(arrow) branch main updated: GH-49325: [C++] Check if YMM register saving is OS enabled (#49326)

[apitrou]

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apitrou pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/arrow.git


The following commit(s) were added to refs/heads/main by this push:
     new aea1ad39d5 GH-49325: [C++] Check if YMM register saving is OS enabled 
(#49326)
aea1ad39d5 is described below

commit aea1ad39d524cdf6871ed13b0f590dc63f8edf9b
Author: Antoine Prouvost <antoine...@users.noreply.github.com>
AuthorDate: Wed Feb 18 18:09:06 2026 +0100

    GH-49325: [C++] Check if YMM register saving is OS enabled (#49326)
    
    ### Rationale for this change
    Current behaviour is not correct.
    
    ### What changes are included in this PR?
    Check if YMM register saving is enabled by the OS before enabling AVX 
detection.
    
    ### Are these changes tested?
    Hard to, because we cannot set the value being read manually.
    
    ### Are there any user-facing changes?
    No.
    
    * GitHub Issue: #49325
    
    Authored-by: AntoinePrv <antoine...@users.noreply.github.com>
    Signed-off-by: Antoine Pitrou <anto...@python.org>
---
 cpp/src/arrow/util/cpu_info.cc | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/cpp/src/arrow/util/cpu_info.cc b/cpp/src/arrow/util/cpu_info.cc
index fdd0728c8e..b858da4a36 100644
--- a/cpp/src/arrow/util/cpu_info.cc
+++ b/cpp/src/arrow/util/cpu_info.cc
@@ -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;
@@ -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;