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Implement a variety of simplifications for ANY_EXTEND.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28121 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-05-05 05:58:59 +00:00
parent 35e5c14b80
commit 5ffc066912
1 changed files with 51 additions and 0 deletions
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51
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -188,6 +188,7 @@ namespace {
SDOperand visitSETCC(SDNode *N);
SDOperand visitSIGN_EXTEND(SDNode *N);
SDOperand visitZERO_EXTEND(SDNode *N);
SDOperand visitANY_EXTEND(SDNode *N);
SDOperand visitSIGN_EXTEND_INREG(SDNode *N);
SDOperand visitTRUNCATE(SDNode *N);
SDOperand visitBIT_CONVERT(SDNode *N);
@ -628,6 +629,7 @@ SDOperand DAGCombiner::visit(SDNode *N) {
case ISD::SETCC: return visitSETCC(N);
case ISD::SIGN_EXTEND: return visitSIGN_EXTEND(N);
case ISD::ZERO_EXTEND: return visitZERO_EXTEND(N);
case ISD::ANY_EXTEND: return visitANY_EXTEND(N);
case ISD::SIGN_EXTEND_INREG: return visitSIGN_EXTEND_INREG(N);
case ISD::TRUNCATE: return visitTRUNCATE(N);
case ISD::BIT_CONVERT: return visitBIT_CONVERT(N);
@ -1869,6 +1871,55 @@ SDOperand DAGCombiner::visitZERO_EXTEND(SDNode *N) {
return SDOperand();
}
SDOperand DAGCombiner::visitANY_EXTEND(SDNode *N) {
SDOperand N0 = N->getOperand(0);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
MVT::ValueType VT = N->getValueType(0);
// fold (aext c1) -> c1
if (N0C)
return DAG.getNode(ISD::ANY_EXTEND, VT, N0);
// fold (aext (aext x)) -> (aext x)
// fold (aext (zext x)) -> (zext x)
// fold (aext (sext x)) -> (sext x)
if (N0.getOpcode() == ISD::ANY_EXTEND ||
N0.getOpcode() == ISD::ZERO_EXTEND ||
N0.getOpcode() == ISD::SIGN_EXTEND)
return DAG.getNode(N0.getOpcode(), VT, N0.getOperand(0));
// fold (aext (truncate x)) -> x iff x size == zext size.
if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT)
return N0.getOperand(0);
// fold (aext (load x)) -> (aext (truncate (extload x)))
if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse() &&
(!AfterLegalize||TLI.isOperationLegal(ISD::EXTLOAD, N0.getValueType()))) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, VT, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2),
N0.getValueType());
CombineTo(N, ExtLoad);
CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
// fold (aext (zextload x)) -> (aext (truncate (zextload x)))
// fold (aext (sextload x)) -> (aext (truncate (sextload x)))
// fold (aext ( extload x)) -> (aext (truncate (extload x)))
if ((N0.getOpcode() == ISD::ZEXTLOAD || N0.getOpcode() == ISD::EXTLOAD ||
N0.getOpcode() == ISD::SEXTLOAD) &&
N0.hasOneUse()) {
SDOperand ExtLoad = DAG.getNode(N0.getOpcode(), VT, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2),
N0.getOperand(3));
CombineTo(N, ExtLoad);
CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
return SDOperand();
}
SDOperand DAGCombiner::visitSIGN_EXTEND_INREG(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);