[CodeGen] Teach X86_64ABIInfo about AVX512.

As specified in the SysV AVX512 ABI drafts. It follows the same scheme
as AVX2: 

    Arguments of type __m512 are split into eight eightbyte chunks.
    The least significant one belongs to class SSE and all the others
    to class SSEUP.

This also means we change the OpenMP SIMD default alignment on AVX512.

Based on r240337.
Differential Revision: http://reviews.llvm.org/D9894

llvm-svn: 240338

1 files changed, 9 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index ed8f10d7848..d4d0e787096 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -1394,12 +1394,15 @@ namespace {
 /// The AVX ABI level for X86 targets.
 enum class X86AVXABILevel {
   None,
-  AVX
+  AVX,
+  AVX512
 };
 
 /// \p returns the size in bits of the largest (native) vector for \p AVXLevel.
 static unsigned getNativeVectorSizeForAVXABI(X86AVXABILevel AVXLevel) {
   switch (AVXLevel) {
+  case X86AVXABILevel::AVX512:
+    return 512;
   case X86AVXABILevel::AVX:
     return 256;
   case X86AVXABILevel::None:
@@ -1956,6 +1959,9 @@ void X86_64ABIInfo::classify(QualType Ty, uint64_t OffsetBase,
       // Note that per 3.5.7 of AMD64-ABI, 256-bit args are only passed in
       // registers if they are "named", i.e. not part of the "..." of a
       // variadic function.
+      //
+      // Similarly, per 3.2.3. of the AVX512 draft, 512-bits ("named") args are
+      // split into eight eightbyte chunks, one SSE and seven SSEUP.
       Lo = SSE;
       Hi = SSEUp;
     }
@@ -7211,7 +7217,8 @@ const TargetCodeGenInfo &CodeGenModule::getTargetCodeGenInfo() {
 
   case llvm::Triple::x86_64: {
     StringRef ABI = getTarget().getABI();
-    X86AVXABILevel AVXLevel = (ABI == "avx" ? X86AVXABILevel::AVX :
+    X86AVXABILevel AVXLevel = (ABI == "avx512" ? X86AVXABILevel::AVX512 :
+                               ABI == "avx" ? X86AVXABILevel::AVX :
                                X86AVXABILevel::None);
 
     switch (Triple.getOS()) {