Discussion about arm testcase failures seen with patch for PR111673
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
Question about the changing the default behavior of ipa-inline
Hi, I recently ran into an inline-related issue and would like to ask about it. This is about the ipa-inline. I'd like to make my function be inlined, but it trapped in the function 'want_inline_small_function_p', more specificly, in the conditional statement 'growth_positive_p (callee, e, growth)'. The offline size of the function is too small and the growth is much bigger. But I still hope it will be inlined. Besides, the reason for its failure in the report file was CIF_MAX_INLINE_INSNS_AUTO_LIMIT. But I don't seem to be able to fix that by modifying the value of that parameter. Is there another way to solve it? Or can I only change the source code to make it? Thanks Hanke Zhang
gcc-12-20231103 is now available
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