{"id":2229745,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2229745/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260428165450.28555-2-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":"<20260428165450.28555-2-peter0x44@disroot.org>","date":"2026-04-28T16:54:50","name":"[v2] c++: Improve -fdump-lang-class output","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"22fbd28418a2f34a7f425d987403c1d6bb87bbc8","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/20260428165450.28555-2-peter0x44@disroot.org/mbox/","series":[{"id":501904,"url":"http://patchwork.ozlabs.org/api/1.1/series/501904/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=501904","date":"2026-04-28T16:54:50","name":"[v2] c++: Improve -fdump-lang-class output","version":2,"mbox":"http://patchwork.ozlabs.org/series/501904/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2229745/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2229745/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=YTSDL6te;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=38.145.34.32; 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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=1777395386; bh=EVKM3UYBJwMD05Pkzy4lBgtCNzryEAdbdFUt5TmyW8E=;\n h=From:To:Cc:Subject:Date;\n b=YTSDL6teK8cahQvQ3pP9JjRkYJ7RhYrxERE6bVPerwAtaXSYQZxL0vAAsPUe+UF6o\n zRhJTynRax7/kO4HTMyAVOLFRdirSXiq8vhlJkxLb7Wvu9XLngkdsZLDPT+78eP2Tg\n 3zfYAYMFQeKB8+dP5Ts2NR0r7DI5srX+XWoyY8f0PeNOavSobvR8uIe4NTyifG4ib4\n +i7GcbtXAJYps+tuoiOECOKzQdzeDKmeaEY7xbxKLziqd4SXJ05SqSuWomtZHJUPgq\n +OWZ1klCz3LRIJDoe4PEzWq0FZTGL3tfzMWXb+0zBXAbJAwhBjsIBdF6/oaIDLu9ks\n S4L/L+cDFqk4A==","From":"Peter Damianov ","To":"gcc-patches@gcc.gnu.org","Cc":"Marek Polacek , Peter Damianov ","Subject":"[PATCH v2] c++: Improve -fdump-lang-class output","Date":"Tue, 28 Apr 2026 17:54:50 +0100","Message-ID":"<20260428165450.28555-2-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\nv2: add comment to dump_vtable_entry\nuse STRIP_NOPS\nsimplify code using print_decs instead of print_dec with SIGNED\n\n gcc/cp/class.cc | 31 ++++++++++++++++++++++++++-----\n 1 file changed, 26 insertions(+), 5 deletions(-)","diff":"diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc\nindex 8beeb797a08..4d2284b1891 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 +9846,23 @@ dump_class_hierarchy (tree t)\n }\n }\n \n+/* Dump VALUE, a vtable entry, to STREAM. Print integer offsets as signed\n+ values. */\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+ STRIP_NOPS (cst);\n+\n+ if (TREE_CODE (cst) == INTEGER_CST)\n+ print_decs (wi::to_wide (cst), stream);\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 +9881,11 @@ 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 +9907,7 @@ 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":["v2"]}