Fixing TargetHasAVXSupportCheck to read ECX not EDX (#42089)

dotnet · Sep 11, 2020 · ff533b8 · ff533b8
1 parent 0956285
commit ff533b8
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Showing 2 changed files with 10 additions and 5 deletions.
diff --git a/src/coreclr/src/vm/cgensys.h b/src/coreclr/src/vm/cgensys.h
@@ -105,12 +105,17 @@ extern "C" void __stdcall __cpuidex(int cpuInfo[4], int function_id, int subFunc
 extern "C" DWORD __stdcall xmmYmmStateSupport();
 #endif
 
+const int CPUID_EAX = 0;
+const int CPUID_EBX = 1;
+const int CPUID_ECX = 2;
+const int CPUID_EDX = 3;
+
 inline bool TargetHasAVXSupport()
 {
 #if (defined(TARGET_X86) || defined(TARGET_AMD64)) && !defined(CROSSGEN_COMPILE)
     int cpuInfo[4];
     __cpuid(cpuInfo, 0x00000001);           // All x86/AMD64 targets support cpuid.
-    return ((cpuInfo[3] & (1 << 28)) != 0); // The AVX feature is ECX bit 28.
+    return ((cpuInfo[CPUID_ECX] & (1 << 28)) != 0); // The AVX feature is ECX bit 28.
 #endif // (defined(TARGET_X86) || defined(TARGET_AMD64)) && !defined(CROSSGEN_COMPILE)
     return false;
 }

diff --git a/src/coreclr/src/vm/codeman.cpp b/src/coreclr/src/vm/codeman.cpp
@@ -1353,10 +1353,10 @@ void EEJitManager::SetCpuInfo()
 
     int cpuidInfo[4];
 
-    const int EAX = 0;
-    const int EBX = 1;
-    const int ECX = 2;
-    const int EDX = 3;
+    const int EAX = CPUID_EAX;
+    const int EBX = CPUID_EBX;
+    const int ECX = CPUID_ECX;
+    const int EDX = CPUID_EDX;
 
     __cpuid(cpuidInfo, 0x00000000);
     uint32_t maxCpuId = static_cast<uint32_t>(cpuidInfo[EAX]);