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[SCEV] Add stricter verification option. 

Currently -verify-scev only fails if there is a constant difference
between two BE counts. This misses a lot of cases.

This patch adds a -verify-scev-strict options, which fails for any
non-zero differences, if used together with -verify-scev.

With the stricter checking, some unit tests fail because
of mis-matches, especially around IndVarSimplify.

If there is no reason I am missing for just checking constant deltas, I
am planning on looking into the various failures.

Reviewers: efriedma, sanjoy.google, reames, atrick

Reviewed By: sanjoy.google

Differential Revision: https://reviews.llvm.org/D68592

llvm-svn: 374535
This commit is contained in:
Florian Hahn 2019-10-11 11:46:40 +00:00
parent 6434eac860
commit 77fbf069f6
1 changed files with 8 additions and 5 deletions
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13
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -158,6 +158,9 @@ MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
static cl::opt<bool> VerifySCEV(
"verify-scev", cl::Hidden,
cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
static cl::opt<bool> VerifySCEVStrict(
"verify-scev-strict", cl::Hidden,
cl::desc("Enable stricter verification with -verify-scev is passed"));
static cl::opt<bool>
VerifySCEVMap("verify-scev-maps", cl::Hidden,
cl::desc("Verify no dangling value in ScalarEvolution's "
@ -11922,14 +11925,14 @@ void ScalarEvolution::verify() const {
SE.getTypeSizeInBits(NewBECount->getType()))
CurBECount = SE2.getZeroExtendExpr(CurBECount, NewBECount->getType());
auto *ConstantDelta =
dyn_cast<SCEVConstant>(SE2.getMinusSCEV(CurBECount, NewBECount));
const SCEV *Delta = SE2.getMinusSCEV(CurBECount, NewBECount);
if (ConstantDelta && ConstantDelta->getAPInt() != 0) {
dbgs() << "Trip Count Changed!\n";
// Unless VerifySCEVStrict is set, we only compare constant deltas.
if ((VerifySCEVStrict || isa<SCEVConstant>(Delta)) && !Delta->isZero()) {
dbgs() << "Trip Count for " << *L << " Changed!\n";
dbgs() << "Old: " << *CurBECount << "\n";
dbgs() << "New: " << *NewBECount << "\n";
dbgs() << "Delta: " << *ConstantDelta << "\n";
dbgs() << "Delta: " << *Delta << "\n";
std::abort();
}
}