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Teach instcombine to promote stuff like (cast (malloc sbyte, 8*X) to int*)

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into: malloc int, (2*X)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24032 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-27 06:24:46 +00:00
parent 8142b0a54b
commit e679288a30
1 changed files with 26 additions and 7 deletions
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33
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -3834,19 +3834,38 @@ Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements)) {
ArraySizeScale = CI->getValue();
NumElements = ConstantUInt::get(Type::UIntTy, 1);
} else if (ShiftInst *SI = dyn_cast<ShiftInst>(NumElements)) {
if (SI->getOpcode() == Instruction::Shl)
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
// This is a value scaled by '1 << the shift amt'.
NumElements = SI->getOperand(0);
ArraySizeScale = 1U << CUI->getValue();
}
} else if (isa<Instruction>(NumElements) &&
cast<Instruction>(NumElements)->getOpcode() == Instruction::Mul){
BinaryOperator *BO = cast<BinaryOperator>(NumElements);
if (ConstantUInt *Scale = cast<ConstantUInt>(BO->getOperand(1))) {
// This value is scaled by 'Scale'.
NumElements = BO->getOperand(0);
ArraySizeScale = Scale->getValue();
}
}
// If we can now satisfy the modulus, by using a non-1 scale, we really can
// do the xform.
if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0) return 0;
Amt = ConstantUInt::get(Type::UIntTy,
(AllocElTySize*ArraySizeScale)/CastElTySize);
if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements))
Amt = ConstantExpr::getMul(CI, cast<ConstantUInt>(Amt));
else {
Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
Amt = InsertNewInstBefore(Tmp, AI);
unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
if (Scale == 1) {
Amt = NumElements;
} else {
Amt = ConstantUInt::get(Type::UIntTy, Scale);
if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements))
Amt = ConstantExpr::getMul(CI, cast<ConstantUInt>(Amt));
else if (cast<ConstantUInt>(Amt)->getValue() == 1) {
Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
Amt = InsertNewInstBefore(Tmp, AI);
}
}
}