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Fix PR7755: knowing something about an inval for a pred 

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 f0b5b67ba5
commit 3c603024bb
2 changed files with 28 additions and 8 deletions
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12
llvm/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
llvm/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
}