https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102014
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
No, that is not a safe optimization. The x86 128-bit by 64-bit DIV instruction
will #DE if the quotient is larger than ~(uint64_t) 0, you won't get a modulo
in that case even when the modulo is guaranteed to be representable.
Consider e.g. a == b == 0x3fffffffffffffffULL and n == 3.
