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GH-49325: [C++] Check if YMM register saving is OS enabled #49326

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Merged
pitrou merged 1 commit into from
Feb 18, 2026
+7 −4
Merged

GH-49325: [C++] Check if YMM register saving is OS enabled #49326

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11 changes: 7 additions & 4 deletions cpp/src/arrow/util/cpu_info.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -184,17 +184,19 @@ void OsRetrieveCpuInfo(int64_t* hardware_flags, CpuInfo::Vendor* vendor,
}

bool zmm_enabled = false;
bool ymm_enabled = false;
if (features_ECX[27]) { // OSXSAVE
// Query if the OS supports saving ZMM registers when switching contexts
// Query if the OS supports saving YMM and ZMM registers when switching contexts
int64_t xcr0 = _xgetbv(0);
zmm_enabled = (xcr0 & 0xE0) == 0xE0;
ymm_enabled = (xcr0 & 0b110) == 0b110;
}

if (features_ECX[9]) *hardware_flags |= CpuInfo::SSSE3;
if (features_ECX[19]) *hardware_flags |= CpuInfo::SSE4_1;
if (features_ECX[20]) *hardware_flags |= CpuInfo::SSE4_2;
if (features_ECX[23]) *hardware_flags |= CpuInfo::POPCNT;
if (features_ECX[28]) *hardware_flags |= CpuInfo::AVX;
if (ymm_enabled && features_ECX[28]) *hardware_flags |= CpuInfo::AVX;

// cpuid with EAX=7, ECX=0: Extended Features
register_EAX_id = 7;
Expand All @@ -203,10 +205,11 @@ void OsRetrieveCpuInfo(int64_t* hardware_flags, CpuInfo::Vendor* vendor,
std::bitset<32> features_EBX = cpu_info[1];

if (features_EBX[3]) *hardware_flags |= CpuInfo::BMI1;
if (features_EBX[5]) *hardware_flags |= CpuInfo::AVX2;
if (features_EBX[8]) *hardware_flags |= CpuInfo::BMI2;
// Only use AVX/AVX2 if enabled by the OS
if (ymm_enabled && features_EBX[5]) *hardware_flags |= CpuInfo::AVX2;
// ARROW-11427: only use AVX512 if enabled by the OS
if (zmm_enabled) {
if (ymm_enabled && zmm_enabled) {
if (features_EBX[16]) *hardware_flags |= CpuInfo::AVX512F;
if (features_EBX[17]) *hardware_flags |= CpuInfo::AVX512DQ;
if (features_EBX[28]) *hardware_flags |= CpuInfo::AVX512CD;
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