[llvm-commits] CVS: llvm/lib/Transforms/Scalar/InstructionCombining.cpp

[Chris Lattner]

> For this transform: store V, (cast P) -> store (cast V), P
> don't allow the transform if V and the pointer's element type are  
> different
> width integer types.

To fix this, I'd vastly prefer that you add  
TargetData::getTypeSizeInBits, rather than adding special cases for  
variable width integers (the current special case for bool is already  
bad).  Change this code (line 8189):

       if (((SrcPTy->isInteger() && SrcPTy != Type::Int1Ty) ||
            isa<PointerType>(SrcPTy)) &&
           IC.getTargetData().getTypeSize(SrcPTy) ==
                IC.getTargetData().getTypeSize(DestPTy)) {

In any case, with either change, you can take out the "&& SrcPTy !=  
Type::Int1Ty" check.

The same xform happens for load, FWIW.  It should be fixed also.

-Chris

>
>
> ---
> Diffs of the changes:  (+4 -3)
>
>  InstructionCombining.cpp |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
>
>
> Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
> diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.604  
> llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.605
> --- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.604	Fri  
> Jan 19 15:13:56 2007
> +++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Fri Jan 19  
> 15:20:31 2007
> @@ -8162,7 +8162,7 @@
>    return 0;
>  }
>
> -/// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store  
> (cast V), P'
> +/// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast  
> V), P
>  /// when possible.
>  static Instruction *InstCombineStoreToCast(InstCombiner &IC,  
> StoreInst &SI) {
>    User *CI = cast<User>(SI.getOperand(1));
> @@ -8206,8 +8206,9 @@
>            if (isa<PointerType>(SIOp0->getType()))
>              opcode = Instruction::PtrToInt;
>            else if (const IntegerType* SITy = dyn_cast<IntegerType> 
> (CastSrcTy))
> -            assert(DITy->getBitWidth() == SITy->getBitWidth() &&
> -                   "Illegal store instruction");
> +            if (SITy->getBitWidth() != DITy->getBitWidth())
> +              return 0; // Don't do this transform on unequal bit  
> widths.
> +            // else, BitCast is fine
>          }
>          if (Constant *C = dyn_cast<Constant>(SIOp0))
>            NewCast = ConstantExpr::getCast(opcode, C, CastDstTy);
>
>
>
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