Remove function pointer cast deletion in SPIRVRegularizeLLVM.

It seems to be another remnant of earlier versions of dealing with block types,
as it is looking for SPIR-V builtins that have function pointer arguments. With
blocks now represented as structs, it seems that nothing will trigger this code
any more. In any case, with opaque pointers, this code becomes unnecessary (as
the bitcasts that would be deleted won't exist anymore).

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@1341e54

Author: jcranmer-intel

llvm-spirv/lib/SPIRV/SPIRVInternal.h

@@ -716,10 +716,6 @@ bool isVoidFuncTy(FunctionType *FT);
 /// \returns true if \p T is a function pointer type.
 bool isFunctionPointerType(Type *T);
 
-/// \returns true if function \p F has function pointer type argument.
-/// \param AI points to the function pointer type argument if returns true.
-bool hasFunctionPointerArg(Function *F, Function::arg_iterator &AI);
-
 /// \returns true if function \p F has array type argument.
 bool hasArrayArg(Function *F);
 
@@ -1018,9 +1014,6 @@ std::string getSPIRVFriendlyIRFunctionName(OCLExtOpKind ExtOpId,
 std::string getSPIRVFriendlyIRFunctionName(const std::string &UniqName,
                                            spv::Op OC, ArrayRef<Type *> ArgTys);
 
-/// Remove cast from a value.
-Value *removeCast(Value *V);
-
 /// Cast a function to a void(void) funtion pointer.
 Constant *castToVoidFuncPtr(Function *F);
 

llvm-spirv/lib/SPIRV/SPIRVRegularizeLLVM.cpp

@@ -72,11 +72,6 @@ class SPIRVRegularizeLLVMBase {
   // Lower functions
   bool regularize();
 
-  /// Erase cast inst of function and replace with the function.
-  /// Assuming F is a SPIR-V builtin function with op code \param OC.
-  void lowerFuncPtr(Function *F, Op OC);
-  void lowerFuncPtr(Module *M);
-
   /// Some LLVM intrinsics that have no SPIR-V counterpart may be wrapped in
   /// @spirv.llvm_intrinsic_* function. During reverse translation from SPIR-V
   /// to LLVM IR we can detect this @spirv.llvm_intrinsic_* function and
@@ -567,7 +562,6 @@ bool SPIRVRegularizeLLVMBase::runRegularizeLLVM(Module &Module) {
 /// Remove entities not representable by SPIR-V
 bool SPIRVRegularizeLLVMBase::regularize() {
   eraseUselessFunctions(M);
-  lowerFuncPtr(M);
   expandSYCLTypeUsing(M);
 
   for (auto I = M->begin(), E = M->end(); I != E;) {
@@ -722,43 +716,6 @@ bool SPIRVRegularizeLLVMBase::regularize() {
   return true;
 }
 
-// Assume F is a SPIR-V builtin function with a function pointer argument which
-// is a bitcast instruction casting a function to a void(void) function pointer.
-void SPIRVRegularizeLLVMBase::lowerFuncPtr(Function *F, Op OC) {
-  LLVM_DEBUG(dbgs() << "[lowerFuncPtr] " << *F << '\n');
-  auto Name = decorateSPIRVFunction(getName(OC));
-  std::set<Value *> InvokeFuncPtrs;
-  auto Attrs = F->getAttributes();
-  mutateFunction(
-      F,
-      [=, &InvokeFuncPtrs](CallInst *CI, std::vector<Value *> &Args) {
-        for (auto &I : Args) {
-          if (isFunctionPointerType(I->getType())) {
-            InvokeFuncPtrs.insert(I);
-            I = removeCast(I);
-          }
-        }
-        return Name;
-      },
-      nullptr, &Attrs, false);
-  for (auto &I : InvokeFuncPtrs)
-    eraseIfNoUse(I);
-}
-
-void SPIRVRegularizeLLVMBase::lowerFuncPtr(Module *M) {
-  std::vector<std::pair<Function *, Op>> Work;
-  for (auto &F : *M) {
-    auto AI = F.arg_begin();
-    if (hasFunctionPointerArg(&F, AI)) {
-      auto OC = getSPIRVFuncOC(F.getName());
-      if (OC != OpNop) // builtin with a function pointer argument
-        Work.push_back(std::make_pair(&F, OC));
-    }
-  }
-  for (auto &I : Work)
-    lowerFuncPtr(I.first, I.second);
-}
-
 } // namespace SPIRV
 
 INITIALIZE_PASS(SPIRVRegularizeLLVMLegacy, "spvregular",

llvm-spirv/lib/SPIRV/SPIRVUtil.cpp

@@ -89,16 +89,6 @@ void removeFnAttr(CallInst *Call, Attribute::AttrKind Attr) {
   Call->removeFnAttr(Attr);
 }
 
-Value *removeCast(Value *V) {
-  auto Cast = dyn_cast<ConstantExpr>(V);
-  if (Cast && Cast->isCast()) {
-    return removeCast(Cast->getOperand(0));
-  }
-  if (auto Cast = dyn_cast<CastInst>(V))
-    return removeCast(Cast->getOperand(0));
-  return V;
-}
-
 void saveLLVMModule(Module *M, const std::string &OutputFile) {
   std::error_code EC;
   ToolOutputFile Out(OutputFile.c_str(), EC, sys::fs::OF_None);
@@ -652,17 +642,6 @@ bool isFunctionPointerType(Type *T) {
   return false;
 }
 
-bool hasFunctionPointerArg(Function *F, Function::arg_iterator &AI) {
-  AI = F->arg_begin();
-  for (auto AE = F->arg_end(); AI != AE; ++AI) {
-    LLVM_DEBUG(dbgs() << "[hasFuncPointerArg] " << *AI << '\n');
-    if (isFunctionPointerType(AI->getType())) {
-      return true;
-    }
-  }
-  return false;
-}
-
 Constant *castToVoidFuncPtr(Function *F) {
   auto T = getVoidFuncPtrType(F->getParent());
   return ConstantExpr::getBitCast(F, T);