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[SCEV] Use isKnownViaNonRecursiveReasoning for smax simplification

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Summary:
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	rL331949: SCEV] Do not use induction in isKnownPredicate for simplification umax

changed the codepath for umax from isKnownPredicate to
isKnownViaNonRecursiveReasoning to avoid compile time blow up (and as
I found out also stack overflows). However, there is an exact copy of
the code for umax that was lacking this change. In D50167 I want to unify
these codepaths, but to avoid that being a behavior change for the smax
case, pull this independent bit out of it.

Reviewed By: sanjoy
Differential Revision: https://reviews.llvm.org/D61166

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@359693 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Keno Fischer 2019-05-01 15:58:24 +00:00
parent 92bb3811f2
commit f951f15770
1 changed files with 4 additions and 3 deletions
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7
lib/Analysis/ScalarEvolution.cpp
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@ -3605,11 +3605,12 @@ ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
// X smax Y smax Y --> X smax Y
// X smax Y --> X, if X is always greater than Y
if (Ops[i] == Ops[i+1] ||
isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
if (Ops[i] == Ops[i + 1] || isKnownViaNonRecursiveReasoning(
ICmpInst::ICMP_SGE, Ops[i], Ops[i + 1])) {
Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
--i; --e;
} else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
} else if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, Ops[i],
Ops[i + 1])) {
Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
--i; --e;
}