[shrink-wrap] should not sink instructions which may cause trap ?
Fri Sep 26 16:13:00 GMT 2014
On 09/26/14 08:50, Jiong Wang wrote:
>>>> if (may_trap_p (x))
>>>> don't sink this instruction.
>>>> any comments?
>>> Should be checking if x may throw internally instead.
>> Richard, thanks for the suggestion, have used insn_could_throw_p to do
>> the check,
>> which will only do the check when flag_exception and
>> flag_non_call_exception be true,
>> so those instruction could still be sink for normal c/c++ program.
>> below is the fix for pr49847.C regression on aarch64. I re-run
>> full test on
>> aarch64-none-elf bare metal, no regression.
>> bootstrap ok on x86, no regression on check-gcc/g++.
>> ok for trunk?
> (re-sent with changelog entry)
> 2014-09-26 Jiong Wang<firstname.lastname@example.org>
> * shrink-wrap.c (move_insn_for_shrink_wrap): Check
> "insn_could_throw_p" before
> sinking insn.
I think can_throw_internal, per Richi's recommendation is better.
Note that can_throw_internal keys off the existence of the EH landing
pads for the particular insn.
If flag_exceptions is false (for example), then would not expect those
landing pads to exist and the insn would not be considered as
Can you test with can_throw_internal to verify it's behaviour and resubmit
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