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Fix PR7755: knowing something about an inval for a pred

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from the LHS should disable reconsidering that pred on the
RHS.  However, knowing something about the pred on the RHS
shouldn't disable subsequent additions on the RHS from
happening.

llvm-svn: 111349
This commit is contained in:
Chris Lattner 2010-08-18 03:14:36 +00:00
parent 4c6e9192d1
commit ab876b6ce8
2 changed files with 28 additions and 8 deletions
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12
lib/Transforms/Scalar/JumpThreading.cpp
View File

@ -341,25 +341,21 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
else
InterestingVal = ConstantInt::getFalse(I->getContext());
SmallPtrSet<BasicBlock*, 4> LHSKnownBBs;
// Scan for the sentinel. If we find an undef, force it to the
// interesting value: x|undef -> true and x&undef -> false.
for (unsigned i = 0, e = LHSVals.size(); i != e; ++i)
if (LHSVals[i].first == InterestingVal || LHSVals[i].first == 0) {
Result.push_back(LHSVals[i]);
Result.back().first = InterestingVal;
LHSKnownBBs.insert(LHSVals[i].second);
}
for (unsigned i = 0, e = RHSVals.size(); i != e; ++i)
if (RHSVals[i].first == InterestingVal || RHSVals[i].first == 0) {
// If we already inferred a value for this block on the LHS, don't
// re-add it.
bool HasValue = false;
for (unsigned r = 0, e = Result.size(); r != e; ++r)
if (Result[r].second == RHSVals[i].second) {
HasValue = true;
break;
}
if (!HasValue) {
if (!LHSKnownBBs.count(RHSVals[i].second)) {
Result.push_back(RHSVals[i]);
Result.back().first = InterestingVal;
}

24
test/Transforms/JumpThreading/crash.ll
View File

@ -436,4 +436,28 @@ for.cond1040: ; preds = %for.body1044, %for.
ret void
}
; PR7755
define void @test16(i1 %c, i1 %c2, i1 %c3, i1 %c4) nounwind ssp {
entry:
%cmp = icmp sgt i32 undef, 1 ; <i1> [#uses=1]
br i1 %c, label %land.end, label %land.rhs
land.rhs: ; preds = %entry
br i1 %c2, label %lor.lhs.false.i, label %land.end
lor.lhs.false.i: ; preds = %land.rhs
br i1 %c3, label %land.end, label %land.end
land.end:
%0 = phi i1 [ true, %entry ], [ false, %land.rhs ], [false, %lor.lhs.false.i], [false, %lor.lhs.false.i] ; <i1> [#uses=1]
%cmp12 = and i1 %cmp, %0
%xor1 = xor i1 %cmp12, %c4
br i1 %xor1, label %if.then, label %if.end
if.then:
ret void
if.end:
ret void
}