Add default calling convention support for regcall.

Added support for regcall as default calling convention. Also added code to
exclude main when applying default calling conventions.

Patch-By: eandrews

Differential Revision: https://reviews.llvm.org/D39210

llvm-svn: 317268

1 files changed, 7 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 0c00ef7e26c..ab1a66ad8fb 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9673,6 +9673,13 @@ void Sema::CheckMain(FunctionDecl* FD, const DeclSpec& DS) {
   assert(T->isFunctionType() && "function decl is not of function type");
   const FunctionType* FT = T->castAs<FunctionType>();
 
+  // Set default calling convention for main()
+  if (FT->getCallConv() != CC_C) {
+    FT = Context.adjustFunctionType(FT, FT->getExtInfo().withCallingConv(CC_C));
+    FD->setType(QualType(FT, 0));
+    T = Context.getCanonicalType(FD->getType());
+  }
+
   if (getLangOpts().GNUMode && !getLangOpts().CPlusPlus) {
     // In C with GNU extensions we allow main() to have non-integer return
     // type, but we should warn about the extension, and we disable the