[PATCH] D96534: [SCEV] Use both known bits and sign bits when computing range of SCEV unknowns
Philip Reames via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 18 08:58:03 PST 2021
reames added inline comments.
================
Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:5873
+ if (NS > 1)
+ ConservativeResult = ConservativeResult.intersectWith(
+ ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
----------------
lebedev.ri wrote:
> If `computeKnownBits()`-returned `KnownBits` claims to know one of the `NS` high (sign) bits,
> would we get better results if instead of doing this here,
> if we'd merge `NS` knowledge into `Known`, and repeated lines 5856-5858?
Yes actually. I'll do that in a follow up, thanks for the idea.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D96534/new/
https://reviews.llvm.org/D96534
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