[PATCH][AArch64] Set TREE_TARGET_GLOBALS in aarch64_set_current_function when new tree is the default node to recalculate optab availability

[Christophe Lyon]

On 29 February 2016 at 15:28, Kyrill Tkachov
<kyrylo.tkachov@foss.arm.com> wrote:
> Hi Crhistophe,
>
>
> On 29/02/16 14:10, Christophe Lyon wrote:
>>
>> On 26 February 2016 at 16:51, James Greenhalgh <james.greenhalgh@arm.com>
>> wrote:
>>>
>>> On Thu, Feb 25, 2016 at 11:04:21AM +0000, Kyrill Tkachov wrote:
>>>>
>>>> Hi all,
>>>>
>>>> Seems like aarch64 is suffering from something similar to PR 69245 as
>>>> well.
>>>> If a target pragma sets the target state to the same as the
>>>> target_option_default_node the node is just a pointer to
>>>> target_option_default_node rather than a distinct identical node. So we
>>>> must
>>>> still restore the target globals even when setting to
>>>> target_option_default_node in order to force the midend to recompute the
>>>> availability of various optabs.
>>>>
>>>> If we don't do it, we can get in a problem like in the testcase where
>>>> the
>>>> isa_flags are all set correctly, but the optab HAVE_* predicates have
>>>> not
>>>> been recomputed.
>>>>
>>>> There is also a related issue present when popping/resetting target
>>>> pragmas
>>>> for which I'll send out a patch separately.
>>>>
>>>> Bootstrapped and tested on aarch64.
>>>>
>>>> Ok for trunk?
>>>
>>> OK.
>>>
>> Hi Kyrill,
>>
>> Since this patch, I'm seeing:
>>    gcc.dg/torture/pr52429.c   -O2 -flto -fno-use-linker-plugin
>> -flto-partition=none  (internal compiler error)
>> on target aarch64-none-linux-gnu
>>
>> The log has:
>> spawn -ignore SIGHUP
>>
>> /aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/gcc3/gcc/xgcc
>> -B/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/gcc
>> 3/gcc/
>> /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/testsuite/gcc.dg/torture/pr52429.c
>> -fno-diagnostics-show-caret -fdiagnostics-color=never -O2 -flto
>> -fno-use-linker-pl
>> ugin -flto-partition=none -g -ftree-parallelize-loops=4
>> -DSTACK_SIZE=16384 -S -o pr52429.s
>>
>> /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/testsuite/gcc.dg/torture/pr52429.c:
>> In function 'foo':
>>
>> /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/testsuite/gcc.dg/torture/pr52429.c:24:1:
>> internal compiler error: Segmentation fault
>> 0xade075 crash_signal
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/toplev.c:335
>> 0x91f88e record_operand_costs
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/ira-costs.c:1293
>> 0x91fdba scan_one_insn
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/ira-costs.c:1471
>> 0x91fdba process_bb_for_costs
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/ira-costs.c:1592
>> 0x9214e7 find_costs_and_classes
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/ira-costs.c:1699
>> 0x922552 ira_set_pseudo_classes(bool, _IO_FILE*)
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/ira-costs.c:2239
>> 0x1061ecd alloc_global_sched_pressure_data
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/haifa-sched.c:7244
>> 0x1061ecd sched_init()
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/haifa-sched.c:7394
>> 0x10679ed haifa_sched_init()
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/haifa-sched.c:7406
>> 0xa84fae schedule_insns()
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sched-rgn.c:3504
>> 0xa85864 rest_of_handle_sched
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sched-rgn.c:3717
>> 0xa85864 execute
>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sched-rgn.c:3825
>>
>> Don't you see this regression on your side?
>
>
> I've reproduced it just now.
> I had not seen it initially because the test requires a pthread target,
> so it was marked UNSUPPORTED when I tested aarch64-none-elf :(

That's what I noticed too

> But this looks like a latent bug elsewhere.
> I'll try to investigate, can you please open a PR?
Sure, this is PR 70016:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70016

Christophe

> Thanks,
> Kyrill
>
>
>> Thanks,
>>
>> Christophe.
>>
>>
>>
>>> Thanks,
>>> James
>>>
>>>> Thanks,
>>>> Kyrill
>>>>
>>>>
>>>> 2016-02-25  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
>>>>
>>>>      PR target/69245
>>>>      * config/aarch64/aarch64.c (aarch64_set_current_function):
>>>> Save/restore
>>>>      target globals when switching to target_option_default_node.
>>>>
>>>> 2016-02-25  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
>>>>
>>>>      PR target/69245
>>>>      * gcc.target/aarch64/pr69245_1.c: New test.
>>>
>>>
>