https://bugs.llvm.org/show_bug.cgi?id=43199
Bug ID: 43199
Summary: [InstCombine?] Failure to simplify branch-less logic
code
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://godbolt.org/z/MVN3j-
https://rise4fun.com/Alive/UCaS
bool is_not_ub_naive(char *Base, unsigned long Offset, char *&Offseted) {
Offseted = reinterpret_cast<char*>(intptr_t(Base) + Offset);
return ((Base != nullptr || Offset == 0) &&
(Offseted != nullptr || Offset == 0));
}
bool is_not_ub_best(char *Base, unsigned long Offset, char *&Offseted) {
Offseted = reinterpret_cast<char*>(intptr_t(Base) + Offset);
return ((Base != nullptr) == (Offseted != nullptr));
}
`is_not_ub_naive()` doesn't get flattened but that isn't the point here.
Even if i flatten it manually down to `@is_not_ub_flat_naive`, it still
doesn't get optimized down to `@is_not_ub_best`...
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