[PATCH] D65148: [SimplifyCFG] Bump phi-node-folding-threshold from 2 to 3

Thu Aug 29 07:54:47 PDT 2019

dmgreen added a comment.

Hello. Sorry for the delay I missed your earlier email and wanted to grab some more results. This is what it looks like on an Cortex-M0+:

  cmsisdsp/BasicMath/arm_abs_q15                         61280.3209   51891.8918   -15.32
  cmsisdsp/BasicMath/arm_abs_q31                         96690.6474   61414.7322   -36.48
  cmsisdsp/BasicMath/arm_abs_q7                          65869.4373   56112.2244   -14.81
  cmsisdsp/BasicMath/arm_mult_q15                        49288.5433   42873.5485   -13.01
  cmsisdsp/BasicMath/arm_mult_q7                         51843.8512   41171.4250   -20.58
  cmsisdsp/ComplexMath/arm_cmplx_mult_real_q15           33015.6234   27529.7009   -16.61
  cmsisdsp/Filtering/arm_fir_lattice_q15                 9564.20255   9130.68289   -4.53
  cmsisdsp/Transform/arm_cfft_q15                        3854.80244   3656.58566   -5.14
  cmsisdsp/Transform/arm_rfft_q15                        5410.24904   5219.46206   -3.52

  cmsisdsp/BasicMath                                     40822.2401   39464.0989   -3.32
  cmsisdsp/ComplexMath                                   12243.6404   12120.6590   -1.00
  cmsisdsp/Filtering                                     1094.25278   1092.98454   -0.11
  cmsisdsp/Transform                                     1805.07193   1778.58598   -1.46
  total                                                  2450.53110   2433.22327   -0.70 

The first two columns mean very little, but are some measure of items/sec/Mhz (higher is better). The third column is percentage change. The bottom results are geomeans. Any results that didn't change are omitted.

Those results are a load better than they were originally. They are still not great, but they are on a CPU/test suite combo that isn't the most interesting combo. This doesn't come up on other, more dsp like cpus, and there are some AArch64 codesize improvements for this patch too.

But equally I don't think that a lot of these regressions were necessarily about the cpu/architecture used, but about the code they are running. You may find that similar problems come up elsewhere from other peoples code, but we have no problem with this going ahead.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65148/new/

https://reviews.llvm.org/D65148