[X86] Pass __m64 types via SSE registers for GCC compatibility

For compatibility with GCC, classify __m64 as SSE.
However, clang is a platform compiler for certain targets; retain our
old behavior on those targets: classify __m64 as integer.

This fixes PR26832.

llvm-svn: 262688

1 files changed, 22 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index d9f4e7761ae..51949979ad9 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -1857,6 +1857,17 @@ class X86_64ABIInfo : public ABIInfo {
     return !getTarget().getTriple().isOSDarwin();
   }
 
+  /// GCC classifies <1 x long long> as SSE but compatibility with older clang
+  // compilers require us to classify it as INTEGER.
+  bool classifyIntegerMMXAsSSE() const {
+    const llvm::Triple &Triple = getTarget().getTriple();
+    if (Triple.isOSDarwin() || Triple.getOS() == llvm::Triple::PS4)
+      return false;
+    if (Triple.isOSFreeBSD() && Triple.getOSMajorVersion() >= 10)
+      return false;
+    return true;
+  }
+
   X86AVXABILevel AVXLevel;
   // Some ABIs (e.g. X32 ABI and Native Client OS) use 32 bit pointers on
   // 64-bit hardware.
@@ -2298,15 +2309,20 @@ void X86_64ABIInfo::classify(QualType Ty, uint64_t OffsetBase,
       if (EB_Lo != EB_Hi)
         Hi = Lo;
     } else if (Size == 64) {
+      QualType ElementType = VT->getElementType();
+
       // gcc passes <1 x double> in memory. :(
-      if (VT->getElementType()->isSpecificBuiltinType(BuiltinType::Double))
+      if (ElementType->isSpecificBuiltinType(BuiltinType::Double))
         return;
 
-      // gcc passes <1 x long long> as INTEGER.
-      if (VT->getElementType()->isSpecificBuiltinType(BuiltinType::LongLong) ||
-          VT->getElementType()->isSpecificBuiltinType(BuiltinType::ULongLong) ||
-          VT->getElementType()->isSpecificBuiltinType(BuiltinType::Long) ||
-          VT->getElementType()->isSpecificBuiltinType(BuiltinType::ULong))
+      // gcc passes <1 x long long> as SSE but clang used to unconditionally
+      // pass them as integer.  For platforms where clang is the de facto
+      // platform compiler, we must continue to use integer.
+      if (!classifyIntegerMMXAsSSE() &&
+          (ElementType->isSpecificBuiltinType(BuiltinType::LongLong) ||
+           ElementType->isSpecificBuiltinType(BuiltinType::ULongLong) ||
+           ElementType->isSpecificBuiltinType(BuiltinType::Long) ||
+           ElementType->isSpecificBuiltinType(BuiltinType::ULong)))
         Current = Integer;
       else
         Current = SSE;