Commit d5db02728ce3ff3ba74a3e3f9050c3ea9ed34752 | zig

author	Alex Rønne Petersen <alex@alexrp.com> 2025-01-20 07:24:12+01:00
committer	GitHub <noreply@github.com> 2025-01-20 07:24:12+01:00
log	d5db02728ce3ff3ba74a3e3f9050c3ea9ed34752
tree	ff3cdbf992c1072f5e72b856d3fb53d7cd6dd9e3
parent	5cfcb015033864c769235726975ab9919c217ef9
parent	45bb4f955c8c8be40ed8b2247eaaa70661cf1b3d
signature	Signed by PGP key B5690EEEBB952194

Merge pull request #22530 from alexrp/omit-unwind-tables

Fix building the standard library without CFI directives

18 files changed, 147 insertions(+), 8 deletions(-)

lib
- std
  - os
    linux
    aarch64.zig
    hexagon.zig
    loongarch64.zig
    mips.zig
    mips64.zig
    powerpc.zig
    powerpc64.zig
    riscv32.zig
    riscv64.zig
    s390x.zig
    sparc64.zig
    x86.zig
    x86_64.zig
  - start.zig
src
- Package
  - Module.zig
test
- standalone
  - build.zig.zon
  - omit_cfi
    build.zig
    main.zig

lib/std/os/linux/aarch64.zig+7-1

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const maxInt = std.math.maxInt;
3	4	const linux = std.os.linux;
...	...	@@ -122,7 +123,12 @@ pub fn clone() callconv(.Naked) usize {
122	123	\\ ret
123	124	\\
124	125	\\ // child
125		\\1: .cfi_undefined lr
	126	\\1:
	127	);
	128	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
	129	\\ .cfi_undefined lr
	130	);
	131	asm volatile (
126	132	\\ mov fp, 0
127	133	\\ mov lr, 0
128	134	\\

lib/std/os/linux/hexagon.zig+5-1

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const iovec = std.posix.iovec;
3	4	const iovec_const = std.posix.iovec_const;
...	...	@@ -117,8 +118,11 @@ pub fn clone() callconv(.Naked) usize {
117	118	\\
118	119	\\ p0 = cmp.eq(r0, #0)
119	120	\\ if (!p0) dealloc_return
120		\\
	121	);
	122	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
121	123	\\ .cfi_undefined r31
	124	);
	125	asm volatile (
122	126	\\ r30 = #0
123	127	\\ r31 = #0
124	128	\\

lib/std/os/linux/loongarch64.zig+5

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const linux = std.os.linux;
3	4	const SYS = linux.SYS;
...	...	@@ -121,7 +122,11 @@ pub fn clone() callconv(.Naked) usize {
121	122	\\ beqz $a0, 1f # whether child process
122	123	\\ jirl $zero, $ra, 0 # parent process return
123	124	\\1:
	125	);
	126	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
124	127	\\ .cfi_undefined 1
	128	);
	129	asm volatile (
125	130	\\ move $fp, $zero
126	131	\\ move $ra, $zero
127	132	\\

lib/std/os/linux/mips.zig+5

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const maxInt = std.math.maxInt;
3	4	const linux = std.os.linux;
...	...	@@ -231,7 +232,11 @@ pub fn clone() callconv(.Naked) usize {
231	232	\\ jr $ra
232	233	\\ nop
233	234	\\1:
	235	);
	236	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
234	237	\\ .cfi_undefined $ra
	238	);
	239	asm volatile (
235	240	\\ move $fp, $zero
236	241	\\ move $ra, $zero
237	242	\\

lib/std/os/linux/mips64.zig+5

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const maxInt = std.math.maxInt;
3	4	const linux = std.os.linux;
...	...	@@ -210,7 +211,11 @@ pub fn clone() callconv(.Naked) usize {
210	211	\\ jr $ra
211	212	\\ nop
212	213	\\1:
	214	);
	215	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
213	216	\\ .cfi_undefined $ra
	217	);
	218	asm volatile (
214	219	\\ move $fp, $zero
215	220	\\ move $ra, $zero
216	221	\\

lib/std/os/linux/powerpc.zig+5

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const maxInt = std.math.maxInt;
3	4	const linux = std.os.linux;
...	...	@@ -176,7 +177,11 @@ pub fn clone() callconv(.Naked) usize {
176	177	\\
177	178	\\ #else: we're the child
178	179	\\ 2:
	180	);
	181	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
179	182	\\ .cfi_undefined lr
	183	);
	184	asm volatile (
180	185	\\ li 31, 0
181	186	\\ mtlr 0
182	187	\\

lib/std/os/linux/powerpc64.zig+5

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const maxInt = std.math.maxInt;
3	4	const linux = std.os.linux;
...	...	@@ -161,7 +162,11 @@ pub fn clone() callconv(.Naked) usize {
161	162	\\ bnelr cr7
162	163	\\
163	164	\\ # we're the child
	165	);
	166	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
164	167	\\ .cfi_undefined lr
	168	);
	169	asm volatile (
165	170	\\ li 31, 0
166	171	\\ mtlr 0
167	172	\\

lib/std/os/linux/riscv32.zig+7-1

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const iovec = std.posix.iovec;
3	4	const iovec_const = std.posix.iovec_const;
...	...	@@ -120,7 +121,12 @@ pub fn clone() callconv(.Naked) usize {
120	121	\\ ret
121	122	\\
122	123	\\ # Child
123		\\1: .cfi_undefined ra
	124	\\1:
	125	);
	126	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
	127	\\ .cfi_undefined ra
	128	);
	129	asm volatile (
124	130	\\ mv fp, zero
125	131	\\ mv ra, zero
126	132	\\

lib/std/os/linux/riscv64.zig+7-1

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const iovec = std.posix.iovec;
3	4	const iovec_const = std.posix.iovec_const;
...	...	@@ -120,7 +121,12 @@ pub fn clone() callconv(.Naked) usize {
120	121	\\ ret
121	122	\\
122	123	\\ # Child
123		\\1: .cfi_undefined ra
	124	\\1:
	125	);
	126	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
	127	\\ .cfi_undefined ra
	128	);
	129	asm volatile (
124	130	\\ mv fp, zero
125	131	\\ mv ra, zero
126	132	\\

lib/std/os/linux/s390x.zig+5

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const iovec = std.posix.iovec;
3	4	const iovec_const = std.posix.iovec_const;
...	...	@@ -134,7 +135,11 @@ pub fn clone() callconv(.Naked) usize {
134	135	\\bnzr %%r14
135	136	\\
136	137	\\# we're the child
	138	);
	139	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
137	140	\\.cfi_undefined %%r14
	141	);
	142	asm volatile (
138	143	\\lghi %%r11, 0
139	144	\\lghi %%r14, 0
140	145	\\

lib/std/os/linux/sparc64.zig+5

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const maxInt = std.math.maxInt;
3	4	const pid_t = linux.pid_t;
...	...	@@ -215,7 +216,11 @@ pub fn clone() callconv(.Naked) usize {
215	216	\\ restore
216	217	\\2:
217	218	\\ # Child process
	219	);
	220	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
218	221	\\ .cfi_undefined %%i7
	222	);
	223	asm volatile (
219	224	\\ mov %%g0, %%fp
220	225	\\ mov %%g0, %%i7
221	226	\\

lib/std/os/linux/x86.zig+5

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const maxInt = std.math.maxInt;
3	4	const linux = std.os.linux;
...	...	@@ -156,7 +157,11 @@ pub fn clone() callconv(.Naked) usize {
156	157	\\ retl
157	158	\\
158	159	\\1:
	160	);
	161	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
159	162	\\ .cfi_undefined %%eip
	163	);
	164	asm volatile (
160	165	\\ xorl %%ebp,%%ebp
161	166	\\
162	167	\\ popl %%eax

lib/std/os/linux/x86_64.zig+7-1

...	...	@@ -1,3 +1,4 @@
	1	const builtin = @import("builtin");
1	2	const std = @import("../../std.zig");
2	3	const maxInt = std.math.maxInt;
3	4	const linux = std.os.linux;
...	...	@@ -117,7 +118,12 @@ pub fn clone() callconv(.Naked) usize {
117	118	\\ jz 1f
118	119	\\ retq
119	120	\\
120		\\1: .cfi_undefined %%rip
	121	\\1:
	122	);
	123	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
	124	\\ .cfi_undefined %%rip
	125	);
	126	asm volatile (
121	127	\\ xorl %%ebp,%%ebp
122	128	\\
123	129	\\ popq %%rdi

lib/std/start.zig+2-2

...	...	@@ -231,8 +231,8 @@ fn _start() callconv(.naked) noreturn {
231	231	}
232	232
233	233	// This is the first userspace frame. Prevent DWARF-based unwinders from unwinding further. We
234		// prevent FP-based unwinders from unwinding further by zeroing the register further below.
235		asm volatile (switch (native_arch) {
	234	// prevent FP-based unwinders from unwinding further by zeroing the register below.
	235	if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (switch (native_arch) {
236	236	.arc => ".cfi_undefined blink",
237	237	.arm, .armeb, .thumb, .thumbeb => "", // https://github.com/llvm/llvm-project/issues/115891
238	238	.aarch64, .aarch64_be => ".cfi_undefined lr",

src/Package/Module.zig+1-1

...	...	@@ -387,7 +387,7 @@ pub fn create(arena: Allocator, options: CreateOptions) !*Package.Module {
387	387	.zig_backend = zig_backend,
388	388	.output_mode = options.global.output_mode,
389	389	.link_mode = options.global.link_mode,
390		.unwind_tables = options.global.any_unwind_tables,
	390	.unwind_tables = unwind_tables,
391	391	.is_test = options.global.is_test,
392	392	.single_threaded = single_threaded,
393	393	.link_libc = options.global.link_libc,

test/standalone/build.zig.zon+3

...	...	@@ -183,6 +183,9 @@
183	183	.empty_global_error_set = .{
184	184	.path = "empty_global_error_set",
185	185	},
	186	.omit_cfi = .{
	187	.path = "omit_cfi",
	188	},
186	189	},
187	190	.paths = .{
188	191	"build.zig",

test/standalone/omit_cfi/build.zig created+67

...	...	@@ -0,0 +1,67 @@
	1	const std = @import("std");
	2
	3	pub fn build(b: *std.Build) void {
	4	inline for (.{
	5	.aarch64,
	6	.aarch64_be,
	7	.hexagon,
	8	.loongarch64,
	9	.mips,
	10	.mipsel,
	11	.mips64,
	12	.mips64el,
	13	.powerpc,
	14	.powerpcle,
	15	.powerpc64,
	16	.powerpc64le,
	17	.riscv32,
	18	.riscv64,
	19	.s390x,
	20	.sparc64,
	21	.x86,
	22	.x86_64,
	23	}) \|arch\| {
	24	const target = b.resolveTargetQuery(.{
	25	.cpu_arch = arch,
	26	.os_tag = .linux,
	27	});
	28
	29	const omit_dbg = b.addExecutable(.{
	30	.name = b.fmt("{s}-linux-omit-dbg", .{@tagName(arch)}),
	31	.root_module = b.createModule(.{
	32	.root_source_file = b.path("main.zig"),
	33	.target = target,
	34	.optimize = .Debug,
	35	// We are mainly concerned with CFI directives in our non-libc startup code and syscall
	36	// code, so make it explicit that we don't want libc.
	37	.link_libc = false,
	38	.strip = true,
	39	}),
	40	});
	41
	42	const omit_uwt = b.addExecutable(.{
	43	.name = b.fmt("{s}-linux-omit-uwt", .{@tagName(arch)}),
	44	.root_module = b.createModule(.{
	45	.root_source_file = b.path("main.zig"),
	46	.target = target,
	47	.optimize = .Debug,
	48	.link_libc = false,
	49	.unwind_tables = .none,
	50	}),
	51	});
	52
	53	const omit_both = b.addExecutable(.{
	54	.name = b.fmt("{s}-linux-omit-both", .{@tagName(arch)}),
	55	.root_module = b.createModule(.{
	56	.root_source_file = b.path("main.zig"),
	57	.target = target,
	58	.optimize = .Debug,
	59	.link_libc = false,
	60	.strip = true,
	61	.unwind_tables = .none,
	62	}),
	63	});
	64
	65	inline for (.{ omit_dbg, omit_uwt, omit_both }) \|step\| b.installArtifact(step);
	66	}
	67	}

test/standalone/omit_cfi/main.zig created+1

...	...	@@ -0,0 +1 @@
	1	pub fn main() void {}