https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26724
pskocik at gmail dot com changed:
What |Removed |Added
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CC| |pskocik at gmail dot com
--- Comment #3 from pskocik at gmail dot com ---
I don't know if this is related, but what's been bugging me is that gcc's
__builtin_constant_p (clang's also, but in different situations) fails to
recognize the constness/non-constness of a `memcmp` call when it's used for
equality comparisons.
In such situations, I would like to use
__builtin_constant_p(!memcmp(...))?!memcmp(...):!my_memcmp(...) to call a
custom backend function (one not named `memcmp`) if real `memcmp` would be
called, but inline a constant otherwise.
Unfortunately there seem to be edge cases where this doesn't work and while the
assembly for a !memcmp(...) expression shows it's been folded to a constant, a
__builtin_constant_p around such an expression doesn't reflect that.
E.g., in functions eq_eh{2,3}_cexprEh in
https://gcc.godbolt.org/z/6oefRX (on clang the correspondence breaks in
eq_eh1_cexprEh).
