https://bugs.llvm.org/show_bug.cgi?id=42470
Bug ID: 42470
Summary: [InstCombine] icmp eq/ne (and (lshr C, X), Y), 0 fold
missed
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: lebedev...@gmail.com
CC: llvm-bugs@lists.llvm.org
https://rise4fun.com/Alive/Aq6
Name:
Pre: isPowerOf2(-C)
%o0 = lshr i8 C, %y
%o1 = and i8 %o0, %x
%r = icmp eq i8 %o1, 0
=>
%n1 = shl i8 %x, %y
%r = icmp ult i8 %n1, -C
Name:
Pre: isPowerOf2(-C)
%o0 = lshr i8 C, %y
%o1 = and i8 %o0, %x
%r = icmp ne i8 %o1, 0
=>
%n1 = shl i8 %x, %y
%r = icmp uge i8 %n1, -C
* Transforms/InstCombine/shl-and-negC-icmpeq-zero.ll
* Transforms/InstCombine/shl-and-signbit-icmpeq-zero.ll
regress in #42466 because of lack of the fold
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