Commit 37f763560b020ae0ef5ed076afc1872a57266b45 | zig

author	Jacob Young <jacobly@ziglang.org> 2025-06-05 22:25:13-04:00
committer	Andrew Kelley <andrew@ziglang.org> 2025-06-06 23:42:15-07:00
log	37f763560b020ae0ef5ed076afc1872a57266b45
tree	5fd862f59483a95a04f30fe137e668cf78b37764
parent	f28ef7ee29ee1e8a1df092f5c4fff0497718415c

x86_64: fix switch dispatch bug

Also closes #23902

6 files changed, 33 insertions(+), 18 deletions(-)

src
- Compilation.zig
- IncrementalDebugServer.zig
- arch
  - x86_64
    CodeGen.zig
- main.zig
test
- behavior
  - switch.zig
- standalone
  - stack_iterator
    build.zig

src/Compilation.zig+1-1

...	...	@@ -774,7 +774,7 @@ pub const Directories = struct {
774	774	/// `comp.debug_incremental`. It is inline so that comptime-known `false` propagates to the caller,
775	775	/// preventing debugging features from making it into release builds of the compiler.
776	776	pub inline fn debugIncremental(comp: *const Compilation) bool {
777		if (!build_options.enable_debug_extensions) return false;
	777	if (!build_options.enable_debug_extensions or builtin.single_threaded) return false;
778	778	return comp.debug_incremental;
779	779	}
780	780

src/IncrementalDebugServer.zig+1-1

...	...	@@ -10,7 +10,7 @@
10	10
11	11	comptime {
12	12	// This file should only be referenced when debug extensions are enabled.
13		std.debug.assert(@import("build_options").enable_debug_extensions);
	13	std.debug.assert(@import("build_options").enable_debug_extensions and !@import("builtin").single_threaded);
14	14	}
15	15
16	16	zcu: *Zcu,

src/arch/x86_64/CodeGen.zig+14-14

...	...	@@ -161505,10 +161505,12 @@ fn genBody(cg: *CodeGen, body: []const Air.Inst.Index) InnerError!void {
161505	161505	for (elems, 0..) \|elem_ref, field_index\| {
161506	161506	const elem_dies = bt.feed();
161507	161507	if (loaded_struct.fieldIsComptime(ip, field_index)) continue;
161508		var elem = try cg.tempFromOperand(elem_ref, elem_dies);
161509		try res.write(&elem, .{ .disp = @intCast(loaded_struct.offsets.get(ip)[field_index]) }, cg);
161510		try elem.die(cg);
161511		try cg.resetTemps(reset_index);
	161508	if (!hack_around_sema_opv_bugs or Type.fromInterned(loaded_struct.field_types.get(ip)[field_index]).hasRuntimeBitsIgnoreComptime(zcu)) {
	161509	var elem = try cg.tempFromOperand(elem_ref, elem_dies);
	161510	try res.write(&elem, .{ .disp = @intCast(loaded_struct.offsets.get(ip)[field_index]) }, cg);
	161511	try elem.die(cg);
	161512	try cg.resetTemps(reset_index);
	161513	}
161512	161514	}
161513	161515	},
161514	161516	.@"packed" => return cg.fail("failed to select {s} {}", .{
...	...	@@ -175015,8 +175017,7 @@ fn lowerSwitchBr(
175015	175017	) !void {
175016	175018	const zcu = cg.pt.zcu;
175017	175019	const condition_ty = cg.typeOf(switch_br.operand);
175018		const condition_int_info = cg.intInfo(condition_ty).?;
175019		const condition_int_ty = try cg.pt.intType(condition_int_info.signedness, condition_int_info.bits);
	175020	const unsigned_condition_ty = try cg.pt.intType(.unsigned, cg.intInfo(condition_ty).?.bits);
175020	175021
175021	175022	const ExpectedContents = extern struct {
175022	175023	liveness_deaths: [1 << 8 \| 1]Air.Inst.Index,
...	...	@@ -175087,8 +175088,8 @@ fn lowerSwitchBr(
175087	175088	.{ .air_ref = Air.internedToRef(min.?.toIntern()) },
175088	175089	);
175089	175090	const else_reloc = if (switch_br.else_body_len > 0) else_reloc: {
175090		var cond_temp = try cg.tempInit(condition_ty, condition_index);
175091		var table_max_temp = try cg.tempFromValue(try cg.pt.intValue(condition_int_ty, table_len - 1));
	175091	var cond_temp = try cg.tempInit(unsigned_condition_ty, condition_index);
	175092	var table_max_temp = try cg.tempFromValue(try cg.pt.intValue(unsigned_condition_ty, table_len - 1));
175092	175093	const cc_temp = cond_temp.cmpInts(.gt, &table_max_temp, cg) catch \|err\| switch (err) {
175093	175094	error.SelectFailed => unreachable,
175094	175095	else => \|e\| return e,
...	...	@@ -175416,8 +175417,7 @@ fn airSwitchDispatch(self: *CodeGen, inst: Air.Inst.Index) !void {
175416	175417
175417	175418	if (self.loop_switches.getPtr(br.block_inst)) \|table\| {
175418	175419	const condition_ty = self.typeOf(br.operand);
175419		const condition_int_info = self.intInfo(condition_ty).?;
175420		const condition_int_ty = try self.pt.intType(condition_int_info.signedness, condition_int_info.bits);
	175420	const unsigned_condition_ty = try self.pt.intType(.unsigned, self.intInfo(condition_ty).?.bits);
175421	175421	const condition_mcv = block_tracking.short;
175422	175422	try self.spillEflagsIfOccupied();
175423	175423	if (table.min.orderAgainstZero(self.pt.zcu).compare(.neq)) try self.genBinOpMir(
...	...	@@ -175429,8 +175429,8 @@ fn airSwitchDispatch(self: *CodeGen, inst: Air.Inst.Index) !void {
175429	175429	switch (table.else_relocs) {
175430	175430	.@"unreachable" => {},
175431	175431	.forward => \|*else_relocs\| {
175432		var cond_temp = try self.tempInit(condition_ty, condition_mcv);
175433		var table_max_temp = try self.tempFromValue(try self.pt.intValue(condition_int_ty, table.len - 1));
	175432	var cond_temp = try self.tempInit(unsigned_condition_ty, condition_mcv);
	175433	var table_max_temp = try self.tempFromValue(try self.pt.intValue(unsigned_condition_ty, table.len - 1));
175434	175434	const cc_temp = cond_temp.cmpInts(.gt, &table_max_temp, self) catch \|err\| switch (err) {
175435	175435	error.SelectFailed => unreachable,
175436	175436	else => \|e\| return e,
...	...	@@ -175441,8 +175441,8 @@ fn airSwitchDispatch(self: *CodeGen, inst: Air.Inst.Index) !void {
175441	175441	try cc_temp.die(self);
175442	175442	},
175443	175443	.backward => \|else_reloc\| {
175444		var cond_temp = try self.tempInit(condition_ty, condition_mcv);
175445		var table_max_temp = try self.tempFromValue(try self.pt.intValue(condition_int_ty, table.len - 1));
	175444	var cond_temp = try self.tempInit(unsigned_condition_ty, condition_mcv);
	175445	var table_max_temp = try self.tempFromValue(try self.pt.intValue(unsigned_condition_ty, table.len - 1));
175446	175446	const cc_temp = cond_temp.cmpInts(.gt, &table_max_temp, self) catch \|err\| switch (err) {
175447	175447	error.SelectFailed => unreachable,
175448	175448	else => \|e\| return e,

src/main.zig+2-2

...	...	@@ -39,7 +39,7 @@ test {
39	39	_ = Package;
40	40	}
41	41
42		const thread_stack_size = 50 << 20;
	42	const thread_stack_size = 60 << 20;
43	43
44	44	pub const std_options: std.Options = .{
45	45	.wasiCwd = wasi_cwd,
...	...	@@ -4208,7 +4208,7 @@ fn serve(
4208	4208	const main_progress_node = std.Progress.start(.{});
4209	4209	const file_system_inputs = comp.file_system_inputs.?;
4210	4210
4211		const IncrementalDebugServer = if (build_options.enable_debug_extensions)
	4211	const IncrementalDebugServer = if (build_options.enable_debug_extensions and !builtin.single_threaded)
4212	4212	@import("IncrementalDebugServer.zig")
4213	4213	else
4214	4214	void;

test/behavior/switch.zig+9

...	...	@@ -1056,3 +1056,12 @@ test "unlabeled break ignores switch" {
1056	1056	};
1057	1057	try expect(result == 123);
1058	1058	}
	1059
	1060	test "switch on a signed value smaller than the smallest prong value" {
	1061	var v: i32 = undefined;
	1062	v = -1;
	1063	switch (v) {
	1064	inline 0...10 => return error.TestFailed,
	1065	else => {},
	1066	}
	1067	}

test/standalone/stack_iterator/build.zig+6

...	...	@@ -52,6 +52,8 @@ pub fn build(b: *std.Build) void {
52	52	.unwind_tables = .@"async",
53	53	.omit_frame_pointer = true,
54	54	}),
	55	// self-hosted lacks omit_frame_pointer support
	56	.use_llvm = true,
55	57	});
56	58
57	59	const run_cmd = b.addRunArtifact(exe);
...	...	@@ -97,6 +99,8 @@ pub fn build(b: *std.Build) void {
97	99	.unwind_tables = if (target.result.os.tag.isDarwin()) .@"async" else null,
98	100	.omit_frame_pointer = true,
99	101	}),
	102	// zig objcopy doesn't support incremental binaries
	103	.use_llvm = true,
100	104	});
101	105
102	106	exe.linkLibrary(c_shared_lib);
...	...	@@ -137,6 +141,8 @@ pub fn build(b: *std.Build) void {
137	141	.unwind_tables = null,
138	142	.omit_frame_pointer = false,
139	143	}),
	144	// self-hosted lacks omit_frame_pointer support
	145	.use_llvm = true,
140	146	});
141	147
142	148	// This "freestanding" binary is runnable because it invokes the