zig/lib/std/zig/system/x86.zig
Andrew Kelley 76d04c1662 zig fmt
2025-07-16 10:27:39 -07:00

787 lines
26 KiB
Zig

const std = @import("std");
const builtin = @import("builtin");
const Target = std.Target;
/// Only covers EAX for now.
const Xcr0 = packed struct(u32) {
x87: bool,
sse: bool,
avx: bool,
bndreg: bool,
bndcsr: bool,
opmask: bool,
zmm_hi256: bool,
hi16_zmm: bool,
pt: bool,
pkru: bool,
pasid: bool,
cet_u: bool,
cet_s: bool,
hdc: bool,
uintr: bool,
lbr: bool,
hwp: bool,
xtilecfg: bool,
xtiledata: bool,
apx: bool,
_reserved: u12,
};
fn setFeature(cpu: *Target.Cpu, feature: Target.x86.Feature, enabled: bool) void {
const idx = @as(Target.Cpu.Feature.Set.Index, @intFromEnum(feature));
if (enabled) cpu.features.addFeature(idx) else cpu.features.removeFeature(idx);
}
inline fn bit(input: u32, offset: u5) bool {
return (input >> offset) & 1 != 0;
}
inline fn hasMask(input: u32, mask: u32) bool {
return (input & mask) == mask;
}
pub fn detectNativeCpuAndFeatures(arch: Target.Cpu.Arch, os: Target.Os, query: Target.Query) Target.Cpu {
_ = query;
var cpu = Target.Cpu{
.arch = arch,
.model = Target.Cpu.Model.generic(arch),
.features = Target.Cpu.Feature.Set.empty,
};
// First we detect features, to use as hints when detecting CPU Model.
detectNativeFeatures(&cpu, os.tag);
var leaf = cpuid(0, 0);
const max_leaf = leaf.eax;
const vendor = leaf.ebx;
if (max_leaf > 0) {
leaf = cpuid(0x1, 0);
const brand_id = leaf.ebx & 0xff;
// Detect model and family
var family = (leaf.eax >> 8) & 0xf;
var model = (leaf.eax >> 4) & 0xf;
if (family == 6 or family == 0xf) {
if (family == 0xf) {
family += (leaf.eax >> 20) & 0xff;
}
model += ((leaf.eax >> 16) & 0xf) << 4;
}
// Now we detect the model.
switch (vendor) {
0x756e6547 => {
detectIntelProcessor(&cpu, family, model, brand_id);
},
0x68747541 => {
if (detectAMDProcessor(cpu, family, model)) |m| cpu.model = m;
},
else => {},
}
}
// Add the CPU model's feature set into the working set, but then
// override with actual detected features again.
cpu.features.addFeatureSet(cpu.model.features);
detectNativeFeatures(&cpu, os.tag);
cpu.features.populateDependencies(cpu.arch.allFeaturesList());
return cpu;
}
fn detectIntelProcessor(cpu: *Target.Cpu, family: u32, model: u32, brand_id: u32) void {
if (brand_id != 0) {
return;
}
switch (family) {
3 => {
cpu.model = &Target.x86.cpu.i386;
return;
},
4 => {
cpu.model = &Target.x86.cpu.i486;
return;
},
5 => {
if (cpu.has(.x86, .mmx)) {
cpu.model = &Target.x86.cpu.pentium_mmx;
return;
}
cpu.model = &Target.x86.cpu.pentium;
return;
},
6 => {
switch (model) {
0x01 => {
cpu.model = &Target.x86.cpu.pentiumpro;
return;
},
0x03, 0x05, 0x06 => {
cpu.model = &Target.x86.cpu.pentium2;
return;
},
0x07, 0x08, 0x0a, 0x0b => {
cpu.model = &Target.x86.cpu.pentium3;
return;
},
0x09, 0x0d, 0x15 => {
cpu.model = &Target.x86.cpu.pentium_m;
return;
},
0x0e => {
cpu.model = &Target.x86.cpu.yonah;
return;
},
0x0f, 0x16 => {
cpu.model = &Target.x86.cpu.core2;
return;
},
0x17, 0x1d => {
cpu.model = &Target.x86.cpu.penryn;
return;
},
0x1a, 0x1e, 0x1f, 0x2e => {
cpu.model = &Target.x86.cpu.nehalem;
return;
},
0x25, 0x2c, 0x2f => {
cpu.model = &Target.x86.cpu.westmere;
return;
},
0x2a, 0x2d => {
cpu.model = &Target.x86.cpu.sandybridge;
return;
},
0x3a, 0x3e => {
cpu.model = &Target.x86.cpu.ivybridge;
return;
},
0x3c, 0x3f, 0x45, 0x46 => {
cpu.model = &Target.x86.cpu.haswell;
return;
},
0x3d, 0x47, 0x4f, 0x56 => {
cpu.model = &Target.x86.cpu.broadwell;
return;
},
0x4e, 0x5e, 0x8e, 0x9e, 0xa5, 0xa6 => {
cpu.model = &Target.x86.cpu.skylake;
return;
},
0xa7 => {
cpu.model = &Target.x86.cpu.rocketlake;
return;
},
0x55 => {
if (cpu.has(.x86, .avx512bf16)) {
cpu.model = &Target.x86.cpu.cooperlake;
return;
} else if (cpu.has(.x86, .avx512vnni)) {
cpu.model = &Target.x86.cpu.cascadelake;
return;
} else {
cpu.model = &Target.x86.cpu.skylake_avx512;
return;
}
},
0x66 => {
cpu.model = &Target.x86.cpu.cannonlake;
return;
},
0x7d, 0x7e => {
cpu.model = &Target.x86.cpu.icelake_client;
return;
},
0x6a, 0x6c => {
cpu.model = &Target.x86.cpu.icelake_server;
return;
},
0x8c, 0x8d => {
cpu.model = &Target.x86.cpu.tigerlake;
return;
},
0x97, 0x9a => {
cpu.model = &Target.x86.cpu.alderlake;
return;
},
0xbe => {
cpu.model = &Target.x86.cpu.gracemont;
return;
},
0xb7, 0xba, 0xbf => {
cpu.model = &Target.x86.cpu.raptorlake;
return;
},
0xaa, 0xac => {
cpu.model = &Target.x86.cpu.meteorlake;
return;
},
0xc5, 0xb5 => {
cpu.model = &Target.x86.cpu.arrowlake;
return;
},
0xc6 => {
cpu.model = &Target.x86.cpu.arrowlake_s;
return;
},
0xbd => {
cpu.model = &Target.x86.cpu.lunarlake;
return;
},
0xcc => {
cpu.model = &Target.x86.cpu.pantherlake;
return;
},
0xad => {
cpu.model = &Target.x86.cpu.graniterapids;
return;
},
0xae => {
cpu.model = &Target.x86.cpu.graniterapids_d;
return;
},
0xcf => {
cpu.model = &Target.x86.cpu.emeraldrapids;
return;
},
0x8f => {
cpu.model = &Target.x86.cpu.sapphirerapids;
return;
},
0x1c, 0x26, 0x27, 0x35, 0x36 => {
cpu.model = &Target.x86.cpu.bonnell;
return;
},
0x37, 0x4a, 0x4d, 0x5a, 0x5d, 0x4c => {
cpu.model = &Target.x86.cpu.silvermont;
return;
},
0x5c, 0x5f => {
cpu.model = &Target.x86.cpu.goldmont;
return;
},
0x7a => {
cpu.model = &Target.x86.cpu.goldmont_plus;
return;
},
0x86, 0x8a, 0x96, 0x9c => {
cpu.model = &Target.x86.cpu.tremont;
return;
},
0xaf => {
cpu.model = &Target.x86.cpu.sierraforest;
return;
},
0xb6 => {
cpu.model = &Target.x86.cpu.grandridge;
return;
},
0xdd => {
cpu.model = &Target.x86.cpu.clearwaterforest;
return;
},
0x57 => {
cpu.model = &Target.x86.cpu.knl;
return;
},
0x85 => {
cpu.model = &Target.x86.cpu.knm;
return;
},
else => return, // Unknown CPU Model
}
},
15 => {
if (cpu.has(.x86, .@"64bit")) {
cpu.model = &Target.x86.cpu.nocona;
return;
}
if (cpu.has(.x86, .sse3)) {
cpu.model = &Target.x86.cpu.prescott;
return;
}
cpu.model = &Target.x86.cpu.pentium4;
return;
},
else => return, // Unknown CPU Model
}
}
fn detectAMDProcessor(cpu: Target.Cpu, family: u32, model: u32) ?*const Target.Cpu.Model {
return switch (family) {
4 => &Target.x86.cpu.i486,
5 => switch (model) {
6, 7 => &Target.x86.cpu.k6,
8 => &Target.x86.cpu.k6_2,
9, 13 => &Target.x86.cpu.k6_3,
10 => &Target.x86.cpu.geode,
else => &Target.x86.cpu.pentium,
},
6 => if (cpu.has(.x86, .sse))
&Target.x86.cpu.athlon_xp
else
&Target.x86.cpu.athlon,
15 => if (cpu.has(.x86, .sse3))
&Target.x86.cpu.k8_sse3
else
&Target.x86.cpu.k8,
16, 18 => &Target.x86.cpu.amdfam10,
20 => &Target.x86.cpu.btver1,
21 => switch (model) {
0x60...0x7f => &Target.x86.cpu.bdver4,
0x30...0x3f => &Target.x86.cpu.bdver3,
0x02, 0x10...0x1f => &Target.x86.cpu.bdver2,
else => &Target.x86.cpu.bdver1,
},
22 => &Target.x86.cpu.btver2,
23 => switch (model) {
0x30...0x3f, 0x47, 0x60...0x6f, 0x70...0x7f, 0x84...0x87, 0x90...0x9f, 0xa0...0xaf => &Target.x86.cpu.znver2,
else => &Target.x86.cpu.znver1,
},
25 => switch (model) {
0x10...0x1f, 0x60...0x6f, 0x70...0x7f, 0xa0...0xaf => &Target.x86.cpu.znver4,
else => &Target.x86.cpu.znver3,
},
26 => &Target.x86.cpu.znver5,
else => null,
};
}
fn detectNativeFeatures(cpu: *Target.Cpu, os_tag: Target.Os.Tag) void {
var leaf = cpuid(0, 0);
const max_level = leaf.eax;
leaf = cpuid(1, 0);
setFeature(cpu, .sse3, bit(leaf.ecx, 0));
setFeature(cpu, .pclmul, bit(leaf.ecx, 1));
setFeature(cpu, .ssse3, bit(leaf.ecx, 9));
setFeature(cpu, .cx16, bit(leaf.ecx, 13));
setFeature(cpu, .sse4_1, bit(leaf.ecx, 19));
setFeature(cpu, .sse4_2, bit(leaf.ecx, 20));
setFeature(cpu, .movbe, bit(leaf.ecx, 22));
setFeature(cpu, .popcnt, bit(leaf.ecx, 23));
setFeature(cpu, .aes, bit(leaf.ecx, 25));
setFeature(cpu, .rdrnd, bit(leaf.ecx, 30));
setFeature(cpu, .cx8, bit(leaf.edx, 8));
setFeature(cpu, .cmov, bit(leaf.edx, 15));
setFeature(cpu, .mmx, bit(leaf.edx, 23));
setFeature(cpu, .fxsr, bit(leaf.edx, 24));
setFeature(cpu, .sse, bit(leaf.edx, 25));
setFeature(cpu, .sse2, bit(leaf.edx, 26));
const has_xsave = bit(leaf.ecx, 27);
const has_avx = bit(leaf.ecx, 28);
// Make sure not to call xgetbv if xsave is not supported
const xcr0: Xcr0 = if (has_xsave and has_avx) @bitCast(getXCR0()) else @bitCast(@as(u32, 0));
const has_avx_save = xcr0.sse and xcr0.avx;
// LLVM approaches avx512_save by hardcoding it to true on Darwin,
// because the kernel saves the context even if the bit is not set.
// https://github.com/llvm/llvm-project/blob/bca373f73fc82728a8335e7d6cd164e8747139ec/llvm/lib/Support/Host.cpp#L1378
//
// Google approaches this by using a different series of checks and flags,
// and this may report the feature more accurately on a technically correct
// but ultimately less useful level.
// https://github.com/google/cpu_features/blob/b5c271c53759b2b15ff91df19bd0b32f2966e275/src/cpuinfo_x86.c#L113
// (called from https://github.com/google/cpu_features/blob/b5c271c53759b2b15ff91df19bd0b32f2966e275/src/cpuinfo_x86.c#L1052)
//
// Right now, we use LLVM's approach, because even if the target doesn't support
// the feature, the kernel should provide the same functionality transparently,
// so the implementation details don't make a difference.
// That said, this flag impacts other CPU features' availability,
// so until we can verify that this doesn't come with side affects,
// we'll say TODO verify this.
// Darwin lazily saves the AVX512 context on first use: trust that the OS will
// save the AVX512 context if we use AVX512 instructions, even if the bit is not
// set right now.
const has_avx512_save = if (os_tag.isDarwin())
true
else
xcr0.zmm_hi256 and xcr0.hi16_zmm;
// AMX requires additional context to be saved by the OS.
const has_amx_save = xcr0.xtilecfg and xcr0.xtiledata;
setFeature(cpu, .avx, has_avx_save);
setFeature(cpu, .fma, bit(leaf.ecx, 12) and has_avx_save);
// Only enable XSAVE if OS has enabled support for saving YMM state.
setFeature(cpu, .xsave, bit(leaf.ecx, 26) and has_avx_save);
setFeature(cpu, .f16c, bit(leaf.ecx, 29) and has_avx_save);
leaf = cpuid(0x80000000, 0);
const max_ext_level = leaf.eax;
if (max_ext_level >= 0x80000001) {
leaf = cpuid(0x80000001, 0);
setFeature(cpu, .sahf, bit(leaf.ecx, 0));
setFeature(cpu, .lzcnt, bit(leaf.ecx, 5));
setFeature(cpu, .sse4a, bit(leaf.ecx, 6));
setFeature(cpu, .prfchw, bit(leaf.ecx, 8));
setFeature(cpu, .xop, bit(leaf.ecx, 11) and has_avx_save);
setFeature(cpu, .lwp, bit(leaf.ecx, 15));
setFeature(cpu, .fma4, bit(leaf.ecx, 16) and has_avx_save);
setFeature(cpu, .tbm, bit(leaf.ecx, 21));
setFeature(cpu, .mwaitx, bit(leaf.ecx, 29));
setFeature(cpu, .@"64bit", bit(leaf.edx, 29));
} else {
for ([_]Target.x86.Feature{
.sahf,
.lzcnt,
.sse4a,
.prfchw,
.xop,
.lwp,
.fma4,
.tbm,
.mwaitx,
.@"64bit",
}) |feat| {
setFeature(cpu, feat, false);
}
}
// Misc. memory-related features.
if (max_ext_level >= 0x80000008) {
leaf = cpuid(0x80000008, 0);
setFeature(cpu, .clzero, bit(leaf.ebx, 0));
setFeature(cpu, .rdpru, bit(leaf.ebx, 4));
setFeature(cpu, .wbnoinvd, bit(leaf.ebx, 9));
} else {
for ([_]Target.x86.Feature{
.clzero,
.rdpru,
.wbnoinvd,
}) |feat| {
setFeature(cpu, feat, false);
}
}
if (max_level >= 0x7) {
leaf = cpuid(0x7, 0);
setFeature(cpu, .fsgsbase, bit(leaf.ebx, 0));
setFeature(cpu, .sgx, bit(leaf.ebx, 2));
setFeature(cpu, .bmi, bit(leaf.ebx, 3));
// AVX2 is only supported if we have the OS save support from AVX.
setFeature(cpu, .avx2, bit(leaf.ebx, 5) and has_avx_save);
setFeature(cpu, .smep, bit(leaf.ebx, 7));
setFeature(cpu, .bmi2, bit(leaf.ebx, 8));
setFeature(cpu, .invpcid, bit(leaf.ebx, 10));
setFeature(cpu, .rtm, bit(leaf.ebx, 11));
// AVX512 is only supported if the OS supports the context save for it.
setFeature(cpu, .avx512f, bit(leaf.ebx, 16) and has_avx512_save);
setFeature(cpu, .evex512, bit(leaf.ebx, 16) and has_avx512_save);
setFeature(cpu, .avx512dq, bit(leaf.ebx, 17) and has_avx512_save);
setFeature(cpu, .rdseed, bit(leaf.ebx, 18));
setFeature(cpu, .adx, bit(leaf.ebx, 19));
setFeature(cpu, .smap, bit(leaf.ebx, 20));
setFeature(cpu, .avx512ifma, bit(leaf.ebx, 21) and has_avx512_save);
setFeature(cpu, .clflushopt, bit(leaf.ebx, 23));
setFeature(cpu, .clwb, bit(leaf.ebx, 24));
setFeature(cpu, .avx512pf, bit(leaf.ebx, 26) and has_avx512_save);
setFeature(cpu, .avx512er, bit(leaf.ebx, 27) and has_avx512_save);
setFeature(cpu, .avx512cd, bit(leaf.ebx, 28) and has_avx512_save);
setFeature(cpu, .sha, bit(leaf.ebx, 29));
setFeature(cpu, .avx512bw, bit(leaf.ebx, 30) and has_avx512_save);
setFeature(cpu, .avx512vl, bit(leaf.ebx, 31) and has_avx512_save);
setFeature(cpu, .prefetchwt1, bit(leaf.ecx, 0));
setFeature(cpu, .avx512vbmi, bit(leaf.ecx, 1) and has_avx512_save);
setFeature(cpu, .pku, bit(leaf.ecx, 4));
setFeature(cpu, .waitpkg, bit(leaf.ecx, 5));
setFeature(cpu, .avx512vbmi2, bit(leaf.ecx, 6) and has_avx512_save);
setFeature(cpu, .shstk, bit(leaf.ecx, 7));
setFeature(cpu, .gfni, bit(leaf.ecx, 8));
setFeature(cpu, .vaes, bit(leaf.ecx, 9) and has_avx_save);
setFeature(cpu, .vpclmulqdq, bit(leaf.ecx, 10) and has_avx_save);
setFeature(cpu, .avx512vnni, bit(leaf.ecx, 11) and has_avx512_save);
setFeature(cpu, .avx512bitalg, bit(leaf.ecx, 12) and has_avx512_save);
setFeature(cpu, .avx512vpopcntdq, bit(leaf.ecx, 14) and has_avx512_save);
setFeature(cpu, .rdpid, bit(leaf.ecx, 22));
setFeature(cpu, .kl, bit(leaf.ecx, 23));
setFeature(cpu, .cldemote, bit(leaf.ecx, 25));
setFeature(cpu, .movdiri, bit(leaf.ecx, 27));
setFeature(cpu, .movdir64b, bit(leaf.ecx, 28));
setFeature(cpu, .enqcmd, bit(leaf.ecx, 29));
// There are two CPUID leafs which information associated with the pconfig
// instruction:
// EAX=0x7, ECX=0x0 indicates the availability of the instruction (via the 18th
// bit of EDX), while the EAX=0x1b leaf returns information on the
// availability of specific pconfig leafs.
// The target feature here only refers to the the first of these two.
// Users might need to check for the availability of specific pconfig
// leaves using cpuid, since that information is ignored while
// detecting features using the "-march=native" flag.
// For more info, see X86 ISA docs.
setFeature(cpu, .uintr, bit(leaf.edx, 5));
setFeature(cpu, .avx512vp2intersect, bit(leaf.edx, 8) and has_avx512_save);
setFeature(cpu, .serialize, bit(leaf.edx, 14));
setFeature(cpu, .tsxldtrk, bit(leaf.edx, 16));
setFeature(cpu, .pconfig, bit(leaf.edx, 18));
setFeature(cpu, .amx_bf16, bit(leaf.edx, 22) and has_amx_save);
setFeature(cpu, .avx512fp16, bit(leaf.edx, 23) and has_avx512_save);
setFeature(cpu, .amx_tile, bit(leaf.edx, 24) and has_amx_save);
setFeature(cpu, .amx_int8, bit(leaf.edx, 25) and has_amx_save);
if (leaf.eax >= 1) {
leaf = cpuid(0x7, 0x1);
setFeature(cpu, .sha512, bit(leaf.eax, 0));
setFeature(cpu, .sm3, bit(leaf.eax, 1));
setFeature(cpu, .sm4, bit(leaf.eax, 2));
setFeature(cpu, .raoint, bit(leaf.eax, 3));
setFeature(cpu, .avxvnni, bit(leaf.eax, 4) and has_avx_save);
setFeature(cpu, .avx512bf16, bit(leaf.eax, 5) and has_avx512_save);
setFeature(cpu, .cmpccxadd, bit(leaf.eax, 7));
setFeature(cpu, .amx_fp16, bit(leaf.eax, 21) and has_amx_save);
setFeature(cpu, .hreset, bit(leaf.eax, 22));
setFeature(cpu, .avxifma, bit(leaf.eax, 23) and has_avx_save);
setFeature(cpu, .avxvnniint8, bit(leaf.edx, 4) and has_avx_save);
setFeature(cpu, .avxneconvert, bit(leaf.edx, 5) and has_avx_save);
setFeature(cpu, .amx_complex, bit(leaf.edx, 8) and has_amx_save);
setFeature(cpu, .avxvnniint16, bit(leaf.edx, 10) and has_avx_save);
setFeature(cpu, .prefetchi, bit(leaf.edx, 14));
setFeature(cpu, .usermsr, bit(leaf.edx, 15));
setFeature(cpu, .avx10_1_256, bit(leaf.edx, 19));
// APX
setFeature(cpu, .egpr, bit(leaf.edx, 21));
setFeature(cpu, .push2pop2, bit(leaf.edx, 21));
setFeature(cpu, .ppx, bit(leaf.edx, 21));
setFeature(cpu, .ndd, bit(leaf.edx, 21));
setFeature(cpu, .ccmp, bit(leaf.edx, 21));
setFeature(cpu, .cf, bit(leaf.edx, 21));
} else {
for ([_]Target.x86.Feature{
.sha512,
.sm3,
.sm4,
.raoint,
.avxvnni,
.avx512bf16,
.cmpccxadd,
.amx_fp16,
.hreset,
.avxifma,
.avxvnniint8,
.avxneconvert,
.amx_complex,
.avxvnniint16,
.prefetchi,
.usermsr,
.avx10_1_256,
.egpr,
.push2pop2,
.ppx,
.ndd,
.ccmp,
.cf,
}) |feat| {
setFeature(cpu, feat, false);
}
}
} else {
for ([_]Target.x86.Feature{
.fsgsbase,
.sgx,
.bmi,
.avx2,
.smep,
.bmi2,
.invpcid,
.rtm,
.avx512f,
.evex512,
.avx512dq,
.rdseed,
.adx,
.smap,
.avx512ifma,
.clflushopt,
.clwb,
.avx512pf,
.avx512er,
.avx512cd,
.sha,
.avx512bw,
.avx512vl,
.prefetchwt1,
.avx512vbmi,
.pku,
.waitpkg,
.avx512vbmi2,
.shstk,
.gfni,
.vaes,
.vpclmulqdq,
.avx512vnni,
.avx512bitalg,
.avx512vpopcntdq,
.rdpid,
.kl,
.cldemote,
.movdiri,
.movdir64b,
.enqcmd,
.uintr,
.avx512vp2intersect,
.serialize,
.tsxldtrk,
.pconfig,
.amx_bf16,
.avx512fp16,
.amx_tile,
.amx_int8,
.sha512,
.sm3,
.sm4,
.raoint,
.avxvnni,
.avx512bf16,
.cmpccxadd,
.amx_fp16,
.hreset,
.avxifma,
.avxvnniint8,
.avxneconvert,
.amx_complex,
.avxvnniint16,
.prefetchi,
.usermsr,
.avx10_1_256,
.egpr,
.push2pop2,
.ppx,
.ndd,
.ccmp,
.cf,
}) |feat| {
setFeature(cpu, feat, false);
}
}
if (max_level >= 0xD and has_avx_save) {
leaf = cpuid(0xD, 0x1);
// Only enable XSAVE if OS has enabled support for saving YMM state.
setFeature(cpu, .xsaveopt, bit(leaf.eax, 0));
setFeature(cpu, .xsavec, bit(leaf.eax, 1));
setFeature(cpu, .xsaves, bit(leaf.eax, 3));
} else {
for ([_]Target.x86.Feature{
.xsaveopt,
.xsavec,
.xsaves,
}) |feat| {
setFeature(cpu, feat, false);
}
}
if (max_level >= 0x14) {
leaf = cpuid(0x14, 0);
setFeature(cpu, .ptwrite, bit(leaf.ebx, 4));
} else {
for ([_]Target.x86.Feature{
.ptwrite,
}) |feat| {
setFeature(cpu, feat, false);
}
}
if (max_level >= 0x19) {
leaf = cpuid(0x19, 0);
setFeature(cpu, .widekl, bit(leaf.ebx, 2));
} else {
for ([_]Target.x86.Feature{
.widekl,
}) |feat| {
setFeature(cpu, feat, false);
}
}
if (max_level >= 0x24) {
leaf = cpuid(0x24, 0);
setFeature(cpu, .avx10_1_512, bit(leaf.ebx, 18));
} else {
for ([_]Target.x86.Feature{
.avx10_1_512,
}) |feat| {
setFeature(cpu, feat, false);
}
}
}
const CpuidLeaf = packed struct {
eax: u32,
ebx: u32,
ecx: u32,
edx: u32,
};
/// This is a workaround for the C backend until zig has the ability to put
/// C code in inline assembly.
extern fn zig_x86_cpuid(leaf_id: u32, subid: u32, eax: *u32, ebx: *u32, ecx: *u32, edx: *u32) callconv(.c) void;
fn cpuid(leaf_id: u32, subid: u32) CpuidLeaf {
// valid for both x86 and x86_64
var eax: u32 = undefined;
var ebx: u32 = undefined;
var ecx: u32 = undefined;
var edx: u32 = undefined;
if (builtin.zig_backend == .stage2_c) {
zig_x86_cpuid(leaf_id, subid, &eax, &ebx, &ecx, &edx);
} else {
asm volatile ("cpuid"
: [_] "={eax}" (eax),
[_] "={ebx}" (ebx),
[_] "={ecx}" (ecx),
[_] "={edx}" (edx),
: [_] "{eax}" (leaf_id),
[_] "{ecx}" (subid),
);
}
return .{ .eax = eax, .ebx = ebx, .ecx = ecx, .edx = edx };
}
/// This is a workaround for the C backend until zig has the ability to put
/// C code in inline assembly.
extern fn zig_x86_get_xcr0() callconv(.c) u32;
// Read control register 0 (XCR0). Used to detect features such as AVX.
fn getXCR0() u32 {
if (builtin.zig_backend == .stage2_c) {
return zig_x86_get_xcr0();
}
return asm volatile (
\\ xor %%ecx, %%ecx
\\ xgetbv
: [_] "={eax}" (-> u32),
:
: .{ .edx = true, .ecx = true });
}