[llvm] 8efaf7a - [ConstantFold] Remove redundant zero index gep fold (NFCI)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-11-03T14:33:01+01:00
New Revision: 8efaf7a518fa3cf719cdeff3917b9fedf8f2cf19

URL: https://github.com/llvm/llvm-project/commit/8efaf7a518fa3cf719cdeff3917b9fedf8f2cf19
DIFF: https://github.com/llvm/llvm-project/commit/8efaf7a518fa3cf719cdeff3917b9fedf8f2cf19.diff

LOG: [ConstantFold] Remove redundant zero index gep fold (NFCI)

We already handle the more general case of zero index GEPs above,
so we don't need to also handle GEPs with null based and zero
indices. (Strictly speaking, this code could handle the special
case of an inrange gep with null base and zero indices, but that
has no practical relevance.)

Added: 
    

Modified: 
    llvm/lib/IR/ConstantFold.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
index f877fb614c65da8..0358f996f285165 100644
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -1617,39 +1617,6 @@ Constant *llvm::ConstantFoldGetElementPtr(Type *PointeeTy, Constant *C,
                      cast<VectorType>(GEPTy)->getElementCount(), C)
                : C;
 
-  if (C->isNullValue()) {
-    bool isNull = true;
-    for (Value *Idx : Idxs)
-      if (!isa<UndefValue>(Idx) && !cast<Constant>(Idx)->isNullValue()) {
-        isNull = false;
-        break;
-      }
-    if (isNull) {
-      PointerType *PtrTy = cast<PointerType>(C->getType()->getScalarType());
-      Type *Ty = GetElementPtrInst::getIndexedType(PointeeTy, Idxs);
-
-      assert(Ty && "Invalid indices for GEP!");
-      Type *OrigGEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
-      Type *GEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
-      if (VectorType *VT = dyn_cast<VectorType>(C->getType()))
-        GEPTy = VectorType::get(OrigGEPTy, VT->getElementCount());
-
-      // The GEP returns a vector of pointers when one of more of
-      // its arguments is a vector.
-      for (Value *Idx : Idxs) {
-        if (auto *VT = dyn_cast<VectorType>(Idx->getType())) {
-          assert((!isa<VectorType>(GEPTy) || isa<ScalableVectorType>(GEPTy) ==
-                                                 isa<ScalableVectorType>(VT)) &&
-                 "Mismatched GEPTy vector types");
-          GEPTy = VectorType::get(OrigGEPTy, VT->getElementCount());
-          break;
-        }
-      }
-
-      return Constant::getNullValue(GEPTy);
-    }
-  }
-
   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
     if (auto *GEP = dyn_cast<GEPOperator>(CE))
       if (Constant *C = foldGEPOfGEP(GEP, PointeeTy, InBounds, Idxs))