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[IRCE][NFC] Better get SCEV for 1 in calculateSubRanges 

A slightly more efficient way to get constant, we avoid resolving in getSCEV and excessive
invocations, and we don't create a ConstantInt if 'true' branch is taken.

Differential Revision: https://reviews.llvm.org/D34672

llvm-svn: 306503
This commit is contained in:
Max Kazantsev 2017-06-28 04:57:45 +00:00
parent 261d97332d
commit 6c466a376e
1 changed files with 3 additions and 3 deletions
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6
llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
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@ -917,7 +917,6 @@ LoopConstrainer::calculateSubRanges() const {
// I think we can be more aggressive here and make this nuw / nsw if the
// addition that feeds into the icmp for the latch's terminating branch is nuw
// / nsw. In any case, a wrapping 2's complement addition is safe.
ConstantInt *One = ConstantInt::get(Ty, 1);
const SCEV *Start = SE.getSCEV(MainLoopStructure.IndVarStart);
const SCEV *End = SE.getSCEV(MainLoopStructure.LoopExitAt);
@ -948,8 +947,9 @@ LoopConstrainer::calculateSubRanges() const {
// will be an empty range. Returning an empty range is always safe.
//
Smallest = SE.getAddExpr(End, SE.getSCEV(One));
Greatest = SE.getAddExpr(Start, SE.getSCEV(One));
const SCEV *One = SE.getOne(Ty);
Smallest = SE.getAddExpr(End, One);
Greatest = SE.getAddExpr(Start, One);
}
auto Clamp = [this, Smallest, Greatest](const SCEV *S) {