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For better or worse, load from i1 is assumed to be zero extended. Do not

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form a load from i1 from larger loads that may not be zext'd.

llvm-svn: 31933
This commit is contained in:
Chris Lattner 2006-11-27 04:40:53 +00:00
parent c0bdf03e26
commit aa8f67c2b5
1 changed files with 6 additions and 1 deletions
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7
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -2192,7 +2192,12 @@ SDOperand DAGCombiner::visitTRUNCATE(SDNode *N) {
return N0.getOperand(0);
}
// fold (truncate (load x)) -> (smaller load x)
if (ISD::isNON_EXTLoad(N0.Val) && N0.hasOneUse()) {
if (ISD::isNON_EXTLoad(N0.Val) && N0.hasOneUse() &&
// Do not allow folding to i1 here. i1 is implicitly stored in memory in
// zero extended form: by shrinking the load, we lose track of the fact
// that it is already zero extended.
// FIXME: This should be reevaluated.
VT != MVT::i1) {
assert(MVT::getSizeInBits(N0.getValueType()) > MVT::getSizeInBits(VT) &&
"Cannot truncate to larger type!");
LoadSDNode *LN0 = cast<LoadSDNode>(N0);