{"id":2227702,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2227702/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260424054237.134225-2-peter0x44@disroot.org/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.1/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},"msgid":"<20260424054237.134225-2-peter0x44@disroot.org>","date":"2026-04-24T05:42:38","name":"c++: Improve -fdump-lang-class output","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"c87ef2203b9de3114573e31430afd57b6de28e72","submitter":{"id":88243,"url":"http://patchwork.ozlabs.org/api/1.1/people/88243/?format=json","name":"Peter Damianov","email":"peter0x44@disroot.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260424054237.134225-2-peter0x44@disroot.org/mbox/","series":[{"id":501302,"url":"http://patchwork.ozlabs.org/api/1.1/series/501302/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=501302","date":"2026-04-24T05:42:38","name":"c++: Improve -fdump-lang-class output","version":1,"mbox":"http://patchwork.ozlabs.org/series/501302/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2227702/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2227702/checks/","tags":{},"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 secure) header.d=disroot.org header.i=@disroot.org header.a=rsa-sha256\n header.s=mail header.b=kIpkYBAg;\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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server2.sourceware.org","X-Virus-Scanned":"SPAM Filter at disroot.org","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=disroot.org; s=mail;\n t=1777009362; bh=I69CezaCckb6kq57jB67XBnjgzgBF2luJUTi5U2E2+E=;\n h=From:To:Cc:Subject:Date;\n b=kIpkYBAgkxfVhQButCSKdQYLVr9fNJHIMP+lxoJlxEipuHkYXXpmfqN4X0PfboQFb\n NL5/1dmBC4v2b/tQT/ErRoKc5b0sGEOh7pSWiwakqu9mDG9LLSA1VxUA4MnZraTIlA\n on3a7UvbDw5MVbrxIfQCg40F77v2i1RzFmlTEatm1AkWjwL12IifTspztQRRoXkpeR\n eaftWcC264aL+sptbKuQhVB9JnfqAX/SfFXsZZaTlrklpUQnTMX6Qav/EfY0yyv+DJ\n g7Nxma7SDW4OcAsL63pq5Ys6ozfvwitMNU8dnZ3ifPSZdNvAqQ77NPJkRPk+POT2Oj\n YmhFP4cml5vAw==","From":"Peter Damianov ","To":"gcc-patches@gcc.gnu.org","Cc":"Peter Damianov ","Subject":"[PATCH] c++: Improve -fdump-lang-class output","Date":"Fri, 24 Apr 2026 06:42:38 +0100","Message-ID":"<20260424054237.134225-2-peter0x44@disroot.org>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","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 ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"When I was researching to write my blogpost about vtables:\nhttps://peter0x44.github.io/posts/vtables-itanium-abi/\n\nI noticed a few improvements I could make to -fdump-lang-class's output\n\n-fdump-lang-class prepended \"0x\" to HOST_WIDE_INT_PRINT_HEX outputs, but the\nmacro already includes that prefix, producing \"0x0x...\" in dumps.\n\nSome vtable entries hold signed values e.g. vcall offsets, vbase offsets,\n offset-to-top. When expr_as_string prints those INTEGER_CSTs,\nnegative offsets appear as large (unsigned) values. Print integer vtable\nentries as signed values, and keep expr_as_string for all other entries.\n\ngcc/cp/ChangeLog:\n\n\t* class.cc (dump_vtable_entry): New function.\n\t(dump_array): Use it.\n\t(dump_class_hierarchy_r): Drop redundant literal 0x from\n\tHOST_WIDE_INT_PRINT_HEX formatting.\n\t(dump_vtable): Likewise.\n\nSigned-off-by: Peter Damianov \n---\n gcc/cp/class.cc | 29 ++++++++++++++++++++++++-----\n 1 file changed, 24 insertions(+), 5 deletions(-)","diff":"diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc\nindex 8beeb797a08..e15e5e509a0 100644\n--- a/gcc/cp/class.cc\n+++ b/gcc/cp/class.cc\n@@ -167,6 +167,7 @@ static int maybe_indent_hierarchy (FILE *, int, int);\n static tree dump_class_hierarchy_r (FILE *, dump_flags_t, tree, tree, int);\n static void dump_class_hierarchy (tree);\n static void dump_class_hierarchy_1 (FILE *, dump_flags_t, tree);\n+static void dump_vtable_entry (FILE *, tree);\n static void dump_array (FILE *, tree);\n static void dump_vtable (tree, tree, tree);\n static void dump_vtt (tree, tree);\n@@ -9729,7 +9730,7 @@ dump_class_hierarchy_r (FILE *stream,\n tree base_binfo;\n int i;\n \n- fprintf (stream, \"%s (0x\" HOST_WIDE_INT_PRINT_HEX \") \",\n+ fprintf (stream, \"%s (\" HOST_WIDE_INT_PRINT_HEX \") \",\n \t type_as_string (BINFO_TYPE (binfo), TFF_PLAIN_IDENTIFIER),\n \t (HOST_WIDE_INT) (uintptr_t) binfo);\n if (binfo != igo)\n@@ -9752,7 +9753,7 @@ dump_class_hierarchy_r (FILE *stream,\n if (BINFO_PRIMARY_P (binfo))\n {\n indented = maybe_indent_hierarchy (stream, indent + 3, indented);\n- fprintf (stream, \" primary-for %s (0x\" HOST_WIDE_INT_PRINT_HEX \")\",\n+ fprintf (stream, \" primary-for %s (\" HOST_WIDE_INT_PRINT_HEX \")\",\n \t type_as_string (BINFO_TYPE (BINFO_INHERITANCE_CHAIN (binfo)),\n \t\t\t TFF_PLAIN_IDENTIFIER),\n \t (HOST_WIDE_INT) (uintptr_t) BINFO_INHERITANCE_CHAIN (binfo));\n@@ -9845,6 +9846,21 @@ dump_class_hierarchy (tree t)\n }\n }\n \n+static void\n+dump_vtable_entry (FILE *stream, tree value)\n+{\n+ /* Vtable offset entries are stored in the pointer-sized vtable entry\n+ type, but should be displayed as signed ptrdiff_t values. */\n+ tree cst = value;\n+ while (CONVERT_EXPR_P (cst))\n+ cst = TREE_OPERAND (cst, 0);\n+\n+ if (TREE_CODE (cst) == INTEGER_CST)\n+ print_dec (wi::to_wide (cst), stream, SIGNED);\n+ else\n+ fprintf (stream, \"%s\", expr_as_string (value, TFF_PLAIN_IDENTIFIER));\n+}\n+\n static void\n dump_array (FILE * stream, tree decl)\n {\n@@ -9863,8 +9879,11 @@ dump_array (FILE * stream, tree decl)\n \n FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (DECL_INITIAL (decl)),\n \t\t\t ix, value)\n- fprintf (stream, \"%-4ld %s\\n\", (long)(ix * elt),\n-\t expr_as_string (value, TFF_PLAIN_IDENTIFIER));\n+ {\n+ fprintf (stream, \"%-4ld \", (long)(ix * elt));\n+ dump_vtable_entry (stream, value);\n+ fprintf (stream, \"\\n\");\n+ }\n }\n \n static void\n@@ -9886,7 +9905,7 @@ dump_vtable (tree t, tree binfo, tree vtable)\n if (ctor_vtbl_p)\n \t{\n \t if (!BINFO_VIRTUAL_P (binfo))\n-\t fprintf (stream, \" (0x\" HOST_WIDE_INT_PRINT_HEX \" instance)\",\n+\t fprintf (stream, \" (\" HOST_WIDE_INT_PRINT_HEX \" instance)\",\n \t\t (HOST_WIDE_INT) (uintptr_t) binfo);\n \t fprintf (stream, \" in %s\", type_as_string (t, TFF_PLAIN_IDENTIFIER));\n \t}\n","prefixes":[]}