[InstCombine] Remove convertBitCastToGEP() fold (NFC)

This only applies to typed pointers, so the fold is no longer
necessary.

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index f1751c6..e0872c8 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -2554,57 +2554,6 @@ Instruction *InstCombinerImpl::optimizeBitCastFromPhi(CastInst &CI,
   return RetVal;
 }
 
-static Instruction *convertBitCastToGEP(BitCastInst &CI, IRBuilderBase &Builder,
-                                        const DataLayout &DL) {
-  Value *Src = CI.getOperand(0);
-  PointerType *SrcPTy = cast<PointerType>(Src->getType());
-  PointerType *DstPTy = cast<PointerType>(CI.getType());
-
-  // Bitcasts involving opaque pointers cannot be converted into a GEP.
-  if (SrcPTy->isOpaque() || DstPTy->isOpaque())
-    return nullptr;
-
-  Type *DstElTy = DstPTy->getNonOpaquePointerElementType();
-  Type *SrcElTy = SrcPTy->getNonOpaquePointerElementType();
-
-  // When the type pointed to is not sized the cast cannot be
-  // turned into a gep.
-  if (!SrcElTy->isSized())
-    return nullptr;
-
-  // If the source and destination are pointers, and this cast is equivalent
-  // to a getelementptr X, 0, 0, 0...  turn it into the appropriate gep.
-  // This can enhance SROA and other transforms that want type-safe pointers.
-  unsigned NumZeros = 0;
-  while (SrcElTy && SrcElTy != DstElTy) {
-    SrcElTy = GetElementPtrInst::getTypeAtIndex(SrcElTy, (uint64_t)0);
-    ++NumZeros;
-  }
-
-  // If we found a path from the src to dest, create the getelementptr now.
-  if (SrcElTy == DstElTy) {
-    SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder.getInt32(0));
-    GetElementPtrInst *GEP = GetElementPtrInst::Create(
-        SrcPTy->getNonOpaquePointerElementType(), Src, Idxs);
-
-    // If the source pointer is dereferenceable, then assume it points to an
-    // allocated object and apply "inbounds" to the GEP.
-    bool CanBeNull, CanBeFreed;
-    if (Src->getPointerDereferenceableBytes(DL, CanBeNull, CanBeFreed)) {
-      // In a non-default address space (not 0), a null pointer can not be
-      // assumed inbounds, so ignore that case (dereferenceable_or_null).
-      // The reason is that 'null' is not treated differently in these address
-      // spaces, and we consequently ignore the 'gep inbounds' special case
-      // for 'null' which allows 'inbounds' on 'null' if the indices are
-      // zeros.
-      if (SrcPTy->getAddressSpace() == 0 || !CanBeNull)
-        GEP->setIsInBounds();
-    }
-    return GEP;
-  }
-  return nullptr;
-}
-
 Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
   // If the operands are integer typed then apply the integer transforms,
   // otherwise just apply the common ones.
@@ -2617,10 +2566,6 @@ Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
   if (DestTy == Src->getType())
     return replaceInstUsesWith(CI, Src);
 
-  if (isa<PointerType>(SrcTy) && isa<PointerType>(DestTy))
-    if (Instruction *I = convertBitCastToGEP(CI, Builder, DL))
-      return I;
-
   if (FixedVectorType *DestVTy = dyn_cast<FixedVectorType>(DestTy)) {
     // Beware: messing with this target-specific oddity may cause trouble.
     if (DestVTy->getNumElements() == 1 && SrcTy->isX86_MMXTy()) {