Preserve exceptions information during calls code generation.

This patch changes the generation of CGFunctionInfo to contain 
the FunctionProtoType if it is available. This enables the code 
generation for call instructions to look into this type for 
exception information and therefore generate better quality 
IR - it will not create invoke instructions for functions that 
are know not to throw.

llvm-svn: 253926

clang/lib/CodeGen/CGExprComplex.cpp

@@ -585,19 +585,25 @@ ComplexPairTy ComplexExprEmitter::EmitComplexBinOpLibCall(StringRef LibCallName,
   // We *must* use the full CG function call building logic here because the
   // complex type has special ABI handling. We also should not forget about
   // special calling convention which may be used for compiler builtins.
-  const CGFunctionInfo &FuncInfo =
-    CGF.CGM.getTypes().arrangeFreeFunctionCall(
-      Op.Ty, Args, FunctionType::ExtInfo(/* No CC here - will be added later */),
-      RequiredArgs::All);
+
+  // We create a function qualified type to state that this call does not have
+  // any exceptions.
+  FunctionProtoType::ExtProtoInfo EPI;
+  EPI = EPI.withExceptionSpec(
+      FunctionProtoType::ExceptionSpecInfo(EST_BasicNoexcept));
+  SmallVector<QualType, 4> ArgsQTys(
+      4, Op.Ty->castAs<ComplexType>()->getElementType());
+  QualType FQTy = CGF.getContext().getFunctionType(Op.Ty, ArgsQTys, EPI);
+  const CGFunctionInfo &FuncInfo = CGF.CGM.getTypes().arrangeFreeFunctionCall(
+      Args, cast<FunctionType>(FQTy.getTypePtr()), false);
+
   llvm::FunctionType *FTy = CGF.CGM.getTypes().GetFunctionType(FuncInfo);
   llvm::Constant *Func = CGF.CGM.CreateBuiltinFunction(FTy, LibCallName);
   llvm::Instruction *Call;
 
   RValue Res = CGF.EmitCall(FuncInfo, Func, ReturnValueSlot(), Args,
-                            nullptr, &Call);
+                            FQTy->getAs<FunctionProtoType>(), &Call);
   cast<llvm::CallInst>(Call)->setCallingConv(CGF.CGM.getBuiltinCC());
-  cast<llvm::CallInst>(Call)->setDoesNotThrow();
-
   return Res.getComplexVal();
 }