https://bugs.llvm.org/show_bug.cgi?id=42720
Bug ID: 42720
Summary: [InstCombine] Not-of-and or or-of-not's ?
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
https://godbolt.org/z/Ojj1d0
declare { i4, i1 } @llvm.smul.with.overflow.i4(i4, i4) #1
define i1 @t0_umul_sinked(i4 %size, i4 %nmemb) {
%cmp = icmp eq i4 %size, 0
%smul = tail call { i4, i1 } @llvm.smul.with.overflow.i4(i4 %size, i4 %nmemb)
%smul.ov = extractvalue { i4, i1 } %smul, 1
%phitmp = xor i1 %smul.ov, true
%or = or i1 %cmp, %phitmp
ret i1 %or
}
define i1 @t0_umu2222l_hoisted(i4 %size, i4 %nmemb) {
%cmp = icmp ne i4 %size, 0
%smul = tail call { i4, i1 } @llvm.smul.with.overflow.i4(i4 %size, i4 %nmemb)
%smul.ov = extractvalue { i4, i1 } %smul, 1
%or = and i1 %cmp, %smul.ov
%not = xor i1 %or, -1
ret i1 %not
}
We could transform one into another freely, but we don't.
https://rise4fun.com/Alive/1Uy8
Shall we have a preference here?
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