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Fold (zext (load x) to (zextload x).

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24702 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2005-12-14 02:19:23 +00:00
parent 3fb6877cb4
commit 110dec2000
1 changed files with 18 additions and 1 deletions
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19
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -1552,7 +1552,7 @@ SDOperand DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, N0.getValueType())))
return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0),
DAG.getValueType(N0.getValueType()));
// fold (sext (load x)) -> (sextload x)
// fold (sext (load x)) -> (sext (truncate (sextload x)))
if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse()) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2),
@ -1576,6 +1576,23 @@ SDOperand DAGCombiner::visitZERO_EXTEND(SDNode *N) {
// fold (zext (zext x)) -> (zext x)
if (N0.getOpcode() == ISD::ZERO_EXTEND)
return DAG.getNode(ISD::ZERO_EXTEND, VT, N0.getOperand(0));
// fold (zext (zextload x)) -> (zextload x)
if (N0.getOpcode() == ISD::ZEXTLOAD && VT == N0.getValueType())
return N0;
// fold (zext (truncate x)) -> (zextinreg x) iff x size == zext size.
if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT&&
!AfterLegalize)
return DAG.getZeroExtendInReg(N0.getOperand(0), VT);
// fold (zext (load x)) -> (zext (truncate (zextload x)))
if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse()) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2),
N0.getValueType());
WorkList.push_back(N);
CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
return SDOperand();
}
return SDOperand();
}