{"id":2235281,"url":"http://patchwork.ozlabs.org/api/patches/2235281/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260509013939.279561-1-pengxuan.zheng@oss.qualcomm.com/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/projects/17/?format=json","name":"GNU Compiler Collection","link_name":"gcc","list_id":"gcc-patches.gcc.gnu.org","list_email":"gcc-patches@gcc.gnu.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260509013939.279561-1-pengxuan.zheng@oss.qualcomm.com>","list_archive_url":null,"date":"2026-05-09T01:39:39","name":"[v2] cselim: Allow middle_bb to have more than one statement [PR124405]","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"5ffc5073bfc3eb7de3643d2ea67d6b3314a325fa","submitter":{"id":92245,"url":"http://patchwork.ozlabs.org/api/people/92245/?format=json","name":"Pengxuan Zheng","email":"pengxuan.zheng@oss.qualcomm.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260509013939.279561-1-pengxuan.zheng@oss.qualcomm.com/mbox/","series":[{"id":503472,"url":"http://patchwork.ozlabs.org/api/series/503472/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=503472","date":"2026-05-09T01:39:39","name":"[v2] cselim: Allow middle_bb to have more than one statement [PR124405]","version":2,"mbox":"http://patchwork.ozlabs.org/series/503472/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2235281/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2235281/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=qualcomm.com header.i=@qualcomm.com header.a=rsa-sha256\n header.s=qcppdkim1 header.b=Yjo9dtNP;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com\n header.a=rsa-sha256 header.s=google header.b=AO3Ap5Wi;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; 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This\npatch relaxes this restriction if the following pattern is found and also when\nit is safe to do the optimization.\n\nSPLIT_BB:\n ...\n STORE = X\n if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)\nMIDDLE_BB:\n ...\n STORE = Y;\n ...\n fallthrough (edge E0)\nJOIN_BB:\n some more\n\nBootstrapped and tested on x86_64-linux-gnu and aarch64-linux-gnu.\n\nChanges since v1:\n* v2: Revert changes to trailing_store_in_bb and do not call\n trailing_store_in_bb to get split_assign.\n Remove some unnecessary checks in cselim_candidate.\n Pass the result of cselim_candidate which is the candidate store for\n cselim as an argument to cond_store_replacement instead.\n\n\tPR tree-optimization/124405\n\ngcc/ChangeLog:\n\n\t* tree-ssa-phiopt.cc (cond_store_replacement): Make ASSIGN (the\n\tcandidate store for cselim) an argument of the function instead.\n\t(cselim_candidate): New.\n\t(pass_cselim::execute): Call cselim_candidate and pass the result to\n\tcond_store_replacement.\n\ngcc/testsuite/ChangeLog:\n\n\t* gcc.dg/tree-ssa/pr124405.c: New test.\n\nSigned-off-by: Pengxuan Zheng \n---\n gcc/testsuite/gcc.dg/tree-ssa/pr124405.c | 12 +++++\n gcc/tree-ssa-phiopt.cc | 68 +++++++++++++++++++++---\n 2 files changed, 73 insertions(+), 7 deletions(-)\n create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr124405.c","diff":"diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr124405.c b/gcc/testsuite/gcc.dg/tree-ssa/pr124405.c\nnew file mode 100644\nindex 00000000000..9ba230d2b56\n--- /dev/null\n+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr124405.c\n@@ -0,0 +1,12 @@\n+/* { dg-do compile } */\n+/* { dg-options \"-O1 -fdump-tree-cselim-details\" } */\n+\n+void\n+f (int *a, int b)\n+{\n+ *a &= ~3;\n+ if (b)\n+ *a |= 1;\n+}\n+\n+/* { dg-final { scan-tree-dump-times \"Conditional store replacement happened\" 1 \"cselim\"} } */\ndiff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc\nindex 324559e6a7d..e55d6efaa2b 100644\n--- a/gcc/tree-ssa-phiopt.cc\n+++ b/gcc/tree-ssa-phiopt.cc\n@@ -2991,16 +2991,16 @@ get_non_trapping (void)\n JOIN_BB:\n some more\n \n- We check that MIDDLE_BB contains only one store, that that store\n+ ASSIGN is a store in MIDDLE_BB which is the candidate for cselim. We check\n+ that MIDDLE_BB contains only one store (i.e., ASSIGN), that that store\n doesn't trap (not via NOTRAP, but via checking if an access to the same\n- memory location dominates us, or the store is to a local addressable\n- object) and that the store has a \"simple\" RHS. */\n+ memory location dominates us, or the store is to a local addressable object)\n+ and that the store has a \"simple\" RHS. */\n \n static bool\n-cond_store_replacement (basic_block middle_bb, basic_block join_bb,\n-\t\t\tedge e0, edge e1, hash_set *nontrap)\n+cond_store_replacement (basic_block middle_bb, basic_block join_bb, edge e0,\n+\t\t\tedge e1, gimple *assign, hash_set *nontrap)\n {\n- gimple *assign = last_and_only_stmt (middle_bb);\n tree lhs, rhs, name, name2;\n gphi *newphi;\n gassign *new_stmt;\n@@ -3289,6 +3289,58 @@ trailing_store_in_bb (basic_block bb, tree vdef, gphi *vphi, bool onlyonestore)\n return store;\n }\n \n+/* Return the candidate store for cselim. If there is only a single statement\n+ in MIDDLE_BB, return that statement. Otherwise, try to find the following\n+ pattern and return the only store in MIDDLE_BB.\n+\n+ SPLIT_BB:\n+ ...\n+ STORE = X\n+ if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)\n+ MIDDLE_BB:\n+ ...\n+ STORE = Y;\n+ ...\n+ fallthrough (edge E0)\n+ JOIN_BB:\n+ some more\n+*/\n+\n+static gimple *\n+cselim_candidate (basic_block middle_bb, basic_block join_bb, edge e0, edge e1)\n+{\n+ gimple *middle_assign = last_and_only_stmt (middle_bb);\n+ if (middle_assign)\n+ return middle_assign;\n+\n+ gphi *vphi = get_virtual_phi (join_bb);\n+ if (!vphi)\n+ return NULL;\n+\n+ tree middle_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, e0);\n+ middle_assign = trailing_store_in_bb (middle_bb, middle_vdef, vphi, true);\n+\n+ if (!middle_assign || !gimple_assign_single_p (middle_assign)\n+ || gimple_has_volatile_ops (middle_assign)\n+ || stmt_references_abnormal_ssa_name (middle_assign))\n+ return NULL;\n+\n+ tree split_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, e1);\n+ gimple *split_assign = SSA_NAME_DEF_STMT (split_vdef);\n+\n+ if (!split_assign || !gimple_assign_single_p (split_assign)\n+ || gimple_has_volatile_ops (split_assign)\n+ || stmt_references_abnormal_ssa_name (split_assign))\n+ return NULL;\n+\n+ if (gimple_vdef (split_assign) != gimple_vuse (middle_assign)\n+ || !operand_equal_p (gimple_assign_lhs (middle_assign),\n+\t\t\t gimple_assign_lhs (split_assign), 0))\n+ return NULL;\n+\n+ return middle_assign;\n+}\n+\n /* Limited Conditional store replacement. We already know\n that the recognized pattern looks like so:\n \n@@ -4260,7 +4312,9 @@ pass_cselim::execute (function *)\n \t optimization if the join block has more than two predecessors. */\n if (EDGE_COUNT (bb2->preds) > 2)\n \treturn;\n- if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))\n+\n+ gimple *assign = cselim_candidate (bb1, bb2, e1, e2);\n+ if (cond_store_replacement (bb1, bb2, e1, e2, assign, nontrap))\n \tcfgchanged = true;\n };\n \n","prefixes":["v2"]}