On 09/29/2014 11:12 AM, Jiong Wang wrote:
> +inline rtx single_set_no_clobber_use (const rtx_insn *insn)
> +{
> + if (!INSN_P (insn))
> + return NULL_RTX;
> +
> + if (GET_CODE (PATTERN (insn)) == SET)
> + return PATTERN (insn);
> +
> + /* Defer to the more expensive case, and return NULL_RTX if there is
> + USE or CLOBBER. */
> + return single_set_2 (insn, PATTERN (insn), true);
> }
What more expensive case?
If you're disallowing USE and CLOBBER, then single_set is just GET_CODE == SET.
I think this function is somewhat useless, and should not be added.
An adjustment to move_insn_for_shrink_wrap may be reasonable though. I haven't
tried to understand the miscompilation yet. I can imagine that this would
disable quite a bit of shrink wrapping for x86 though. Can we do better in
understanding when the clobbered register is live at the location to which we'd
like to move then insns?
r~
