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author | Jeff Law <jlaw@ventanamicro.com> | 2024-05-01 11:28:41 -0600 |
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committer | Jeff Law <jlaw@ventanamicro.com> | 2024-05-01 11:28:41 -0600 |
commit | fad93e7617ce1aafb006983a71b6edc9ae1eb2d1 (patch) | |
tree | 5089cf7e74c1b10fcfefae091295ba86ca490305 /gcc/testsuite/g++.dg/ext/packed12.C | |
parent | 1fbe1a50d86df11f434351cf62461a32747f9710 (diff) |
[committed] [RISC-V] Fix detection of store pair fusion cases
We've got the ability to count the number of store pair fusions happening in
the front-end of the pipeline. When comparing some code from last year vs the
current trunk we saw a fairly dramatic drop.
The problem is the store pair fusion detection code was actively harmful due to
a minor bug in checking offsets. So instead of pairing up 8 byte stores such
as sp+0 with sp+8, it tried to pair up sp+8 and sp+16.
Given uarch sensitivity I didn't try to pull together a testcase. But we could
certainly see the undesirable behavior in benchmarks as simplistic as dhrystone
up through spec2017.
Anyway, bootstrapped a while back. Also verified through our performance
counters that store pair fusion rates are back up. Regression tested with
crosses a few minutes ago.
gcc/
* config/riscv/riscv.cc (riscv_macro_fusion_pair_p): Break out
tests for easier debugging in store pair fusion case. Fix offset
check in same.
Diffstat (limited to 'gcc/testsuite/g++.dg/ext/packed12.C')
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