[llvm][Coroutines] Remove no-op ptr-to-ptr bitcasts (NFC) (#73427)

Opaque ptr cleanup effort

Author: JOE1994

llvm/lib/Transforms/Coroutines/CoroCleanup.cpp

@@ -29,15 +29,13 @@ struct Lowerer : coro::LowererBase {
 
 static void lowerSubFn(IRBuilder<> &Builder, CoroSubFnInst *SubFn) {
   Builder.SetInsertPoint(SubFn);
-  Value *FrameRaw = SubFn->getFrame();
+  Value *FramePtr = SubFn->getFrame();
   int Index = SubFn->getIndex();
 
   auto *FrameTy = StructType::get(SubFn->getContext(),
                                   {Builder.getPtrTy(), Builder.getPtrTy()});
-  PointerType *FramePtrTy = FrameTy->getPointerTo();
 
   Builder.SetInsertPoint(SubFn);
-  auto *FramePtr = Builder.CreateBitCast(FrameRaw, FramePtrTy);
   auto *Gep = Builder.CreateConstInBoundsGEP2_32(FrameTy, FramePtr, 0, Index);
   auto *Load = Builder.CreateLoad(FrameTy->getElementType(Index), Gep);
 

llvm/lib/Transforms/Coroutines/Coroutines.cpp

@@ -42,11 +42,10 @@ coro::LowererBase::LowererBase(Module &M)
                                      /*isVarArg=*/false)),
       NullPtr(ConstantPointerNull::get(Int8Ptr)) {}
 
-// Creates a sequence of instructions to obtain a resume function address using
-// llvm.coro.subfn.addr. It generates the following sequence:
+// Creates a call to llvm.coro.subfn.addr to obtain a resume function address.
+// It generates the following:
 //
-//    call i8* @llvm.coro.subfn.addr(i8* %Arg, i8 %index)
-//    bitcast i8* %2 to void(i8*)*
+//    call ptr @llvm.coro.subfn.addr(ptr %Arg, i8 %index)
 
 Value *coro::LowererBase::makeSubFnCall(Value *Arg, int Index,
                                         Instruction *InsertPt) {
@@ -56,11 +55,7 @@ Value *coro::LowererBase::makeSubFnCall(Value *Arg, int Index,
   assert(Index >= CoroSubFnInst::IndexFirst &&
          Index < CoroSubFnInst::IndexLast &&
          "makeSubFnCall: Index value out of range");
-  auto *Call = CallInst::Create(Fn, {Arg, IndexVal}, "", InsertPt);
-
-  auto *Bitcast =
-      new BitCastInst(Call, ResumeFnType->getPointerTo(), "", InsertPt);
-  return Bitcast;
+  return CallInst::Create(Fn, {Arg, IndexVal}, "", InsertPt);
 }
 
 // NOTE: Must be sorted!

llvm/test/Transforms/Coroutines/coro-resume-destroy.ll

@@ -6,13 +6,11 @@ define void @callResume(ptr %hdl) {
 ; CHECK-NEXT: entry
 entry:
 ; CHECK-NEXT: %0 = call ptr @llvm.coro.subfn.addr(ptr %hdl, i8 0)
-; CHECK-NEXT: %1 = bitcast ptr %0 to ptr
-; CHECK-NEXT: call fastcc void %1(ptr %hdl)
+; CHECK-NEXT: call fastcc void %0(ptr %hdl)
   call void @llvm.coro.resume(ptr %hdl)
 
-; CHECK-NEXT: %2 = call ptr @llvm.coro.subfn.addr(ptr %hdl, i8 1)
-; CHECK-NEXT: %3 = bitcast ptr %2 to ptr
-; CHECK-NEXT: call fastcc void %3(ptr %hdl)
+; CHECK-NEXT: %1 = call ptr @llvm.coro.subfn.addr(ptr %hdl, i8 1)
+; CHECK-NEXT: call fastcc void %1(ptr %hdl)
   call void @llvm.coro.destroy(ptr %hdl)
 
   ret void
@@ -24,8 +22,7 @@ define void @eh(ptr %hdl) personality ptr null {
 ; CHECK-NEXT: entry
 entry:
 ;  CHECK-NEXT: %0 = call ptr @llvm.coro.subfn.addr(ptr %hdl, i8 0)
-;  CHECK-NEXT: %1 = bitcast ptr %0 to ptr
-;  CHECK-NEXT: invoke fastcc void %1(ptr %hdl)
+;  CHECK-NEXT: invoke fastcc void %0(ptr %hdl)
   invoke void @llvm.coro.resume(ptr %hdl)
           to label %cont unwind label %ehcleanup
 cont: