{"id":2226333,"url":"http://patchwork.ozlabs.org/api/1.2/patches/2226333/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/bmm.hhubwh7m90.gcc.gcc-TEST.pinskia.33.1.11@forge-stage.sourceware.org/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.2/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":"","list_archive_url":null,"date":"2026-04-22T10:49:20","name":"[v1,11/15] gimple-fold: Improve optimize_memcpy_to_memset to handle STRING_CST [PR78408]","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"a3b9b10a5aff9de824fd337d21a8af1f4f98ce37","submitter":{"id":93219,"url":"http://patchwork.ozlabs.org/api/1.2/people/93219/?format=json","name":"Andrew Pinski via Sourceware Forge","email":"forge-bot+pinskia@forge-stage.sourceware.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/bmm.hhubwh7m90.gcc.gcc-TEST.pinskia.33.1.11@forge-stage.sourceware.org/mbox/","series":[{"id":500990,"url":"http://patchwork.ozlabs.org/api/1.2/series/500990/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=500990","date":"2026-04-22T10:49:12","name":"copy-prop-arg","version":1,"mbox":"http://patchwork.ozlabs.org/series/500990/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2226333/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2226333/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 spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; 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server2.sourceware.org","From":"Andrew Pinski via Sourceware Forge\n ","Date":"Wed, 22 Apr 2026 10:49:20 +0000","Subject":"[PATCH v1 11/15] gimple-fold: Improve optimize_memcpy_to_memset to\n handle STRING_CST [PR78408]","To":"gcc-patches mailing list ","Message-ID":"\n ","X-Mailer":"batrachomyomachia","X-Pull-Request-Organization":"gcc","X-Pull-Request-Repository":"gcc-TEST","X-Pull-Request":"https://forge.sourceware.org/gcc/gcc-TEST/pulls/33","References":"\n ","In-Reply-To":"\n ","X-Patch-URL":"\n https://forge.sourceware.org/pinskia/gcc-TEST/commit/8c198de37a9912e3fd19bbbea106efe3256dfe7f","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Reply-To":"gcc-patches mailing list ,\n pinskia@gcc.gnu.org","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"From: Andrew Pinski \n\nWhile looking into PR 118947, I noticed that optimize_memcpy_to_memset didn't\nhandle STRING_CST which are also used for a memset of 0 but for char arrays.\nThis fixes that and improves optimize_memcpy_to_memset to handle that case.\n\nThis fixes part of PR 118947 but not the whole thing; we still need to skip over\nvdefs in some cases.\n\nBoostrapped and tested on x86_64-linux-gnu.\n\n\tPR tree-optimization/78408\n\tPR tree-optimization/118947\n\ngcc/ChangeLog:\n\n\t* gimple-fold.cc (optimize_memcpy_to_memset): Handle STRING_CST case too.\n\ngcc/testsuite/ChangeLog:\n\n\t* gcc.dg/pr78408-3.c: New test.\n\nSigned-off-by: Andrew Pinski \n---\n gcc/gimple-fold.cc | 17 +++++++++++++++++\n gcc/testsuite/gcc.dg/pr78408-3.c | 14 ++++++++++++++\n 2 files changed, 31 insertions(+)\n create mode 100644 gcc/testsuite/gcc.dg/pr78408-3.c","diff":"diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc\nindex 0380c7af4c21..1a48778da5a6 100644\n--- a/gcc/gimple-fold.cc\n+++ b/gcc/gimple-fold.cc\n@@ -919,6 +919,23 @@ optimize_memcpy_to_memset (gimple_stmt_iterator *gsip, tree dest, tree src, tree\n poly_int64 offset, offset2;\n tree val = integer_zero_node;\n if (gimple_store_p (defstmt)\n+ && gimple_assign_single_p (defstmt)\n+ && TREE_CODE (gimple_assign_rhs1 (defstmt)) == STRING_CST\n+ && !gimple_clobber_p (defstmt))\n+ {\n+ tree str = gimple_assign_rhs1 (defstmt);\n+ src2 = gimple_assign_lhs (defstmt);\n+ /* The string must contain all null char's for now. */\n+ for (int i = 0; i < TREE_STRING_LENGTH (str); i++)\n+\t{\n+\t if (TREE_STRING_POINTER (str)[i] != 0)\n+\t {\n+\t src2 = NULL_TREE;\n+\t break;\n+\t }\n+\t}\n+ }\n+ else if (gimple_store_p (defstmt)\n && gimple_assign_single_p (defstmt)\n && TREE_CODE (gimple_assign_rhs1 (defstmt)) == CONSTRUCTOR\n && !gimple_clobber_p (defstmt))\ndiff --git a/gcc/testsuite/gcc.dg/pr78408-3.c b/gcc/testsuite/gcc.dg/pr78408-3.c\nnew file mode 100644\nindex 000000000000..3de90d023923\n--- /dev/null\n+++ b/gcc/testsuite/gcc.dg/pr78408-3.c\n@@ -0,0 +1,14 @@\n+/* PR tree-optimization/78408 */\n+/* { dg-do compile { target size32plus } } */\n+/* { dg-options \"-O2 -fdump-tree-forwprop1-details\" } */\n+/* { dg-final { scan-tree-dump-times \"after previous\" 1 \"forwprop1\" } } */\n+\n+void* aaa();\n+void* bbb()\n+{\n+ void* ret = aaa();\n+ char buf[32] = {};\n+ __builtin_memcpy(ret, buf, 32);\n+ return ret;\n+}\n+\n","prefixes":["v1","11/15"]}