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Fold multiplies by 3,5,9 into addressing modes when possible.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19480 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-01-11 19:37:02 +00:00
parent 7f5875a56a
commit 947d544e29
1 changed files with 28 additions and 0 deletions
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28
lib/Target/X86/X86ISelPattern.cpp
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@ -447,6 +447,34 @@ bool ISel::SelectAddress(SDOperand N, X86AddressMode &AM) {
}
}
break;
case ISD::MUL:
// X*[3,5,9] -> X+X*[2,4,8]
if (AM.IndexReg == 0 && AM.BaseType == X86AddressMode::RegBase &&
AM.Base.Reg == 0)
if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N.Val->getOperand(1)))
if (CN->getValue() == 3 || CN->getValue() == 5 || CN->getValue() == 9) {
AM.Scale = unsigned(CN->getValue())-1;
SDOperand MulVal = N.Val->getOperand(0);
unsigned Reg;
// Okay, we know that we have a scale by now. However, if the scaled
// value is an add of something and a constant, we can fold the
// constant into the disp field here.
if (MulVal.Val->getOpcode() == ISD::ADD &&
isa<ConstantSDNode>(MulVal.Val->getOperand(1))) {
Reg = SelectExpr(MulVal.Val->getOperand(0));
ConstantSDNode *AddVal =
cast<ConstantSDNode>(MulVal.Val->getOperand(1));
AM.Disp += AddVal->getValue() * CN->getValue();
} else {
Reg = SelectExpr(N.Val->getOperand(0));
}
AM.IndexReg = AM.Base.Reg = Reg;
return false;
}
break;
case ISD::ADD: {
X86AddressMode Backup = AM;