[PATCH] D56355: [InstCombine] Simplify cttz/ctlz + icmp ugt/ult into mask check
Simon Pilgrim via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Jan 16 14:00:41 PST 2019
RKSimon added a reviewer: RKSimon.
RKSimon added inline comments.
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Comment at: lib/Transforms/InstCombine/InstCombineCompares.cpp:2617
+ return I;
+ }
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(style) Remove unnecessary braces
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Comment at: lib/Transforms/InstCombine/InstCombineCompares.cpp:2836
+ unsigned Num = C.getLimitedValue();
+ if (Cmp.getPredicate() == ICmpInst::ICMP_UGT && Num < BitWidth) {
+ APInt Limit = APInt::getOneBitSet(BitWidth, BitWidth - Num - 1);
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In case of "silly" numbers from fuzzers etc. better to use C.ult(BitWidth) etc.and move C.getLimitedValue() calls inside the ifs.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D56355/new/
https://reviews.llvm.org/D56355
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