[all-commits] [llvm/llvm-project] f8919d: [NFC][GVN] Put phi-translation of 'add' behind a s...
Peter Waller via All-commits
all-commits at lists.llvm.org
Mon Jul 25 01:01:38 PDT 2022
Author: Peter Waller <peter.waller at arm.com>
Date: 2022-07-25 (Mon, 25 Jul 2022)
[NFC][GVN] Put phi-translation of 'add' behind a switch
The code in this `#if 0` block appears to be a net benefit. Put it
behind a switch defaulting to off to support experimentation and as a
request for comment.
The codegen impact of enabling this that I'm currently persuing is that
it allows PRE to take place more frequently, particularly in loops with
second order recurrences.
Preliminary experimental data:
Across LNT on AArch64, 54 benchmarks are sped up by >1%, and 42 are
regressed by >1%, the geomean (exec_time_enabled / exec_time_disabled)
of these 96 "1% or greater significance" benchmarks is 0.991. For the
full set of 770 benchmarks it's 0.998.
There are two benchmarks which experience a >30% speedup, and the worst
slowdown is ~12%, and for every benchmark with a slowdown there is a
benckmark which is sped up by a greater factor.
Differential Revision: https://reviews.llvm.org/D130241
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