Support Swift calling convention for PPC64 targets

[bob.wilson]

Summary

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

[bob.wilson]

Previous review (for the swift-llvm GitHub repo): https://github.com/apple/swift-clang/pull/167

[aschwaighofer]

Looks good.

[bob.wilson]

Committed in Clang r333316

lib/Basic/Targets/PPC.h

     }
     return false;
   }
+
+  CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
+    switch (CC) {
+    case CC_Swift:
+      return CCCR_OK;
+    default:
+      return CCCR_Warning;
+    }
+  }
 };
 
 class LLVM_LIBRARY_VISIBILITY DarwinPPC32TargetInfo

lib/CodeGen/TargetInfo.cpp

 
 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,

 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;

 
   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 {