https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87984
--- Comment #29 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #28)
> Any comments?
> --- gcc/gimple.c (revision 270012)
> +++ gcc/gimple.c (working copy)
> @@ -2727,11 +2738,16 @@ gimple_asm_clobbers_memory_p (const gasm
> {
> unsigned i;
>
> + /* While strictly speaking only a "memory" clobber denotes clobbering
> + memory in GIMPLE we also treat local hard-register variables as
> + memory so simply treat all clobbers as memory. The only exception
> + is the special clobber "cc". */
> for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
> {
> tree op = gimple_asm_clobber_op (stmt, i);
> - if (strcmp (TREE_STRING_POINTER (TREE_VALUE (op)), "memory") == 0)
> - return true;
> + if (strcmp (TREE_STRING_POINTER (TREE_VALUE (op)), "cc") == 0)
> + continue;
> + return true;
> }
>
> /* Non-empty basic ASM implicitly clobbers memory. */
This will affect not just tree-ssa-operands.c, where it is ok I guess, as it
will just mean a vdef and the alias oracle then can figure out if something
aliases or not, but also ipa-pure-const.c and sanopt. Do we want to say that
functions with register clobbers are no longer pure/const and for sanopt
consider them to be potential spots to free memory?
