[CodeGen, X86] Classify vectors <= 32 bits as INTEGER

We shouldn't crash despite the AMD64 ABI not giving clear guidance as to
how to pass around vector types <= 32 bits.  Instead, classify such
vectors as INTEGER to be compatible with GCC.

This fixes PR24162.

llvm-svn: 242508

clang/lib/CodeGen/TargetInfo.cpp

@@ -1907,16 +1907,18 @@ void X86_64ABIInfo::classify(QualType Ty, uint64_t OffsetBase,
 
   if (const VectorType *VT = Ty->getAs<VectorType>()) {
     uint64_t Size = getContext().getTypeSize(VT);
-    if (Size == 32) {
-      // gcc passes all <4 x char>, <2 x short>, <1 x int>, <1 x
-      // float> as integer.
+    if (Size == 1 || Size == 8 || Size == 16 || Size == 32) {
+      // gcc passes the following as integer:
+      // 4 bytes - <4 x char>, <2 x short>, <1 x int>, <1 x float>
+      // 2 bytes - <2 x char>, <1 x short>
+      // 1 byte  - <1 x char>
       Current = Integer;
 
       // If this type crosses an eightbyte boundary, it should be
       // split.
-      uint64_t EB_Real = (OffsetBase) / 64;
-      uint64_t EB_Imag = (OffsetBase + Size - 1) / 64;
-      if (EB_Real != EB_Imag)
+      uint64_t EB_Lo = (OffsetBase) / 64;
+      uint64_t EB_Hi = (OffsetBase + Size - 1) / 64;
+      if (EB_Lo != EB_Hi)
         Hi = Lo;
     } else if (Size == 64) {
       // gcc passes <1 x double> in memory. :(

clang/test/CodeGenCXX/x86_64-arguments.cpp

@@ -212,3 +212,12 @@ int FuncForDerivedPacked(DerivedPacked d) {
   return d.three;
 }
 }
+
+namespace test11 {
+union U {
+  float f1;
+  char __attribute__((__vector_size__(1))) f2;
+};
+int f(union U u) { return u.f2[1]; }
+// CHECK-LABEL: define i32 @_ZN6test111fENS_1UE(i32
+}