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A couple of bug fixes for reducing load width xform:

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1. Address offset is in bytes.
2. Make sure truncate node uses are replaced with new load.

llvm-svn: 35274
This commit is contained in:
Evan Cheng 2007-03-23 02:16:52 +00:00
parent 9881580cec
commit 62ccdaea67
1 changed files with 16 additions and 7 deletions
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23
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -2017,8 +2017,11 @@ SDOperand DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
// fold (sext (truncate (srl (load x), c))) -> (sext (smaller load (x+c/n)))
if (N0.getOpcode() == ISD::TRUNCATE) {
SDOperand NarrowLoad = ReduceLoadWidth(N0.Val);
if (NarrowLoad.Val)
N0 = NarrowLoad;
if (NarrowLoad.Val) {
if (NarrowLoad.Val != N0.Val)
CombineTo(N0.Val, NarrowLoad);
return DAG.getNode(ISD::SIGN_EXTEND, VT, NarrowLoad);
}
}
// See if the value being truncated is already sign extended. If so, just
@ -2109,8 +2112,11 @@ SDOperand DAGCombiner::visitZERO_EXTEND(SDNode *N) {
// fold (zext (truncate (srl (load x), c))) -> (zext (small load (x+c/n)))
if (N0.getOpcode() == ISD::TRUNCATE) {
SDOperand NarrowLoad = ReduceLoadWidth(N0.Val);
if (NarrowLoad.Val)
N0 = NarrowLoad;
if (NarrowLoad.Val) {
if (NarrowLoad.Val != N0.Val)
CombineTo(N0.Val, NarrowLoad);
return DAG.getNode(ISD::ZERO_EXTEND, VT, NarrowLoad);
}
}
// fold (zext (truncate x)) -> (and x, mask)
@ -2189,8 +2195,11 @@ SDOperand DAGCombiner::visitANY_EXTEND(SDNode *N) {
// fold (aext (truncate (srl (load x), c))) -> (aext (small load (x+c/n)))
if (N0.getOpcode() == ISD::TRUNCATE) {
SDOperand NarrowLoad = ReduceLoadWidth(N0.Val);
if (NarrowLoad.Val)
N0 = NarrowLoad;
if (NarrowLoad.Val) {
if (NarrowLoad.Val != N0.Val)
CombineTo(N0.Val, NarrowLoad);
return DAG.getNode(ISD::ANY_EXTEND, VT, NarrowLoad);
}
}
// fold (aext (truncate x))
@ -2278,7 +2287,7 @@ SDOperand DAGCombiner::ReduceLoadWidth(SDNode *N) {
N0 = N0.getOperand(0);
if (MVT::getSizeInBits(N0.getValueType()) <= EVTBits)
return SDOperand();
ShAmt /= EVTBits;
ShAmt /= 8;
}
}
}