[TCWG CI] Regression caused by gcc: tree-optimization/102880 - make PHI-OPT recognize more CFGs: commit f98f373dd822b35c52356b753d528924e9f89678 Author: Richard Biener rguenther@suse.de
tree-optimization/102880 - make PHI-OPT recognize more CFGs
Results regressed to # reset_artifacts: -10 # build_abe binutils: -9 # build_abe stage1: -5 # build_abe qemu: -2 # linux_n_obj: 21059 # First few build errors in logs: # 00:20:13 drivers/net/wireless/realtek/rtlwifi/rtl8192se/hw.c:2521:1: error: definition in block 22 does not dominate use in block 21 # 00:20:13 drivers/net/wireless/realtek/rtlwifi/rtl8192se/hw.c:2521:1: internal compiler error: verify_ssa failed # 00:20:13 make[6]: *** [scripts/Makefile.build:280: drivers/net/wireless/realtek/rtlwifi/rtl8192se/hw.o] Error 1 # 00:20:20 make[5]: *** [scripts/Makefile.build:497: drivers/net/wireless/realtek/rtlwifi/rtl8192se] Error 2 # 00:24:02 make[4]: *** [scripts/Makefile.build:497: drivers/net/wireless/realtek/rtlwifi] Error 2 # 00:24:02 make[3]: *** [scripts/Makefile.build:497: drivers/net/wireless/realtek] Error 2 # 00:24:02 make[2]: *** [scripts/Makefile.build:497: drivers/net/wireless] Error 2 # 00:25:21 drivers/staging/comedi/drivers/addi_apci_3120.c:1117:1: error: definition in block 10 does not dominate use in block 11 # 00:25:21 drivers/staging/comedi/drivers/addi_apci_3120.c:1117:1: internal compiler error: verify_ssa failed # 00:25:22 make[4]: *** [scripts/Makefile.build:280: drivers/staging/comedi/drivers/addi_apci_3120.o] Error 1
from # reset_artifacts: -10 # build_abe binutils: -9 # build_abe stage1: -5 # build_abe qemu: -2 # linux_n_obj: 28893 # linux build successful: all
THIS IS THE END OF INTERESTING STUFF. BELOW ARE LINKS TO BUILDS, REPRODUCTION INSTRUCTIONS, AND THE RAW COMMIT.
This commit has regressed these CI configurations: - tcwg_kernel/gnu-master-arm-lts-allmodconfig
First_bad build: https://ci.linaro.org/job/tcwg_kernel-gnu-bisect-gnu-master-arm-lts-allmodco... Last_good build: https://ci.linaro.org/job/tcwg_kernel-gnu-bisect-gnu-master-arm-lts-allmodco... Baseline build: https://ci.linaro.org/job/tcwg_kernel-gnu-bisect-gnu-master-arm-lts-allmodco... Even more details: https://ci.linaro.org/job/tcwg_kernel-gnu-bisect-gnu-master-arm-lts-allmodco...
Reproduce builds: <cut> mkdir investigate-gcc-f98f373dd822b35c52356b753d528924e9f89678 cd investigate-gcc-f98f373dd822b35c52356b753d528924e9f89678
# Fetch scripts git clone https://git.linaro.org/toolchain/jenkins-scripts
# Fetch manifests and test.sh script mkdir -p artifacts/manifests curl -o artifacts/manifests/build-baseline.sh https://ci.linaro.org/job/tcwg_kernel-gnu-bisect-gnu-master-arm-lts-allmodco... --fail curl -o artifacts/manifests/build-parameters.sh https://ci.linaro.org/job/tcwg_kernel-gnu-bisect-gnu-master-arm-lts-allmodco... --fail curl -o artifacts/test.sh https://ci.linaro.org/job/tcwg_kernel-gnu-bisect-gnu-master-arm-lts-allmodco... --fail chmod +x artifacts/test.sh
# Reproduce the baseline build (build all pre-requisites) ./jenkins-scripts/tcwg_kernel-build.sh @@ artifacts/manifests/build-baseline.sh
# Save baseline build state (which is then restored in artifacts/test.sh) mkdir -p ./bisect rsync -a --del --delete-excluded --exclude /bisect/ --exclude /artifacts/ --exclude /gcc/ ./ ./bisect/baseline/
cd gcc
# Reproduce first_bad build git checkout --detach f98f373dd822b35c52356b753d528924e9f89678 ../artifacts/test.sh
# Reproduce last_good build git checkout --detach d699f03720fce57b319276226ac4a463a8538e9f ../artifacts/test.sh
cd .. </cut>
Full commit (up to 1000 lines): <cut> commit f98f373dd822b35c52356b753d528924e9f89678 Author: Richard Biener rguenther@suse.de Date: Mon Nov 15 15:19:36 2021 +0100
tree-optimization/102880 - make PHI-OPT recognize more CFGs
This allows extra edges into the middle BB for the PHI-OPT transforms using replace_phi_edge_with_variable that do not end up moving stmts from that middle BB. This avoids regressing gcc.dg/tree-ssa/ssa-hoist-4.c with the actual fix for PR102880 where CFG cleanup has the choice to remove two forwarders and picks "the wrong" leading to
if (a > b) / /\ / / <BB> / | # PHI <a, b>
rather than
if (a > b) | /\ | <BB> \ | / \ | # PHI <a, b, b>
but it's relatively straight-forward to support extra edges into the middle-BB in paths ending in replace_phi_edge_with_variable and that do not require moving stmts. That's because we really only want to remove the edge from the condition to the middle BB. Of course actually doing that means updating dominators in non-trival ways which is why I kept the original code for the single edge case and simply defer to CFG cleanup by adjusting the condition for the complicated case.
The testcase needs to be a GIMPLE one since it's quite unreliable to produce the desired CFG.
2021-11-15 Richard Biener rguenther@suse.de
PR tree-optimization/102880 * tree-ssa-phiopt.c (tree_ssa_phiopt_worker): Push single_pred (bb1) condition to places that really need it. (match_simplify_replacement): Likewise. (value_replacement): Likewise. (replace_phi_edge_with_variable): Deal with extra edges into the middle BB.
* gcc.dg/tree-ssa/phi-opt-26.c: New testcase. --- gcc/testsuite/gcc.dg/tree-ssa/phi-opt-26.c | 31 +++++++++++++ gcc/tree-ssa-phiopt.c | 71 +++++++++++++++++------------- 2 files changed, 72 insertions(+), 30 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-26.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-26.c new file mode 100644 index 00000000000..21aa66e38b8 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-26.c @@ -0,0 +1,31 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fgimple -fdump-tree-phiopt1" } */ + +int __GIMPLE (ssa,startwith("phiopt")) +foo (int a, int b, int flag) +{ + int res; + + __BB(2): + if (flag_2(D) != 0) + goto __BB6; + else + goto __BB4; + + __BB(4): + if (a_3(D) > b_4(D)) + goto __BB7; + else + goto __BB6; + + __BB(6): + goto __BB7; + + __BB(7): + res_1 = __PHI (__BB4: a_3(D), __BB6: b_4(D)); + return res_1; +} + +/* We should be able to detect MAX despite the extra edge into + the middle BB. */ +/* { dg-final { scan-tree-dump "MAX" "phiopt1" } } */ diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c index 173ac835ca6..6b22f6bedd4 100644 --- a/gcc/tree-ssa-phiopt.c +++ b/gcc/tree-ssa-phiopt.c @@ -220,7 +220,6 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
/* If either bb1's succ or bb2 or bb2's succ is non NULL. */ if (EDGE_COUNT (bb1->succs) == 0 - || bb2 == NULL || EDGE_COUNT (bb2->succs) == 0) continue;
@@ -276,14 +275,14 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p) || (e1->flags & EDGE_FALLTHRU) == 0) continue;
- /* Also make sure that bb1 only have one predecessor and that it - is bb. */ - if (!single_pred_p (bb1) - || single_pred (bb1) != bb) - continue; - if (do_store_elim) { + /* Also make sure that bb1 only have one predecessor and that it + is bb. */ + if (!single_pred_p (bb1) + || single_pred (bb1) != bb) + continue; + /* bb1 is the middle block, bb2 the join block, bb the split block, e1 the fallthrough edge from bb1 to bb2. We can't do the optimization if the join block has more than two predecessors. */ @@ -328,10 +327,11 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p) node. */ gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE);
- gphi *newphi = factor_out_conditional_conversion (e1, e2, phi, - arg0, arg1, - cond_stmt); - if (newphi != NULL) + gphi *newphi; + if (single_pred_p (bb1) + && (newphi = factor_out_conditional_conversion (e1, e2, phi, + arg0, arg1, + cond_stmt))) { phi = newphi; /* factor_out_conditional_conversion may create a new PHI in @@ -350,12 +350,14 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p) early_p)) cfgchanged = true; else if (!early_p + && single_pred_p (bb1) && cond_removal_in_builtin_zero_pattern (bb, bb1, e1, e2, phi, arg0, arg1)) cfgchanged = true; else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) cfgchanged = true; - else if (spaceship_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) + else if (single_pred_p (bb1) + && spaceship_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) cfgchanged = true; } } @@ -386,7 +388,6 @@ replace_phi_edge_with_variable (basic_block cond_block, edge e, gphi *phi, tree new_tree) { basic_block bb = gimple_bb (phi); - basic_block block_to_remove; gimple_stmt_iterator gsi; tree phi_result = PHI_RESULT (phi);
@@ -422,28 +423,33 @@ replace_phi_edge_with_variable (basic_block cond_block, SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree);
/* Remove the empty basic block. */ + edge edge_to_remove; if (EDGE_SUCC (cond_block, 0)->dest == bb) + edge_to_remove = EDGE_SUCC (cond_block, 1); + else + edge_to_remove = EDGE_SUCC (cond_block, 0); + if (EDGE_COUNT (edge_to_remove->dest->preds) == 1) { - EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU; - EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); - EDGE_SUCC (cond_block, 0)->probability = profile_probability::always (); + e->flags |= EDGE_FALLTHRU; + e->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); + e->probability = profile_probability::always (); + delete_basic_block (edge_to_remove->dest);
- block_to_remove = EDGE_SUCC (cond_block, 1)->dest; + /* Eliminate the COND_EXPR at the end of COND_BLOCK. */ + gsi = gsi_last_bb (cond_block); + gsi_remove (&gsi, true); } else { - EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU; - EDGE_SUCC (cond_block, 1)->flags - &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); - EDGE_SUCC (cond_block, 1)->probability = profile_probability::always (); - - block_to_remove = EDGE_SUCC (cond_block, 0)->dest; + /* If there are other edges into the middle block make + CFG cleanup deal with the edge removal to avoid + updating dominators here in a non-trivial way. */ + gcond *cond = as_a <gcond *> (last_stmt (cond_block)); + if (edge_to_remove->flags & EDGE_TRUE_VALUE) + gimple_cond_make_false (cond); + else + gimple_cond_make_true (cond); } - delete_basic_block (block_to_remove); - - /* Eliminate the COND_EXPR at the end of COND_BLOCK. */ - gsi = gsi_last_bb (cond_block); - gsi_remove (&gsi, true);
statistics_counter_event (cfun, "Replace PHI with variable", 1);
@@ -959,6 +965,9 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb, allow it and move it once the transformation is done. */ if (!empty_block_p (middle_bb)) { + if (!single_pred_p (middle_bb)) + return false; + stmt_to_move = last_and_only_stmt (middle_bb); if (!stmt_to_move) return false; @@ -1351,7 +1360,10 @@ value_replacement (basic_block cond_bb, basic_block middle_bb, } else { - statistics_counter_event (cfun, "Replace PHI with variable/value_replacement", 1); + if (!single_pred_p (middle_bb)) + return 0; + statistics_counter_event (cfun, "Replace PHI with " + "variable/value_replacement", 1);
/* Replace the PHI arguments with arg. */ SET_PHI_ARG_DEF (phi, e0->dest_idx, arg); @@ -1367,7 +1379,6 @@ value_replacement (basic_block cond_bb, basic_block middle_bb, } return 1; } - }
/* Now optimize (x != 0) ? x + y : y to just x + y. */ </cut>