Hi, Gentle ping this:
https://gcc.gnu.org/pipermail/gcc-patches/2021-May/571258.html BR, Kewen on 2021/6/9 上午10:26, Kewen.Lin via Gcc-patches wrote: > Hi, > > Gentle ping this: > > https://gcc.gnu.org/pipermail/gcc-patches/2021-May/571258.html > > BR, > Kewen > > on 2021/5/26 上午10:59, Kewen.Lin via Gcc-patches wrote: >> Hi, >> >> This is the updated version of patch to deal with the bwaves_r >> degradation due to vector construction fed by strided loads. >> >> As Richi's comments [1], this follows the similar idea to over >> price the vector construction fed by VMAT_ELEMENTWISE or >> VMAT_STRIDED_SLP. Instead of adding the extra cost on vector >> construction costing immediately, it firstly records how many >> loads and vectorized statements in the given loop, later in >> rs6000_density_test (called by finish_cost) it computes the >> load density ratio against all vectorized stmts, and check >> with the corresponding thresholds DENSITY_LOAD_NUM_THRESHOLD >> and DENSITY_LOAD_PCT_THRESHOLD, do the actual extra pricing >> if both thresholds are exceeded. >> >> Note that this new load density heuristic check is based on >> some fields in target cost which are updated as needed when >> scanning each add_stmt_cost entry, it's independent of the >> current function rs6000_density_test which requires to scan >> non_vect stmts. Since it's checking the load stmts count >> vs. all vectorized stmts, it's kind of density, so I put >> it in function rs6000_density_test. With the same reason to >> keep it independent, I didn't put it as an else arm of the >> current existing density threshold check hunk or before this >> hunk. >> >> In the investigation of -1.04% degradation from 526.blender_r >> on Power8, I noticed that the extra penalized cost 320 on one >> single vector construction with type V16QI is much exaggerated, >> which makes the final body cost unreliable, so this patch adds >> one maximum bound for the extra penalized cost for each vector >> construction statement. >> >> Bootstrapped/regtested on powerpc64le-linux-gnu P9. >> >> Full SPEC2017 performance evaluation on Power8/Power9 with >> option combinations: >> * -O2 -ftree-vectorize {,-fvect-cost-model=very-cheap} {,-ffast-math} >> * {-O3, -Ofast} {,-funroll-loops} >> >> bwaves_r degradations on P8/P9 have been fixed, nothing else >> remarkable was observed. >> >> Is it ok for trunk? >> >> [1] https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570076.html >> >> BR, >> Kewen >> ----- >> gcc/ChangeLog: >> >> * config/rs6000/rs6000.c (struct rs6000_cost_data): New members >> nstmts, nloads and extra_ctor_cost. >> (rs6000_density_test): Add load density related heuristics and the >> checks, do extra costing on vector construction statements if need. >> (rs6000_init_cost): Init new members. >> (rs6000_update_target_cost_per_stmt): New function. >> (rs6000_add_stmt_cost): Factor vect_nonmem hunk out to function >> rs6000_update_target_cost_per_stmt and call it. >> >
