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Re: Shouldn't convert_scalars_to_vector call free_dominance_info?


On March 10, 2016 6:02:58 PM GMT+01:00, "H.J. Lu" <hjl.tools@gmail.com> wrote:
>On Thu, Mar 10, 2016 at 6:57 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Thu, Mar 10, 2016 at 5:49 AM, Jakub Jelinek <jakub@redhat.com>
>wrote:
>>> On Thu, Mar 10, 2016 at 05:43:27AM -0800, H.J. Lu wrote:
>>>> > free_dominance_info (CDI_DOMINATORS);
>>>>
>>>> Since convert_scalars_to_vector may add instructions, dominance
>>>> info is no longer up to date.
>>>
>>> Adding instructions doesn't change anything on the dominance info,
>just
>>> cfg manipulations that don't keep the dominators updated.
>>> You can try to verify the dominance info at the end of the stv pass,
>>
>> I added
>>
>> verify_dominators (CDI_DOMINATORS);
>> '
>> It did trigger assert in my 64-bit STV pass in 64-bit libgcc build:
>>
>> /export/gnu/import/git/sources/gcc/libgcc/config/libbid/bid128_fma.c:
>> In function \u2018add_and_round.constprop\u2019:
>>
>/export/gnu/import/git/sources/gcc/libgcc/config/libbid/bid128_fma.c:629:1:
>> error: dominator of 158 should be 107, not 101
>>
>> I will investigate.
>
>Here is the problem:
>
>1. I extended the STV pass to 64-bit to convert TI load/store to
>V1TI load/store to use SSE load/store for 128-bit load/store.
>2. The 64-bit STV pass generates settings of CONST0_RTX and
>CONSTM1_RTX to store 128-bit 0 and -1.
>3. I placed the 64-bit STV pass before the CSE pass so that
>CONST0_RTX and CONSTM1_RTX generated by the STV pass
>can be CSEed.
>4. After settings of CONST0_RTX and CONSTM1_RTX are CSEed,
>dominance info will be wrong.

Can't see how cse can ever invalidate dominators.

Richard.

>We can call free_dominance_info in convert_scalars_to_vector in
>64-bit or unconditionally.



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