Revert "[DirectX] legalize memset (llvm#136244)"

This reverts commit 02e316c.

Author: bogner

llvm/lib/Target/DirectX/DXILLegalizePass.cpp

@@ -13,7 +13,6 @@
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
-#include "llvm/IR/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include <functional>
@@ -175,22 +174,16 @@ static void upcastI8AllocasAndUses(Instruction &I,
 
   Type *SmallestType = nullptr;
 
+  // Gather all cast targets
   for (User *U : AI->users()) {
     auto *Load = dyn_cast<LoadInst>(U);
     if (!Load)
       continue;
     for (User *LU : Load->users()) {
-      Type *Ty = nullptr;
-      if (auto *Cast = dyn_cast<CastInst>(LU))
-        Ty = Cast->getType();
-      if (CallInst *CI = dyn_cast<CallInst>(LU)) {
-        if (CI->getIntrinsicID() == Intrinsic::memset)
-          Ty = Type::getInt32Ty(CI->getContext());
-      }
-
-      if (!Ty)
+      auto *Cast = dyn_cast<CastInst>(LU);
+      if (!Cast)
         continue;
-
+      Type *Ty = Cast->getType();
       if (!SmallestType ||
           Ty->getPrimitiveSizeInBits() < SmallestType->getPrimitiveSizeInBits())
         SmallestType = Ty;
@@ -246,77 +239,6 @@ downcastI64toI32InsertExtractElements(Instruction &I,
   }
 }
 
-static void emitMemsetExpansion(IRBuilder<> &Builder, Value *Dst, Value *Val,
-                                ConstantInt *SizeCI,
-                                DenseMap<Value *, Value *> &ReplacedValues) {
-  LLVMContext &Ctx = Builder.getContext();
-  [[maybe_unused]] const DataLayout &DL =
-      Builder.GetInsertBlock()->getModule()->getDataLayout();
-  [[maybe_unused]] uint64_t OrigSize = SizeCI->getZExtValue();
-
-  AllocaInst *Alloca = dyn_cast<AllocaInst>(Dst);
-
-  assert(Alloca && "Expected memset on an Alloca");
-  assert(OrigSize == Alloca->getAllocationSize(DL)->getFixedValue() &&
-         "Expected for memset size to match DataLayout size");
-
-  Type *AllocatedTy = Alloca->getAllocatedType();
-  ArrayType *ArrTy = dyn_cast<ArrayType>(AllocatedTy);
-  assert(ArrTy && "Expected Alloca for an Array Type");
-
-  Type *ElemTy = ArrTy->getElementType();
-  uint64_t Size = ArrTy->getArrayNumElements();
-
-  [[maybe_unused]] uint64_t ElemSize = DL.getTypeStoreSize(ElemTy);
-
-  assert(ElemSize > 0 && "Size must be set");
-  assert(OrigSize == ElemSize * Size && "Size in bytes must match");
-
-  Value *TypedVal = Val;
-
-  if (Val->getType() != ElemTy) {
-    if (ReplacedValues[Val]) {
-      // Note for i8 replacements if we know them we should use them.
-      // Further if this is a constant ReplacedValues will return null
-      // so we will stick to TypedVal = Val
-      TypedVal = ReplacedValues[Val];
-
-    } else {
-      // This case Val is a ConstantInt so the cast folds away.
-      // However if we don't do the cast the store below ends up being
-      // an i8.
-      TypedVal = Builder.CreateIntCast(Val, ElemTy, false);
-    }
-  }
-
-  for (uint64_t I = 0; I < Size; ++I) {
-    Value *Offset = ConstantInt::get(Type::getInt32Ty(Ctx), I);
-    Value *Ptr = Builder.CreateGEP(ElemTy, Dst, Offset, "gep");
-    Builder.CreateStore(TypedVal, Ptr);
-  }
-}
-
-static void removeMemSet(Instruction &I,
-                         SmallVectorImpl<Instruction *> &ToRemove,
-                         DenseMap<Value *, Value *> &ReplacedValues) {
-
-  CallInst *CI = dyn_cast<CallInst>(&I);
-  if (!CI)
-    return;
-
-  Intrinsic::ID ID = CI->getIntrinsicID();
-  if (ID != Intrinsic::memset)
-    return;
-
-  IRBuilder<> Builder(&I);
-  Value *Dst = CI->getArgOperand(0);
-  Value *Val = CI->getArgOperand(1);
-  ConstantInt *Size = dyn_cast<ConstantInt>(CI->getArgOperand(2));
-  assert(Size && "Expected Size to be a ConstantInt");
-  emitMemsetExpansion(Builder, Dst, Val, Size, ReplacedValues);
-  ToRemove.push_back(CI);
-}
-
 namespace {
 class DXILLegalizationPipeline {
 
@@ -348,7 +270,6 @@ class DXILLegalizationPipeline {
     LegalizationPipeline.push_back(fixI8UseChain);
     LegalizationPipeline.push_back(downcastI64toI32InsertExtractElements);
     LegalizationPipeline.push_back(legalizeFreeze);
-    LegalizationPipeline.push_back(removeMemSet);
   }
 };