From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 30100 invoked by alias); 26 Mar 2009 21:21:48 -0000 Received: (qmail 30090 invoked by uid 22791); 26 Mar 2009 21:21:46 -0000 X-SWARE-Spam-Status: No, hits=-1.6 required=5.0 tests=AWL,BAYES_00,KAM_STOCKGEN,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx2.redhat.com (HELO mx2.redhat.com) (66.187.237.31) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 26 Mar 2009 21:21:35 +0000 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n2QLLYca026455 for ; Thu, 26 Mar 2009 17:21:34 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n2QLLQnq029750 for ; Thu, 26 Mar 2009 17:21:26 -0400 Received: from host0.dyn.jankratochvil.net (sebastian-int.corp.redhat.com [172.16.52.221]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id n2QLLV1T003104 for ; Thu, 26 Mar 2009 17:21:33 -0400 Received: from host0.dyn.jankratochvil.net (localhost [127.0.0.1]) by host0.dyn.jankratochvil.net (8.14.3/8.14.3) with ESMTP id n2QLLTx9003917 for ; Thu, 26 Mar 2009 22:21:30 +0100 Received: (from jkratoch@localhost) by host0.dyn.jankratochvil.net (8.14.3/8.14.2/Submit) id n2QLLSO7003910 for gdb-patches@sourceware.org; Thu, 26 Mar 2009 22:21:28 +0100 Date: Thu, 26 Mar 2009 21:38:00 -0000 From: Jan Kratochvil To: gdb-patches@sourceware.org Subject: [patch] Fix C `extern' shadowing in a local block Message-ID: <20090326212128.GA32657@host0.dyn.jankratochvil.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2009-03/txt/msg00596.txt.bz2 Hi, fix GDB evaluation for: { int var = 1; { extern int var; Access "var" at this point from GDB which must access the `extern' variable. } } Such code will still not work due to GCC PR debug/39563. GCC may also fix it a way compatible with current GDB (`extern var' to be global and use DW_TAG_imported_declaration in the local block). Still IMO a valid DWARF layout used in the attached .S testcase currently fails for GDB. The testcase was written primarily as currently removing LOC_UNRESOLVED from the GDB codebase had no effect on the testsuite results. I did remove LOC_UNRESOLVED before but that patch was wrong (+got no replies): http://sourceware.org/ml/gdb-patches/2008-08/msg00117.html Maybe during LOC_UNRESOLVED parsing GDB could already lookup the minimal symbol and create LOC_STATIC instead (but what to create for TLS minimal symbols?). Did not try this way but it would remove LOC_UNRESOLVED. No regressions on x86_64-unknown-linux-gnu. Thanks, Jan gdb/ 2009-03-26 Jan Kratochvil * dwarf2read.c (new_symbol ): Create the symbol in local scope. * symtab.h (cu->list_in_scope ): New comment part. gdb/testsuite/ 2009-03-26 Jan Kratochvil * gdb.dwarf2/dw2-unresolved-main.c, gdb.dwarf2/dw2-unresolved.S, gdb.dwarf2/dw2-unresolved.exp: New. --- gdb/dwarf2read.c 26 Mar 2009 14:47:18 -0000 1.298 +++ gdb/dwarf2read.c 26 Mar 2009 21:09:04 -0000 @@ -7657,7 +7657,7 @@ new_symbol (struct die_info *die, struct && dwarf2_attr (die, DW_AT_type, cu) != NULL) { SYMBOL_CLASS (sym) = LOC_UNRESOLVED; - add_symbol_to_list (sym, &global_symbols); + add_symbol_to_list (sym, cu->list_in_scope); } else if (!die_is_declaration (die, cu)) { --- gdb/symtab.h 6 Feb 2009 21:33:58 -0000 1.135 +++ gdb/symtab.h 26 Mar 2009 21:09:04 -0000 @@ -472,7 +472,13 @@ enum address_class in another object file or runtime common storage. The linker might even remove the minimal symbol if the global symbol is never referenced, in which case the symbol remains - unresolved. */ + unresolved. + + GDB would normally find the symbol in the minimal symbol table if it will + not find it in the full symbol table. But a reference to an external + symbol in a local block shadowing other definition requires full symbol + without possibly having its address available for LOC_STATIC. Testcase + is provided as `gdb.dwarf2/dw2-unresolved.exp'. */ LOC_UNRESOLVED, --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ gdb/testsuite/gdb.dwarf2/dw2-unresolved-main.c 26 Mar 2009 21:09:05 -0000 @@ -0,0 +1,46 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2009 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include + +asm (".globl cu_text_start"); +asm ("cu_text_start:"); + +int +main (void) +{ + unsigned char var = 1; + + if (var != 1) + abort (); + { + extern unsigned char var; + + /* Do not rely on the `extern' DIE output by GCC (GCC PR debug/39563). */ +asm (".globl extern_block_start"); +asm ("extern_block_start:"); + if (var != 2) + abort (); +asm (".globl extern_block_end"); +asm ("extern_block_end:"); + } + + return 0; +} + +asm (".globl cu_text_end"); +asm ("cu_text_end:"); --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ gdb/testsuite/gdb.dwarf2/dw2-unresolved.S 26 Mar 2009 21:09:05 -0000 @@ -0,0 +1,171 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2007, 2008, 2009 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + + .data + +/* VAR1 is wrong here, in the real inferior it is located on stack. As both + places are never modified and they are initialized to the same value it + makes no difference. Ensure the name clash for "var". */ +var1: .byte 1 + + .globl var +var: .byte 2 + +/* Debug information */ + + .section .debug_info +.Lcu1_begin: + /* CU header */ + .4byte .Lcu1_end - .Lcu1_start /* Length of Compilation Unit */ +.Lcu1_start: + .2byte 2 /* DWARF Version */ + .4byte .Labbrev1_begin /* Offset into abbrev section */ + .byte 4 /* Pointer size */ + + /* CU die */ + .uleb128 1 /* Abbrev: DW_TAG_compile_unit */ + .4byte cu_text_end /* DW_AT_high_pc */ + .4byte cu_text_start /* DW_AT_low_pc */ + .ascii "dw2-unresolved-main.c\0" /* DW_AT_name */ + .ascii "GNU C 4.3.2\0" /* DW_AT_producer */ + .byte 1 /* DW_AT_language (C) */ + +.Ltype_uchar: + .uleb128 2 /* Abbrev: DW_TAG_base_type */ + .ascii "unsigned char\0" /* DW_AT_name */ + .byte 1 /* DW_AT_byte_size */ + .byte 7 /* DW_AT_encoding */ + + /* main */ + .uleb128 3 /* Abbrev: DW_TAG_subprogram */ + .byte 1 /* DW_AT_decl_file */ + .byte 2 /* DW_AT_decl_line */ + .ascii "main\0" /* DW_AT_name */ + .4byte .Ltype_uchar-.Lcu1_begin /* DW_AT_type */ + .4byte cu_text_start /* DW_AT_low_pc */ + .4byte cu_text_end /* DW_AT_high_pc */ + + .uleb128 4 /* Abbrev: DW_TAG_variable (location) */ + .ascii "var\0" /* DW_AT_name */ + .byte 2f - 1f /* DW_AT_location */ +1: .byte 3 /* DW_OP_addr */ +/* See VAR1 definition why this DIE is not correct. */ + .4byte var1 /* */ +2: .4byte .Ltype_uchar-.Lcu1_begin /* DW_AT_type */ + + .uleb128 6 /* Abbrev: DW_TAG_lexical_block */ + .4byte extern_block_start /* DW_AT_low_pc */ + .4byte extern_block_end /* DW_AT_high_pc */ + + .uleb128 5 /* Abbrev: DW_TAG_variable (extern) */ + .ascii "var\0" /* DW_AT_name */ + .4byte .Ltype_uchar-.Lcu1_begin /* DW_AT_type */ + .byte 1 /* DW_AT_external */ + + .byte 0 /* End of children of the lexical block */ + + .byte 0 /* End of children of main */ + + .byte 0 /* End of children of CU */ + +.Lcu1_end: + +/* Abbrev table */ + .section .debug_abbrev +.Labbrev1_begin: + .uleb128 1 /* Abbrev code */ + .uleb128 0x11 /* DW_TAG_compile_unit */ + .byte 1 /* has_children */ + .uleb128 0x12 /* DW_AT_high_pc */ + .uleb128 0x1 /* DW_FORM_addr */ + .uleb128 0x11 /* DW_AT_low_pc */ + .uleb128 0x1 /* DW_FORM_addr */ + .uleb128 0x3 /* DW_AT_name */ + .uleb128 0x8 /* DW_FORM_string */ + .uleb128 0x25 /* DW_AT_producer */ + .uleb128 0x8 /* DW_FORM_string */ + .uleb128 0x13 /* DW_AT_language */ + .uleb128 0xb /* DW_FORM_data1 */ + .byte 0x0 /* Terminator */ + .byte 0x0 /* Terminator */ + + .uleb128 2 /* Abbrev code */ + .uleb128 0x24 /* DW_TAG_base_type */ + .byte 0 /* has_children */ + .uleb128 0x3 /* DW_AT_name */ + .uleb128 0x8 /* DW_FORM_string */ + .uleb128 0xb /* DW_AT_byte_size */ + .uleb128 0xb /* DW_FORM_data1 */ + .uleb128 0x3e /* DW_AT_encoding */ + .uleb128 0xb /* DW_FORM_data1 */ + .byte 0x0 /* Terminator */ + .byte 0x0 /* Terminator */ + + .uleb128 3 /* Abbrev code */ + .uleb128 0x2e /* DW_TAG_subprogram */ + .byte 1 /* has_children */ + .uleb128 0x3a /* DW_AT_decl_file */ + .uleb128 0xb /* DW_FORM_data1 */ + .uleb128 0x3b /* DW_AT_decl_line */ + .uleb128 0xb /* DW_FORM_data1 */ + .uleb128 0x3 /* DW_AT_name */ + .uleb128 0x8 /* DW_FORM_string */ + .uleb128 0x49 /* DW_AT_type */ + .uleb128 0x13 /* DW_FORM_ref4 */ + .uleb128 0x11 /* DW_AT_low_pc */ + .uleb128 0x1 /* DW_FORM_addr */ + .uleb128 0x12 /* DW_AT_high_pc */ + .uleb128 0x1 /* DW_FORM_addr */ + .byte 0x0 /* Terminator */ + .byte 0x0 /* Terminator */ + + .uleb128 4 /* Abbrev code (location) */ + .uleb128 0x34 /* DW_TAG_variable */ + .byte 0 /* has_children */ + .uleb128 0x3 /* DW_AT_name */ + .uleb128 0x8 /* DW_FORM_string */ + .uleb128 0x2 /* DW_AT_location */ + .uleb128 0xa /* DW_FORM_block1 */ + .uleb128 0x49 /* DW_AT_type */ + .uleb128 0x13 /* DW_FORM_ref4 */ + .byte 0x0 /* Terminator */ + .byte 0x0 /* Terminator */ + + .uleb128 5 /* Abbrev code (extern) */ + .uleb128 0x34 /* DW_TAG_variable */ + .byte 0 /* has_children */ + .uleb128 0x3 /* DW_AT_name */ + .uleb128 0x8 /* DW_FORM_string */ + .uleb128 0x49 /* DW_AT_type */ + .uleb128 0x13 /* DW_FORM_ref4 */ + .uleb128 0x3f /* DW_AT_external */ + .uleb128 0xc /* DW_FORM_flag */ + .byte 0x0 /* Terminator */ + .byte 0x0 /* Terminator */ + + .uleb128 6 /* Abbrev code */ + .uleb128 0x0b /* DW_TAG_lexical_block */ + .byte 1 /* has_children */ + .uleb128 0x11 /* DW_AT_low_pc */ + .uleb128 0x1 /* DW_FORM_addr */ + .uleb128 0x12 /* DW_AT_high_pc */ + .uleb128 0x1 /* DW_FORM_addr */ + .byte 0x0 /* Terminator */ + .byte 0x0 /* Terminator */ + + .byte 0x0 /* Terminator */ + .byte 0x0 /* Terminator */ --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ gdb/testsuite/gdb.dwarf2/dw2-unresolved.exp 26 Mar 2009 21:09:05 -0000 @@ -0,0 +1,41 @@ +# Copyright 2009 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +# This test can only be run on targets which support DWARF-2 and use gas. +# For now pick a sampling of likely targets. +if {![istarget *-*-linux*] + && ![istarget *-*-gnu*] + && ![istarget *-*-elf*] + && ![istarget *-*-openbsd*] + && ![istarget arm-*-eabi*] + && ![istarget powerpc-*-eabi*]} { + return 0 +} + +if { [prepare_for_testing dw2-unresolved.exp "dw2-unresolved" {dw2-unresolved-main.c dw2-unresolved.S} {nodebug}] } { + return -1 +} + +if ![runto_main] { + return -1 +} + +# This testcase tests LOC_UNRESOLVED works right. + +gdb_breakpoint "*extern_block_start" +gdb_continue_to_breakpoint "*extern_block_start" + +# Expect the inner value 2. Value 1 from the outer local block is shadowed. +gdb_test "print var" "= 2( '.*')?"