Hi all,

I'm pinging this patch 
now that Jeff has approved the prerequisite simplify-rtx.c change 
(https://gcc.gnu.org/ml/gcc-patches/2018-03/msg00143.html) (thanks!)


On 08/02/18 17:10, Kyrill Tkachov wrote:
Hi all,

This is a followup to the other PR target/84164 patch [1] that fixes the 
testsuite regression
The regression is that with the new subreg+masking simplification we no longer 
match the
pattern for BFXIL that has the form:
(set (zero_extract:DI (reg/v:DI 76 [ a ])
        (const_int 8 [0x8])
        (const_int 0 [0]))
    (zero_extract:DI (reg/v:DI 76 [ a ])
        (const_int 8 [0x8])
        (const_int 16 [0x10])))

This is now instead represented as:
(set (zero_extract:DI (reg/v:DI 93 [ a ])
        (const_int 8 [0x8])
        (const_int 0 [0]))
    (lshiftrt:DI (reg/v:DI 93 [ a ])
        (const_int 16 [0x10])))

As far as I can see the two are equivalent semantically and the LSHIFTRT form 
is a bit
simpler, so I think the simplified form is valid, but we have no pattern to 
match it.
This patch adds that pattern to catch this form as well.
This fixes the aforementioned regression and bootstrap and testing on 
shows no problem.

Is this ok for trunk if the first patch goes in?

[1] https://gcc.gnu.org/ml/gcc-patches/2018-02/msg00443.html

2018-02-08  Kyrylo Tkachov  <kyrylo.tkac...@arm.com>

    PR target/84164
    * config/aarch64/aarch64.md (*extr_insv_lower_reg_lshiftrt<mode>):
    New pattern.

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