Re-apply r216491 (Win64 ABI shouldn't extend integer type arguments.)

This time though, preserve the extension for bool types since that's compatible
with what MSVC expects.

See http://reviews.llvm.org/D4380

llvm-svn: 216507

clang/lib/CodeGen/TargetInfo.cpp

@@ -2773,7 +2773,10 @@ ABIArgInfo WinX86_64ABIInfo::classify(QualType Ty, bool IsReturnType) const {
     return ABIArgInfo::getDirect(llvm::IntegerType::get(getVMContext(), Size));
   }
 
-  if (Ty->isPromotableIntegerType())
+  // Bool type is always extended to the ABI, other builtin types are not
+  // extended.
+  const BuiltinType *BT = Ty->getAs<BuiltinType>();
+  if (BT && BT->getKind() == BuiltinType::Bool)
     return ABIArgInfo::getExtend();
 
   return ABIArgInfo::getDirect();

clang/test/CodeGen/2007-06-18-SextAttrAggregate.c

@@ -1,11 +1,13 @@
 // RUN: %clang_cc1 %s -o - -emit-llvm | FileCheck %s
-// XFAIL: aarch64, arm64
+// XFAIL: aarch64, arm64, x86_64-pc-win32
 
 // PR1513
 
 // AArch64 ABI actually requires the reverse of what this is testing: the callee
 // does any extensions and remaining bits are unspecified.
 
+// Win64 ABI does expect extensions for type smaller than 64bits.
+
 // Technically this test wasn't written to test that feature, but it's a
 // valuable check nevertheless.
 

clang/test/CodeGen/x86_64-arguments-win32.c

@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -w -triple x86_64-pc-win32 -emit-llvm -o - %s | FileCheck %s
+
+// To be ABI compatible with code generated by MSVC, there shouldn't be any
+// sign/zero extensions on types smaller than 64bit.
+
+// CHECK-LABEL: define void @f1(i8 %a)
+void f1(char a) {}
+
+// CHECK-LABEL: define void @f2(i8 %a)
+void f2(unsigned char a) {}
+
+// CHECK-LABEL: define void @f3(i16 %a)
+void f3(short a) {}
+
+// CHECK-LABEL: define void @f4(i16 %a)
+void f4(unsigned short a) {}