regcall: Implement regcall Calling Conv in clang

This patch implements the register call calling convention, which ensures
as many values as possible are passed in registers. CodeGen changes
were committed in https://reviews.llvm.org/rL284108.

Differential Revision: https://reviews.llvm.org/D25204

llvm-svn: 285849

1 files changed, 10 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 291ff8ed57b..0e93e403af4 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -673,7 +673,16 @@ StringRef CodeGenModule::getMangledName(GlobalDecl GD) {
   } else {
     IdentifierInfo *II = ND->getIdentifier();
     assert(II && "Attempt to mangle unnamed decl.");
-    Str = II->getName();
+    const auto *FD = dyn_cast<FunctionDecl>(ND);
+
+    if (FD &&
+        FD->getType()->castAs<FunctionType>()->getCallConv() == CC_X86RegCall) {
+      llvm::raw_svector_ostream Out(Buffer);
+      Out << "__regcall3__" << II->getName();
+      Str = Out.str();
+    } else {
+      Str = II->getName();
+    }
   }
 
   // Keep the first result in the case of a mangling collision.