https://bugs.llvm.org/show_bug.cgi?id=52429
Bug ID: 52429
Summary: InstSimplify incorrectly folds signed comparisons of
'gep inbounds'
Product: libraries
Version: trunk
Hardware: All
OS: All
Status: NEW
Keywords: miscompilation
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected],
[email protected], [email protected]
File: Transforms/InstSimplify/compare.ll
define i1 @gep_same_base_constant_indices(i8* %a) {
; CHECK-NEXT: ret i1 true
;
%arrayidx1 = getelementptr inbounds i8, i8* %a, i64 1
%arrayidx2 = getelementptr inbounds i8, i8* %a, i64 10
%cmp = icmp slt i8* %arrayidx1, %arrayidx2
ret i1 %cmp
}
Folding such unsigned comparisons is correct, but not for signed as an object
may cross the unsigned/signed line, e.g:
ptr = malloc(42) // 0x7fff..ff0
ptr + 42 // 0x8....
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