From: Surya Kumari Jangala <jskumari@linux.vnet.ibm.com>
To: Richard Sandiford <richard.sandiford@arm.com>,
Peter Bergner <bergner@linux.ibm.com>
Cc: GCC Development <gcc@gcc.gnu.org>, vmakarov@redhat.com
Subject: Re: Discussion about arm testcase failures seen with patch for PR111673
Date: Fri, 24 Nov 2023 13:39:44 +0530 [thread overview]
Message-ID: <2a2060c7-5288-422d-ba1d-dfe4306b4c3f@linux.vnet.ibm.com> (raw)
In-Reply-To: <51f4b26f-1462-45c2-8106-fbfe8dc61975@linux.vnet.ibm.com>
Hi Richard,
Ping. Please let me know if the test failure that I mentioned in the mail below can be handled by changing the expected generated code. I am not conversant with arm, and hence would appreciate your help.
Regards,
Surya
On 03/11/23 4:58 pm, Surya Kumari Jangala wrote:
> Hi Richard,
> I had submitted a patch for review (https://gcc.gnu.org/pipermail/gcc-patches/2023-October/631849.html)
> regarding scaling save/restore costs of callee save registers with block
> frequency in the IRA pass (PR111673).
>
> This patch has been approved by VMakarov
> (https://gcc.gnu.org/pipermail/gcc-patches/2023-October/632089.html).
>
> With this patch, we are seeing performance improvements with spec on x86
> (exchange: 5%, xalancbmk: 2.5%) and on Power (perlbench: 5.57%).
>
> I received a mail from Linaro about some failures seen in the CI pipeline with
> this patch. I have analyzed the failures and I wish to discuss the analysis with you.
>
> One failure reported by the Linaro CI is:
>
> FAIL: gcc.target/arm/pr111235.c scan-assembler-times ldrexd\tr[0-9]+, r[0-9]+, \\[r[0-9]+\\] 2
>
> The diff in the assembly between trunk and patch is:
>
> 93c93
> < push {r4, r5}
> ---
>> push {fp}
> 95c95
> < ldrexd r4, r5, [r0]
> ---
>> ldrexd fp, ip, [r0]
> 99c99
> < pop {r4, r5}
> ---
>> ldr fp, [sp], #4
>
>
> The test fails with patch because the ldrexd insn uses fp & ip registers instead
> of r[0-9]+
>
> But the code produced by patch is better because it is pushing and restoring only
> one register (fp) instead of two registers (r4, r5). Hence, this test can be
> modified to allow it to pass on arm. Please let me know what you think.
>
> If you need more information, please let me know. I will be sending separate mails
> for the other test failures.
>
> Regards,
> Surya
>
>
>
next prev parent reply other threads:[~2023-11-24 8:09 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-03 11:28 Surya Kumari Jangala
2023-11-24 8:09 ` Surya Kumari Jangala [this message]
2023-11-24 10:48 ` Richard Earnshaw
2023-11-28 12:52 ` Discussion about arm/aarch64 " Surya Kumari Jangala
2023-11-28 13:48 ` Richard Earnshaw
2023-11-28 15:41 ` Richard Sandiford
2023-12-14 7:17 ` Surya Kumari Jangala
2023-12-14 16:11 ` Richard Earnshaw (lists)
2023-12-15 17:04 ` Surya Kumari Jangala
2024-01-29 6:14 ` Surya Kumari Jangala
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