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aarch64: implement stack probing

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This commit is contained in:
Jacob Young 2025-07-25 16:38:17 -04:00
parent 7c349da49c
commit 1274254c48
4 changed files with 59 additions and 28 deletions
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2
src/Package/Module.zig
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@ -250,7 +250,7 @@ pub fn create(arena: Allocator, options: CreateOptions) !*Package.Module {
}; };
const stack_check = b: { const stack_check = b: {
if (!target_util.supportsStackProbing(target)) { if (!target_util.supportsStackProbing(target, zig_backend)) {
if (options.inherited.stack_check == true) if (options.inherited.stack_check == true)
return error.StackCheckUnsupportedByTarget; return error.StackCheckUnsupportedByTarget;
break :b false; break :b false;

73
src/codegen/aarch64/Select.zig
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@ -6693,8 +6693,8 @@ pub fn layout(
wip_mir_log.debug("{f}<body>:\n", .{nav.fqn.fmt(ip)}); wip_mir_log.debug("{f}<body>:\n", .{nav.fqn.fmt(ip)});
const stack_size: u24 = @intCast(InternPool.Alignment.@"16".forward(isel.stack_size)); const stack_size: u24 = @intCast(InternPool.Alignment.@"16".forward(isel.stack_size));
const stack_size_low: u12 = @truncate(stack_size >> 0); const stack_size_lo: u12 = @truncate(stack_size >> 0);
const stack_size_high: u12 = @truncate(stack_size >> 12); const stack_size_hi: u12 = @truncate(stack_size >> 12);
var saves_buf: [10 + 8 + 8 + 2 + 8]struct { var saves_buf: [10 + 8 + 8 + 2 + 8]struct {
class: enum { integer, vector }, class: enum { integer, vector },
@ -6881,28 +6881,53 @@ pub fn layout(
} }
} }
try isel.emit(.add(.fp, .sp, .{ .immediate = frame_record_offset }));
const scratch_reg: Register = if (isel.stack_align == .@"16") const scratch_reg: Register = if (isel.stack_align == .@"16")
.sp .sp
else if (stack_size == 0) else if (stack_size == 0 and frame_record_offset == 0)
.fp .fp
else else
.x9; .ip0;
try isel.emit(.add(.fp, .sp, .{ .immediate = frame_record_offset })); if (mod.stack_check) {
if (stack_size_high > 0) try isel.emit(.sub(scratch_reg, .sp, .{ if (stack_size_hi > 2) {
.shifted_immediate = .{ .immediate = stack_size_high, .lsl = .@"12" }, try isel.movImmediate(.ip1, stack_size_hi);
})); const loop_label = isel.instructions.items.len;
if (stack_size_low > 0) try isel.emit(.sub( try isel.emit(.sub(.sp, .sp, .{
scratch_reg, .shifted_immediate = .{ .immediate = 1, .lsl = .@"12" },
if (stack_size_high > 0) scratch_reg else .sp, }));
.{ .immediate = stack_size_low }, try isel.emit(.sub(.ip1, .ip1, .{ .immediate = 1 }));
)); try isel.emit(.ldr(.xzr, .{ .base = .sp }));
if (isel.stack_align != .@"16") { try isel.emit(.cbnz(.ip1, -@as(i21, @intCast(
try isel.emit(.@"and"(.sp, scratch_reg, .{ .immediate = .{ (isel.instructions.items.len - loop_label) << 2,
.N = .doubleword, ))));
.immr = -%isel.stack_align.toLog2Units(), } else for (0..stack_size_hi) |_| {
.imms = ~isel.stack_align.toLog2Units(), try isel.emit(.sub(.sp, .sp, .{
} })); .shifted_immediate = .{ .immediate = 1, .lsl = .@"12" },
}));
try isel.emit(.ldr(.xzr, .{ .base = .sp }));
}
if (stack_size_lo > 0) try isel.emit(.sub(
scratch_reg,
.sp,
.{ .immediate = stack_size_lo },
)) else if (scratch_reg.alias == Register.Alias.ip0)
try isel.emit(.add(scratch_reg, .sp, .{ .immediate = 0 }));
} else {
if (stack_size_hi > 0) try isel.emit(.sub(scratch_reg, .sp, .{
.shifted_immediate = .{ .immediate = stack_size_hi, .lsl = .@"12" },
}));
if (stack_size_lo > 0) try isel.emit(.sub(
scratch_reg,
if (stack_size_hi > 0) scratch_reg else .sp,
.{ .immediate = stack_size_lo },
)) else if (scratch_reg.alias == Register.Alias.ip0 and stack_size_hi == 0)
try isel.emit(.add(scratch_reg, .sp, .{ .immediate = 0 }));
} }
if (isel.stack_align != .@"16") try isel.emit(.@"and"(.sp, scratch_reg, .{ .immediate = .{
.N = .doubleword,
.immr = -%isel.stack_align.toLog2Units(),
.imms = ~isel.stack_align.toLog2Units(),
} }));
wip_mir_log.debug("", .{}); wip_mir_log.debug("", .{});
} }
@ -6947,17 +6972,17 @@ pub fn layout(
save_index += 1; save_index += 1;
} else save_index += 1; } else save_index += 1;
} }
if (isel.stack_align != .@"16" or (stack_size_low > 0 and stack_size_high > 0)) { if (isel.stack_align != .@"16" or (stack_size_lo > 0 and stack_size_hi > 0)) {
try isel.emit(switch (frame_record_offset) { try isel.emit(switch (frame_record_offset) {
0 => .add(.sp, .fp, .{ .immediate = 0 }), 0 => .add(.sp, .fp, .{ .immediate = 0 }),
else => |offset| .sub(.sp, .fp, .{ .immediate = offset }), else => |offset| .sub(.sp, .fp, .{ .immediate = offset }),
}); });
} else { } else {
if (stack_size_high > 0) try isel.emit(.add(.sp, .sp, .{ if (stack_size_hi > 0) try isel.emit(.add(.sp, .sp, .{
.shifted_immediate = .{ .immediate = stack_size_high, .lsl = .@"12" }, .shifted_immediate = .{ .immediate = stack_size_hi, .lsl = .@"12" },
})); }));
if (stack_size_low > 0) try isel.emit(.add(.sp, .sp, .{ if (stack_size_lo > 0) try isel.emit(.add(.sp, .sp, .{
.immediate = stack_size_low, .immediate = stack_size_lo,
})); }));
} }
wip_mir_log.debug("{f}<epilogue>:\n", .{nav.fqn.fmt(ip)}); wip_mir_log.debug("{f}<epilogue>:\n", .{nav.fqn.fmt(ip)});

2
src/codegen/aarch64/encoding.zig
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@ -151,6 +151,7 @@ pub const Register = struct {
pub const wzr: Register = .{ .alias = .zr, .format = .{ .integer = .word } }; pub const wzr: Register = .{ .alias = .zr, .format = .{ .integer = .word } };
pub const wsp: Register = .{ .alias = .sp, .format = .{ .integer = .word } }; pub const wsp: Register = .{ .alias = .sp, .format = .{ .integer = .word } };
pub const ip = x16;
pub const ip0 = x16; pub const ip0 = x16;
pub const ip1 = x17; pub const ip1 = x17;
pub const fp = x29; pub const fp = x29;
@ -774,6 +775,7 @@ pub const Register = struct {
ffr, ffr,
pub const ip: Alias = .r16;
pub const ip0: Alias = .r16; pub const ip0: Alias = .r16;
pub const ip1: Alias = .r17; pub const ip1: Alias = .r17;
pub const fp: Alias = .r29; pub const fp: Alias = .r29;

10
src/target.zig
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@ -248,9 +248,13 @@ pub fn selfHostedBackendIsAsRobustAsLlvm(target: *const std.Target) bool {
return false; return false;
} }
pub fn supportsStackProbing(target: *const std.Target) bool { pub fn supportsStackProbing(target: *const std.Target, backend: std.builtin.CompilerBackend) bool {
return target.os.tag != .windows and target.os.tag != .uefi and return switch (backend) {
(target.cpu.arch == .x86 or target.cpu.arch == .x86_64); .stage2_aarch64, .stage2_x86_64 => true,
.stage2_llvm => target.os.tag != .windows and target.os.tag != .uefi and
(target.cpu.arch == .x86 or target.cpu.arch == .x86_64),
else => false,
};
} }
pub fn supportsStackProtector(target: *const std.Target, backend: std.builtin.CompilerBackend) bool { pub fn supportsStackProtector(target: *const std.Target, backend: std.builtin.CompilerBackend) bool {