[Bug tree-optimization/127853] x86 (non BMI): .CTZ(x, N) returns 32 when bsr insn result could be undefined

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127853

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Testcase?
The macros for non-BMI/LZCNT return 0, what they set VALUE to is irrelevant in
that case.
match.pd only does something with these if the macros return 2:
          else if (direct_internal_fn_supported_p (IFN_CLZ, TREE_TYPE (@3),
                                                   OPTIMIZE_FOR_BOTH)
                   && CLZ_DEFINED_VALUE_AT_ZERO
                        (SCALAR_INT_TYPE_MODE (TREE_TYPE (@3)), val) == 2)
and
          else if (direct_internal_fn_supported_p (IFN_CTZ, TREE_TYPE (@3),
                                                   OPTIMIZE_FOR_BOTH)
                   && CTZ_DEFINED_VALUE_AT_ZERO
                        (SCALAR_INT_TYPE_MODE (TREE_TYPE (@3)), val) == 2)
            ifn = IFN_CTZ;