[PATCH] D70454: [compiler-rt] Don't require the XCR0 OSXSAVE bits when detecting skylake-avx512.

[Florian Hahn via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGa70c3f9f45c8: [compiler-rt] Don't check XCR0 when detecting avx512 on Darwin. (authored by fhahn).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70454/new/

https://reviews.llvm.org/D70454

Files:
  compiler-rt/lib/builtins/cpu_model.c


Index: compiler-rt/lib/builtins/cpu_model.c
===================================================================
--- compiler-rt/lib/builtins/cpu_model.c
+++ compiler-rt/lib/builtins/cpu_model.c
@@ -532,7 +532,15 @@
   const unsigned AVXBits = (1 << 27) | (1 << 28);
   bool HasAVX = ((ECX & AVXBits) == AVXBits) && !getX86XCR0(&EAX, &EDX) &&
                 ((EAX & 0x6) == 0x6);
+#if defined(__APPLE__)
+  // Darwin lazily saves the AVX512 context on first use: trust that the OS will
+  // save the AVX512 context if we use AVX512 instructions, even the bit is not
+  // set right now.
+  bool HasAVX512Save = true;
+#else
+  // AVX512 requires additional context to be saved by the OS.
   bool HasAVX512Save = HasAVX && ((EAX & 0xe0) == 0xe0);
+#endif
 
   if (HasAVX)
     setFeature(FEATURE_AVX);


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