Support Swift calling convention for PPC64 targets

This adds basic support for the Swift calling convention with PPC64 targets.
Patch provided by Atul Sowani in bug report #37223

llvm-svn: 333316
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 4e25c72..3ec0055 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -4287,7 +4287,7 @@
 
 namespace {
 /// PPC64_SVR4_ABIInfo - The 64-bit PowerPC ELF (SVR4) ABI information.
-class PPC64_SVR4_ABIInfo : public ABIInfo {
+class PPC64_SVR4_ABIInfo : public SwiftABIInfo {
 public:
   enum ABIKind {
     ELFv1 = 0,
@@ -4331,7 +4331,7 @@
 public:
   PPC64_SVR4_ABIInfo(CodeGen::CodeGenTypes &CGT, ABIKind Kind, bool HasQPX,
                      bool SoftFloatABI)
-      : ABIInfo(CGT), Kind(Kind), HasQPX(HasQPX),
+      : SwiftABIInfo(CGT), Kind(Kind), HasQPX(HasQPX),
         IsSoftFloatABI(SoftFloatABI) {}
 
   bool isPromotableTypeForABI(QualType Ty) const;
@@ -4374,6 +4374,15 @@
 
   Address EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
                     QualType Ty) const override;
+
+  bool shouldPassIndirectlyForSwift(ArrayRef<llvm::Type*> scalars,
+                                    bool asReturnValue) const override {
+    return occupiesMoreThan(CGT, scalars, /*total*/ 4);
+  }
+
+  bool isSwiftErrorInRegister() const override {
+    return false;
+  }
 };
 
 class PPC64_SVR4_TargetCodeGenInfo : public TargetCodeGenInfo {