[InlineFunction] Preserve calling convention when forwarding VarArgs.

[rnk]

lgtm

[davide]

LG

llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp

for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E;
           SmallVector<Value *, 6> Params(CI->arg_operands());
           Params.append(VarArgsToForward.begin(), VarArgsToForward.end());
           CallInst *NewCI =
               CallInst::Create(CI->getCalledFunction() ? CI->getCalledFunction()
                                                        : CI->getCalledValue(),
                                Params, "", CI);
           NewCI->setDebugLoc(CI->getDebugLoc());
           NewCI->setAttributes(Attrs);
+          NewCI->setCallingConv(CI->getCallingConv());
           CI->replaceAllUsesWith(NewCI);
           CI->eraseFromParent();
           CI = NewCI;
         }
 
         if (Function *F = CI->getCalledFunction())
           InlinedDeoptimizeCalls |=
               F->getIntrinsicID() == Intrinsic::experimental_deoptimize;

llvm/trunk/test/Transforms/Inline/inline-varargs.ll

 ; RUN: opt < %s -inline -S | FileCheck %s
 ; RUN: opt < %s -passes='cgscc(inline,function(instcombine))' -S | FileCheck %s
 
 declare void @ext_method(i8*, i32)
 declare signext i16 @vararg_fn(...) #0
+declare "cc 9" void @vararg_fn_cc9(i8* %p, ...)
 
 define linkonce_odr void @thunk(i8* %this, ...) {
   %this_adj = getelementptr i8, i8* %this, i32 4
   musttail call void (i8*, ...) bitcast (void (i8*, i32)* @ext_method to void (i8*, ...)*)(i8* nonnull %this_adj, ...)
   ret void
 }
 
 define void @thunk_caller(i8* %p) {

 
 define void @test_caller_3(i8* %p, i8* %q) {
   call void (i8*, ...) @test_callee_3(i8* nonnull %p, i8* %q)
   ret void
 }
 ; CHECK-LABEL: define void @test_caller_3
 ; CHECK: call signext i16 (...) @vararg_fn()
 
+define void @test_preserve_cc(i8* %p, ...) {
+  musttail call "cc 9" void (i8*, ...) @vararg_fn_cc9(i8* %p, ...)
+  ret void
+}
+
+define void @test_caller_preserve_cc(i8* %p, i8* %q) {
+  call void (i8*, ...) @test_preserve_cc(i8* %p, i8* %q)
+  ret void
+}
+; CHECK-LABEL: define void @test_caller_preserve_cc
+; CHECK: call "cc 9" void (i8*, ...) @vararg_fn_cc9(i8* %p, i8* %q)
+
 define internal i32 @varg_accessed(...) {
 entry:
   %vargs = alloca i8*, align 8
   %vargs.ptr = bitcast i8** %vargs to i8*
   call void @llvm.va_start(i8* %vargs.ptr)
   %va1 = va_arg i8** %vargs, i32
   call void @llvm.va_end(i8* %vargs.ptr)
   ret i32 %va1