[ms-inline asm] Add support for clobbers in CodeGen.

This is a reapplication of r161914 now that the scoping issue has been resolved
in r161966.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161967 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 1 deletions

diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 467c77945e..d78908dee8 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -1691,14 +1691,36 @@ void CodeGenFunction::EmitMSAsmStmt(const MSAsmStmt &S) {
 
   std::vector<llvm::Value*> Args;
   std::vector<llvm::Type *> ArgTypes;
+  std::string Constraints;
+
+  // Clobbers
+  for (unsigned i = 0, e = S.getNumClobbers(); i != e; ++i) {
+    StringRef Clobber = S.getClobber(i);
+
+    if (Clobber != "memory" && Clobber != "cc")
+      Clobber = Target.getNormalizedGCCRegisterName(Clobber);
+
+    if (i != 0)
+      Constraints += ',';
+
+    Constraints += "~{";
+    Constraints += Clobber;
+    Constraints += '}';
+  }
 
+  // Add machine specific clobbers
   std::string MachineClobbers = Target.getClobbers();
+  if (!MachineClobbers.empty()) {
+    if (!Constraints.empty())
+      Constraints += ',';
+    Constraints += MachineClobbers;
+  }
 
   llvm::FunctionType *FTy =
     llvm::FunctionType::get(VoidTy, ArgTypes, false);
 
   llvm::InlineAsm *IA =
-    llvm::InlineAsm::get(FTy, *S.getAsmString(), MachineClobbers, true);
+    llvm::InlineAsm::get(FTy, *S.getAsmString(), Constraints, true);
   llvm::CallInst *Result = Builder.CreateCall(IA, Args);
   Result->addAttribute(~0, llvm::Attribute::NoUnwind);
   Result->addAttribute(~0, llvm::Attribute::IANSDialect);