Re: [PATCH AARCH64]load store pair optimization using sched_fusion pass.

[Andrew Pinski <pinskia at gmail dot com>]

On Sat, Dec 6, 2014 at 5:54 PM, Andrew Pinski <pinskia@gmail.com> wrote:
> On Fri, Dec 5, 2014 at 9:08 AM, Marcus Shawcroft
> <marcus.shawcroft@gmail.com> wrote:
>> On 18 November 2014 at 08:34, Bin Cheng <bin.cheng@arm.com> wrote:
>>
>>> 2014-11-18  Bin Cheng  <bin.cheng@arm.com>
>>>
>>>         * config/aarch64/aarch64.md (load_pair<mode>): Split to
>>>         load_pairsi, load_pairdi, load_pairsf and load_pairdf.
>>>         (load_pairsi, load_pairdi, load_pairsf, load_pairdf): Split
>>>         from load_pair<mode>.  New alternative to support int/fp
>>>         registers in fp/int mode patterns.
>>>         (store_pair<mode>:): Split to store_pairsi, store_pairdi,
>>>         store_pairsf and store_pairdi.
>>>         (store_pairsi, store_pairdi, store_pairsf, store_pairdf): Split
>>>         from store_pair<mode>.  New alternative to support int/fp
>>>         registers in fp/int mode patterns.
>>>         (*load_pair_extendsidi2_aarch64): New pattern.
>>>         (*load_pair_zero_extendsidi2_aarch64): New pattern.
>>>         (aarch64-ldpstp.md): Include.
>>>         * config/aarch64/aarch64-ldpstp.md: New file.
>>>         * config/aarch64/aarch64-protos.h (aarch64_gen_adjusted_ldpstp):
>>> New.
>>>         (extract_base_offset_in_addr): New.
>>>         (aarch64_operands_ok_for_ldpstp): New.
>>>         (aarch64_operands_adjust_ok_for_ldpstp): New.
>>>         * config/aarch64/aarch64.c (enum sched_fusion_type): New enum.
>>>         (TARGET_SCHED_FUSION_PRIORITY): New hook.
>>>         (fusion_load_store): New functon.
>>>         (extract_base_offset_in_addr): New function.
>>>         (aarch64_gen_adjusted_ldpstp): New function.
>>>         (aarch64_sched_fusion_priority): New function.
>>>         (aarch64_operands_ok_for_ldpstp): New function.
>>>         (aarch64_operands_adjust_ok_for_ldpstp): New function.
>>>
>>> 2014-11-18  Bin Cheng  <bin.cheng@arm.com>
>>>
>>>         * gcc.target/aarch64/ldp-stp-1.c: New test.
>>>         * gcc.target/aarch64/ldp-stp-2.c: New test.
>>>         * gcc.target/aarch64/ldp-stp-3.c: New test.
>>>         * gcc.target/aarch64/ldp-stp-4.c: New test.
>>>         * gcc.target/aarch64/ldp-stp-5.c: New test.
>>>         * gcc.target/aarch64/lr_free_1.c: Disable scheduling fusion
>>>         and peephole2 pass.
>>
>> Committed, thanks. /Marcus
>
>
> This patch has a bug in it dealing with volatile mems.  It will do a
> peephole of two volatile mems into a pair which is not correct as the
> order in the architecture is not defined and might even swap the order
> of the load/store incorrectly.
> I noticed this when I was merging in my changes for an improved
> peephone which already has a check for volatile.

Something like:
@@ -10555,6 +10863,10 @@ aarch64_operands_ok_for_ldpstp (rtx
*operands, bool load,
       reg_2 = operands[3];
     }

+  /* The mems cannot be volatile.  */
+  if (MEM_VOLATILE_P (mem_1) || MEM_VOLATILE_P (mem_2))
+    return false;
+
   /* Check if the addresses are in the form of [base+offset].  */
   extract_base_offset_in_addr (mem_1, &base_1, &offset_1);
   if (base_1 == NULL_RTX || offset_1 == NULL_RTX)


---- CUT ----
gcc.target/aarch64/rev16_1.c is the testcase where two volatile loads
being merged into one load pair.

Thanks,
Andrew

>
> Thanks,
> Andrew Pinski