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Combine and-mask+icmp eq -> icmp ule when mask was all-ones in high bits #38139

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LebedevRI opened this issue Aug 31, 2018 · 2 comments
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Combine and-mask+icmp eq -> icmp ule when mask was all-ones in high bits #38139

LebedevRI opened this issue Aug 31, 2018 · 2 comments
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bugzilla Issues migrated from bugzilla llvm:instcombine missed-optimization

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@LebedevRI
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Bugzilla Link 38791
Version trunk
OS Linux
CC @davidbolvansky

Extended Description

Copied from #37471

Name: range using high bits
%masked = or i8 %arg, 192
%r = icmp ne i8 %masked, %arg
=>
%r = icmp ult i8 %arg, 192

https://rise4fun.com/Alive/lv5
@davidbolvansky
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Also
%masked = or i8 %arg, 192
%r = icmp eq i8 %masked, %arg
=>
%r = icmp uge i8 %arg, 192

@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 10, 2021
RKSimon added a commit that referenced this issue Jun 11, 2024
@RKSimon
[InstCombine] Add #38139 test coverage
264bcbe
@RKSimon
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RKSimon commented Jun 11, 2024

Missing fold was fixed by 3cf54c5

@RKSimon RKSimon closed this as completed Jun 11, 2024
Lukacma pushed a commit to Lukacma/llvm-project that referenced this issue Jun 12, 2024
@RKSimon @Lukacma
[InstCombine] Add llvm#38139 test coverage
f7c6fe7
@HerrCai0907 HerrCai0907 mentioned this issue Jun 13, 2024
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@LebedevRI @RKSimon @davidbolvansky