2238	2248	// Look for the label in the scope.
2239	2249	var scope = parent_scope;
...	...	@@ -2258,6 +2268,15 @@ fn continueExpr(parent_gz: GenZir, parent_scope: Scope, node: Ast.Node.Index)
2258	2268	if (break_label != 0) blk: {
2259	2269	if (gen_zir.label) \|*label\| {
2260	2270	if (try astgen.tokenIdentEql(label.token, break_label)) {
	2271	const maybe_switch_tag = astgen.instructions.items(.tag)[@intFromEnum(label.block_inst)];
	2272	if (rhs != 0) switch (maybe_switch_tag) {
	2273	.switch_block, .switch_block_ref => {},
	2274	else => return astgen.failNode(node, "cannot continue loop with operand", .{}),
	2275	} else switch (maybe_switch_tag) {
	2276	.switch_block, .switch_block_ref => return astgen.failNode(node, "cannot continue switch without operand", .{}),
	2277	else => {},
	2278	}
	2279
2261	2280	label.used = true;
2262	2281	break :blk;
2263	2282	}
...	...	@@ -2265,8 +2284,35 @@ fn continueExpr(parent_gz: GenZir, parent_scope: Scope, node: Ast.Node.Index)
2265	2284	// found continue but either it has a different label, or no label
2266	2285	scope = gen_zir.parent;
2267	2286	continue;
	2287	} else if (gen_zir.label) \|label\| {
	2288	// This `continue` is unlabeled. If the gz we've found corresponds to a labeled
	2289	// `switch`, ignore it and continue to parent scopes.
	2290	switch (astgen.instructions.items(.tag)[@intFromEnum(label.block_inst)]) {
	2291	.switch_block, .switch_block_ref => {
	2292	scope = gen_zir.parent;
	2293	continue;
	2294	},
	2295	else => {},
	2296	}
	2297	}
	2298
	2299	if (rhs != 0) {
	2300	// We need to figure out the result info to use.
	2301	// The type should match
	2302	const operand = try reachableExpr(parent_gz, parent_scope, gen_zir.continue_result_info, rhs, node);
	2303
	2304	try genDefers(parent_gz, scope, parent_scope, .normal_only);
	2305
	2306	// As our last action before the continue, "pop" the error trace if needed
	2307	if (!gen_zir.is_comptime)
	2308	_ = try parent_gz.addRestoreErrRetIndex(.{ .block = continue_block }, .always, node);
	2309
	2310	_ = try parent_gz.addBreakWithSrcNode(.switch_continue, continue_block, operand, rhs);
	2311	return Zir.Inst.Ref.unreachable_value;
2268	2312	}
2269	2313
	2314	try genDefers(parent_gz, scope, parent_scope, .normal_only);
	2315
2270	2316	const break_tag: Zir.Inst.Tag = if (gen_zir.is_inline)
2271	2317	.break_inline
2272	2318	else
...	...	@@ -2284,12 +2330,7 @@ fn continueExpr(parent_gz: GenZir, parent_scope: Scope, node: Ast.Node.Index)
2284	2330	},
2285	2331	.local_val => scope = scope.cast(Scope.LocalVal).?.parent,
2286	2332	.local_ptr => scope = scope.cast(Scope.LocalPtr).?.parent,
2287		.defer_normal => {
2288		const defer_scope = scope.cast(Scope.Defer).?;
2289		scope = defer_scope.parent;
2290		try parent_gz.addDefer(defer_scope.index, defer_scope.len);
2291		},
2292		.defer_error => scope = scope.cast(Scope.Defer).?.parent,
	2333	.defer_normal, .defer_error => scope = scope.cast(Scope.Defer).?.parent,
2293	2334	.namespace => break,
2294	2335	.top => unreachable,
2295	2336	}
...	...	@@ -2881,6 +2922,7 @@ fn addEnsureResult(gz: *GenZir, maybe_unused_result: Zir.Inst.Ref, statement: As
2881	2922	.panic,
2882	2923	.trap,
2883	2924	.check_comptime_control_flow,
	2925	.switch_continue,
2884	2926	=> {
2885	2927	noreturn_src_node = statement;
2886	2928	break :b true;
...	...	@@ -7546,7 +7588,8 @@ fn switchExpr(
7546	7588	parent_gz: *GenZir,
7547	7589	scope: *Scope,
7548	7590	ri: ResultInfo,
7549		switch_node: Ast.Node.Index,
	7591	node: Ast.Node.Index,
	7592	switch_full: Ast.full.Switch,
7550	7593	) InnerError!Zir.Inst.Ref {
7551	7594	const astgen = parent_gz.astgen;
7552	7595	const gpa = astgen.gpa;
...	...	@@ -7555,14 +7598,14 @@ fn switchExpr(
7555	7598	const node_tags = tree.nodes.items(.tag);
7556	7599	const main_tokens = tree.nodes.items(.main_token);
7557	7600	const token_tags = tree.tokens.items(.tag);
7558		const operand_node = node_datas[switch_node].lhs;
7559		const extra = tree.extraData(node_datas[switch_node].rhs, Ast.Node.SubRange);
	7601	const operand_node = node_datas[node].lhs;
	7602	const extra = tree.extraData(node_datas[node].rhs, Ast.Node.SubRange);
7560	7603	const case_nodes = tree.extra_data[extra.start..extra.end];
7561	7604
7562		const need_rl = astgen.nodes_need_rl.contains(switch_node);
	7605	const need_rl = astgen.nodes_need_rl.contains(node);
7563	7606	const block_ri: ResultInfo = if (need_rl) ri else .{
7564	7607	.rl = switch (ri.rl) {
7565		.ptr => .{ .ty = (try ri.rl.resultType(parent_gz, switch_node)).? },
	7608	.ptr => .{ .ty = (try ri.rl.resultType(parent_gz, node)).? },
7566	7609	.inferred_ptr => .none,
7567	7610	else => ri.rl,
7568	7611	},
...	...	@@ -7573,11 +7616,16 @@ fn switchExpr(
7573	7616	const LocTag = @typeInfo(ResultInfo.Loc).@"union".tag_type.?;
7574	7617	const need_result_rvalue = @as(LocTag, block_ri.rl) != @as(LocTag, ri.rl);
7575	7618
	7619	if (switch_full.label_token) \|label_token\| {
	7620	try astgen.checkLabelRedefinition(scope, label_token);
	7621	}
	7622
7576	7623	// We perform two passes over the AST. This first pass is to collect information
7577	7624	// for the following variables, make note of the special prong AST node index,
7578	7625	// and bail out with a compile error if there are multiple special prongs present.
7579	7626	var any_payload_is_ref = false;
7580	7627	var any_has_tag_capture = false;
	7628	var any_non_inline_capture = false;
7581	7629	var scalar_cases_len: u32 = 0;
7582	7630	var multi_cases_len: u32 = 0;
7583	7631	var inline_cases_len: u32 = 0;
...	...	@@ -7595,6 +7643,15 @@ fn switchExpr(
7595	7643	if (token_tags[ident + 1] == .comma) {
7596	7644	any_has_tag_capture = true;
7597	7645	}
	7646
	7647	// If the first capture is ignored, then there is no runtime-known
	7648	// capture, as the tag capture must be for an inline prong.
	7649	// This check isn't perfect, because for things like enums, the
	7650	// first prong is comptime-known for inline prongs! But such
	7651	// knowledge requires semantic analysis.
	7652	if (!mem.eql(u8, tree.tokenSlice(ident), "_")) {
	7653	any_non_inline_capture = true;
	7654	}
7598	7655	}
7599	7656	// Check for else/`_` prong.
7600	7657	if (case.ast.values.len == 0) {
...	...	@@ -7614,7 +7671,7 @@ fn switchExpr(
7614	7671	);
7615	7672	} else if (underscore_src) \|some_underscore\| {
7616	7673	return astgen.failNodeNotes(
7617		switch_node,
	7674	node,
7618	7675	"else and '_' prong in switch expression",
7619	7676	.{},
7620	7677	&[_]u32{
...	...	@@ -7655,7 +7712,7 @@ fn switchExpr(
7655	7712	);
7656	7713	} else if (else_src) \|some_else\| {
7657	7714	return astgen.failNodeNotes(
7658		switch_node,
	7715	node,
7659	7716	"else and '_' prong in switch expression",
7660	7717	.{},
7661	7718	&[_]u32{
...	...	@@ -7704,6 +7761,12 @@ fn switchExpr(
7704	7761	const raw_operand = try expr(parent_gz, scope, operand_ri, operand_node);
7705	7762	const item_ri: ResultInfo = .{ .rl = .none };
7706	7763
	7764	// If this switch is labeled, it will have `continue`s targeting it, and thus we need the operand type
	7765	// to provide a result type.
	7766	const raw_operand_ty_ref = if (switch_full.label_token != null) t: {
	7767	break :t try parent_gz.addUnNode(.typeof, raw_operand, operand_node);
	7768	} else undefined;
	7769
7707	7770	// This contains the data that goes into the `extra` array for the SwitchBlock/SwitchBlockMulti,
7708	7771	// except the first cases_nodes.len slots are a table that indexes payloads later in the array, with
7709	7772	// the special case index coming first, then scalar_case_len indexes, then multi_cases_len indexes
...	...	@@ -7725,7 +7788,22 @@ fn switchExpr(
7725	7788	try emitDbgStmtForceCurrentIndex(parent_gz, operand_lc);
7726	7789	// This gets added to the parent block later, after the item expressions.
7727	7790	const switch_tag: Zir.Inst.Tag = if (any_payload_is_ref) .switch_block_ref else .switch_block;
7728		const switch_block = try parent_gz.makeBlockInst(switch_tag, switch_node);
	7791	const switch_block = try parent_gz.makeBlockInst(switch_tag, node);
	7792
	7793	if (switch_full.label_token) \|label_token\| {
	7794	block_scope.continue_block = switch_block.toOptional();
	7795	block_scope.continue_result_info = .{
	7796	.rl = if (any_payload_is_ref)
	7797	.{ .ref_coerced_ty = raw_operand_ty_ref }
	7798	else
	7799	.{ .coerced_ty = raw_operand_ty_ref },
	7800	};
	7801
	7802	block_scope.label = .{
	7803	.token = label_token,
	7804	.block_inst = switch_block,
	7805	};
	7806	}
7729	7807
7730	7808	// We re-use this same scope for all cases, including the special prong, if any.
7731	7809	var case_scope = parent_gz.makeSubBlock(&block_scope.base);
...	...	@@ -7946,6 +8024,8 @@ fn switchExpr(
7946	8024	.has_else = special_prong == .@"else",
7947	8025	.has_under = special_prong == .under,
7948	8026	.any_has_tag_capture = any_has_tag_capture,
	8027	.any_non_inline_capture = any_non_inline_capture,
	8028	.has_continue = switch_full.label_token != null,
7949	8029	.scalar_cases_len = @intCast(scalar_cases_len),
7950	8030	},
7951	8031	});
...	...	@@ -7982,7 +8062,7 @@ fn switchExpr(
7982	8062	}
7983	8063
7984	8064	if (need_result_rvalue) {
7985		return rvalue(parent_gz, ri, switch_block.toRef(), switch_node);
	8065	return rvalue(parent_gz, ri, switch_block.toRef(), node);
7986	8066	} else {
7987	8067	return switch_block.toRef();
7988	8068	}
...	...	@@ -11824,6 +11904,7 @@ const GenZir = struct {
11824	11904	continue_block: Zir.Inst.OptionalIndex = .none,
11825	11905	/// Only valid when setBreakResultInfo is called.
11826	11906	break_result_info: AstGen.ResultInfo = undefined,
	11907	continue_result_info: AstGen.ResultInfo = undefined,
11827	11908
11828	11909	suspend_node: Ast.Node.Index = 0,
11829	11910	nosuspend_node: Ast.Node.Index = 0,

lib/std/zig/Parse.zig+20-6

...	...	@@ -924,7 +924,6 @@ fn expectContainerField(p: *Parse) !Node.Index {
924	924	/// / KEYWORD_errdefer Payload? BlockExprStatement
925	925	/// / IfStatement
926	926	/// / LabeledStatement
927		/// / SwitchExpr
928	927	/// / VarDeclExprStatement
929	928	fn expectStatement(p: *Parse, allow_defer_var: bool) Error!Node.Index {
930	929	if (p.eatToken(.keyword_comptime)) \|comptime_token\| {
...	...	@@ -995,7 +994,6 @@ fn expectStatement(p: *Parse, allow_defer_var: bool) Error!Node.Index {
995	994	.rhs = try p.expectBlockExprStatement(),
996	995	},
997	996	}),
998		.keyword_switch => return p.expectSwitchExpr(),
999	997	.keyword_if => return p.expectIfStatement(),
1000	998	.keyword_enum, .keyword_struct, .keyword_union => {
1001	999	const identifier = p.tok_i + 1;
...	...	@@ -1238,7 +1236,7 @@ fn expectIfStatement(p: *Parse) !Node.Index {
1238	1236	});
1239	1237	}
1240	1238
1241		/// LabeledStatement <- BlockLabel? (Block / LoopStatement)
	1239	/// LabeledStatement <- BlockLabel? (Block / LoopStatement / SwitchExpr)
1242	1240	fn parseLabeledStatement(p: *Parse) !Node.Index {
1243	1241	const label_token = p.parseBlockLabel();
1244	1242	const block = try p.parseBlock();
...	...	@@ -1247,6 +1245,9 @@ fn parseLabeledStatement(p: *Parse) !Node.Index {
1247	1245	const loop_stmt = try p.parseLoopStatement();
1248	1246	if (loop_stmt != 0) return loop_stmt;
1249	1247
	1248	const switch_expr = try p.parseSwitchExpr();
	1249	if (switch_expr != 0) return switch_expr;
	1250
1250	1251	if (label_token != 0) {
1251	1252	const after_colon = p.tok_i;
1252	1253	const node = try p.parseTypeExpr();
...	...	@@ -2072,7 +2073,7 @@ fn expectTypeExpr(p: *Parse) Error!Node.Index {
2072	2073	/// / KEYWORD_break BreakLabel? Expr?
2073	2074	/// / KEYWORD_comptime Expr
2074	2075	/// / KEYWORD_nosuspend Expr
2075		/// / KEYWORD_continue BreakLabel?
	2076	/// / KEYWORD_continue BreakLabel? Expr?
2076	2077	/// / KEYWORD_resume Expr
2077	2078	/// / KEYWORD_return Expr?
2078	2079	/// / BlockLabel? LoopExpr
...	...	@@ -2098,7 +2099,7 @@ fn parsePrimaryExpr(p: *Parse) !Node.Index {
2098	2099	.main_token = p.nextToken(),
2099	2100	.data = .{
2100	2101	.lhs = try p.parseBreakLabel(),
2101		.rhs = undefined,
	2102	.rhs = try p.parseExpr(),
2102	2103	},
2103	2104	});
2104	2105	},
...	...	@@ -2627,7 +2628,6 @@ fn parseSuffixExpr(p: *Parse) !Node.Index {
2627	2628	/// / KEYWORD_anyframe
2628	2629	/// / KEYWORD_unreachable
2629	2630	/// / STRINGLITERAL
2630		/// / SwitchExpr
2631	2631	///
2632	2632	/// ContainerDecl <- (KEYWORD_extern / KEYWORD_packed)? ContainerDeclAuto
2633	2633	///
...	...	@@ -2647,6 +2647,7 @@ fn parseSuffixExpr(p: *Parse) !Node.Index {
2647	2647	/// LabeledTypeExpr
2648	2648	/// <- BlockLabel Block
2649	2649	/// / BlockLabel? LoopTypeExpr
	2650	/// / BlockLabel? SwitchExpr
2650	2651	///
2651	2652	/// LoopTypeExpr <- KEYWORD_inline? (ForTypeExpr / WhileTypeExpr)
2652	2653	fn parsePrimaryTypeExpr(p: *Parse) !Node.Index {
...	...	@@ -2753,6 +2754,10 @@ fn parsePrimaryTypeExpr(p: *Parse) !Node.Index {
2753	2754	p.tok_i += 2;
2754	2755	return p.parseWhileTypeExpr();
2755	2756	},
	2757	.keyword_switch => {
	2758	p.tok_i += 2;
	2759	return p.expectSwitchExpr();
	2760	},
2756	2761	.l_brace => {
2757	2762	p.tok_i += 2;
2758	2763	return p.parseBlock();
...	...	@@ -3029,8 +3034,17 @@ fn parseWhileTypeExpr(p: *Parse) !Node.Index {
3029	3034	}
3030	3035
3031	3036	/// SwitchExpr <- KEYWORD_switch LPAREN Expr RPAREN LBRACE SwitchProngList RBRACE
	3037	fn parseSwitchExpr(p: *Parse) !Node.Index {
	3038	const switch_token = p.eatToken(.keyword_switch) orelse return null_node;
	3039	return p.expectSwitchSuffix(switch_token);
	3040	}
	3041
3032	3042	fn expectSwitchExpr(p: *Parse) !Node.Index {
3033	3043	const switch_token = p.assertToken(.keyword_switch);
	3044	return p.expectSwitchSuffix(switch_token);
	3045	}
	3046
	3047	fn expectSwitchSuffix(p: *Parse, switch_token: TokenIndex) !Node.Index {
3034	3048	_ = try p.expectToken(.l_paren);
3035	3049	const expr_node = try p.expectExpr();
3036	3050	_ = try p.expectToken(.r_paren);

lib/std/zig/Zir.zig+13-1

...	...	@@ -314,6 +314,9 @@ pub const Inst = struct {
314	314	/// break instruction in a block, and the target block is the parent.
315	315	/// Uses the `break` union field.
316	316	break_inline,
	317	/// Branch from within a switch case to the case specified by the operand.
	318	/// Uses the `break` union field. `block_inst` refers to a `switch_block` or `switch_block_ref`.
	319	switch_continue,
317	320	/// Checks that comptime control flow does not happen inside a runtime block.
318	321	/// Uses the `un_node` union field.
319	322	check_comptime_control_flow,
...	...	@@ -1273,6 +1276,7 @@ pub const Inst = struct {
1273	1276	.panic,
1274	1277	.trap,
1275	1278	.check_comptime_control_flow,
	1279	.switch_continue,
1276	1280	=> true,
1277	1281	};
1278	1282	}
...	...	@@ -1512,6 +1516,7 @@ pub const Inst = struct {
1512	1516	.break_inline,
1513	1517	.condbr,
1514	1518	.condbr_inline,
	1519	.switch_continue,
1515	1520	.compile_error,
1516	1521	.ret_node,
1517	1522	.ret_load,
...	...	@@ -1597,6 +1602,7 @@ pub const Inst = struct {
1597	1602	.bool_br_or = .pl_node,
1598	1603	.@"break" = .@"break",
1599	1604	.break_inline = .@"break",
	1605	.switch_continue = .@"break",
1600	1606	.check_comptime_control_flow = .un_node,
1601	1607	.for_len = .pl_node,
1602	1608	.call = .pl_node,
...	...	@@ -2288,6 +2294,7 @@ pub const Inst = struct {
2288	2294	},
2289	2295	@"break": struct {
2290	2296	operand: Ref,
	2297	/// Index of a `Break` payload.
2291	2298	payload_index: u32,
2292	2299	},
2293	2300	dbg_stmt: LineColumn,
...	...	@@ -2945,9 +2952,13 @@ pub const Inst = struct {
2945	2952	has_under: bool,
2946	2953	/// If true, at least one prong has an inline tag capture.
2947	2954	any_has_tag_capture: bool,
	2955	/// If true, at least one prong has a capture which may not
	2956	/// be comptime-known via `inline`.
	2957	any_non_inline_capture: bool,
	2958	has_continue: bool,
2948	2959	scalar_cases_len: ScalarCasesLen,
2949	2960
2950		pub const ScalarCasesLen = u28;
	2961	pub const ScalarCasesLen = u26;
2951	2962
2952	2963	pub fn specialProng(bits: Bits) SpecialProng {
2953	2964	const has_else: u2 = @intFromBool(bits.has_else);
...	...	@@ -3750,6 +3761,7 @@ fn findDeclsInner(
3750	3761	.bool_br_or,
3751	3762	.@"break",
3752	3763	.break_inline,
	3764	.switch_continue,
3753	3765	.check_comptime_control_flow,
3754	3766	.builtin_call,
3755	3767	.cmp_lt,

src/Air.zig+16-1

...	...	@@ -429,6 +429,14 @@ pub const Inst = struct {
429	429	/// Result type is always noreturn; no instructions in a block follow this one.
430	430	/// Uses the `pl_op` field. Operand is the condition. Payload is `SwitchBr`.
431	431	switch_br,
	432	/// Switch branch which can dispatch back to itself with a different operand.
	433	/// Result type is always noreturn; no instructions in a block follow this one.
	434	/// Uses the `pl_op` field. Operand is the condition. Payload is `SwitchBr`.
	435	loop_switch_br,
	436	/// Dispatches back to a branch of a parent `loop_switch_br`.
	437	/// Result type is always noreturn; no instructions in a block follow this one.
	438	/// Uses the `br` field. `block_inst` is a `loop_switch_br` instruction.
	439	switch_dispatch,
432	440	/// Given an operand which is an error union, splits control flow. In
433	441	/// case of error, control flow goes into the block that is part of this
434	442	/// instruction, which is guaranteed to end with a return instruction
...	...	@@ -1454,6 +1462,8 @@ pub fn typeOfIndex(air: const Air, inst: Air.Inst.Index, ip: const InternPool)
1454	1462	.br,
1455	1463	.cond_br,
1456	1464	.switch_br,
	1465	.loop_switch_br,
	1466	.switch_dispatch,
1457	1467	.ret,
1458	1468	.ret_safe,
1459	1469	.ret_load,
...	...	@@ -1618,6 +1628,8 @@ pub fn mustLower(air: Air, inst: Air.Inst.Index, ip: *const InternPool) bool {
1618	1628	.call_never_inline,
1619	1629	.cond_br,
1620	1630	.switch_br,
	1631	.loop_switch_br,
	1632	.switch_dispatch,
1621	1633	.@"try",
1622	1634	.try_cold,
1623	1635	.try_ptr,
...	...	@@ -1903,7 +1915,10 @@ pub const UnwrappedSwitch = struct {
1903	1915
1904	1916	pub fn unwrapSwitch(air: *const Air, switch_inst: Inst.Index) UnwrappedSwitch {
1905	1917	const inst = air.instructions.get(@intFromEnum(switch_inst));
1906		assert(inst.tag == .switch_br);
	1918	switch (inst.tag) {
	1919	.switch_br, .loop_switch_br => {},
	1920	else => unreachable, // assertion failure
	1921	}
1907	1922	const pl_op = inst.data.pl_op;
1908	1923	const extra = air.extraData(SwitchBr, pl_op.payload);
1909	1924	const hint_bag_count = std.math.divCeil(usize, extra.data.cases_len + 1, 10) catch unreachable;

src/Air/types_resolved.zig+2-2

...	...	@@ -222,7 +222,7 @@ fn checkBody(air: Air, body: []const Air.Inst.Index, zcu: *Zcu) bool {
222	222	if (!checkRef(data.un_op, zcu)) return false;
223	223	},
224	224
225		.br => {
	225	.br, .switch_dispatch => {
226	226	if (!checkRef(data.br.operand, zcu)) return false;
227	227	},
228	228
...	...	@@ -380,7 +380,7 @@ fn checkBody(air: Air, body: []const Air.Inst.Index, zcu: *Zcu) bool {
380	380	)) return false;
381	381	},
382	382
383		.switch_br => {
	383	.switch_br, .loop_switch_br => {
384	384	const switch_br = air.unwrapSwitch(inst);
385	385	if (!checkRef(switch_br.operand, zcu)) return false;
386	386	var it = switch_br.iterateCases();

src/Liveness.zig+174-93

...	...	@@ -31,6 +31,7 @@ tomb_bits: []usize,
31	31	/// * `try`, `try_ptr` - points to a `CondBr` in `extra` at this index. The error path (the block
32	32	/// in the instruction) is considered the "else" path, and the rest of the block the "then".
33	33	/// * `switch_br` - points to a `SwitchBr` in `extra` at this index.
	34	/// * `loop_switch_br` - points to a `SwitchBr` in `extra` at this index.
34	35	/// * `block` - points to a `Block` in `extra` at this index.
35	36	/// * `asm`, `call`, `aggregate_init` - the value is a set of bits which are the extra tomb
36	37	/// bits of operands.
...	...	@@ -68,8 +69,8 @@ pub const Block = struct {
68	69	/// Liveness analysis runs in several passes. Each pass iterates backwards over instructions in
69	70	/// bodies, and recurses into bodies.
70	71	const LivenessPass = enum {
71		/// In this pass, we perform some basic analysis of loops to gain information the main pass
72		/// needs. In particular, for every `loop`, we track the following information:
	72	/// In this pass, we perform some basic analysis of loops to gain information the main pass needs.
	73	/// In particular, for every `loop` and `loop_switch_br`, we track the following information:
73	74	/// * Every outer block which the loop body contains a `br` to.
74	75	/// * Every outer loop which the loop body contains a `repeat` to.
75	76	/// * Every operand referenced within the loop body but created outside the loop.
...	...	@@ -91,7 +92,8 @@ fn LivenessPassData(comptime pass: LivenessPass) type {
91	92	.loop_analysis => struct {
92	93	/// The set of blocks which are exited with a `br` instruction at some point within this
93	94	/// body and which we are currently within. Also includes `loop`s which are the target
94		/// of a `repeat` instruction.
	95	/// of a `repeat` instruction, and `loop_switch_br`s which are the target of a
	96	/// `switch_dispatch` instruction.
95	97	breaks: std.AutoHashMapUnmanaged(Air.Inst.Index, void) = .{},
96	98
97	99	/// The set of operands for which we have seen at least one usage but not their birth.
...	...	@@ -330,6 +332,7 @@ pub fn categorizeOperand(
330	332	.trap,
331	333	.breakpoint,
332	334	.repeat,
	335	.switch_dispatch,
333	336	.dbg_stmt,
334	337	.unreach,
335	338	.ret_addr,
...	...	@@ -662,21 +665,17 @@ pub fn categorizeOperand(
662	665
663	666	return .complex;
664	667	},
665		.@"try", .try_cold => {
666		return .complex;
667		},
668		.try_ptr, .try_ptr_cold => {
669		return .complex;
670		},
671		.loop => {
672		return .complex;
673		},
674		.cond_br => {
675		return .complex;
676		},
677		.switch_br => {
678		return .complex;
679		},
	668
	669	.@"try",
	670	.try_cold,
	671	.try_ptr,
	672	.try_ptr_cold,
	673	.loop,
	674	.cond_br,
	675	.switch_br,
	676	.loop_switch_br,
	677	=> return .complex,
	678
680	679	.wasm_memory_grow => {
681	680	const pl_op = air_datas[@intFromEnum(inst)].pl_op;
682	681	if (pl_op.operand == operand_ref) return matchOperandSmallIndex(l, inst, 0, .none);
...	...	@@ -1206,6 +1205,7 @@ fn analyzeInst(
1206	1205
1207	1206	.br => return analyzeInstBr(a, pass, data, inst),
1208	1207	.repeat => return analyzeInstRepeat(a, pass, data, inst),
	1208	.switch_dispatch => return analyzeInstSwitchDispatch(a, pass, data, inst),
1209	1209
1210	1210	.assembly => {
1211	1211	const extra = a.air.extraData(Air.Asm, inst_datas[@intFromEnum(inst)].ty_pl.payload);
...	...	@@ -1262,7 +1262,8 @@ fn analyzeInst(
1262	1262	.@"try", .try_cold => return analyzeInstCondBr(a, pass, data, inst, .@"try"),
1263	1263	.try_ptr, .try_ptr_cold => return analyzeInstCondBr(a, pass, data, inst, .try_ptr),
1264	1264	.cond_br => return analyzeInstCondBr(a, pass, data, inst, .cond_br),
1265		.switch_br => return analyzeInstSwitchBr(a, pass, data, inst),
	1265	.switch_br => return analyzeInstSwitchBr(a, pass, data, inst, false),
	1266	.loop_switch_br => return analyzeInstSwitchBr(a, pass, data, inst, true),
1266	1267
1267	1268	.wasm_memory_grow => {
1268	1269	const pl_op = inst_datas[@intFromEnum(inst)].pl_op;
...	...	@@ -1412,6 +1413,35 @@ fn analyzeInstRepeat(
1412	1413	return analyzeOperands(a, pass, data, inst, .{ .none, .none, .none });
1413	1414	}
1414	1415
	1416	fn analyzeInstSwitchDispatch(
	1417	a: *Analysis,
	1418	comptime pass: LivenessPass,
	1419	data: *LivenessPassData(pass),
	1420	inst: Air.Inst.Index,
	1421	) !void {
	1422	// This happens to be identical to `analyzeInstBr`, but is separated anyway for clarity.
	1423
	1424	const inst_datas = a.air.instructions.items(.data);
	1425	const br = inst_datas[@intFromEnum(inst)].br;
	1426	const gpa = a.gpa;
	1427
	1428	switch (pass) {
	1429	.loop_analysis => {
	1430	try data.breaks.put(gpa, br.block_inst, {});
	1431	},
	1432
	1433	.main_analysis => {
	1434	const block_scope = data.block_scopes.get(br.block_inst).?; // we should always be repeating an enclosing loop
	1435
	1436	const new_live_set = try block_scope.live_set.clone(gpa);
	1437	data.live_set.deinit(gpa);
	1438	data.live_set = new_live_set;
	1439	},
	1440	}
	1441
	1442	return analyzeOperands(a, pass, data, inst, .{ br.operand, .none, .none });
	1443	}
	1444
1415	1445	fn analyzeInstBlock(
1416	1446	a: *Analysis,
1417	1447	comptime pass: LivenessPass,
...	...	@@ -1482,109 +1512,133 @@ fn analyzeInstBlock(
1482	1512	}
1483	1513	}
1484	1514
1485		fn analyzeInstLoop(
	1515	fn writeLoopInfo(
1486	1516	a: *Analysis,
1487		comptime pass: LivenessPass,
1488		data: *LivenessPassData(pass),
	1517	data: *LivenessPassData(.loop_analysis),
1489	1518	inst: Air.Inst.Index,
	1519	old_breaks: std.AutoHashMapUnmanaged(Air.Inst.Index, void),
	1520	old_live: std.AutoHashMapUnmanaged(Air.Inst.Index, void),
1490	1521	) !void {
1491		const inst_datas = a.air.instructions.items(.data);
1492		const extra = a.air.extraData(Air.Block, inst_datas[@intFromEnum(inst)].ty_pl.payload);
1493		const body: []const Air.Inst.Index = @ptrCast(a.air.extra[extra.end..][0..extra.data.body_len]);
1494	1522	const gpa = a.gpa;
1495	1523
1496		try analyzeOperands(a, pass, data, inst, .{ .none, .none, .none });
	1524	// `loop`s are guaranteed to have at least one matching `repeat`.
	1525	// Similarly, `loop_switch_br`s have a matching `switch_dispatch`.
	1526	// However, we no longer care about repeats of this loop for resolving
	1527	// which operands must live within it.
	1528	assert(data.breaks.remove(inst));
1497	1529
1498		switch (pass) {
1499		.loop_analysis => {
1500		var old_breaks = data.breaks.move();
1501		defer old_breaks.deinit(gpa);
	1530	const extra_index: u32 = @intCast(a.extra.items.len);
1502	1531
1503		var old_live = data.live_set.move();
1504		defer old_live.deinit(gpa);
	1532	const num_breaks = data.breaks.count();
	1533	try a.extra.ensureUnusedCapacity(gpa, 1 + num_breaks);
1505	1534
1506		try analyzeBody(a, pass, data, body);
	1535	a.extra.appendAssumeCapacity(num_breaks);
1507	1536
1508		// `loop`s are guaranteed to have at least one matching `repeat`.
1509		// However, we no longer care about repeats of this loop itself.
1510		assert(data.breaks.remove(inst));
	1537	var it = data.breaks.keyIterator();
	1538	while (it.next()) \|key\| {
	1539	const block_inst = key.*;
	1540	a.extra.appendAssumeCapacity(@intFromEnum(block_inst));
	1541	}
	1542	log.debug("[{}] %{}: includes breaks to {}", .{ LivenessPass.loop_analysis, inst, fmtInstSet(&data.breaks) });
1511	1543
1512		const extra_index: u32 = @intCast(a.extra.items.len);
	1544	// Now we put the live operands from the loop body in too
	1545	const num_live = data.live_set.count();
	1546	try a.extra.ensureUnusedCapacity(gpa, 1 + num_live);
1513	1547
1514		const num_breaks = data.breaks.count();
1515		try a.extra.ensureUnusedCapacity(gpa, 1 + num_breaks);
	1548	a.extra.appendAssumeCapacity(num_live);
	1549	it = data.live_set.keyIterator();
	1550	while (it.next()) \|key\| {
	1551	const alive = key.*;
	1552	a.extra.appendAssumeCapacity(@intFromEnum(alive));
	1553	}
	1554	log.debug("[{}] %{}: maintain liveness of {}", .{ LivenessPass.loop_analysis, inst, fmtInstSet(&data.live_set) });
1516	1555
1517		a.extra.appendAssumeCapacity(num_breaks);
	1556	try a.special.put(gpa, inst, extra_index);
1518	1557
1519		var it = data.breaks.keyIterator();
1520		while (it.next()) \|key\| {
1521		const block_inst = key.*;
1522		a.extra.appendAssumeCapacity(@intFromEnum(block_inst));
1523		}
1524		log.debug("[{}] %{}: includes breaks to {}", .{ pass, inst, fmtInstSet(&data.breaks) });
	1558	// Add back operands which were previously alive
	1559	it = old_live.keyIterator();
	1560	while (it.next()) \|key\| {
	1561	const alive = key.*;
	1562	try data.live_set.put(gpa, alive, {});
	1563	}
1525	1564
1526		// Now we put the live operands from the loop body in too
1527		const num_live = data.live_set.count();
1528		try a.extra.ensureUnusedCapacity(gpa, 1 + num_live);
	1565	// And the same for breaks
	1566	it = old_breaks.keyIterator();
	1567	while (it.next()) \|key\| {
	1568	const block_inst = key.*;
	1569	try data.breaks.put(gpa, block_inst, {});
	1570	}
	1571	}
1529	1572
1530		a.extra.appendAssumeCapacity(num_live);
1531		it = data.live_set.keyIterator();
1532		while (it.next()) \|key\| {
1533		const alive = key.*;
1534		a.extra.appendAssumeCapacity(@intFromEnum(alive));
1535		}
1536		log.debug("[{}] %{}: maintain liveness of {}", .{ pass, inst, fmtInstSet(&data.live_set) });
	1573	/// When analyzing a loop in the main pass, sets up `data.live_set` to be the set
	1574	/// of operands known to be alive when the loop repeats.
	1575	fn resolveLoopLiveSet(
	1576	a: *Analysis,
	1577	data: *LivenessPassData(.main_analysis),
	1578	inst: Air.Inst.Index,
	1579	) !void {
	1580	const gpa = a.gpa;
1537	1581
1538		try a.special.put(gpa, inst, extra_index);
	1582	const extra_idx = a.special.fetchRemove(inst).?.value;
	1583	const num_breaks = data.old_extra.items[extra_idx];
	1584	const breaks: []const Air.Inst.Index = @ptrCast(data.old_extra.items[extra_idx + 1 ..][0..num_breaks]);
1539	1585
1540		// Add back operands which were previously alive
1541		it = old_live.keyIterator();
1542		while (it.next()) \|key\| {
1543		const alive = key.*;
1544		try data.live_set.put(gpa, alive, {});
1545		}
	1586	const num_loop_live = data.old_extra.items[extra_idx + num_breaks + 1];
	1587	const loop_live: []const Air.Inst.Index = @ptrCast(data.old_extra.items[extra_idx + num_breaks + 2 ..][0..num_loop_live]);
1546	1588
1547		// And the same for breaks
1548		it = old_breaks.keyIterator();
1549		while (it.next()) \|key\| {
1550		const block_inst = key.*;
1551		try data.breaks.put(gpa, block_inst, {});
1552		}
1553		},
	1589	// This is necessarily not in the same control flow branch, because loops are noreturn
	1590	data.live_set.clearRetainingCapacity();
1554	1591
1555		.main_analysis => {
1556		const extra_idx = a.special.fetchRemove(inst).?.value; // remove because this data does not exist after analysis
	1592	try data.live_set.ensureUnusedCapacity(gpa, @intCast(loop_live.len));
	1593	for (loop_live) \|alive\| data.live_set.putAssumeCapacity(alive, {});
1557	1594
1558		const num_breaks = data.old_extra.items[extra_idx];
1559		const breaks: []const Air.Inst.Index = @ptrCast(data.old_extra.items[extra_idx + 1 ..][0..num_breaks]);
	1595	log.debug("[{}] %{}: block live set is {}", .{ LivenessPass.main_analysis, inst, fmtInstSet(&data.live_set) });
1560	1596
1561		const num_loop_live = data.old_extra.items[extra_idx + num_breaks + 1];
1562		const loop_live: []const Air.Inst.Index = @ptrCast(data.old_extra.items[extra_idx + num_breaks + 2 ..][0..num_loop_live]);
	1597	for (breaks) \|block_inst\| {
	1598	// We might break to this block, so include every operand that the block needs alive
	1599	const block_scope = data.block_scopes.get(block_inst).?;
1563	1600
1564		// This is necessarily not in the same control flow branch, because loops are noreturn
1565		data.live_set.clearRetainingCapacity();
	1601	var it = block_scope.live_set.keyIterator();
	1602	while (it.next()) \|key\| {
	1603	const alive = key.*;
	1604	try data.live_set.put(gpa, alive, {});
	1605	}
	1606	}
1566	1607
1567		try data.live_set.ensureUnusedCapacity(gpa, @intCast(loop_live.len));
1568		for (loop_live) \|alive\| {
1569		data.live_set.putAssumeCapacity(alive, {});
1570		}
	1608	log.debug("[{}] %{}: loop live set is {}", .{ LivenessPass.main_analysis, inst, fmtInstSet(&data.live_set) });
	1609	}
1571	1610
1572		log.debug("[{}] %{}: block live set is {}", .{ pass, inst, fmtInstSet(&data.live_set) });
	1611	fn analyzeInstLoop(
	1612	a: *Analysis,
	1613	comptime pass: LivenessPass,
	1614	data: *LivenessPassData(pass),
	1615	inst: Air.Inst.Index,
	1616	) !void {
	1617	const inst_datas = a.air.instructions.items(.data);
	1618	const extra = a.air.extraData(Air.Block, inst_datas[@intFromEnum(inst)].ty_pl.payload);
	1619	const body: []const Air.Inst.Index = @ptrCast(a.air.extra[extra.end..][0..extra.data.body_len]);
	1620	const gpa = a.gpa;
1573	1621
1574		for (breaks) \|block_inst\| {
1575		// We might break to this block, so include every operand that the block needs alive
1576		const block_scope = data.block_scopes.get(block_inst).?;
	1622	try analyzeOperands(a, pass, data, inst, .{ .none, .none, .none });
1577	1623
1578		var it = block_scope.live_set.keyIterator();
1579		while (it.next()) \|key\| {
1580		const alive = key.*;
1581		try data.live_set.put(gpa, alive, {});
1582		}
1583		}
	1624	switch (pass) {
	1625	.loop_analysis => {
	1626	var old_breaks = data.breaks.move();
	1627	defer old_breaks.deinit(gpa);
	1628
	1629	var old_live = data.live_set.move();
	1630	defer old_live.deinit(gpa);
	1631
	1632	try analyzeBody(a, pass, data, body);
	1633
	1634	try writeLoopInfo(a, data, inst, old_breaks, old_live);
	1635	},
	1636
	1637	.main_analysis => {
	1638	try resolveLoopLiveSet(a, data, inst);
1584	1639
1585	1640	// Now, `data.live_set` is the operands which must be alive when the loop repeats.
1586	1641	// Move them into a block scope for corresponding `repeat` instructions to notice.
1587		log.debug("[{}] %{}: loop live set is {}", .{ pass, inst, fmtInstSet(&data.live_set) });
1588	1642	try data.block_scopes.putNoClobber(gpa, inst, .{
1589	1643	.live_set = data.live_set.move(),
1590	1644	});
...	...	@@ -1720,6 +1774,7 @@ fn analyzeInstSwitchBr(
1720	1774	comptime pass: LivenessPass,
1721	1775	data: *LivenessPassData(pass),
1722	1776	inst: Air.Inst.Index,
	1777	is_dispatch_loop: bool,
1723	1778	) !void {
1724	1779	const inst_datas = a.air.instructions.items(.data);
1725	1780	const pl_op = inst_datas[@intFromEnum(inst)].pl_op;
...	...	@@ -1730,6 +1785,17 @@ fn analyzeInstSwitchBr(
1730	1785
1731	1786	switch (pass) {
1732	1787	.loop_analysis => {
	1788	var old_breaks: std.AutoHashMapUnmanaged(Air.Inst.Index, void) = .{};
	1789	defer old_breaks.deinit(gpa);
	1790
	1791	var old_live: std.AutoHashMapUnmanaged(Air.Inst.Index, void) = .{};
	1792	defer old_live.deinit(gpa);
	1793
	1794	if (is_dispatch_loop) {
	1795	old_breaks = data.breaks.move();
	1796	old_live = data.live_set.move();
	1797	}
	1798
1733	1799	var it = switch_br.iterateCases();
1734	1800	while (it.next()) \|case\| {
1735	1801	try analyzeBody(a, pass, data, case.body);
...	...	@@ -1738,9 +1804,24 @@ fn analyzeInstSwitchBr(
1738	1804	const else_body = it.elseBody();
1739	1805	try analyzeBody(a, pass, data, else_body);
1740	1806	}
	1807
	1808	if (is_dispatch_loop) {
	1809	try writeLoopInfo(a, data, inst, old_breaks, old_live);
	1810	}
1741	1811	},
1742	1812
1743	1813	.main_analysis => {
	1814	if (is_dispatch_loop) {
	1815	try resolveLoopLiveSet(a, data, inst);
	1816	try data.block_scopes.putNoClobber(gpa, inst, .{
	1817	.live_set = data.live_set.move(),
	1818	});
	1819	}
	1820	defer if (is_dispatch_loop) {
	1821	log.debug("[{}] %{}: popped loop block scop", .{ pass, inst });
	1822	var scope = data.block_scopes.fetchRemove(inst).?.value;
	1823	scope.live_set.deinit(gpa);
	1824	};
1744	1825	// This is, all in all, just a messier version of the `cond_br` logic. If you're trying
1745	1826	// to understand it, I encourage looking at `analyzeInstCondBr` first.
1746	1827

src/Liveness/Verify.zig+25-6

...	...	@@ -447,6 +447,16 @@ fn verifyBody(self: *Verify, body: []const Air.Inst.Index) Error!void {
447	447
448	448	try self.verifyMatchingLiveness(repeat.loop_inst, expected_live);
449	449	},
	450	.switch_dispatch => {
	451	const br = data[@intFromEnum(inst)].br;
	452
	453	try self.verifyOperand(inst, br.operand, self.liveness.operandDies(inst, 0));
	454
	455	const expected_live = self.loops.get(br.block_inst) orelse
	456	return invalid("%{}: loop %{} not in scope", .{ @intFromEnum(inst), @intFromEnum(br.block_inst) });
	457
	458	try self.verifyMatchingLiveness(br.block_inst, expected_live);
	459	},
450	460	.block, .dbg_inline_block => \|tag\| {
451	461	const ty_pl = data[@intFromEnum(inst)].ty_pl;
452	462	const block_ty = ty_pl.ty.toType();
...	...	@@ -494,11 +504,11 @@ fn verifyBody(self: *Verify, body: []const Air.Inst.Index) Error!void {
494	504
495	505	// The same stuff should be alive after the loop as before it.
496	506	const gop = try self.loops.getOrPut(self.gpa, inst);
	507	if (gop.found_existing) return invalid("%{}: loop already exists", .{@intFromEnum(inst)});
497	508	defer {
498	509	var live = self.loops.fetchRemove(inst).?;
499	510	live.value.deinit(self.gpa);
500	511	}
501		if (gop.found_existing) return invalid("%{}: loop already exists", .{@intFromEnum(inst)});
502	512	gop.value_ptr.* = try self.live.clone(self.gpa);
503	513
504	514	try self.verifyBody(loop_body);
...	...	@@ -528,7 +538,7 @@ fn verifyBody(self: *Verify, body: []const Air.Inst.Index) Error!void {
528	538
529	539	try self.verifyInst(inst);
530	540	},
531		.switch_br => {
	541	.switch_br, .loop_switch_br => {
532	542	const switch_br = self.air.unwrapSwitch(inst);
533	543	const switch_br_liveness = try self.liveness.getSwitchBr(
534	544	self.gpa,
...	...	@@ -539,13 +549,22 @@ fn verifyBody(self: *Verify, body: []const Air.Inst.Index) Error!void {
539	549
540	550	try self.verifyOperand(inst, switch_br.operand, self.liveness.operandDies(inst, 0));
541	551
542		var live = self.live.move();
543		defer live.deinit(self.gpa);
	552	// Excluding the operand (which we just handled), the same stuff should be alive
	553	// after the loop as before it.
	554	{
	555	const gop = try self.loops.getOrPut(self.gpa, inst);
	556	if (gop.found_existing) return invalid("%{}: loop already exists", .{@intFromEnum(inst)});
	557	gop.value_ptr.* = self.live.move();
	558	}
	559	defer {
	560	var live = self.loops.fetchRemove(inst).?;
	561	live.value.deinit(self.gpa);
	562	}
544	563
545	564	var it = switch_br.iterateCases();
546	565	while (it.next()) \|case\| {
547	566	self.live.deinit(self.gpa);
548		self.live = try live.clone(self.gpa);
	567	self.live = try self.loops.get(inst).?.clone(self.gpa);
549	568
550	569	for (switch_br_liveness.deaths[case.idx]) \|death\| try self.verifyDeath(inst, death);
551	570	try self.verifyBody(case.body);
...	...	@@ -554,7 +573,7 @@ fn verifyBody(self: *Verify, body: []const Air.Inst.Index) Error!void {
554	573	const else_body = it.elseBody();
555	574	if (else_body.len > 0) {
556	575	self.live.deinit(self.gpa);
557		self.live = try live.clone(self.gpa);
	576	self.live = try self.loops.get(inst).?.clone(self.gpa);
558	577	for (switch_br_liveness.deaths[switch_br.cases_len]) \|death\| try self.verifyDeath(inst, death);
559	578	try self.verifyBody(else_body);
560	579	}

src/Sema.zig+479-141

...	...	@@ -503,11 +503,21 @@ pub const Block = struct {
503	503	/// to enable more precise compile errors.
504	504	/// Same indexes, capacity, length as `results`.
505	505	src_locs: std.ArrayListUnmanaged(?LazySrcLoc),
506
507		pub fn deinit(merges: *@This(), allocator: mem.Allocator) void {
	506	/// Most blocks do not utilize this field. When it is used, its use is
	507	/// contextual. The possible uses are as follows:
	508	/// * for a `switch_block[_ref]`, this refers to dummy `br` instructions
	509	/// which correspond to `switch_continue` ZIR. The switch logic will
	510	/// rewrite these to appropriate AIR switch dispatches.
	511	extra_insts: std.ArrayListUnmanaged(Air.Inst.Index) = .{},
	512	/// Same indexes, capacity, length as `extra_insts`.
	513	extra_src_locs: std.ArrayListUnmanaged(LazySrcLoc) = .{},
	514
	515	pub fn deinit(merges: *@This(), allocator: Allocator) void {
508	516	merges.results.deinit(allocator);
509	517	merges.br_list.deinit(allocator);
510	518	merges.src_locs.deinit(allocator);
	519	merges.extra_insts.deinit(allocator);
	520	merges.extra_src_locs.deinit(allocator);
511	521	}
512	522	};
513	523
...	...	@@ -946,14 +956,21 @@ fn analyzeInlineBody(
946	956	error.ComptimeBreak => {},
947	957	else => \|e\| return e,
948	958	}
949		const break_inst = sema.comptime_break_inst;
950		const break_data = sema.code.instructions.items(.data)[@intFromEnum(break_inst)].@"break";
951		const extra = sema.code.extraData(Zir.Inst.Break, break_data.payload_index).data;
	959	const break_inst = sema.code.instructions.get(@intFromEnum(sema.comptime_break_inst));
	960	switch (break_inst.tag) {
	961	.switch_continue => {
	962	// This is handled by separate logic.
	963	return error.ComptimeBreak;
	964	},
	965	.break_inline, .@"break" => {},
	966	else => unreachable,
	967	}
	968	const extra = sema.code.extraData(Zir.Inst.Break, break_inst.data.@"break".payload_index).data;
952	969	if (extra.block_inst != break_target) {
953	970	// This control flow goes further up the stack.
954	971	return error.ComptimeBreak;
955	972	}
956		return try sema.resolveInst(break_data.operand);
	973	return try sema.resolveInst(break_inst.data.@"break".operand);
957	974	}
958	975
959	976	/// Like `analyzeInlineBody`, but if the body does not break with a value, returns
...	...	@@ -1571,6 +1588,13 @@ fn analyzeBodyInner(
1571	1588	i = 0;
1572	1589	continue;
1573	1590	},
	1591	.switch_continue => if (block.is_comptime) {
	1592	sema.comptime_break_inst = inst;
	1593	return error.ComptimeBreak;
	1594	} else {
	1595	try sema.zirSwitchContinue(block, inst);
	1596	break;
	1597	},
1574	1598	.loop => blk: {
1575	1599	if (!block.is_comptime) break :blk try sema.zirLoop(block, inst);
1576	1600	// Same as `block_inline`. TODO https://github.com/ziglang/zig/issues/8220
...	...	@@ -6531,6 +6555,56 @@ fn zirBreak(sema: Sema, start_block: Block, inst: Zir.Inst.Index) CompileError
6531	6555	}
6532	6556	}
6533	6557
	6558	fn zirSwitchContinue(sema: Sema, start_block: Block, inst: Zir.Inst.Index) CompileError!void {
	6559	const tracy = trace(@src());
	6560	defer tracy.end();
	6561
	6562	const inst_data = sema.code.instructions.items(.data)[@intFromEnum(inst)].@"break";
	6563	const extra = sema.code.extraData(Zir.Inst.Break, inst_data.payload_index).data;
	6564	assert(extra.operand_src_node != Zir.Inst.Break.no_src_node);
	6565	const operand_src = start_block.nodeOffset(extra.operand_src_node);
	6566	const uncoerced_operand = try sema.resolveInst(inst_data.operand);
	6567	const switch_inst = extra.block_inst;
	6568
	6569	switch (sema.code.instructions.items(.tag)[@intFromEnum(switch_inst)]) {
	6570	.switch_block, .switch_block_ref => {},
	6571	else => unreachable, // assertion failure
	6572	}
	6573
	6574	const switch_payload_index = sema.code.instructions.items(.data)[@intFromEnum(switch_inst)].pl_node.payload_index;
	6575	const switch_operand_ref = sema.code.extraData(Zir.Inst.SwitchBlock, switch_payload_index).data.operand;
	6576	const switch_operand_ty = sema.typeOf(try sema.resolveInst(switch_operand_ref));
	6577
	6578	const operand = try sema.coerce(start_block, switch_operand_ty, uncoerced_operand, operand_src);
	6579
	6580	try sema.validateRuntimeValue(start_block, operand_src, operand);
	6581
	6582	// We want to generate a `switch_dispatch` instruction with the switch condition,
	6583	// possibly preceded by a store to the stack alloc containing the raw operand.
	6584	// However, to avoid too much special-case state in Sema, this is handled by the
	6585	// `switch` lowering logic. As such, we will find the `Block` corresponding to the
	6586	// parent `switch_block[_ref]` instruction, create a dummy `br`, and add a merge
	6587	// to signal to the switch logic to rewrite this into an appropriate dispatch.
	6588
	6589	var block = start_block;
	6590	while (true) {
	6591	if (block.label) \|label\| {
	6592	if (label.zir_block == switch_inst) {
	6593	const br_ref = try start_block.addBr(label.merges.block_inst, operand);
	6594	try label.merges.extra_insts.append(sema.gpa, br_ref.toIndex().?);
	6595	try label.merges.extra_src_locs.append(sema.gpa, operand_src);
	6596	block.runtime_index.increment();
	6597	if (block.runtime_cond == null and block.runtime_loop == null) {
	6598	block.runtime_cond = start_block.runtime_cond orelse start_block.runtime_loop;
	6599	block.runtime_loop = start_block.runtime_loop;
	6600	}
	6601	return;
	6602	}
	6603	}
	6604	block = block.parent.?;
	6605	}
	6606	}
	6607
6534	6608	fn zirDbgStmt(sema: Sema, block: Block, inst: Zir.Inst.Index) CompileError!void {
6535	6609	if (block.is_comptime or block.ownerModule().strip) return;
6536	6610
...	...	@@ -10940,12 +11014,7 @@ const SwitchProngAnalysis = struct {
10940	11014	sema: *Sema,
10941	11015	/// The block containing the `switch_block` itself.
10942	11016	parent_block: *Block,
10943		/// The raw switch operand value (not the condition). Always defined.
10944		operand: Air.Inst.Ref,
10945		/// May be `undefined` if no prong has a by-ref capture.
10946		operand_ptr: Air.Inst.Ref,
10947		/// The switch condition value. For unions, `operand` is the union and `cond` is its tag.
10948		cond: Air.Inst.Ref,
	11017	operand: Operand,
10949	11018	/// If this switch is on an error set, this is the type to assign to the
10950	11019	/// `else` prong. If `null`, the prong should be unreachable.
10951	11020	else_error_ty: ?Type,
...	...	@@ -10955,6 +11024,34 @@ const SwitchProngAnalysis = struct {
10955	11024	/// undefined if no prong has a tag capture.
10956	11025	tag_capture_inst: Zir.Inst.Index,
10957	11026
	11027	const Operand = union(enum) {
	11028	/// This switch will be dispatched only once, with the given operand.
	11029	simple: struct {
	11030	/// The raw switch operand value. Always defined.
	11031	by_val: Air.Inst.Ref,
	11032	/// The switch operand pointer. Defined only if there is a prong
	11033	/// with a by-ref capture.
	11034	by_ref: Air.Inst.Ref,
	11035	/// The switch condition value. For unions, `operand` is the union
	11036	/// and `cond` is its enum tag value.
	11037	cond: Air.Inst.Ref,
	11038	},
	11039	/// This switch may be dispatched multiple times with `continue` syntax.
	11040	/// As such, the operand is stored in an alloc if needed.
	11041	loop: struct {
	11042	/// The `alloc` containing the `switch` operand for the active dispatch.
	11043	/// Each prong must load from this `alloc` to get captures.
	11044	/// If there are no captures, this may be undefined.
	11045	operand_alloc: Air.Inst.Ref,
	11046	/// Whether `operand_alloc` contains a by-val operand or a by-ref
	11047	/// operand.
	11048	operand_is_ref: bool,
	11049	/// The switch condition value for the initial dispatch. For
	11050	/// unions, this is the enum tag value.
	11051	init_cond: Air.Inst.Ref,
	11052	},
	11053	};
	11054
10958	11055	/// Resolve a switch prong which is determined at comptime to have no peers.
10959	11056	/// Uses `resolveBlockBody`. Sets up captures as needed.
10960	11057	fn resolveProngComptime(
...	...	@@ -11086,7 +11183,15 @@ const SwitchProngAnalysis = struct {
11086	11183	const sema = spa.sema;
11087	11184	const pt = sema.pt;
11088	11185	const zcu = pt.zcu;
11089		const operand_ty = sema.typeOf(spa.operand);
	11186	const operand_ty = switch (spa.operand) {
	11187	.simple => \|s\| sema.typeOf(s.by_val),
	11188	.loop => \|l\| ty: {
	11189	const alloc_ty = sema.typeOf(l.operand_alloc);
	11190	const alloc_child = alloc_ty.childType(zcu);
	11191	if (l.operand_is_ref) break :ty alloc_child.childType(zcu);
	11192	break :ty alloc_child;
	11193	},
	11194	};
11090	11195	if (operand_ty.zigTypeTag(zcu) != .@"union") {
11091	11196	const tag_capture_src: LazySrcLoc = .{
11092	11197	.base_node_inst = capture_src.base_node_inst,
...	...	@@ -11117,10 +11222,24 @@ const SwitchProngAnalysis = struct {
11117	11222	const zir_datas = sema.code.instructions.items(.data);
11118	11223	const switch_node_offset = zir_datas[@intFromEnum(spa.switch_block_inst)].pl_node.src_node;
11119	11224
11120		const operand_ty = sema.typeOf(spa.operand);
11121		const operand_ptr_ty = if (capture_byref) sema.typeOf(spa.operand_ptr) else undefined;
11122	11225	const operand_src = block.src(.{ .node_offset_switch_operand = switch_node_offset });
11123	11226
	11227	const operand_val, const operand_ptr = switch (spa.operand) {
	11228	.simple => \|s\| .{ s.by_val, s.by_ref },
	11229	.loop => \|l\| op: {
	11230	const loaded = try sema.analyzeLoad(block, operand_src, l.operand_alloc, operand_src);
	11231	if (l.operand_is_ref) {
	11232	const by_val = try sema.analyzeLoad(block, operand_src, loaded, operand_src);
	11233	break :op .{ by_val, loaded };
	11234	} else {
	11235	break :op .{ loaded, undefined };
	11236	}
	11237	},
	11238	};
	11239
	11240	const operand_ty = sema.typeOf(operand_val);
	11241	const operand_ptr_ty = if (capture_byref) sema.typeOf(operand_ptr) else undefined;
	11242
11124	11243	if (inline_case_capture != .none) {
11125	11244	const item_val = sema.resolveConstDefinedValue(block, LazySrcLoc.unneeded, inline_case_capture, undefined) catch unreachable;
11126	11245	if (operand_ty.zigTypeTag(zcu) == .@"union") {
...	...	@@ -11136,16 +11255,16 @@ const SwitchProngAnalysis = struct {
11136	11255	.address_space = operand_ptr_ty.ptrAddressSpace(zcu),
11137	11256	},
11138	11257	});
11139		if (try sema.resolveDefinedValue(block, operand_src, spa.operand_ptr)) \|union_ptr\| {
	11258	if (try sema.resolveDefinedValue(block, operand_src, operand_ptr)) \|union_ptr\| {
11140	11259	return Air.internedToRef((try union_ptr.ptrField(field_index, pt)).toIntern());
11141	11260	}
11142		return block.addStructFieldPtr(spa.operand_ptr, field_index, ptr_field_ty);
	11261	return block.addStructFieldPtr(operand_ptr, field_index, ptr_field_ty);
11143	11262	} else {
11144		if (try sema.resolveDefinedValue(block, operand_src, spa.operand)) \|union_val\| {
	11263	if (try sema.resolveDefinedValue(block, operand_src, operand_val)) \|union_val\| {
11145	11264	const tag_and_val = ip.indexToKey(union_val.toIntern()).un;
11146	11265	return Air.internedToRef(tag_and_val.val);
11147	11266	}
11148		return block.addStructFieldVal(spa.operand, field_index, field_ty);
	11267	return block.addStructFieldVal(operand_val, field_index, field_ty);
11149	11268	}
11150	11269	} else if (capture_byref) {
11151	11270	return sema.uavRef(item_val.toIntern());
...	...	@@ -11156,17 +11275,17 @@ const SwitchProngAnalysis = struct {
11156	11275
11157	11276	if (is_special_prong) {
11158	11277	if (capture_byref) {
11159		return spa.operand_ptr;
	11278	return operand_ptr;
11160	11279	}
11161	11280
11162	11281	switch (operand_ty.zigTypeTag(zcu)) {
11163	11282	.error_set => if (spa.else_error_ty) \|ty\| {
11164		return sema.bitCast(block, ty, spa.operand, operand_src, null);
	11283	return sema.bitCast(block, ty, operand_val, operand_src, null);
11165	11284	} else {
11166	11285	try sema.analyzeUnreachable(block, operand_src, false);
11167	11286	return .unreachable_value;
11168	11287	},
11169		else => return spa.operand,
	11288	else => return operand_val,
11170	11289	}
11171	11290	}
11172	11291
...	...	@@ -11265,19 +11384,19 @@ const SwitchProngAnalysis = struct {
11265	11384	};
11266	11385	};
11267	11386
11268		if (try sema.resolveDefinedValue(block, operand_src, spa.operand_ptr)) \|op_ptr_val\| {
	11387	if (try sema.resolveDefinedValue(block, operand_src, operand_ptr)) \|op_ptr_val\| {
11269	11388	if (op_ptr_val.isUndef(zcu)) return pt.undefRef(capture_ptr_ty);
11270	11389	const field_ptr_val = try op_ptr_val.ptrField(first_field_index, pt);
11271	11390	return Air.internedToRef((try pt.getCoerced(field_ptr_val, capture_ptr_ty)).toIntern());
11272	11391	}
11273	11392
11274	11393	try sema.requireRuntimeBlock(block, operand_src, null);
11275		return block.addStructFieldPtr(spa.operand_ptr, first_field_index, capture_ptr_ty);
	11394	return block.addStructFieldPtr(operand_ptr, first_field_index, capture_ptr_ty);
11276	11395	}
11277	11396
11278		if (try sema.resolveDefinedValue(block, operand_src, spa.operand)) \|operand_val\| {
11279		if (operand_val.isUndef(zcu)) return pt.undefRef(capture_ty);
11280		const union_val = ip.indexToKey(operand_val.toIntern()).un;
	11397	if (try sema.resolveDefinedValue(block, operand_src, operand_val)) \|operand_val_val\| {
	11398	if (operand_val_val.isUndef(zcu)) return pt.undefRef(capture_ty);
	11399	const union_val = ip.indexToKey(operand_val_val.toIntern()).un;
11281	11400	if (Value.fromInterned(union_val.tag).isUndef(zcu)) return pt.undefRef(capture_ty);
11282	11401	const uncoerced = Air.internedToRef(union_val.val);
11283	11402	return sema.coerce(block, capture_ty, uncoerced, operand_src);
...	...	@@ -11286,7 +11405,7 @@ const SwitchProngAnalysis = struct {
11286	11405	try sema.requireRuntimeBlock(block, operand_src, null);
11287	11406
11288	11407	if (same_types) {
11289		return block.addStructFieldVal(spa.operand, first_field_index, capture_ty);
	11408	return block.addStructFieldVal(operand_val, first_field_index, capture_ty);
11290	11409	}
11291	11410
11292	11411	// We may have to emit a switch block which coerces the operand to the capture type.
...	...	@@ -11300,7 +11419,7 @@ const SwitchProngAnalysis = struct {
11300	11419	}
11301	11420	// All fields are in-memory coercible to the resolved type!
11302	11421	// Just take the first field and bitcast the result.
11303		const uncoerced = try block.addStructFieldVal(spa.operand, first_field_index, first_field_ty);
	11422	const uncoerced = try block.addStructFieldVal(operand_val, first_field_index, first_field_ty);
11304	11423	return block.addBitCast(capture_ty, uncoerced);
11305	11424	};
11306	11425
...	...	@@ -11364,7 +11483,7 @@ const SwitchProngAnalysis = struct {
11364	11483
11365	11484	const field_idx = field_indices[idx];
11366	11485	const field_ty = Type.fromInterned(union_obj.field_types.get(ip)[field_idx]);
11367		const uncoerced = try coerce_block.addStructFieldVal(spa.operand, field_idx, field_ty);
	11486	const uncoerced = try coerce_block.addStructFieldVal(operand_val, field_idx, field_ty);
11368	11487	const coerced = try sema.coerce(&coerce_block, capture_ty, uncoerced, case_src);
11369	11488	_ = try coerce_block.addBr(capture_block_inst, coerced);
11370	11489
...	...	@@ -11388,7 +11507,7 @@ const SwitchProngAnalysis = struct {
11388	11507	const first_imc_item_idx = in_mem_coercible.findFirstSet().?;
11389	11508	const first_imc_field_idx = field_indices[first_imc_item_idx];
11390	11509	const first_imc_field_ty = Type.fromInterned(union_obj.field_types.get(ip)[first_imc_field_idx]);
11391		const uncoerced = try coerce_block.addStructFieldVal(spa.operand, first_imc_field_idx, first_imc_field_ty);
	11510	const uncoerced = try coerce_block.addStructFieldVal(operand_val, first_imc_field_idx, first_imc_field_ty);
11392	11511	const coerced = try coerce_block.addBitCast(capture_ty, uncoerced);
11393	11512	_ = try coerce_block.addBr(capture_block_inst, coerced);
11394	11513
...	...	@@ -11404,21 +11523,47 @@ const SwitchProngAnalysis = struct {
11404	11523	const switch_br_inst: u32 = @intCast(sema.air_instructions.len);
11405	11524	try sema.air_instructions.append(sema.gpa, .{
11406	11525	.tag = .switch_br,
11407		.data = .{ .pl_op = .{
11408		.operand = spa.cond,
11409		.payload = sema.addExtraAssumeCapacity(Air.SwitchBr{
11410		.cases_len = @intCast(prong_count),
11411		.else_body_len = @intCast(else_body_len),
11412		}),
11413		} },
	11526	.data = .{
	11527	.pl_op = .{
	11528	.operand = undefined, // set by switch below
	11529	.payload = sema.addExtraAssumeCapacity(Air.SwitchBr{
	11530	.cases_len = @intCast(prong_count),
	11531	.else_body_len = @intCast(else_body_len),
	11532	}),
	11533	},
	11534	},
11414	11535	});
11415	11536	sema.air_extra.appendSliceAssumeCapacity(cases_extra.items);
11416	11537
11417	11538	// Set up block body
11418		sema.air_instructions.items(.data)[@intFromEnum(capture_block_inst)].ty_pl.payload = sema.addExtraAssumeCapacity(Air.Block{
11419		.body_len = 1,
11420		});
11421		sema.air_extra.appendAssumeCapacity(switch_br_inst);
	11539	switch (spa.operand) {
	11540	.simple => \|s\| {
	11541	const air_datas = sema.air_instructions.items(.data);
	11542	air_datas[switch_br_inst].pl_op.operand = s.cond;
	11543	air_datas[@intFromEnum(capture_block_inst)].ty_pl.payload = sema.addExtraAssumeCapacity(Air.Block{
	11544	.body_len = 1,
	11545	});
	11546	sema.air_extra.appendAssumeCapacity(switch_br_inst);
	11547	},
	11548	.loop => {
	11549	// The block must first extract the tag from the loaded union.
	11550	const tag_inst: Air.Inst.Index = @enumFromInt(sema.air_instructions.len);
	11551	try sema.air_instructions.append(sema.gpa, .{
	11552	.tag = .get_union_tag,
	11553	.data = .{ .ty_op = .{
	11554	.ty = Air.internedToRef(union_obj.enum_tag_ty),
	11555	.operand = operand_val,
	11556	} },
	11557	});
	11558	const air_datas = sema.air_instructions.items(.data);
	11559	air_datas[switch_br_inst].pl_op.operand = tag_inst.toRef();
	11560	air_datas[@intFromEnum(capture_block_inst)].ty_pl.payload = sema.addExtraAssumeCapacity(Air.Block{
	11561	.body_len = 2,
	11562	});
	11563	sema.air_extra.appendAssumeCapacity(@intFromEnum(tag_inst));
	11564	sema.air_extra.appendAssumeCapacity(switch_br_inst);
	11565	},
	11566	}
11422	11567
11423	11568	return capture_block_inst.toRef();
11424	11569	},
...	...	@@ -11435,7 +11580,7 @@ const SwitchProngAnalysis = struct {
11435	11580	if (case_vals.len == 1) {
11436	11581	const item_val = sema.resolveConstDefinedValue(block, LazySrcLoc.unneeded, case_vals[0], undefined) catch unreachable;
11437	11582	const item_ty = try pt.singleErrorSetType(item_val.getErrorName(zcu).unwrap().?);
11438		return sema.bitCast(block, item_ty, spa.operand, operand_src, null);
	11583	return sema.bitCast(block, item_ty, operand_val, operand_src, null);
11439	11584	}
11440	11585
11441	11586	var names: InferredErrorSet.NameMap = .{};
...	...	@@ -11445,15 +11590,15 @@ const SwitchProngAnalysis = struct {
11445	11590	names.putAssumeCapacityNoClobber(err_val.getErrorName(zcu).unwrap().?, {});
11446	11591	}
11447	11592	const error_ty = try pt.errorSetFromUnsortedNames(names.keys());
11448		return sema.bitCast(block, error_ty, spa.operand, operand_src, null);
	11593	return sema.bitCast(block, error_ty, operand_val, operand_src, null);
11449	11594	},
11450	11595	else => {
11451	11596	// In this case the capture value is just the passed-through value
11452	11597	// of the switch condition.
11453	11598	if (capture_byref) {
11454		return spa.operand_ptr;
	11599	return operand_ptr;
11455	11600	} else {
11456		return spa.operand;
	11601	return operand_val;
11457	11602	}
11458	11603	},
11459	11604	}
...	...	@@ -11686,9 +11831,13 @@ fn zirSwitchBlockErrUnion(sema: Sema, block: Block, inst: Zir.Inst.Index) Comp
11686	11831	var spa: SwitchProngAnalysis = .{
11687	11832	.sema = sema,
11688	11833	.parent_block = block,
11689		.operand = undefined, // must be set to the unwrapped error code before use
11690		.operand_ptr = .none,
11691		.cond = raw_operand_val,
	11834	.operand = .{
	11835	.simple = .{
	11836	.by_val = undefined, // must be set to the unwrapped error code before use
	11837	.by_ref = undefined,
	11838	.cond = raw_operand_val,
	11839	},
	11840	},
11692	11841	.else_error_ty = else_error_ty,
11693	11842	.switch_block_inst = inst,
11694	11843	.tag_capture_inst = undefined,
...	...	@@ -11709,13 +11858,13 @@ fn zirSwitchBlockErrUnion(sema: Sema, block: Block, inst: Zir.Inst.Index) Comp
11709	11858	.name = operand_val.getErrorName(zcu).unwrap().?,
11710	11859	},
11711	11860	}));
11712		spa.operand = if (extra.data.bits.payload_is_ref)
	11861	spa.operand.simple.by_val = if (extra.data.bits.payload_is_ref)
11713	11862	try sema.analyzeErrUnionCodePtr(block, switch_operand_src, raw_operand_val)
11714	11863	else
11715	11864	try sema.analyzeErrUnionCode(block, switch_operand_src, raw_operand_val);
11716	11865
11717	11866	if (extra.data.bits.any_uses_err_capture) {
11718		sema.inst_map.putAssumeCapacity(err_capture_inst, spa.operand);
	11867	sema.inst_map.putAssumeCapacity(err_capture_inst, spa.operand.simple.by_val);
11719	11868	}
11720	11869	defer if (extra.data.bits.any_uses_err_capture) assert(sema.inst_map.remove(err_capture_inst));
11721	11870
...	...	@@ -11723,7 +11872,7 @@ fn zirSwitchBlockErrUnion(sema: Sema, block: Block, inst: Zir.Inst.Index) Comp
11723	11872	sema,
11724	11873	spa,
11725	11874	&child_block,
11726		try sema.switchCond(block, switch_operand_src, spa.operand),
	11875	try sema.switchCond(block, switch_operand_src, spa.operand.simple.by_val),
11727	11876	err_val,
11728	11877	operand_err_set_ty,
11729	11878	switch_src_node_offset,
...	...	@@ -11777,20 +11926,20 @@ fn zirSwitchBlockErrUnion(sema: Sema, block: Block, inst: Zir.Inst.Index) Comp
11777	11926	const true_instructions = try sub_block.instructions.toOwnedSlice(gpa);
11778	11927	defer gpa.free(true_instructions);
11779	11928
11780		spa.operand = if (extra.data.bits.payload_is_ref)
	11929	spa.operand.simple.by_val = if (extra.data.bits.payload_is_ref)
11781	11930	try sema.analyzeErrUnionCodePtr(&sub_block, switch_operand_src, raw_operand_val)
11782	11931	else
11783	11932	try sema.analyzeErrUnionCode(&sub_block, switch_operand_src, raw_operand_val);
11784	11933
11785	11934	if (extra.data.bits.any_uses_err_capture) {
11786		sema.inst_map.putAssumeCapacity(err_capture_inst, spa.operand);
	11935	sema.inst_map.putAssumeCapacity(err_capture_inst, spa.operand.simple.by_val);
11787	11936	}
11788	11937	defer if (extra.data.bits.any_uses_err_capture) assert(sema.inst_map.remove(err_capture_inst));
11789	11938	_ = try sema.analyzeSwitchRuntimeBlock(
11790	11939	spa,
11791	11940	&sub_block,
11792	11941	switch_src,
11793		try sema.switchCond(block, switch_operand_src, spa.operand),
	11942	try sema.switchCond(block, switch_operand_src, spa.operand.simple.by_val),
11794	11943	operand_err_set_ty,
11795	11944	switch_operand_src,
11796	11945	case_vals,
...	...	@@ -11859,17 +12008,63 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
11859	12008	const special_prong_src = block.src(.{ .node_offset_switch_special_prong = src_node_offset });
11860	12009	const extra = sema.code.extraData(Zir.Inst.SwitchBlock, inst_data.payload_index);
11861	12010
11862		const raw_operand_val: Air.Inst.Ref, const raw_operand_ptr: Air.Inst.Ref = blk: {
	12011	const operand: SwitchProngAnalysis.Operand, const raw_operand_ty: Type = op: {
11863	12012	const maybe_ptr = try sema.resolveInst(extra.data.operand);
11864		if (operand_is_ref) {
11865		const val = try sema.analyzeLoad(block, src, maybe_ptr, operand_src);
11866		break :blk .{ val, maybe_ptr };
11867		} else {
11868		break :blk .{ maybe_ptr, undefined };
	12013	const val, const ref = if (operand_is_ref)
	12014	.{ try sema.analyzeLoad(block, src, maybe_ptr, operand_src), maybe_ptr }
	12015	else
	12016	.{ maybe_ptr, undefined };
	12017
	12018	const init_cond = try sema.switchCond(block, operand_src, val);
	12019
	12020	const operand_ty = sema.typeOf(val);
	12021
	12022	if (extra.data.bits.has_continue and !block.is_comptime) {
	12023	// Even if the operand is comptime-known, this `switch` is runtime.
	12024	if (try operand_ty.comptimeOnlySema(pt)) {
	12025	return sema.failWithOwnedErrorMsg(block, msg: {
	12026	const msg = try sema.errMsg(operand_src, "operand of switch loop has comptime-only type '{}'", .{operand_ty.fmt(pt)});
	12027	errdefer msg.destroy(gpa);
	12028	try sema.errNote(operand_src, msg, "switch loops are evalauted at runtime outside of comptime scopes", .{});
	12029	break :msg msg;
	12030	});
	12031	}
	12032	try sema.validateRuntimeValue(block, operand_src, maybe_ptr);
	12033	const operand_alloc = if (extra.data.bits.any_non_inline_capture) a: {
	12034	const operand_ptr_ty = try pt.singleMutPtrType(sema.typeOf(maybe_ptr));
	12035	const operand_alloc = try block.addTy(.alloc, operand_ptr_ty);
	12036	_ = try block.addBinOp(.store, operand_alloc, maybe_ptr);
	12037	break :a operand_alloc;
	12038	} else undefined;
	12039	break :op .{
	12040	.{ .loop = .{
	12041	.operand_alloc = operand_alloc,
	12042	.operand_is_ref = operand_is_ref,
	12043	.init_cond = init_cond,
	12044	} },
	12045	operand_ty,
	12046	};
11869	12047	}
	12048
	12049	// We always use `simple` in the comptime case, because as far as the dispatching logic
	12050	// is concerned, it really is dispatching a single prong. `resolveSwitchComptime` will
	12051	// be resposible for recursively resolving different prongs as needed.
	12052	break :op .{
	12053	.{ .simple = .{
	12054	.by_val = val,
	12055	.by_ref = ref,
	12056	.cond = init_cond,
	12057	} },
	12058	operand_ty,
	12059	};
11870	12060	};
11871	12061
11872		const operand = try sema.switchCond(block, operand_src, raw_operand_val);
	12062	const union_originally = raw_operand_ty.zigTypeTag(zcu) == .@"union";
	12063	const err_set = raw_operand_ty.zigTypeTag(zcu) == .error_set;
	12064	const cond_ty = switch (raw_operand_ty.zigTypeTag(zcu)) {
	12065	.@"union" => raw_operand_ty.unionTagType(zcu).?, // validated by `switchCond` above
	12066	else => raw_operand_ty,
	12067	};
11873	12068
11874	12069	// AstGen guarantees that the instruction immediately preceding
11875	12070	// switch_block(_ref) is a dbg_stmt
...	...	@@ -11919,9 +12114,6 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
11919	12114	},
11920	12115	};
11921	12116
11922		const maybe_union_ty = sema.typeOf(raw_operand_val);
11923		const union_originally = maybe_union_ty.zigTypeTag(zcu) == .@"union";
11924
11925	12117	// Duplicate checking variables later also used for `inline else`.
11926	12118	var seen_enum_fields: []?LazySrcLoc = &.{};
11927	12119	var seen_errors = SwitchErrorSet.init(gpa);
...	...	@@ -11937,13 +12129,10 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
11937	12129
11938	12130	var empty_enum = false;
11939	12131
11940		const operand_ty = sema.typeOf(operand);
11941		const err_set = operand_ty.zigTypeTag(zcu) == .error_set;
11942
11943	12132	var else_error_ty: ?Type = null;
11944	12133
11945	12134	// Validate usage of '_' prongs.
11946		if (special_prong == .under and (!operand_ty.isNonexhaustiveEnum(zcu) or union_originally)) {
	12135	if (special_prong == .under and !raw_operand_ty.isNonexhaustiveEnum(zcu)) {
11947	12136	const msg = msg: {
11948	12137	const msg = try sema.errMsg(
11949	12138	src,
...	...	@@ -11969,11 +12158,11 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
11969	12158	}
11970	12159
11971	12160	// Validate for duplicate items, missing else prong, and invalid range.
11972		switch (operand_ty.zigTypeTag(zcu)) {
	12161	switch (cond_ty.zigTypeTag(zcu)) {
11973	12162	.@"union" => unreachable, // handled in `switchCond`
11974	12163	.@"enum" => {
11975		seen_enum_fields = try gpa.alloc(?LazySrcLoc, operand_ty.enumFieldCount(zcu));
11976		empty_enum = seen_enum_fields.len == 0 and !operand_ty.isNonexhaustiveEnum(zcu);
	12164	seen_enum_fields = try gpa.alloc(?LazySrcLoc, cond_ty.enumFieldCount(zcu));
	12165	empty_enum = seen_enum_fields.len == 0 and !cond_ty.isNonexhaustiveEnum(zcu);
11977	12166	@memset(seen_enum_fields, null);
11978	12167	// `range_set` is used for non-exhaustive enum values that do not correspond to any tags.
11979	12168
...	...	@@ -11991,7 +12180,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
11991	12180	seen_enum_fields,
11992	12181	&range_set,
11993	12182	item_ref,
11994		operand_ty,
	12183	cond_ty,
11995	12184	block.src(.{ .switch_case_item = .{
11996	12185	.switch_node_offset = src_node_offset,
11997	12186	.case_idx = .{ .kind = .scalar, .index = @intCast(scalar_i) },
...	...	@@ -12019,7 +12208,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12019	12208	seen_enum_fields,
12020	12209	&range_set,
12021	12210	item_ref,
12022		operand_ty,
	12211	cond_ty,
12023	12212	block.src(.{ .switch_case_item = .{
12024	12213	.switch_node_offset = src_node_offset,
12025	12214	.case_idx = .{ .kind = .multi, .index = @intCast(multi_i) },
...	...	@@ -12028,7 +12217,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12028	12217	));
12029	12218	}
12030	12219
12031		try sema.validateSwitchNoRange(block, ranges_len, operand_ty, src_node_offset);
	12220	try sema.validateSwitchNoRange(block, ranges_len, cond_ty, src_node_offset);
12032	12221	}
12033	12222	}
12034	12223	const all_tags_handled = for (seen_enum_fields) \|seen_src\| {
...	...	@@ -12036,7 +12225,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12036	12225	} else true;
12037	12226
12038	12227	if (special_prong == .@"else") {
12039		if (all_tags_handled and !operand_ty.isNonexhaustiveEnum(zcu)) return sema.fail(
	12228	if (all_tags_handled and !cond_ty.isNonexhaustiveEnum(zcu)) return sema.fail(
12040	12229	block,
12041	12230	special_prong_src,
12042	12231	"unreachable else prong; all cases already handled",
...	...	@@ -12053,9 +12242,9 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12053	12242	for (seen_enum_fields, 0..) \|seen_src, i\| {
12054	12243	if (seen_src != null) continue;
12055	12244
12056		const field_name = operand_ty.enumFieldName(i, zcu);
	12245	const field_name = cond_ty.enumFieldName(i, zcu);
12057	12246	try sema.addFieldErrNote(
12058		operand_ty,
	12247	cond_ty,
12059	12248	i,
12060	12249	msg,
12061	12250	"unhandled enumeration value: '{}'",
...	...	@@ -12063,15 +12252,15 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12063	12252	);
12064	12253	}
12065	12254	try sema.errNote(
12066		operand_ty.srcLoc(zcu),
	12255	cond_ty.srcLoc(zcu),
12067	12256	msg,
12068	12257	"enum '{}' declared here",
12069		.{operand_ty.fmt(pt)},
	12258	.{cond_ty.fmt(pt)},
12070	12259	);
12071	12260	break :msg msg;
12072	12261	};
12073	12262	return sema.failWithOwnedErrorMsg(block, msg);
12074		} else if (special_prong == .none and operand_ty.isNonexhaustiveEnum(zcu) and !union_originally) {
	12263	} else if (special_prong == .none and cond_ty.isNonexhaustiveEnum(zcu) and !union_originally) {
12075	12264	return sema.fail(
12076	12265	block,
12077	12266	src,
...	...	@@ -12085,7 +12274,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12085	12274	block,
12086	12275	&seen_errors,
12087	12276	&case_vals,
12088		operand_ty,
	12277	cond_ty,
12089	12278	inst_data,
12090	12279	scalar_cases_len,
12091	12280	multi_cases_len,
...	...	@@ -12106,7 +12295,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12106	12295	block,
12107	12296	&range_set,
12108	12297	item_ref,
12109		operand_ty,
	12298	cond_ty,
12110	12299	block.src(.{ .switch_case_item = .{
12111	12300	.switch_node_offset = src_node_offset,
12112	12301	.case_idx = .{ .kind = .scalar, .index = @intCast(scalar_i) },
...	...	@@ -12133,7 +12322,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12133	12322	block,
12134	12323	&range_set,
12135	12324	item_ref,
12136		operand_ty,
	12325	cond_ty,
12137	12326	block.src(.{ .switch_case_item = .{
12138	12327	.switch_node_offset = src_node_offset,
12139	12328	.case_idx = .{ .kind = .multi, .index = @intCast(multi_i) },
...	...	@@ -12155,7 +12344,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12155	12344	&range_set,
12156	12345	item_first,
12157	12346	item_last,
12158		operand_ty,
	12347	cond_ty,
12159	12348	block.src(.{ .switch_case_item = .{
12160	12349	.switch_node_offset = src_node_offset,
12161	12350	.case_idx = .{ .kind = .multi, .index = @intCast(multi_i) },
...	...	@@ -12171,9 +12360,9 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12171	12360	}
12172	12361
12173	12362	check_range: {
12174		if (operand_ty.zigTypeTag(zcu) == .int) {
12175		const min_int = try operand_ty.minInt(pt, operand_ty);
12176		const max_int = try operand_ty.maxInt(pt, operand_ty);
	12363	if (cond_ty.zigTypeTag(zcu) == .int) {
	12364	const min_int = try cond_ty.minInt(pt, cond_ty);
	12365	const max_int = try cond_ty.maxInt(pt, cond_ty);
12177	12366	if (try range_set.spans(min_int.toIntern(), max_int.toIntern())) {
12178	12367	if (special_prong == .@"else") {
12179	12368	return sema.fail(
...	...	@@ -12246,7 +12435,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12246	12435	));
12247	12436	}
12248	12437
12249		try sema.validateSwitchNoRange(block, ranges_len, operand_ty, src_node_offset);
	12438	try sema.validateSwitchNoRange(block, ranges_len, cond_ty, src_node_offset);
12250	12439	}
12251	12440	}
12252	12441	switch (special_prong) {
...	...	@@ -12278,7 +12467,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12278	12467	block,
12279	12468	src,
12280	12469	"else prong required when switching on type '{}'",
12281		.{operand_ty.fmt(pt)},
	12470	.{cond_ty.fmt(pt)},
12282	12471	);
12283	12472	}
12284	12473
...	...	@@ -12299,7 +12488,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12299	12488	block,
12300	12489	&seen_values,
12301	12490	item_ref,
12302		operand_ty,
	12491	cond_ty,
12303	12492	block.src(.{ .switch_case_item = .{
12304	12493	.switch_node_offset = src_node_offset,
12305	12494	.case_idx = .{ .kind = .scalar, .index = @intCast(scalar_i) },
...	...	@@ -12326,7 +12515,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12326	12515	block,
12327	12516	&seen_values,
12328	12517	item_ref,
12329		operand_ty,
	12518	cond_ty,
12330	12519	block.src(.{ .switch_case_item = .{
12331	12520	.switch_node_offset = src_node_offset,
12332	12521	.case_idx = .{ .kind = .multi, .index = @intCast(multi_i) },
...	...	@@ -12335,7 +12524,7 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12335	12524	));
12336	12525	}
12337	12526
12338		try sema.validateSwitchNoRange(block, ranges_len, operand_ty, src_node_offset);
	12527	try sema.validateSwitchNoRange(block, ranges_len, cond_ty, src_node_offset);
12339	12528	}
12340	12529	}
12341	12530	},
...	...	@@ -12354,16 +12543,14 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12354	12543	.comptime_float,
12355	12544	.float,
12356	12545	=> return sema.fail(block, operand_src, "invalid switch operand type '{}'", .{
12357		operand_ty.fmt(pt),
	12546	raw_operand_ty.fmt(pt),
12358	12547	}),
12359	12548	}
12360	12549
12361	12550	const spa: SwitchProngAnalysis = .{
12362	12551	.sema = sema,
12363	12552	.parent_block = block,
12364		.operand = raw_operand_val,
12365		.operand_ptr = raw_operand_ptr,
12366		.cond = operand,
	12553	.operand = operand,
12367	12554	.else_error_ty = else_error_ty,
12368	12555	.switch_block_inst = inst,
12369	12556	.tag_capture_inst = tag_capture_inst,
...	...	@@ -12407,24 +12594,6 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12407	12594	defer child_block.instructions.deinit(gpa);
12408	12595	defer merges.deinit(gpa);
12409	12596
12410		if (try sema.resolveDefinedValue(&child_block, src, operand)) \|operand_val\| {
12411		return resolveSwitchComptime(
12412		sema,
12413		spa,
12414		&child_block,
12415		operand,
12416		operand_val,
12417		operand_ty,
12418		src_node_offset,
12419		special,
12420		case_vals,
12421		scalar_cases_len,
12422		multi_cases_len,
12423		err_set,
12424		empty_enum,
12425		);
12426		}
12427
12428	12597	if (scalar_cases_len + multi_cases_len == 0 and !special.is_inline) {
12429	12598	if (empty_enum) {
12430	12599	return .void_value;
...	...	@@ -12432,54 +12601,90 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12432	12601	if (special_prong == .none) {
12433	12602	return sema.fail(block, src, "switch must handle all possibilities", .{});
12434	12603	}
12435		if (err_set and try sema.maybeErrorUnwrap(block, special.body, operand, operand_src, false)) {
12436		return .unreachable_value;
12437		}
12438		if (zcu.backendSupportsFeature(.is_named_enum_value) and block.wantSafety() and operand_ty.zigTypeTag(zcu) == .@"enum" and
12439		(!operand_ty.isNonexhaustiveEnum(zcu) or union_originally))
	12604	const init_cond = switch (operand) {
	12605	.simple => \|s\| s.cond,
	12606	.loop => \|l\| l.init_cond,
	12607	};
	12608	if (zcu.backendSupportsFeature(.is_named_enum_value) and block.wantSafety() and
	12609	raw_operand_ty.zigTypeTag(zcu) == .@"enum" and !raw_operand_ty.isNonexhaustiveEnum(zcu))
12440	12610	{
12441	12611	try sema.zirDbgStmt(block, cond_dbg_node_index);
12442		const ok = try block.addUnOp(.is_named_enum_value, operand);
	12612	const ok = try block.addUnOp(.is_named_enum_value, init_cond);
12443	12613	try sema.addSafetyCheck(block, src, ok, .corrupt_switch);
12444	12614	}
	12615	if (err_set and try sema.maybeErrorUnwrap(block, special.body, init_cond, operand_src, false)) {
	12616	return .unreachable_value;
	12617	}
	12618	}
12445	12619
12446		return spa.resolveProngComptime(
12447		&child_block,
12448		.special,
12449		special.body,
12450		special.capture,
12451		block.src(.{ .switch_capture = .{
12452		.switch_node_offset = src_node_offset,
12453		.case_idx = LazySrcLoc.Offset.SwitchCaseIndex.special,
12454		} }),
12455		undefined, // case_vals may be undefined for special prongs
12456		.none,
12457		false,
12458		merges,
12459		);
	12620	switch (operand) {
	12621	.loop => {}, // always runtime; evaluation in comptime scope uses `simple`
	12622	.simple => \|s\| {
	12623	if (try sema.resolveDefinedValue(&child_block, src, s.cond)) \|cond_val\| {
	12624	return resolveSwitchComptimeLoop(
	12625	sema,
	12626	spa,
	12627	&child_block,
	12628	if (operand_is_ref)
	12629	sema.typeOf(s.by_ref)
	12630	else
	12631	raw_operand_ty,
	12632	cond_ty,
	12633	cond_val,
	12634	src_node_offset,
	12635	special,
	12636	case_vals,
	12637	scalar_cases_len,
	12638	multi_cases_len,
	12639	err_set,
	12640	empty_enum,
	12641	operand_is_ref,
	12642	);
	12643	}
	12644
	12645	if (scalar_cases_len + multi_cases_len == 0 and !special.is_inline and !extra.data.bits.has_continue) {
	12646	return spa.resolveProngComptime(
	12647	&child_block,
	12648	.special,
	12649	special.body,
	12650	special.capture,
	12651	block.src(.{ .switch_capture = .{
	12652	.switch_node_offset = src_node_offset,
	12653	.case_idx = LazySrcLoc.Offset.SwitchCaseIndex.special,
	12654	} }),
	12655	undefined, // case_vals may be undefined for special prongs
	12656	.none,
	12657	false,
	12658	merges,
	12659	);
	12660	}
	12661	},
12460	12662	}
12461	12663
12462	12664	if (child_block.is_comptime) {
12463		_ = try sema.resolveConstDefinedValue(&child_block, operand_src, operand, .{
	12665	_ = try sema.resolveConstDefinedValue(&child_block, operand_src, operand.simple.cond, .{
12464	12666	.needed_comptime_reason = "condition in comptime switch must be comptime-known",
12465	12667	.block_comptime_reason = child_block.comptime_reason,
12466	12668	});
12467	12669	unreachable;
12468	12670	}
12469	12671
12470		_ = try sema.analyzeSwitchRuntimeBlock(
	12672	const air_switch_ref = try sema.analyzeSwitchRuntimeBlock(
12471	12673	spa,
12472	12674	&child_block,
12473	12675	src,
12474		operand,
12475		operand_ty,
	12676	switch (operand) {
	12677	.simple => \|s\| s.cond,
	12678	.loop => \|l\| l.init_cond,
	12679	},
	12680	cond_ty,
12476	12681	operand_src,
12477	12682	case_vals,
12478	12683	special,
12479	12684	scalar_cases_len,
12480	12685	multi_cases_len,
12481	12686	union_originally,
12482		maybe_union_ty,
	12687	raw_operand_ty,
12483	12688	err_set,
12484	12689	src_node_offset,
12485	12690	special_prong_src,
...	...	@@ -12492,6 +12697,67 @@ fn zirSwitchBlock(sema: Sema, block: Block, inst: Zir.Inst.Index, operand_is_r
12492	12697	false,
12493	12698	);
12494	12699
	12700	for (merges.extra_insts.items, merges.extra_src_locs.items) \|placeholder_inst, dispatch_src\| {
	12701	var replacement_block = block.makeSubBlock();
	12702	defer replacement_block.instructions.deinit(gpa);
	12703
	12704	assert(sema.air_instructions.items(.tag)[@intFromEnum(placeholder_inst)] == .br);
	12705	const new_operand_maybe_ref = sema.air_instructions.items(.data)[@intFromEnum(placeholder_inst)].br.operand;
	12706
	12707	if (extra.data.bits.any_non_inline_capture) {
	12708	_ = try replacement_block.addBinOp(.store, operand.loop.operand_alloc, new_operand_maybe_ref);
	12709	}
	12710
	12711	const new_operand_val = if (operand_is_ref)
	12712	try sema.analyzeLoad(&replacement_block, dispatch_src, new_operand_maybe_ref, dispatch_src)
	12713	else
	12714	new_operand_maybe_ref;
	12715
	12716	const new_cond = try sema.switchCond(&replacement_block, dispatch_src, new_operand_val);
	12717
	12718	if (zcu.backendSupportsFeature(.is_named_enum_value) and block.wantSafety() and
	12719	cond_ty.zigTypeTag(zcu) == .@"enum" and !cond_ty.isNonexhaustiveEnum(zcu) and
	12720	!try sema.isComptimeKnown(new_cond))
	12721	{
	12722	const ok = try replacement_block.addUnOp(.is_named_enum_value, new_cond);
	12723	try sema.addSafetyCheck(&replacement_block, src, ok, .corrupt_switch);
	12724	}
	12725
	12726	_ = try replacement_block.addInst(.{
	12727	.tag = .switch_dispatch,
	12728	.data = .{ .br = .{
	12729	.block_inst = air_switch_ref.toIndex().?,
	12730	.operand = new_cond,
	12731	} },
	12732	});
	12733
	12734	if (replacement_block.instructions.items.len == 1) {
	12735	// Optimization: we don't need a block!
	12736	sema.air_instructions.set(
	12737	@intFromEnum(placeholder_inst),
	12738	sema.air_instructions.get(@intFromEnum(replacement_block.instructions.items[0])),
	12739	);
	12740	continue;
	12741	}
	12742
	12743	// Replace placeholder with a block.
	12744	// No `br` is needed as the block is a switch dispatch so necessarily `noreturn`.
	12745	try sema.air_extra.ensureUnusedCapacity(
	12746	gpa,
	12747	@typeInfo(Air.Block).@"struct".fields.len + replacement_block.instructions.items.len,
	12748	);
	12749	sema.air_instructions.set(@intFromEnum(placeholder_inst), .{
	12750	.tag = .block,
	12751	.data = .{ .ty_pl = .{
	12752	.ty = .noreturn_type,
	12753	.payload = sema.addExtraAssumeCapacity(Air.Block{
	12754	.body_len = @intCast(replacement_block.instructions.items.len),
	12755	}),
	12756	} },
	12757	});
	12758	sema.air_extra.appendSliceAssumeCapacity(@ptrCast(replacement_block.instructions.items));
	12759	}
	12760
12495	12761	return sema.resolveAnalyzedBlock(block, src, &child_block, merges, false);
12496	12762	}
12497	12763
...	...	@@ -13123,7 +13389,7 @@ fn analyzeSwitchRuntimeBlock(
13123	13389	sema.air_extra.appendSliceAssumeCapacity(@ptrCast(else_body));
13124	13390
13125	13391	return try child_block.addInst(.{
13126		.tag = .switch_br,
	13392	.tag = if (spa.operand == .loop) .loop_switch_br else .switch_br,
13127	13393	.data = .{ .pl_op = .{
13128	13394	.operand = operand,
13129	13395	.payload = payload_index,
...	...	@@ -13131,6 +13397,77 @@ fn analyzeSwitchRuntimeBlock(
13131	13397	});
13132	13398	}
13133	13399
	13400	fn resolveSwitchComptimeLoop(
	13401	sema: *Sema,
	13402	init_spa: SwitchProngAnalysis,
	13403	child_block: *Block,
	13404	maybe_ptr_operand_ty: Type,
	13405	cond_ty: Type,
	13406	init_cond_val: Value,
	13407	switch_node_offset: i32,
	13408	special: SpecialProng,
	13409	case_vals: std.ArrayListUnmanaged(Air.Inst.Ref),
	13410	scalar_cases_len: u32,
	13411	multi_cases_len: u32,
	13412	err_set: bool,
	13413	empty_enum: bool,
	13414	operand_is_ref: bool,
	13415	) CompileError!Air.Inst.Ref {
	13416	var spa = init_spa;
	13417	var cond_val = init_cond_val;
	13418
	13419	while (true) {
	13420	if (resolveSwitchComptime(
	13421	sema,
	13422	spa,
	13423	child_block,
	13424	spa.operand.simple.cond,
	13425	cond_val,
	13426	cond_ty,
	13427	switch_node_offset,
	13428	special,
	13429	case_vals,
	13430	scalar_cases_len,
	13431	multi_cases_len,
	13432	err_set,
	13433	empty_enum,
	13434	)) \|result\| {
	13435	return result;
	13436	} else \|err\| switch (err) {
	13437	error.ComptimeBreak => {
	13438	const break_inst = sema.code.instructions.get(@intFromEnum(sema.comptime_break_inst));
	13439	if (break_inst.tag != .switch_continue) return error.ComptimeBreak;
	13440	const extra = sema.code.extraData(Zir.Inst.Break, break_inst.data.@"break".payload_index).data;
	13441	if (extra.block_inst != spa.switch_block_inst) return error.ComptimeBreak;
	13442	// This is a `switch_continue` targeting this block. Change the operand and start over.
	13443	const src = child_block.nodeOffset(extra.operand_src_node);
	13444	const new_operand_uncoerced = try sema.resolveInst(break_inst.data.@"break".operand);
	13445	const new_operand = try sema.coerce(child_block, maybe_ptr_operand_ty, new_operand_uncoerced, src);
	13446
	13447	try sema.emitBackwardBranch(child_block, src);
	13448
	13449	const val, const ref = if (operand_is_ref)
	13450	.{ try sema.analyzeLoad(child_block, src, new_operand, src), new_operand }
	13451	else
	13452	.{ new_operand, undefined };
	13453
	13454	const cond_ref = try sema.switchCond(child_block, src, val);
	13455
	13456	cond_val = try sema.resolveConstDefinedValue(child_block, src, cond_ref, .{
	13457	.needed_comptime_reason = "condition in comptime switch must be comptime-known",
	13458	.block_comptime_reason = child_block.comptime_reason,
	13459	});
	13460	spa.operand = .{ .simple = .{
	13461	.by_val = val,
	13462	.by_ref = ref,
	13463	.cond = cond_ref,
	13464	} };
	13465	},
	13466	else => \|e\| return e,
	13467	}
	13468	}
	13469	}
	13470
13134	13471	fn resolveSwitchComptime(
13135	13472	sema: *Sema,
13136	13473	spa: SwitchProngAnalysis,
...	...	@@ -13148,6 +13485,7 @@ fn resolveSwitchComptime(
13148	13485	) CompileError!Air.Inst.Ref {
13149	13486	const merges = &child_block.label.?.merges;
13150	13487	const resolved_operand_val = try sema.resolveLazyValue(operand_val);
	13488
13151	13489	var extra_index: usize = special.end;
13152	13490	{
13153	13491	var scalar_i: usize = 0;

src/Value.zig+1

...	...	@@ -292,6 +292,7 @@ pub fn getUnsignedIntInner(
292	292	.none => 0,
293	293	else => \|payload\| Value.fromInterned(payload).getUnsignedIntInner(strat, zcu, tid),
294	294	},
	295	.enum_tag => \|enum_tag\| return Value.fromInterned(enum_tag.int).getUnsignedIntInner(strat, zcu, tid),
295	296	else => null,
296	297	},
297	298	};

src/arch/aarch64/CodeGen.zig+2

...	...	@@ -735,6 +735,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
735	735	.block => try self.airBlock(inst),
736	736	.br => try self.airBr(inst),
737	737	.repeat => return self.fail("TODO implement `repeat`", .{}),
	738	.switch_dispatch => return self.fail("TODO implement `switch_dispatch`", .{}),
738	739	.trap => try self.airTrap(),
739	740	.breakpoint => try self.airBreakpoint(),
740	741	.ret_addr => try self.airRetAddr(inst),
...	...	@@ -825,6 +826,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
825	826	.field_parent_ptr => try self.airFieldParentPtr(inst),
826	827
827	828	.switch_br => try self.airSwitch(inst),
	829	.loop_switch_br => return self.fail("TODO implement `loop_switch_br`", .{}),
828	830	.slice_ptr => try self.airSlicePtr(inst),
829	831	.slice_len => try self.airSliceLen(inst),
830	832

src/arch/arm/CodeGen.zig+2

...	...	@@ -722,6 +722,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
722	722	.block => try self.airBlock(inst),
723	723	.br => try self.airBr(inst),
724	724	.repeat => return self.fail("TODO implement `repeat`", .{}),
	725	.switch_dispatch => return self.fail("TODO implement `switch_dispatch`", .{}),
725	726	.trap => try self.airTrap(),
726	727	.breakpoint => try self.airBreakpoint(),
727	728	.ret_addr => try self.airRetAddr(inst),
...	...	@@ -812,6 +813,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
812	813	.field_parent_ptr => try self.airFieldParentPtr(inst),
813	814
814	815	.switch_br => try self.airSwitch(inst),
	816	.loop_switch_br => return self.fail("TODO implement `loop_switch_br`", .{}),
815	817	.slice_ptr => try self.airSlicePtr(inst),
816	818	.slice_len => try self.airSliceLen(inst),
817	819

src/arch/riscv64/CodeGen.zig+2

...	...	@@ -1580,6 +1580,7 @@ fn genBody(func: *Func, body: []const Air.Inst.Index) InnerError!void {
1580	1580	.block => try func.airBlock(inst),
1581	1581	.br => try func.airBr(inst),
1582	1582	.repeat => return func.fail("TODO implement `repeat`", .{}),
	1583	.switch_dispatch => return func.fail("TODO implement `switch_dispatch`", .{}),
1583	1584	.trap => try func.airTrap(),
1584	1585	.breakpoint => try func.airBreakpoint(),
1585	1586	.ret_addr => try func.airRetAddr(inst),
...	...	@@ -1669,6 +1670,7 @@ fn genBody(func: *Func, body: []const Air.Inst.Index) InnerError!void {
1669	1670	.field_parent_ptr => try func.airFieldParentPtr(inst),
1670	1671
1671	1672	.switch_br => try func.airSwitchBr(inst),
	1673	.loop_switch_br => return func.fail("TODO implement `loop_switch_br`", .{}),
1672	1674
1673	1675	.ptr_slice_len_ptr => try func.airPtrSliceLenPtr(inst),
1674	1676	.ptr_slice_ptr_ptr => try func.airPtrSlicePtrPtr(inst),

src/arch/sparc64/CodeGen.zig+2

...	...	@@ -577,6 +577,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
577	577	.block => try self.airBlock(inst),
578	578	.br => try self.airBr(inst),
579	579	.repeat => return self.fail("TODO implement `repeat`", .{}),
	580	.switch_dispatch => return self.fail("TODO implement `switch_dispatch`", .{}),
580	581	.trap => try self.airTrap(),
581	582	.breakpoint => try self.airBreakpoint(),
582	583	.ret_addr => @panic("TODO try self.airRetAddr(inst)"),
...	...	@@ -667,6 +668,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
667	668	.field_parent_ptr => @panic("TODO try self.airFieldParentPtr(inst)"),
668	669
669	670	.switch_br => try self.airSwitch(inst),
	671	.loop_switch_br => return self.fail("TODO implement `loop_switch_br`", .{}),
670	672	.slice_ptr => try self.airSlicePtr(inst),
671	673	.slice_len => try self.airSliceLen(inst),
672	674

src/arch/wasm/CodeGen.zig+2

...	...	@@ -1904,6 +1904,7 @@ fn genInst(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
1904	1904	.breakpoint => func.airBreakpoint(inst),
1905	1905	.br => func.airBr(inst),
1906	1906	.repeat => return func.fail("TODO implement `repeat`", .{}),
	1907	.switch_dispatch => return func.fail("TODO implement `switch_dispatch`", .{}),
1907	1908	.int_from_bool => func.airIntFromBool(inst),
1908	1909	.cond_br => func.airCondBr(inst),
1909	1910	.intcast => func.airIntcast(inst),
...	...	@@ -1985,6 +1986,7 @@ fn genInst(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
1985	1986	.field_parent_ptr => func.airFieldParentPtr(inst),
1986	1987
1987	1988	.switch_br => func.airSwitchBr(inst),
	1989	.loop_switch_br => return func.fail("TODO implement `loop_switch_br`", .{}),
1988	1990	.trunc => func.airTrunc(inst),
1989	1991	.unreach => func.airUnreachable(inst),
1990	1992

src/arch/x86_64/CodeGen.zig+2

...	...	@@ -2248,6 +2248,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
2248	2248	.block => try self.airBlock(inst),
2249	2249	.br => try self.airBr(inst),
2250	2250	.repeat => return self.fail("TODO implement `repeat`", .{}),
	2251	.switch_dispatch => return self.fail("TODO implement `switch_dispatch`", .{}),
2251	2252	.trap => try self.airTrap(),
2252	2253	.breakpoint => try self.airBreakpoint(),
2253	2254	.ret_addr => try self.airRetAddr(inst),
...	...	@@ -2336,6 +2337,7 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
2336	2337	.field_parent_ptr => try self.airFieldParentPtr(inst),
2337	2338
2338	2339	.switch_br => try self.airSwitchBr(inst),
	2340	.loop_switch_br => return self.fail("TODO implement `loop_switch_br`", .{}),
2339	2341	.slice_ptr => try self.airSlicePtr(inst),
2340	2342	.slice_len => try self.airSliceLen(inst),
2341	2343

src/codegen/c.zig+105-22

...	...	@@ -321,6 +321,9 @@ pub const Function = struct {
321	321	/// by type alignment.
322	322	/// The value is whether the alloc needs to be emitted in the header.
323	323	allocs: std.AutoArrayHashMapUnmanaged(LocalIndex, bool) = .{},
	324	/// Maps from `loop_switch_br` instructions to the allocated local used
	325	/// for the switch cond. Dispatches should set this local to the new cond.
	326	loop_switch_conds: std.AutoHashMapUnmanaged(Air.Inst.Index, LocalIndex) = .{},
324	327
325	328	fn resolveInst(f: *Function, ref: Air.Inst.Ref) !CValue {
326	329	const gop = try f.value_map.getOrPut(ref);
...	...	@@ -531,6 +534,7 @@ pub const Function = struct {
531	534	f.blocks.deinit(gpa);
532	535	f.value_map.deinit();
533	536	f.lazy_fns.deinit(gpa);
	537	f.loop_switch_conds.deinit(gpa);
534	538	}
535	539
536	540	fn typeOf(f: *Function, inst: Air.Inst.Ref) Type {
...	...	@@ -3376,16 +3380,18 @@ fn genBodyInner(f: *Function, body: []const Air.Inst.Index) error{ AnalysisFail,
3376	3380	=> unreachable,
3377	3381
3378	3382	// Instructions that are known to always be `noreturn` based on their tag.
3379		.br => return airBr(f, inst),
3380		.repeat => return airRepeat(f, inst),
3381		.cond_br => return airCondBr(f, inst),
3382		.switch_br => return airSwitchBr(f, inst),
3383		.loop => return airLoop(f, inst),
3384		.ret => return airRet(f, inst, false),
3385		.ret_safe => return airRet(f, inst, false), // TODO
3386		.ret_load => return airRet(f, inst, true),
3387		.trap => return airTrap(f, f.object.writer()),
3388		.unreach => return airUnreach(f),
	3383	.br => return airBr(f, inst),
	3384	.repeat => return airRepeat(f, inst),
	3385	.switch_dispatch => return airSwitchDispatch(f, inst),
	3386	.cond_br => return airCondBr(f, inst),
	3387	.switch_br => return airSwitchBr(f, inst, false),
	3388	.loop_switch_br => return airSwitchBr(f, inst, true),
	3389	.loop => return airLoop(f, inst),
	3390	.ret => return airRet(f, inst, false),
	3391	.ret_safe => return airRet(f, inst, false), // TODO
	3392	.ret_load => return airRet(f, inst, true),
	3393	.trap => return airTrap(f, f.object.writer()),
	3394	.unreach => return airUnreach(f),
3389	3395
3390	3396	// Instructions which may be `noreturn`.
3391	3397	.block => res: {
...	...	@@ -4786,6 +4792,46 @@ fn airRepeat(f: *Function, inst: Air.Inst.Index) !void {
4786	4792	try writer.print("goto zig_loop_{d};\n", .{@intFromEnum(repeat.loop_inst)});
4787	4793	}
4788	4794
	4795	fn airSwitchDispatch(f: *Function, inst: Air.Inst.Index) !void {
	4796	const pt = f.object.dg.pt;
	4797	const zcu = pt.zcu;
	4798	const br = f.air.instructions.items(.data)[@intFromEnum(inst)].br;
	4799	const writer = f.object.writer();
	4800
	4801	if (try f.air.value(br.operand, pt)) \|cond_val\| {
	4802	// Comptime-known dispatch. Iterate the cases to find the correct
	4803	// one, and branch directly to the corresponding case.
	4804	const switch_br = f.air.unwrapSwitch(br.block_inst);
	4805	var it = switch_br.iterateCases();
	4806	const target_case_idx: u32 = target: while (it.next()) \|case\| {
	4807	for (case.items) \|item\| {
	4808	const val = Value.fromInterned(item.toInterned().?);
	4809	if (cond_val.compareHetero(.eq, val, zcu)) break :target case.idx;
	4810	}
	4811	for (case.ranges) \|range\| {
	4812	const low = Value.fromInterned(range[0].toInterned().?);
	4813	const high = Value.fromInterned(range[1].toInterned().?);
	4814	if (cond_val.compareHetero(.gte, low, zcu) and
	4815	cond_val.compareHetero(.lte, high, zcu))
	4816	{
	4817	break :target case.idx;
	4818	}
	4819	}
	4820	} else switch_br.cases_len;
	4821	try writer.print("goto zig_switch_{d}_dispatch_{d};\n", .{ @intFromEnum(br.block_inst), target_case_idx });
	4822	return;
	4823	}
	4824
	4825	// Runtime-known dispatch. Set the switch condition, and branch back.
	4826	const cond = try f.resolveInst(br.operand);
	4827	const cond_local = f.loop_switch_conds.get(br.block_inst).?;
	4828	try f.writeCValue(writer, .{ .local = cond_local }, .Other);
	4829	try writer.writeAll(" = ");
	4830	try f.writeCValue(writer, cond, .Initializer);
	4831	try writer.writeAll(";\n");
	4832	try writer.print("goto zig_switch_{d}_loop;", .{@intFromEnum(br.block_inst)});
	4833	}
	4834
4789	4835	fn airBitcast(f: *Function, inst: Air.Inst.Index) !CValue {
4790	4836	const ty_op = f.air.instructions.items(.data)[@intFromEnum(inst)].ty_op;
4791	4837	const inst_ty = f.typeOfIndex(inst);
...	...	@@ -5004,15 +5050,34 @@ fn airCondBr(f: *Function, inst: Air.Inst.Index) !void {
5004	5050	try genBodyInner(f, else_body);
5005	5051	}
5006	5052
5007		fn airSwitchBr(f: *Function, inst: Air.Inst.Index) !void {
	5053	fn airSwitchBr(f: *Function, inst: Air.Inst.Index, is_dispatch_loop: bool) !void {
5008	5054	const pt = f.object.dg.pt;
5009	5055	const zcu = pt.zcu;
	5056	const gpa = f.object.dg.gpa;
5010	5057	const switch_br = f.air.unwrapSwitch(inst);
5011		const condition = try f.resolveInst(switch_br.operand);
	5058	const init_condition = try f.resolveInst(switch_br.operand);
5012	5059	try reap(f, inst, &.{switch_br.operand});
5013	5060	const condition_ty = f.typeOf(switch_br.operand);
5014	5061	const writer = f.object.writer();
5015	5062
	5063	// For dispatches, we will create a local alloc to contain the condition value.
	5064	// This may not result in optimal codegen for switch loops, but it minimizes the
	5065	// amount of C code we generate, which is probably more desirable here (and is simpler).
	5066	const condition = if (is_dispatch_loop) cond: {
	5067	const new_local = try f.allocLocal(inst, condition_ty);
	5068	try f.writeCValue(writer, new_local, .Other);
	5069	try writer.writeAll(" = ");
	5070	try f.writeCValue(writer, init_condition, .Initializer);
	5071	try writer.writeAll(";\n");
	5072	try writer.print("zig_switch_{d}_loop:", .{@intFromEnum(inst)});
	5073	try f.loop_switch_conds.put(gpa, inst, new_local.new_local);
	5074	break :cond new_local;
	5075	} else init_condition;
	5076
	5077	defer if (is_dispatch_loop) {
	5078	assert(f.loop_switch_conds.remove(inst));
	5079	};
	5080
5016	5081	try writer.writeAll("switch (");
5017	5082
5018	5083	const lowered_condition_ty = if (condition_ty.toIntern() == .bool_type)
...	...	@@ -5030,7 +5095,6 @@ fn airSwitchBr(f: *Function, inst: Air.Inst.Index) !void {
5030	5095	try writer.writeAll(") {");
5031	5096	f.object.indent_writer.pushIndent();
5032	5097
5033		const gpa = f.object.dg.gpa;
5034	5098	const liveness = try f.liveness.getSwitchBr(gpa, inst, switch_br.cases_len + 1);
5035	5099	defer gpa.free(liveness.deaths);
5036	5100
...	...	@@ -5045,9 +5109,15 @@ fn airSwitchBr(f: *Function, inst: Air.Inst.Index) !void {
5045	5109	try f.object.indent_writer.insertNewline();
5046	5110	try writer.writeAll("case ");
5047	5111	const item_value = try f.air.value(item, pt);
5048		if (item_value.?.getUnsignedInt(zcu)) \|item_int\| try writer.print("{}\n", .{
5049		try f.fmtIntLiteral(try pt.intValue(lowered_condition_ty, item_int)),
5050		}) else {
	5112	// If `item_value` is a pointer with a known integer address, print the address
	5113	// with no cast to avoid a warning.
	5114	write_val: {
	5115	if (condition_ty.isPtrAtRuntime(zcu)) {
	5116	if (item_value.?.getUnsignedInt(zcu)) \|item_int\| {
	5117	try writer.print("{}", .{try f.fmtIntLiteral(try pt.intValue(lowered_condition_ty, item_int))});
	5118	break :write_val;
	5119	}
	5120	}
5051	5121	if (condition_ty.isPtrAtRuntime(zcu)) {
5052	5122	try writer.writeByte('(');
5053	5123	try f.renderType(writer, Type.usize);
...	...	@@ -5057,9 +5127,14 @@ fn airSwitchBr(f: *Function, inst: Air.Inst.Index) !void {
5057	5127	}
5058	5128	try writer.writeByte(':');
5059	5129	}
5060		try writer.writeByte(' ');
5061
5062		try genBodyResolveState(f, inst, liveness.deaths[case.idx], case.body, false);
	5130	try writer.writeAll(" {\n");
	5131	f.object.indent_writer.pushIndent();
	5132	if (is_dispatch_loop) {
	5133	try writer.print("zig_switch_{d}_dispatch_{d}: ", .{ @intFromEnum(inst), case.idx });
	5134	}
	5135	try genBodyResolveState(f, inst, liveness.deaths[case.idx], case.body, true);
	5136	f.object.indent_writer.popIndent();
	5137	try writer.writeByte('}');
5063	5138
5064	5139	// The case body must be noreturn so we don't need to insert a break.
5065	5140	}
...	...	@@ -5095,11 +5170,19 @@ fn airSwitchBr(f: *Function, inst: Air.Inst.Index) !void {
5095	5170	try f.object.dg.renderValue(writer, (try f.air.value(range[1], pt)).?, .Other);
5096	5171	try writer.writeByte(')');
5097	5172	}
5098		try writer.writeAll(") ");
5099		try genBodyResolveState(f, inst, liveness.deaths[case.idx], case.body, false);
	5173	try writer.writeAll(") {\n");
	5174	f.object.indent_writer.pushIndent();
	5175	if (is_dispatch_loop) {
	5176	try writer.print("zig_switch_{d}_dispatch_{d}: ", .{ @intFromEnum(inst), case.idx });
	5177	}
	5178	try genBodyResolveState(f, inst, liveness.deaths[case.idx], case.body, true);
	5179	f.object.indent_writer.popIndent();
	5180	try writer.writeByte('}');
5100	5181	}
5101	5182	}
5102
	5183	if (is_dispatch_loop) {
	5184	try writer.print("zig_switch_{d}_dispatch_{d}: ", .{ @intFromEnum(inst), switch_br.cases_len });
	5185	}
5103	5186	if (else_body.len > 0) {
5104	5187	// Note that this must be the last case, so we do not need to use `genBodyResolveState` since
5105	5188	// the parent block will do it (because the case body is noreturn).

src/codegen/llvm.zig+404-84

...	...	@@ -1721,6 +1721,7 @@ pub const Object = struct {
1721	1721	.func_inst_table = .{},
1722	1722	.blocks = .{},
1723	1723	.loops = .{},
	1724	.switch_dispatch_info = .{},
1724	1725	.sync_scope = if (owner_mod.single_threaded) .singlethread else .system,
1725	1726	.file = file,
1726	1727	.scope = subprogram,
...	...	@@ -4845,6 +4846,10 @@ pub const FuncGen = struct {
4845	4846	/// Maps `loop` instructions to the bb to branch to to repeat the loop.
4846	4847	loops: std.AutoHashMapUnmanaged(Air.Inst.Index, Builder.Function.Block.Index),
4847	4848
	4849	/// Maps `loop_switch_br` instructions to the information required to lower
	4850	/// dispatches (`switch_dispatch` instructions).
	4851	switch_dispatch_info: std.AutoHashMapUnmanaged(Air.Inst.Index, SwitchDispatchInfo),
	4852
4848	4853	sync_scope: Builder.SyncScope,
4849	4854
4850	4855	const Fuzz = struct {
...	...	@@ -4857,6 +4862,33 @@ pub const FuncGen = struct {
4857	4862	}
4858	4863	};
4859	4864
	4865	const SwitchDispatchInfo = struct {
	4866	/// These are the blocks corresponding to each switch case.
	4867	/// The final element corresponds to the `else` case.
	4868	/// Slices allocated into `gpa`.
	4869	case_blocks: []Builder.Function.Block.Index,
	4870	/// This is `.none` if `jmp_table` is set, since we won't use a `switch` instruction to dispatch.
	4871	switch_weights: Builder.Function.Instruction.BrCond.Weights,
	4872	/// If not `null`, we have manually constructed a jump table to reach the desired block.
	4873	/// `table` can be used if the value is between `min` and `max` inclusive.
	4874	/// We perform this lowering manually to avoid some questionable behavior from LLVM.
	4875	/// See `airSwitchBr` for details.
	4876	jmp_table: ?JmpTable,
	4877
	4878	const JmpTable = struct {
	4879	min: Builder.Constant,
	4880	max: Builder.Constant,
	4881	in_bounds_hint: enum { none, unpredictable, likely, unlikely },
	4882	/// Pointer to the jump table itself, to be used with `indirectbr`.
	4883	/// The index into the jump table is the dispatch condition minus `min`.
	4884	/// The table values are `blockaddress` constants corresponding to blocks in `case_blocks`.
	4885	table: Builder.Constant,
	4886	/// `true` if `table` conatins a reference to the `else` block.
	4887	/// In this case, the `indirectbr` must include the `else` block in its target list.
	4888	table_includes_else: bool,
	4889	};
	4890	};
	4891
4860	4892	const BreakList = union {
4861	4893	list: std.MultiArrayList(struct {
4862	4894	bb: Builder.Function.Block.Index,
...	...	@@ -4872,6 +4904,11 @@ pub const FuncGen = struct {
4872	4904	self.func_inst_table.deinit(gpa);
4873	4905	self.blocks.deinit(gpa);
4874	4906	self.loops.deinit(gpa);
	4907	var it = self.switch_dispatch_info.valueIterator();
	4908	while (it.next()) \|info\| {
	4909	self.gpa.free(info.case_blocks);
	4910	}
	4911	self.switch_dispatch_info.deinit(gpa);
4875	4912	}
4876	4913
4877	4914	fn todo(self: *FuncGen, comptime format: []const u8, args: anytype) Error {
...	...	@@ -5182,16 +5219,18 @@ pub const FuncGen = struct {
5182	5219	.work_group_id => try self.airWorkGroupId(inst),
5183	5220
5184	5221	// Instructions that are known to always be `noreturn` based on their tag.
5185		.br => return self.airBr(inst),
5186		.repeat => return self.airRepeat(inst),
5187		.cond_br => return self.airCondBr(inst),
5188		.switch_br => return self.airSwitchBr(inst),
5189		.loop => return self.airLoop(inst),
5190		.ret => return self.airRet(inst, false),
5191		.ret_safe => return self.airRet(inst, true),
5192		.ret_load => return self.airRetLoad(inst),
5193		.trap => return self.airTrap(inst),
5194		.unreach => return self.airUnreach(inst),
	5222	.br => return self.airBr(inst),
	5223	.repeat => return self.airRepeat(inst),
	5224	.switch_dispatch => return self.airSwitchDispatch(inst),
	5225	.cond_br => return self.airCondBr(inst),
	5226	.switch_br => return self.airSwitchBr(inst, false),
	5227	.loop_switch_br => return self.airSwitchBr(inst, true),
	5228	.loop => return self.airLoop(inst),
	5229	.ret => return self.airRet(inst, false),
	5230	.ret_safe => return self.airRet(inst, true),
	5231	.ret_load => return self.airRetLoad(inst),
	5232	.trap => return self.airTrap(inst),
	5233	.unreach => return self.airUnreach(inst),
5195	5234
5196	5235	// Instructions which may be `noreturn`.
5197	5236	.block => res: {
...	...	@@ -6093,6 +6132,202 @@ pub const FuncGen = struct {
6093	6132	_ = try self.wip.br(loop_bb);
6094	6133	}
6095	6134
	6135	fn lowerSwitchDispatch(
	6136	self: *FuncGen,
	6137	switch_inst: Air.Inst.Index,
	6138	cond_ref: Air.Inst.Ref,
	6139	dispatch_info: SwitchDispatchInfo,
	6140	) !void {
	6141	const o = self.ng.object;
	6142	const pt = o.pt;
	6143	const zcu = pt.zcu;
	6144	const cond_ty = self.typeOf(cond_ref);
	6145	const switch_br = self.air.unwrapSwitch(switch_inst);
	6146
	6147	if (try self.air.value(cond_ref, pt)) \|cond_val\| {
	6148	// Comptime-known dispatch. Iterate the cases to find the correct
	6149	// one, and branch to the corresponding element of `case_blocks`.
	6150	var it = switch_br.iterateCases();
	6151	const target_case_idx = target: while (it.next()) \|case\| {
	6152	for (case.items) \|item\| {
	6153	const val = Value.fromInterned(item.toInterned().?);
	6154	if (cond_val.compareHetero(.eq, val, zcu)) break :target case.idx;
	6155	}
	6156	for (case.ranges) \|range\| {
	6157	const low = Value.fromInterned(range[0].toInterned().?);
	6158	const high = Value.fromInterned(range[1].toInterned().?);
	6159	if (cond_val.compareHetero(.gte, low, zcu) and
	6160	cond_val.compareHetero(.lte, high, zcu))
	6161	{
	6162	break :target case.idx;
	6163	}
	6164	}
	6165	} else dispatch_info.case_blocks.len - 1;
	6166	const target_block = dispatch_info.case_blocks[target_case_idx];
	6167	target_block.ptr(&self.wip).incoming += 1;
	6168	_ = try self.wip.br(target_block);
	6169	return;
	6170	}
	6171
	6172	// Runtime-known dispatch.
	6173	const cond = try self.resolveInst(cond_ref);
	6174
	6175	if (dispatch_info.jmp_table) \|jmp_table\| {
	6176	// We should use the constructed jump table.
	6177	// First, check the bounds to branch to the `else` case if needed.
	6178	const inbounds = try self.wip.bin(
	6179	.@"and",
	6180	try self.cmp(.normal, .gte, cond_ty, cond, jmp_table.min.toValue()),
	6181	try self.cmp(.normal, .lte, cond_ty, cond, jmp_table.max.toValue()),
	6182	"",
	6183	);
	6184	const jmp_table_block = try self.wip.block(1, "Then");
	6185	const else_block = dispatch_info.case_blocks[dispatch_info.case_blocks.len - 1];
	6186	else_block.ptr(&self.wip).incoming += 1;
	6187	_ = try self.wip.brCond(inbounds, jmp_table_block, else_block, switch (jmp_table.in_bounds_hint) {
	6188	.none => .none,
	6189	.unpredictable => .unpredictable,
	6190	.likely => .then_likely,
	6191	.unlikely => .else_likely,
	6192	});
	6193
	6194	self.wip.cursor = .{ .block = jmp_table_block };
	6195
	6196	// Figure out the list of blocks we might branch to.
	6197	// This includes all case blocks, but it might not include the `else` block if
	6198	// the table is dense.
	6199	const target_blocks_len = dispatch_info.case_blocks.len - @intFromBool(!jmp_table.table_includes_else);
	6200	const target_blocks = dispatch_info.case_blocks[0..target_blocks_len];
	6201
	6202	// Make sure to cast the index to a usize so it's not treated as negative!
	6203	const table_index = try self.wip.cast(
	6204	.zext,
	6205	try self.wip.bin(.@"sub nuw", cond, jmp_table.min.toValue(), ""),
	6206	try o.lowerType(Type.usize),
	6207	"",
	6208	);
	6209	const target_ptr_ptr = try self.wip.gep(
	6210	.inbounds,
	6211	.ptr,
	6212	jmp_table.table.toValue(),
	6213	&.{table_index},
	6214	"",
	6215	);
	6216	const target_ptr = try self.wip.load(.normal, .ptr, target_ptr_ptr, .default, "");
	6217
	6218	// Do the branch!
	6219	_ = try self.wip.indirectbr(target_ptr, target_blocks);
	6220
	6221	// Mark all target blocks as having one more incoming branch.
	6222	for (target_blocks) \|case_block\| {
	6223	case_block.ptr(&self.wip).incoming += 1;
	6224	}
	6225
	6226	return;
	6227	}
	6228
	6229	// We must lower to an actual LLVM `switch` instruction.
	6230	// The switch prongs will correspond to our scalar cases. Ranges will
	6231	// be handled by conditional branches in the `else` prong.
	6232
	6233	const llvm_usize = try o.lowerType(Type.usize);
	6234	const cond_int = if (cond.typeOfWip(&self.wip).isPointer(&o.builder))
	6235	try self.wip.cast(.ptrtoint, cond, llvm_usize, "")
	6236	else
	6237	cond;
	6238
	6239	const llvm_cases_len, const last_range_case = info: {
	6240	var llvm_cases_len: u32 = 0;
	6241	var last_range_case: ?u32 = null;
	6242	var it = switch_br.iterateCases();
	6243	while (it.next()) \|case\| {
	6244	if (case.ranges.len > 0) last_range_case = case.idx;
	6245	llvm_cases_len += @intCast(case.items.len);
	6246	}
	6247	break :info .{ llvm_cases_len, last_range_case };
	6248	};
	6249
	6250	// The `else` of the LLVM `switch` is the actual `else` prong only
	6251	// if there are no ranges. Otherwise, the `else` will have a
	6252	// conditional chain before the "true" `else` prong.
	6253	const llvm_else_block = if (last_range_case == null)
	6254	dispatch_info.case_blocks[dispatch_info.case_blocks.len - 1]
	6255	else
	6256	try self.wip.block(0, "RangeTest");
	6257
	6258	llvm_else_block.ptr(&self.wip).incoming += 1;
	6259
	6260	var wip_switch = try self.wip.@"switch"(cond_int, llvm_else_block, llvm_cases_len, dispatch_info.switch_weights);
	6261	defer wip_switch.finish(&self.wip);
	6262
	6263	// Construct the actual cases. Set the cursor to the `else` block so
	6264	// we can construct ranges at the same time as scalar cases.
	6265	self.wip.cursor = .{ .block = llvm_else_block };
	6266
	6267	var it = switch_br.iterateCases();
	6268	while (it.next()) \|case\| {
	6269	const case_block = dispatch_info.case_blocks[case.idx];
	6270
	6271	for (case.items) \|item\| {
	6272	const llvm_item = (try self.resolveInst(item)).toConst().?;
	6273	const llvm_int_item = if (llvm_item.typeOf(&o.builder).isPointer(&o.builder))
	6274	try o.builder.castConst(.ptrtoint, llvm_item, llvm_usize)
	6275	else
	6276	llvm_item;
	6277	try wip_switch.addCase(llvm_int_item, case_block, &self.wip);
	6278	}
	6279	case_block.ptr(&self.wip).incoming += @intCast(case.items.len);
	6280
	6281	if (case.ranges.len == 0) continue;
	6282
	6283	// Add a conditional for the ranges, directing to the relevant bb.
	6284	// We don't need to consider `cold` branch hints since that information is stored
	6285	// in the target bb body, but we do care about likely/unlikely/unpredictable.
	6286
	6287	const hint = switch_br.getHint(case.idx);
	6288
	6289	var range_cond: ?Builder.Value = null;
	6290	for (case.ranges) \|range\| {
	6291	const llvm_min = try self.resolveInst(range[0]);
	6292	const llvm_max = try self.resolveInst(range[1]);
	6293	const cond_part = try self.wip.bin(
	6294	.@"and",
	6295	try self.cmp(.normal, .gte, cond_ty, cond, llvm_min),
	6296	try self.cmp(.normal, .lte, cond_ty, cond, llvm_max),
	6297	"",
	6298	);
	6299	if (range_cond) \|prev\| {
	6300	range_cond = try self.wip.bin(.@"or", prev, cond_part, "");
	6301	} else range_cond = cond_part;
	6302	}
	6303
	6304	// If the check fails, we either branch to the "true" `else` case,
	6305	// or to the next range condition.
	6306	const range_else_block = if (case.idx == last_range_case.?)
	6307	dispatch_info.case_blocks[dispatch_info.case_blocks.len - 1]
	6308	else
	6309	try self.wip.block(0, "RangeTest");
	6310
	6311	_ = try self.wip.brCond(range_cond.?, case_block, range_else_block, switch (hint) {
	6312	.none, .cold => .none,
	6313	.unpredictable => .unpredictable,
	6314	.likely => .then_likely,
	6315	.unlikely => .else_likely,
	6316	});
	6317	case_block.ptr(&self.wip).incoming += 1;
	6318	range_else_block.ptr(&self.wip).incoming += 1;
	6319
	6320	// Construct the next range conditional (if any) in the false branch.
	6321	self.wip.cursor = .{ .block = range_else_block };
	6322	}
	6323	}
	6324
	6325	fn airSwitchDispatch(self: *FuncGen, inst: Air.Inst.Index) !void {
	6326	const br = self.air.instructions.items(.data)[@intFromEnum(inst)].br;
	6327	const dispatch_info = self.switch_dispatch_info.get(br.block_inst).?;
	6328	return self.lowerSwitchDispatch(br.block_inst, br.operand, dispatch_info);
	6329	}
	6330
6096	6331	fn airCondBr(self: *FuncGen, inst: Air.Inst.Index) !void {
6097	6332	const pl_op = self.air.instructions.items(.data)[@intFromEnum(inst)].pl_op;
6098	6333	const cond = try self.resolveInst(pl_op.operand);
...	...	@@ -6257,36 +6492,123 @@ pub const FuncGen = struct {
6257	6492	return fg.wip.extractValue(err_union, &.{offset}, "");
6258	6493	}
6259	6494
6260		fn airSwitchBr(self: *FuncGen, inst: Air.Inst.Index) !void {
	6495	fn airSwitchBr(self: *FuncGen, inst: Air.Inst.Index, is_dispatch_loop: bool) !void {
6261	6496	const o = self.ng.object;
	6497	const zcu = o.pt.zcu;
6262	6498
6263	6499	const switch_br = self.air.unwrapSwitch(inst);
6264	6500
6265		const cond = try self.resolveInst(switch_br.operand);
	6501	// For `loop_switch_br`, we need these BBs prepared ahead of time to generate dispatches.
	6502	// For `switch_br`, they allow us to sometimes generate better IR by sharing a BB between
	6503	// scalar and range cases in the same prong.
	6504	// +1 for `else` case. This is not the same as the LLVM `else` prong, as that may first contain
	6505	// conditionals to handle ranges.
	6506	const case_blocks = try self.gpa.alloc(Builder.Function.Block.Index, switch_br.cases_len + 1);
	6507	defer self.gpa.free(case_blocks);
	6508	// We set incoming as 0 for now, and increment it as we construct dispatches.
	6509	for (case_blocks[0 .. case_blocks.len - 1]) \|b\| b. = try self.wip.block(0, "Case");
	6510	case_blocks[case_blocks.len - 1] = try self.wip.block(0, "Default");
	6511
	6512	// There's a special case here to manually generate a jump table in some cases.
	6513	//
	6514	// Labeled switch in Zig is intended to follow the "direct threading" pattern. We would ideally use a jump
	6515	// table, and each `continue` has its own indirect `jmp`, to allow the branch predictor to more accurately
	6516	// use data patterns to predict future dispatches. The problem, however, is that LLVM emits fascinatingly
	6517	// bad asm for this. Not only does it not share the jump table -- which we really need it to do to prevent
	6518	// destroying the cache -- but it also actually generates slightly different jump tables for each case,
	6519	// and a separate conditional branch beforehand to handle dispatching back to the case we're currently
	6520	// within(!!).
	6521	//
	6522	// This asm is really, really, not what we want. As such, we will construct the jump table manually where
	6523	// appropriate (the values are dense and relatively few), and use it when lowering dispatches.
	6524
	6525	const jmp_table: ?SwitchDispatchInfo.JmpTable = jmp_table: {
	6526	if (!is_dispatch_loop) break :jmp_table null;
	6527	// On a 64-bit target, 1024 pointers in our jump table is about 8K of pointers. This seems just
	6528	// about acceptable - it won't fill L1d cache on most CPUs.
	6529	const max_table_len = 1024;
6266	6530
6267		// This is not necessarily the actual `else` prong; it first contains conditionals
6268		// for any range cases. It's just the `else` of the LLVM switch.
6269		const llvm_else_block = try self.wip.block(1, "Default");
	6531	const cond_ty = self.typeOf(switch_br.operand);
	6532	switch (cond_ty.zigTypeTag(zcu)) {
	6533	.bool, .pointer => break :jmp_table null,
	6534	.@"enum", .int, .error_set => {},
	6535	else => unreachable,
	6536	}
6270	6537
6271		const case_blocks = try self.gpa.alloc(Builder.Function.Block.Index, switch_br.cases_len);
6272		defer self.gpa.free(case_blocks);
6273		// We set incoming as 0 for now, and increment it as we construct the switch.
6274		for (case_blocks) \|b\| b. = try self.wip.block(0, "Case");
	6538	if (cond_ty.intInfo(zcu).signedness == .signed) break :jmp_table null;
6275	6539
6276		const llvm_usize = try o.lowerType(Type.usize);
6277		const cond_int = if (cond.typeOfWip(&self.wip).isPointer(&o.builder))
6278		try self.wip.cast(.ptrtoint, cond, llvm_usize, "")
6279		else
6280		cond;
	6540	// Don't worry about the size of the type -- it's irrelevant, because the prong values could be fairly dense.
	6541	// If they are, then we will construct a jump table.
	6542	const min, const max = self.switchCaseItemRange(switch_br);
	6543	const min_int = min.getUnsignedInt(zcu) orelse break :jmp_table null;
	6544	const max_int = max.getUnsignedInt(zcu) orelse break :jmp_table null;
	6545	const table_len = max_int - min_int + 1;
	6546	if (table_len > max_table_len) break :jmp_table null;
	6547
	6548	const table_elems = try self.gpa.alloc(Builder.Constant, @intCast(table_len));
	6549	defer self.gpa.free(table_elems);
6281	6550
6282		const llvm_cases_len = llvm_cases_len: {
6283		var len: u32 = 0;
	6551	// Set them all to the `else` branch, then iterate over the AIR switch
	6552	// and replace all values which correspond to other prongs.
	6553	@memset(table_elems, try o.builder.blockAddrConst(
	6554	self.wip.function,
	6555	case_blocks[case_blocks.len - 1],
	6556	));
	6557	var item_count: u32 = 0;
6284	6558	var it = switch_br.iterateCases();
6285		while (it.next()) \|case\| len += @intCast(case.items.len);
6286		break :llvm_cases_len len;
	6559	while (it.next()) \|case\| {
	6560	const case_block = case_blocks[case.idx];
	6561	const case_block_addr = try o.builder.blockAddrConst(
	6562	self.wip.function,
	6563	case_block,
	6564	);
	6565	for (case.items) \|item\| {
	6566	const val = Value.fromInterned(item.toInterned().?);
	6567	const table_idx = val.toUnsignedInt(zcu) - min_int;
	6568	table_elems[@intCast(table_idx)] = case_block_addr;
	6569	item_count += 1;
	6570	}
	6571	for (case.ranges) \|range\| {
	6572	const low = Value.fromInterned(range[0].toInterned().?);
	6573	const high = Value.fromInterned(range[1].toInterned().?);
	6574	const low_idx = low.toUnsignedInt(zcu) - min_int;
	6575	const high_idx = high.toUnsignedInt(zcu) - min_int;
	6576	@memset(table_elems[@intCast(low_idx)..@intCast(high_idx + 1)], case_block_addr);
	6577	item_count += @intCast(high_idx + 1 - low_idx);
	6578	}
	6579	}
	6580
	6581	const table_llvm_ty = try o.builder.arrayType(table_elems.len, .ptr);
	6582	const table_val = try o.builder.arrayConst(table_llvm_ty, table_elems);
	6583
	6584	const table_variable = try o.builder.addVariable(
	6585	try o.builder.strtabStringFmt("__jmptab_{d}", .{@intFromEnum(inst)}),
	6586	table_llvm_ty,
	6587	.default,
	6588	);
	6589	try table_variable.setInitializer(table_val, &o.builder);
	6590	table_variable.setLinkage(.internal, &o.builder);
	6591	table_variable.setUnnamedAddr(.unnamed_addr, &o.builder);
	6592
	6593	const table_includes_else = item_count != table_len;
	6594
	6595	break :jmp_table .{
	6596	.min = try o.lowerValue(min.toIntern()),
	6597	.max = try o.lowerValue(max.toIntern()),
	6598	.in_bounds_hint = if (table_includes_else) .none else switch (switch_br.getElseHint()) {
	6599	.none, .cold => .none,
	6600	.unpredictable => .unpredictable,
	6601	.likely => .likely,
	6602	.unlikely => .unlikely,
	6603	},
	6604	.table = table_variable.toConst(&o.builder),
	6605	.table_includes_else = table_includes_else,
	6606	};
6287	6607	};
6288	6608
6289	6609	const weights: Builder.Function.Instruction.BrCond.Weights = weights: {
	6610	if (jmp_table != null) break :weights .none; // not used
	6611
6290	6612	// First pass. If any weights are `.unpredictable`, unpredictable.
6291	6613	// If all are `.none` or `.cold`, none.
6292	6614	var any_likely = false;
...	...	@@ -6304,6 +6626,13 @@ pub const FuncGen = struct {
6304	6626	}
6305	6627	if (!any_likely) break :weights .none;
6306	6628
	6629	const llvm_cases_len = llvm_cases_len: {
	6630	var len: u32 = 0;
	6631	var it = switch_br.iterateCases();
	6632	while (it.next()) \|case\| len += @intCast(case.items.len);
	6633	break :llvm_cases_len len;
	6634	};
	6635
6307	6636	var weights = try self.gpa.alloc(Builder.Metadata, llvm_cases_len + 1);
6308	6637	defer self.gpa.free(weights);
6309	6638
...	...	@@ -6336,75 +6665,66 @@ pub const FuncGen = struct {
6336	6665	break :weights @enumFromInt(@intFromEnum(tuple));
6337	6666	};
6338	6667
6339		var wip_switch = try self.wip.@"switch"(cond_int, llvm_else_block, llvm_cases_len, weights);
6340		defer wip_switch.finish(&self.wip);
	6668	const dispatch_info: SwitchDispatchInfo = .{
	6669	.case_blocks = case_blocks,
	6670	.switch_weights = weights,
	6671	.jmp_table = jmp_table,
	6672	};
	6673
	6674	if (is_dispatch_loop) {
	6675	try self.switch_dispatch_info.putNoClobber(self.gpa, inst, dispatch_info);
	6676	}
	6677	defer if (is_dispatch_loop) {
	6678	assert(self.switch_dispatch_info.remove(inst));
	6679	};
	6680
	6681	// Generate the initial dispatch.
	6682	// If this is a simple `switch_br`, this is the only dispatch.
	6683	try self.lowerSwitchDispatch(inst, switch_br.operand, dispatch_info);
6341	6684
	6685	// Iterate the cases and generate their bodies.
6342	6686	var it = switch_br.iterateCases();
6343		var any_ranges = false;
6344	6687	while (it.next()) \|case\| {
6345		if (case.ranges.len > 0) any_ranges = true;
6346	6688	const case_block = case_blocks[case.idx];
6347		case_block.ptr(&self.wip).incoming += @intCast(case.items.len);
6348		// Handle scalar items, and generate the block.
6349		// We'll generate conditionals for the ranges later on.
6350		for (case.items) \|item\| {
6351		const llvm_item = (try self.resolveInst(item)).toConst().?;
6352		const llvm_int_item = if (llvm_item.typeOf(&o.builder).isPointer(&o.builder))
6353		try o.builder.castConst(.ptrtoint, llvm_item, llvm_usize)
6354		else
6355		llvm_item;
6356		try wip_switch.addCase(llvm_int_item, case_block, &self.wip);
6357		}
6358	6689	self.wip.cursor = .{ .block = case_block };
6359	6690	if (switch_br.getHint(case.idx) == .cold) _ = try self.wip.callIntrinsicAssumeCold();
6360		try self.genBodyDebugScope(null, case.body, .poi);
	6691	try self.genBodyDebugScope(null, case.body, .none);
6361	6692	}
6362
	6693	self.wip.cursor = .{ .block = case_blocks[case_blocks.len - 1] };
6363	6694	const else_body = it.elseBody();
6364		self.wip.cursor = .{ .block = llvm_else_block };
6365		if (any_ranges) {
6366		const cond_ty = self.typeOf(switch_br.operand);
6367		// Add conditionals for the ranges, directing to the relevant bb.
6368		// We don't need to consider `cold` branch hints since that information is stored
6369		// in the target bb body, but we do care about likely/unlikely/unpredictable.
6370		it = switch_br.iterateCases();
6371		while (it.next()) \|case\| {
6372		if (case.ranges.len == 0) continue;
6373		const case_block = case_blocks[case.idx];
6374		const hint = switch_br.getHint(case.idx);
6375		case_block.ptr(&self.wip).incoming += 1;
6376		const next_else_block = try self.wip.block(1, "Default");
6377		var range_cond: ?Builder.Value = null;
6378		for (case.ranges) \|range\| {
6379		const llvm_min = try self.resolveInst(range[0]);
6380		const llvm_max = try self.resolveInst(range[1]);
6381		const cond_part = try self.wip.bin(
6382		.@"and",
6383		try self.cmp(.normal, .gte, cond_ty, cond, llvm_min),
6384		try self.cmp(.normal, .lte, cond_ty, cond, llvm_max),
6385		"",
6386		);
6387		if (range_cond) \|prev\| {
6388		range_cond = try self.wip.bin(.@"or", prev, cond_part, "");
6389		} else range_cond = cond_part;
6390		}
6391		_ = try self.wip.brCond(range_cond.?, case_block, next_else_block, switch (hint) {
6392		.none, .cold => .none,
6393		.unpredictable => .unpredictable,
6394		.likely => .then_likely,
6395		.unlikely => .else_likely,
6396		});
6397		self.wip.cursor = .{ .block = next_else_block };
6398		}
6399		}
6400	6695	if (switch_br.getElseHint() == .cold) _ = try self.wip.callIntrinsicAssumeCold();
6401		if (else_body.len != 0) {
6402		try self.genBodyDebugScope(null, else_body, .poi);
	6696	if (else_body.len > 0) {
	6697	try self.genBodyDebugScope(null, it.elseBody(), .none);
6403	6698	} else {
6404	6699	_ = try self.wip.@"unreachable"();
6405	6700	}
	6701	}
6406	6702
6407		// No need to reset the insert cursor since this instruction is noreturn.
	6703	fn switchCaseItemRange(self: *FuncGen, switch_br: Air.UnwrappedSwitch) [2]Value {
	6704	const zcu = self.ng.object.pt.zcu;
	6705	var it = switch_br.iterateCases();
	6706	var min: ?Value = null;
	6707	var max: ?Value = null;
	6708	while (it.next()) \|case\| {
	6709	for (case.items) \|item\| {
	6710	const val = Value.fromInterned(item.toInterned().?);
	6711	const low = if (min) \|m\| val.compareHetero(.lt, m, zcu) else true;
	6712	const high = if (max) \|m\| val.compareHetero(.gt, m, zcu) else true;
	6713	if (low) min = val;
	6714	if (high) max = val;
	6715	}
	6716	for (case.ranges) \|range\| {
	6717	const vals: [2]Value = .{
	6718	Value.fromInterned(range[0].toInterned().?),
	6719	Value.fromInterned(range[1].toInterned().?),
	6720	};
	6721	const low = if (min) \|m\| vals[0].compareHetero(.lt, m, zcu) else true;
	6722	const high = if (max) \|m\| vals[1].compareHetero(.gt, m, zcu) else true;
	6723	if (low) min = vals[0];
	6724	if (high) max = vals[1];
	6725	}
	6726	}
	6727	return .{ min.?, max.? };
6408	6728	}
6409	6729
6410	6730	fn airLoop(self: *FuncGen, inst: Air.Inst.Index) !void {

src/print_air.zig+2-1

...	...	@@ -296,11 +296,12 @@ const Writer = struct {
296	296	.aggregate_init => try w.writeAggregateInit(s, inst),
297	297	.union_init => try w.writeUnionInit(s, inst),
298	298	.br => try w.writeBr(s, inst),
	299	.switch_dispatch => try w.writeBr(s, inst),
299	300	.repeat => try w.writeRepeat(s, inst),
300	301	.cond_br => try w.writeCondBr(s, inst),
301	302	.@"try", .try_cold => try w.writeTry(s, inst),
302	303	.try_ptr, .try_ptr_cold => try w.writeTryPtr(s, inst),
303		.switch_br => try w.writeSwitchBr(s, inst),
	304	.loop_switch_br, .switch_br => try w.writeSwitchBr(s, inst),
304	305	.cmpxchg_weak, .cmpxchg_strong => try w.writeCmpxchg(s, inst),
305	306	.fence => try w.writeFence(s, inst),
306	307	.atomic_load => try w.writeAtomicLoad(s, inst),

src/print_zir.zig+1

...	...	@@ -302,6 +302,7 @@ const Writer = struct {
302	302
303	303	.@"break",
304	304	.break_inline,
	305	.switch_continue,
305	306	=> try self.writeBreak(stream, inst),
306	307
307	308	.slice_start => try self.writeSliceStart(stream, inst),

test/behavior.zig+1

...	...	@@ -88,6 +88,7 @@ test {
88	88	_ = @import("behavior/struct_contains_null_ptr_itself.zig");
89	89	_ = @import("behavior/struct_contains_slice_of_itself.zig");
90	90	_ = @import("behavior/switch.zig");
	91	_ = @import("behavior/switch_loop.zig");
91	92	_ = @import("behavior/switch_prong_err_enum.zig");
92	93	_ = @import("behavior/switch_prong_implicit_cast.zig");
93	94	_ = @import("behavior/switch_on_captured_error.zig");

test/behavior/switch_loop.zig created+205

...	...	@@ -0,0 +1,205 @@
	1	const builtin = @import("builtin");
	2	const std = @import("std");
	3	const expect = std.testing.expect;
	4
	5	test "simple switch loop" {
	6	if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
	7	if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
	8	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
	9	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
	10	if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
	11	if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; // TODO
	12
	13	const S = struct {
	14	fn doTheTest() !void {
	15	var start: u32 = undefined;
	16	start = 32;
	17	const result: u32 = s: switch (start) {
	18	0 => 0,
	19	1 => 1,
	20	2 => 2,
	21	3 => 3,
	22	else => \|x\| continue :s x / 2,
	23	};
	24	try expect(result == 2);
	25	}
	26	};
	27	try S.doTheTest();
	28	try comptime S.doTheTest();
	29	}
	30
	31	test "switch loop with ranges" {
	32	if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
	33	if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
	34	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
	35	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
	36	if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
	37	if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; // TODO
	38
	39	const S = struct {
	40	fn doTheTest() !void {
	41	var start: u32 = undefined;
	42	start = 32;
	43	const result = s: switch (start) {
	44	0...3 => \|x\| x,
	45	else => \|x\| continue :s x / 2,
	46	};
	47	try expect(result == 2);
	48	}
	49	};
	50	try S.doTheTest();
	51	try comptime S.doTheTest();
	52	}
	53
	54	test "switch loop on enum" {
	55	if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
	56	if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
	57	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
	58	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
	59	if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
	60	if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; // TODO
	61
	62	const S = struct {
	63	const E = enum { a, b, c };
	64
	65	fn doTheTest() !void {
	66	var start: E = undefined;
	67	start = .a;
	68	const result: u32 = s: switch (start) {
	69	.a => continue :s .b,
	70	.b => continue :s .c,
	71	.c => 123,
	72	};
	73	try expect(result == 123);
	74	}
	75	};
	76	try S.doTheTest();
	77	try comptime S.doTheTest();
	78	}
	79
	80	test "switch loop on tagged union" {
	81	if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
	82	if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
	83	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
	84	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
	85	if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
	86	if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; // TODO
	87
	88	const S = struct {
	89	const U = union(enum) {
	90	a: u32,
	91	b: f32,
	92	c: f32,
	93	};
	94
	95	fn doTheTest() !void {
	96	var start: U = undefined;
	97	start = .{ .a = 80 };
	98	const result = s: switch (start) {
	99	.a => \|x\| switch (x) {
	100	0...49 => continue :s .{ .b = @floatFromInt(x) },
	101	50 => continue :s .{ .c = @floatFromInt(x) },
	102	else => continue :s .{ .a = x / 2 },
	103	},
	104	.b => \|x\| x,
	105	.c => return error.TestFailed,
	106	};
	107	try expect(result == 40.0);
	108	}
	109	};
	110	try S.doTheTest();
	111	try comptime S.doTheTest();
	112	}
	113
	114	test "switch loop dispatching instructions" {
	115	if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
	116	if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
	117	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
	118	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
	119	if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
	120	if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; // TODO
	121
	122	const S = struct {
	123	const Inst = union(enum) {
	124	set: u32,
	125	add: u32,
	126	sub: u32,
	127	end,
	128	};
	129
	130	fn doTheTest() !void {
	131	var insts: [5]Inst = undefined;
	132	@memcpy(&insts, &[5]Inst{
	133	.{ .set = 123 },
	134	.{ .add = 100 },
	135	.{ .sub = 50 },
	136	.{ .sub = 10 },
	137	.end,
	138	});
	139	var i: u32 = 0;
	140	var cur: u32 = undefined;
	141	eval: switch (insts[0]) {
	142	.set => \|x\| {
	143	cur = x;
	144	i += 1;
	145	continue :eval insts[i];
	146	},
	147	.add => \|x\| {
	148	cur += x;
	149	i += 1;
	150	continue :eval insts[i];
	151	},
	152	.sub => \|x\| {
	153	cur -= x;
	154	i += 1;
	155	continue :eval insts[i];
	156	},
	157	.end => {},
	158	}
	159	try expect(cur == 163);
	160	}
	161	};
	162	try S.doTheTest();
	163	try comptime S.doTheTest();
	164	}
	165
	166	test "switch loop with pointer capture" {
	167	if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
	168	if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
	169	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
	170	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
	171	if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
	172	if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; // TODO
	173
	174	const S = struct {
	175	const U = union(enum) {
	176	a: u32,
	177	b: u32,
	178	c: u32,
	179	};
	180
	181	fn doTheTest() !void {
	182	var a: U = .{ .a = 100 };
	183	var b: U = .{ .b = 200 };
	184	var c: U = .{ .c = 300 };
	185	inc: switch (a) {
	186	.a => \|*x\| {
	187	x.* += 1;
	188	continue :inc b;
	189	},
	190	.b => \|*x\| {
	191	x.* += 10;
	192	continue :inc c;
	193	},
	194	.c => \|*x\| {
	195	x.* += 50;
	196	},
	197	}
	198	try expect(a.a == 101);
	199	try expect(b.b == 210);
	200	try expect(c.c == 350);
	201	}
	202	};
	203	try S.doTheTest();
	204	try comptime S.doTheTest();
	205	}