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AM2 can match 2^n +/- 1. e.g. ldr r3, [r2, r2, lsl #2]

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35088 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-03-13 21:05:54 +00:00
parent 961f879ed8
commit a13fd108f2
1 changed files with 23 additions and 0 deletions
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23
lib/Target/ARM/ARMISelDAGToDAG.cpp
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@ -102,6 +102,29 @@ void ARMDAGToDAGISel::InstructionSelectBasicBlock(SelectionDAG &DAG) {
bool ARMDAGToDAGISel::SelectAddrMode2(SDOperand Op, SDOperand N,
SDOperand &Base, SDOperand &Offset,
SDOperand &Opc) {
if (N.getOpcode() == ISD::MUL) {
if (ConstantSDNode *RHS = dyn_cast<ConstantSDNode>(N.getOperand(1))) {
// X * [3,5,9] -> X + X * [2,4,8] etc.
int RHSC = (int)RHS->getValue();
if (RHSC & 1) {
RHSC = RHSC & ~1;
ARM_AM::AddrOpc AddSub = ARM_AM::add;
if (RHSC < 0) {
AddSub = ARM_AM::sub;
RHSC = - RHSC;
}
if (isPowerOf2_32(RHSC)) {
unsigned ShAmt = Log2_32(RHSC);
Base = Offset = N.getOperand(0);
Opc = CurDAG->getTargetConstant(ARM_AM::getAM2Opc(AddSub, ShAmt,
ARM_AM::lsl),
MVT::i32);
return true;
}
}
}
}
if (N.getOpcode() != ISD::ADD && N.getOpcode() != ISD::SUB) {
Base = N;
if (N.getOpcode() == ISD::FrameIndex) {