[EXTERNAL]Re: [RFC/PATCH v2][PR89245] Check REG_CALL_DECL note during the tail-merging

[Jeff Law]

On 9/6/19 4:23 AM, Dragan Mladjenovic wrote:
> On 24.07.2019. 20:57, Jeff Law wrote:
>> On 7/17/19 2:29 AM, Dragan Mladjenovic wrote:
>>>
>>>
>>> On 09.07.2019. 23:21, Jeff Law wrote:
>>>> On 7/9/19 2:06 PM, Dragan Mladjenovic wrote:
>>>>> This patch prevents merging of CALL instructions that that have different
>>>>> REG_CALL_DECL notes attached to them.
>>>>>
>>>>> On most architectures this is not an important distinction. Usually instruction patterns
>>>>> for calls to different functions reference different SYMBOL_REF-s, so they won't match.
>>>>> On MIPS PIC calls get split into an got_load/*call_internal pair where the latter represents
>>>>> indirect register call w/o SYMBOL_REF attached (until machine_reorg pass). The bugzilla issue
>>>>> had such two internal_call-s merged despite the fact that they had different register usage
>>>>> information assigned by ipa-ra.
>>>>>
>>>>> As per comment form Richard Sandiford, this version compares reg usage for both call
>>>>> instruction instead of shallow comparing the notes. Tests updated accordingly.
>>>>>
>>>>> gcc/ChangeLog:
>>>>>
>>>>> 2019-07-09  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>
>>>>>
>>>>> 	* cfgcleanup.c (old_insns_match_p): Check if used hard regs set is equal
>>>>> 	for both call instructions.
>>>>>
>>>>> gcc/testsuite/ChangeLog:
>>>>>
>>>>> 2019-07-09  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>
>>>>>
>>>>> 	* gcc.target/mips/cfgcleanup-jalr1.c: New test.
>>>>> 	* gcc.target/mips/cfgcleanup-jalr2.c: New test.
>>>>> 	* gcc.target/mips/cfgcleanup-jalr3.c: New test.
>>>> THanks.  I've installed this on the trunk.
>>>>
>>>> jeff
>>> Thanks. Can this be back-ported to active branches also. This issue
>>> seems to be there > since gcc6 if not gcc5.
>> I've asked Matthew to handle the backport.  I'm going to be on PTO the
>> next couple weeks.
>>
>> jeff
>>
> 
> Hi,
> 
> Sorry, I forgot to check up on this patch. Is it still ok for me to try 
> to backport it to gcc 9 and gcc 8 branches?
Yes, this would be fine to backport to gcc-8 and gcc-9 branches.  I'd
expect it to be pretty easy as I don't think old_insns_match_p has
changed much.

Jeff