Hi Richard, This is a report from Linaro’s automatic benchmarking system, which tracks upstream components and automatically bisects performance regressions down to a single commit. We have recently enabled these emails to be sent to patch authors automatically.
It appears that after your patch SPEC CPU2006’s 483.xalancbmk slowed down by 3% on arm-linux-gnueabihf when built with -O2 -flto. Any theories on what could’ve caused it? This is one of the first reports, and we welcome feedback on improving reporting template. Regards, -- Maxim Kuvyrkov https://www.linaro.org > On 26 Jun 2021, at 16:24, ci_not...@linaro.org wrote: > > Successfully identified regression in *gcc* in CI configuration > tcwg_bmk_gnu_tk1/gnu-master-arm-spec2k6-O2_LTO. So far, this commit has > regressed CI configurations: > - tcwg_bmk_gnu_tk1/gnu-master-arm-spec2k6-O2_LTO > > Culprit: > <cut> > commit 32955416d8040b1fa1ba21cd4179b3264e6c5bd6 > Author: Richard Biener <rguent...@suse.de> > Date: Mon May 3 12:07:58 2021 +0200 > > Improve PHI handling in DSE > > This improves handling of PHI defs when walking uses in > dse_classify_store to track two PHI defs. This happens > when there are CFG merges and one PHI feeds into another. > If we decide to want more then using a sbitmap for this might be > the way to go. > > 2021-05-03 Richard Biener <rguent...@suse.de> > > * tree-ssa-dse.c (dse_classify_store): Track two PHI defs. > > * gcc.dg/tree-ssa/ssa-dse-42.c: New testcase. > * gcc.dg/pr81192.c: Disable DSE. > </cut> > > Results regressed to (for first_bad == > 32955416d8040b1fa1ba21cd4179b3264e6c5bd6) > # reset_artifacts: > -10 > # build_abe binutils: > -9 > # build_abe stage1 -- --set gcc_override_configure=--with-mode=arm --set > gcc_override_configure=--disable-libsanitizer: > -8 > # build_abe linux: > -7 > # build_abe glibc: > -6 > # build_abe stage2 -- --set gcc_override_configure=--with-mode=arm --set > gcc_override_configure=--disable-libsanitizer: > -5 > # true: > 0 > # benchmark -O2_LTO_marm -- > artifacts/build-32955416d8040b1fa1ba21cd4179b3264e6c5bd6/results_id: > 1 > # 483.xalancbmk,Xalan_base.default regressed by > 103 > > from (for last_good == ed3c43224cc4e378dbab066122bc63536ccb1276) > # reset_artifacts: > -10 > # build_abe binutils: > -9 > # build_abe stage1 -- --set gcc_override_configure=--with-mode=arm --set > gcc_override_configure=--disable-libsanitizer: > -8 > # build_abe linux: > -7 > # build_abe glibc: > -6 > # build_abe stage2 -- --set gcc_override_configure=--with-mode=arm --set > gcc_override_configure=--disable-libsanitizer: > -5 > # true: > 0 > # benchmark -O2_LTO_marm -- > artifacts/build-ed3c43224cc4e378dbab066122bc63536ccb1276/results_id: > 1 > > Artifacts of last_good build: > https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_tk1-gnu-master-arm-spec2k6-O2_LTO/31/artifact/artifacts/build-ed3c43224cc4e378dbab066122bc63536ccb1276/ > Results ID of last_good: > tk1_32/tcwg_bmk_gnu_tk1/bisect-gnu-master-arm-spec2k6-O2_LTO/458 > Artifacts of first_bad build: > https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_tk1-gnu-master-arm-spec2k6-O2_LTO/31/artifact/artifacts/build-32955416d8040b1fa1ba21cd4179b3264e6c5bd6/ > Results ID of first_bad: > tk1_32/tcwg_bmk_gnu_tk1/bisect-gnu-master-arm-spec2k6-O2_LTO/480 > Build top page/logs: > https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_tk1-gnu-master-arm-spec2k6-O2_LTO/31/ > > Configuration details: > > > Reproduce builds: > <cut> > mkdir investigate-gcc-32955416d8040b1fa1ba21cd4179b3264e6c5bd6 > cd investigate-gcc-32955416d8040b1fa1ba21cd4179b3264e6c5bd6 > > git clone https://git.linaro.org/toolchain/jenkins-scripts > > mkdir -p artifacts/manifests > curl -o artifacts/manifests/build-baseline.sh > https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_tk1-gnu-master-arm-spec2k6-O2_LTO/31/artifact/artifacts/manifests/build-baseline.sh > --fail > curl -o artifacts/manifests/build-parameters.sh > https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_tk1-gnu-master-arm-spec2k6-O2_LTO/31/artifact/artifacts/manifests/build-parameters.sh > --fail > curl -o artifacts/test.sh > https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_tk1-gnu-master-arm-spec2k6-O2_LTO/31/artifact/artifacts/test.sh > --fail > chmod +x artifacts/test.sh > > # Reproduce the baseline build (build all pre-requisites) > ./jenkins-scripts/tcwg_bmk-build.sh @@ artifacts/manifests/build-baseline.sh > > cd gcc > > # Reproduce first_bad build > git checkout --detach 32955416d8040b1fa1ba21cd4179b3264e6c5bd6 > ../artifacts/test.sh > > # Reproduce last_good build > git checkout --detach ed3c43224cc4e378dbab066122bc63536ccb1276 > ../artifacts/test.sh > > cd .. > </cut> > > History of pending regressions and results: > https://git.linaro.org/toolchain/ci/base-artifacts.git/log/?h=linaro-local/ci/tcwg_bmk_gnu_tk1/gnu-master-arm-spec2k6-O2_LTO > > Artifacts: > https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_tk1-gnu-master-arm-spec2k6-O2_LTO/31/artifact/artifacts/ > Build log: > https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_tk1-gnu-master-arm-spec2k6-O2_LTO/31/consoleText > > Full commit (up to 1000 lines): > <cut> > commit 32955416d8040b1fa1ba21cd4179b3264e6c5bd6 > Author: Richard Biener <rguent...@suse.de> > Date: Mon May 3 12:07:58 2021 +0200 > > Improve PHI handling in DSE > > This improves handling of PHI defs when walking uses in > dse_classify_store to track two PHI defs. This happens > when there are CFG merges and one PHI feeds into another. > If we decide to want more then using a sbitmap for this might be > the way to go. > > 2021-05-03 Richard Biener <rguent...@suse.de> > > * tree-ssa-dse.c (dse_classify_store): Track two PHI defs. > > * gcc.dg/tree-ssa/ssa-dse-42.c: New testcase. > * gcc.dg/pr81192.c: Disable DSE. > --- > gcc/testsuite/gcc.dg/pr81192.c | 4 +++- > gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-42.c | 20 ++++++++++++++++++++ > gcc/tree-ssa-dse.c | 23 ++++++++++++++--------- > 3 files changed, 37 insertions(+), 10 deletions(-) > > diff --git a/gcc/testsuite/gcc.dg/pr81192.c b/gcc/testsuite/gcc.dg/pr81192.c > index 71bbc13a0e9..6cab6056558 100644 > --- a/gcc/testsuite/gcc.dg/pr81192.c > +++ b/gcc/testsuite/gcc.dg/pr81192.c > @@ -1,4 +1,4 @@ > -/* { dg-options "-Os -fdump-tree-pre-details -fdisable-tree-evrp" } */ > +/* { dg-options "-Os -fdump-tree-pre-details -fdisable-tree-evrp > -fno-tree-dse" } */ > > /* Disable tree-evrp because the new version of evrp sees > <bb 3> : > @@ -16,6 +16,8 @@ produces > # iftmp.2_12 = PHI <2147483647(3), iftmp.2_11(4)> > which causes the situation being tested to dissapear before we get to PRE. */ > > +/* Likewise disable DSE which also elides the tail merging "opportunity". */ > + > #if __SIZEOF_INT__ == 2 > #define unsigned __UINT32_TYPE__ > #define int __INT32_TYPE__ > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-42.c > b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-42.c > new file mode 100644 > index 00000000000..34108c83828 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-42.c > @@ -0,0 +1,20 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O -fdump-tree-dse1" } */ > + > +int a[2]; > +void foo(int i, int k, int j) > +{ > + a[0] = i; > + if (k) > + a[0] = a[i] + k; > + else > + { > + if (j) > + a[1] = 1; > + a[0] = a[i] + 3; > + } > + a[0] = 0; > +} > + > +/* The last stores to a[0] and a[1] remain. */ > +/* { dg-final { scan-tree-dump-times " = " 2 "dse1" } } */ > diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c > index e0a944c704a..dfa6d314727 100644 > --- a/gcc/tree-ssa-dse.c > +++ b/gcc/tree-ssa-dse.c > @@ -799,7 +799,8 @@ dse_classify_store (ao_ref *ref, gimple *stmt, > return DSE_STORE_LIVE; > > auto_vec<gimple *, 10> defs; > - gimple *phi_def = NULL; > + gimple *first_phi_def = NULL; > + gimple *last_phi_def = NULL; > FOR_EACH_IMM_USE_STMT (use_stmt, ui, defvar) > { > /* Limit stmt walking. */ > @@ -825,7 +826,9 @@ dse_classify_store (ao_ref *ref, gimple *stmt, > SSA_NAME_VERSION (PHI_RESULT (use_stmt)))) > { > defs.safe_push (use_stmt); > - phi_def = use_stmt; > + if (!first_phi_def) > + first_phi_def = use_stmt; > + last_phi_def = use_stmt; > } > } > /* If the statement is a use the store is not dead. */ > @@ -889,6 +892,8 @@ dse_classify_store (ao_ref *ref, gimple *stmt, > gimple *def = defs[i]; > gimple *use_stmt; > use_operand_p use_p; > + tree vdef = (gimple_code (def) == GIMPLE_PHI > + ? gimple_phi_result (def) : gimple_vdef (def)); > /* If the path to check starts with a kill we do not need to > process it further. > ??? With byte tracking we need only kill the bytes currently > @@ -901,8 +906,7 @@ dse_classify_store (ao_ref *ref, gimple *stmt, > } > /* If the path ends here we do not need to process it further. > This for example happens with calls to noreturn functions. */ > - else if (gimple_code (def) != GIMPLE_PHI > - && has_zero_uses (gimple_vdef (def))) > + else if (has_zero_uses (vdef)) > { > /* But if the store is to global memory it is definitely > not dead. */ > @@ -912,12 +916,13 @@ dse_classify_store (ao_ref *ref, gimple *stmt, > } > /* In addition to kills we can remove defs whose only use > is another def in defs. That can only ever be PHIs of which > - we track a single for simplicity reasons (we fail for multiple > - PHIs anyways). We can also ignore defs that feed only into > + we track two for simplicity reasons, the first and last in > + {first,last}_phi_def (we fail for multiple PHIs anyways). > + We can also ignore defs that feed only into > already visited PHIs. */ > - else if (gimple_code (def) != GIMPLE_PHI > - && single_imm_use (gimple_vdef (def), &use_p, &use_stmt) > - && (use_stmt == phi_def > + else if (single_imm_use (vdef, &use_p, &use_stmt) > + && (use_stmt == first_phi_def > + || use_stmt == last_phi_def > || (gimple_code (use_stmt) == GIMPLE_PHI > && bitmap_bit_p (visited, > SSA_NAME_VERSION > </cut> _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org https://lists.linaro.org/mailman/listinfo/linaro-toolchain
