[llvm-branch-commits] [llvm] 85f7923 - [ConstantFold] Remove unnecessary cast of zero gep fold (NFCI)

[Nikita Popov via llvm-branch-commits]

Author: Nikita Popov
Date: 2023-11-03T11:25:40+01:00
New Revision: 85f79233286c78a1b79d01ca0677230658732b35

URL: https://github.com/llvm/llvm-project/commit/85f79233286c78a1b79d01ca0677230658732b35
DIFF: https://github.com/llvm/llvm-project/commit/85f79233286c78a1b79d01ca0677230658732b35.diff

LOG: [ConstantFold] Remove unnecessary cast of zero gep fold (NFCI)

Zero GEPs will be optimized away entirely, except in the cases
which this transform also excludes (splat, inrange).

Added: 
    

Modified: 
    llvm/lib/IR/ConstantFold.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
index 4651767d0655a06..d69665bd6c56ae6 100644
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -233,28 +233,6 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V,
       // Try hard to fold cast of cast because they are often eliminable.
       if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
         return foldMaybeUndesirableCast(newOpc, CE->getOperand(0), DestTy);
-    } else if (CE->getOpcode() == Instruction::GetElementPtr &&
-               // Do not fold addrspacecast (gep 0, .., 0). It might make the
-               // addrspacecast uncanonicalized.
-               opc != Instruction::AddrSpaceCast &&
-               // Do not fold bitcast (gep) with inrange index, as this loses
-               // information.
-               !cast<GEPOperator>(CE)->getInRangeIndex() &&
-               // Do not fold if the gep type is a vector, as bitcasting
-               // operand 0 of a vector gep will result in a bitcast between
-               // 
diff erent sizes.
-               !CE->getType()->isVectorTy()) {
-      // If all of the indexes in the GEP are null values, there is no pointer
-      // adjustment going on.  We might as well cast the source pointer.
-      bool isAllNull = true;
-      for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
-        if (!CE->getOperand(i)->isNullValue()) {
-          isAllNull = false;
-          break;
-        }
-      if (isAllNull)
-        // This is casting one pointer type to another, always BitCast
-        return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
     }
   }