Commit 5e6a1919c730f7c3ad27b9e5c3ddc8938fc2f43f | zig

author	Matthew Lugg <mlugg@mlugg.co.uk> 2025-09-03 13:11:25+01:00
committer	Matthew Lugg <mlugg@mlugg.co.uk> 2025-09-30 13:44:50+01:00
log	5e6a1919c730f7c3ad27b9e5c3ddc8938fc2f43f
tree	9baf2fcb4e104f0e042e4f0ffb4e8cb8afdef2b1
parent	4b47a377175c30ae148bae1191ae49e3ace819db
signature	Commit is signed but in an unrecognized format.

fix aarch64-macos DWARF unwinding

turns out this isn't technically specific to that target at all; other
targets just don't emit mid-function 'ret' instructions as much so
certain CFI instruction patterns were only seen on aarch64.

thanks to jacob for finding the bug <3

1 files changed, 13 insertions(+), 6 deletions(-)

lib
- std
  - debug
    Dwarf
    Unwind
    VirtualMachine.zig

lib/std/debug/Dwarf/Unwind/VirtualMachine.zig+13-6

...	...	@@ -48,7 +48,10 @@ const ColumnRange = struct {
48	48	};
49	49
50	50	columns: std.ArrayList(Column) = .empty,
51		stack: std.ArrayList(ColumnRange) = .empty,
	51	stack: std.ArrayList(struct {
	52	cfa: Column,
	53	columns: ColumnRange,
	54	}) = .empty,
52	55	current_row: Row = .{},
53	56
54	57	/// The result of executing the CIE's initial_instructions
...	...	@@ -205,17 +208,21 @@ pub fn step(
205	208	column.rule = .{ .register = i.target_register };
206	209	},
207	210	.remember_state => {
208		try self.stack.append(gpa, self.current_row.columns);
	211	try self.stack.append(gpa, .{
	212	.cfa = self.current_row.cfa,
	213	.columns = self.current_row.columns,
	214	});
209	215	self.current_row.copy_on_write = true;
210	216	},
211	217	.restore_state => {
212		const restored_columns = self.stack.pop() orelse return error.InvalidOperation;
	218	const restored = self.stack.pop() orelse return error.InvalidOperation;
213	219	self.columns.shrinkRetainingCapacity(self.columns.items.len - self.current_row.columns.len);
214		try self.columns.ensureUnusedCapacity(gpa, restored_columns.len);
	220	try self.columns.ensureUnusedCapacity(gpa, restored.columns.len);
215	221
	222	self.current_row.cfa = restored.cfa;
216	223	self.current_row.columns.start = self.columns.items.len;
217		self.current_row.columns.len = restored_columns.len;
218		self.columns.appendSliceAssumeCapacity(self.columns.items[restored_columns.start..][0..restored_columns.len]);
	224	self.current_row.columns.len = restored.columns.len;
	225	self.columns.appendSliceAssumeCapacity(self.columns.items[restored.columns.start..][0..restored.columns.len]);
219	226	},
220	227	.def_cfa => \|i\| {
221	228	try self.resolveCopyOnWrite(gpa);