Commit be08d2bdbd2f64ccb9ef0f985a57a4bf89b9aebb | zig

author	Luuk de Gram <luuk@degram.dev> 2022-04-17 19:41:05+02:00
committer	Luuk de Gram <luuk@degram.dev> 2022-04-19 19:58:49+02:00
log	be08d2bdbd2f64ccb9ef0f985a57a4bf89b9aebb
tree	727d36adc443701b6aa8221797dc082f3670a290
parent	2193f7c4a2b56f67bf07d27c3f715cf3969c392f
signature	Commit is signed but in an unrecognized format.

wasm: Fix unreachable paths

When the last instruction is a debug instruction, the type of it is void.
Similarly for 'noreturn' emit an 'unreachable' instruction to tell the wasm-validator
the path cannot be reached.

Also respect the '--strip' flag in the self-hosted wasm linker and not emit a 'name' section
when the flag is set to `true`.

3 files changed, 37 insertions(+), 4 deletions(-)

lib
- std
  - debug.zig
src
- arch
  - wasm
    CodeGen.zig
- link
  - Wasm.zig

lib/std/debug.zig+34-2

 @@ -113,11 +113,14 @@ pub fn detectTTYConfig() TTY.Config {
 /// TODO multithreaded awareness
 pub fn dumpCurrentStackTrace(start_addr: ?usize) void {
     nosuspend {
-        const stderr = io.getStdErr().writer();
         if (comptime builtin.target.isWasm()) {
-            stderr.print("Unable to dump stack trace: not implemented for Wasm\n", .{}) catch return;
+            if (native_os == .wasi) {
+                const stderr = io.getStdErr().writer();
+                stderr.print("Unable to dump stack trace: not implemented for Wasm\n", .{}) catch return;
+            }
             return;
         }
+        const stderr = io.getStdErr().writer();
         if (builtin.strip_debug_info) {
             stderr.print("Unable to dump stack trace: debug info stripped\n", .{}) catch return;
             return;
 @@ -138,6 +141,13 @@ pub fn dumpCurrentStackTrace(start_addr: ?usize) void {
 /// TODO multithreaded awareness
 pub fn dumpStackTraceFromBase(bp: usize, ip: usize) void {
     nosuspend {
+        if (comptime builtin.target.isWasm()) {
+            if (native_os == .wasi) {
+                const stderr = io.getStdErr().writer();
+                stderr.print("Unable to dump stack trace: not implemented for Wasm\n", .{}) catch return;
+            }
+            return;
+        }
         const stderr = io.getStdErr().writer();
         if (builtin.strip_debug_info) {
             stderr.print("Unable to dump stack trace: debug info stripped\n", .{}) catch return;
 @@ -208,6 +218,13 @@ pub fn captureStackTrace(first_address: ?usize, stack_trace: *std.builtin.StackT
 /// TODO multithreaded awareness
 pub fn dumpStackTrace(stack_trace: std.builtin.StackTrace) void {
     nosuspend {
+        if (comptime builtin.target.isWasm()) {
+            if (native_os == .wasi) {
+                const stderr = io.getStdErr().writer();
+                stderr.print("Unable to dump stack trace: not implemented for Wasm\n", .{}) catch return;
+            }
+            return;
+        }
         const stderr = io.getStdErr().writer();
         if (builtin.strip_debug_info) {
             stderr.print("Unable to dump stack trace: debug info stripped\n", .{}) catch return;
 @@ -1138,6 +1155,8 @@ pub const DebugInfo = struct {
             return self.lookupModuleWin32(address);
         } else if (native_os == .haiku) {
             return self.lookupModuleHaiku(address);
+        } else if (comptime builtin.target.isWasm()) {
+            return self.lookupModuleWasm(address);
         } else {
             return self.lookupModuleDl(address);
         }
 @@ -1353,6 +1372,12 @@ pub const DebugInfo = struct {
         _ = address;
         @panic("TODO implement lookup module for Haiku");
     }
+    fn lookupModuleWasm(self: *DebugInfo, address: usize) !*ModuleDebugInfo {
+        _ = self;
+        _ = address;
+        @panic("TODO implement lookup module for Wasm");
+    }
 };
 pub const ModuleDebugInfo = switch (native_os) {
 @@ -1632,6 +1657,13 @@ pub const ModuleDebugInfo = switch (native_os) {
             return getSymbolFromDwarf(relocated_address, &self.dwarf);
         }
     },
+    .wasi => struct {
+        pub fn getSymbolAtAddress(self: *@This(), address: usize) !SymbolInfo {
+            _ = self;
+            _ = address;
+            return SymbolInfo{};
+        }
+    },
     else => DW.DwarfInfo,
 };

src/arch/wasm/CodeGen.zig+2-1

...	@@ -871,7 +871,8 @@ fn genFunc(self: *Self) InnerError!void {	...	@@ -871,7 +871,8 @@ fn genFunc(self: *Self) InnerError!void {
871	// we emit an unreachable instruction to tell the stack validator that part will never be reached.	871	// we emit an unreachable instruction to tell the stack validator that part will never be reached.
872	if (func_type.returns.len != 0 and self.air.instructions.len > 0) {	872	if (func_type.returns.len != 0 and self.air.instructions.len > 0) {
873	const inst = @intCast(u32, self.air.instructions.len - 1);	873	const inst = @intCast(u32, self.air.instructions.len - 1);
874	if (self.air.typeOfIndex(inst).isNoReturn()) {	874	const last_inst_ty = self.air.typeOfIndex(inst);
		875	if (!last_inst_ty.hasRuntimeBitsIgnoreComptime() or last_inst_ty.isNoReturn()) {
875	try self.addTag(.@"unreachable");	876	try self.addTag(.@"unreachable");
876	}	877	}
877	}	878	}

src/link/Wasm.zig+1-1

...	@@ -1897,7 +1897,7 @@ pub fn flushModule(self: Wasm, comp: Compilation, prog_node: *std.Progress.Nod	...	@@ -1897,7 +1897,7 @@ pub fn flushModule(self: Wasm, comp: Compilation, prog_node: *std.Progress.Nod
1897	if (data_section_index) \|data_index\| {	1897	if (data_section_index) \|data_index\| {
1898	try self.emitDataRelocations(file, arena, data_index, symbol_table);	1898	try self.emitDataRelocations(file, arena, data_index, symbol_table);
1899	}	1899	}
1900	} else {	1900	} else if (!self.base.options.strip) {
1901	try self.emitNameSection(file, arena);	1901	try self.emitNameSection(file, arena);
1902	}	1902	}
1903	}	1903	}