> Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
> diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.687
> llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.688
> --- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.687 Sun
> Mar 25 00:01:29 2007
> +++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Sun Mar 25
> 00:33:51 2007
> @@ -540,8 +540,9 @@
> if (I->getOpcode() == Instruction::Shl)
> if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
> // The multiplier is really 1 << CST.
> - Constant *One = ConstantInt::get(V->getType(), 1);
> - CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
> + APInt Multiplier(V->getType()->getPrimitiveSizeInBits(),
> 0);
> + Multiplier.set(CST->getZExtValue()); // set bit is == 1
> << CST
This doesn't seem safe. Won't getZextValue assert if CST is > 64 bits?
Also, I don't understand the gymnastics you're doing with Multiplier.
> + CST = ConstantInt::get(Multiplier);
> return I->getOperand(0);
> }
> }
> @@ -558,14 +559,31 @@
> return false;
> }
>
> +/// AddOne - Add one to a ConstantInt
> static ConstantInt *AddOne(ConstantInt *C) {
> + APInt One(C->getType()->getPrimitiveSizeInBits(),1);
> + return ConstantInt::get(C->getValue() + One);
> }
> +/// SubOne - Subtract one from a ConstantInt
> static ConstantInt *SubOne(ConstantInt *C) {
Shouldn't these use ++/-- on APInt? That seems more efficient.
> @@ -2188,14 +2203,12 @@
>
> ConstantInt *C1;
> if (Value *X = dyn_castFoldableMul(Op0, C1)) {
> - if (X == Op1) { // X*C - X --> X * (C-1)
> - Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get
> (I.getType(),1));
> - return BinaryOperator::createMul(Op1, CP1);
> - }
> + if (X == Op1) // X*C - X --> X * (C-1)
> + return BinaryOperator::createMul(Op1, SubOne(C1));
I like this set of changes, much cleaner.
-Chris
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