1 files changed, 28 insertions, 11 deletions
diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 869734ab4e4..f22b96a6a07 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -44,17 +44,7 @@ public:
     return !RD->isPOD();
   }
 
-  RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override {
-    if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialDestructor()) {
-      llvm::Triple::ArchType Arch = CGM.getTarget().getTriple().getArch();
-      if (Arch == llvm::Triple::x86)
-        return RAA_DirectInMemory;
-      // On x64, pass non-trivial records indirectly.
-      // FIXME: Test other Windows architectures.
-      return RAA_Indirect;
-    }
-    return RAA_Default;
-  }
+  RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;
 
   StringRef GetPureVirtualCallName() override { return "_purecall"; }
   // No known support for deleted functions in MSVC yet, so this choice is
@@ -407,6 +397,33 @@ private:
 
 }
 
+CGCXXABI::RecordArgABI
+MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
+  switch (CGM.getTarget().getTriple().getArch()) {
+  default:
+    // FIXME: Implement for other architectures.
+    return RAA_Default;
+
+  case llvm::Triple::x86:
+    // 32-bit x86 constructs non-trivial objects directly in outgoing argument
+    // slots.  LLVM uses the inalloca attribute to implement this.
+    if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialDestructor())
+      return RAA_DirectInMemory;
+    return RAA_Default;
+
+  case llvm::Triple::x86_64:
+    // Win64 passes objects with non-trivial copy ctors indirectly.
+    if (RD->hasNonTrivialCopyConstructor())
+      return RAA_Indirect;
+    // Win64 passes objects larger than 8 bytes indirectly.
+    if (getContext().getTypeSize(RD->getTypeForDecl()) > 64)
+      return RAA_Indirect;
+    return RAA_Default;
+  }
+
+  llvm_unreachable("invalid enum");
+}
+
 llvm::Value *MicrosoftCXXABI::adjustToCompleteObject(CodeGenFunction &CGF,
                                                      llvm::Value *ptr,
                                                      QualType type) {