handle codegen of asms where a small input is tied to a large output.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70672 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 0a8cef2..f435f9c 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -877,6 +877,28 @@
llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints);
+ // If this input argument is tied to a larger output result, extend the
+ // input to be the same size as the output. The LLVM backend wants to see
+ // the input and output of a matching constraint be the same size. Note
+ // that GCC does not define what the top bits are here. We use zext because
+ // that is usually cheaper, but LLVM IR should really get an anyext someday.
+ if (Info.hasTiedOperand()) {
+ unsigned Output = Info.getTiedOperand();
+ QualType OutputTy = S.getOutputExpr(Output)->getType();
+ QualType InputTy = InputExpr->getType();
+
+ if (getContext().getTypeSize(OutputTy) >
+ getContext().getTypeSize(InputTy)) {
+ // Use ptrtoint as appropriate so that we can do our extension.
+ if (isa<llvm::PointerType>(Arg->getType()))
+ Arg = Builder.CreatePtrToInt(Arg,
+ llvm::IntegerType::get(LLVMPointerWidth));
+ unsigned OutputSize = (unsigned)getContext().getTypeSize(OutputTy);
+ Arg = Builder.CreateZExt(Arg, llvm::IntegerType::get(OutputSize));
+ }
+ }
+
+
ArgTypes.push_back(Arg->getType());
Args.push_back(Arg);
Constraints += InputConstraint;