From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31018 invoked by alias); 20 Aug 2009 17:42:48 -0000 Received: (qmail 31009 invoked by uid 22791); 20 Aug 2009 17:42:47 -0000 X-SWARE-Spam-Status: No, hits=-0.5 required=5.0 tests=AWL,BAYES_00,J_CHICKENPOX_37,J_CHICKENPOX_47,J_CHICKENPOX_48,J_CHICKENPOX_53,KAM_STOCKGEN X-Spam-Check-By: sourceware.org Received: from smtp-outbound-2.vmware.com (HELO smtp-outbound-2.vmware.com) (65.115.85.73) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 20 Aug 2009 17:42:32 +0000 Received: from jupiter.vmware.com (mailhost5.vmware.com [10.16.68.131]) by smtp-outbound-2.vmware.com (Postfix) with ESMTP id DF36612249; Thu, 20 Aug 2009 10:42:30 -0700 (PDT) Received: from [10.20.94.141] (msnyder-server.eng.vmware.com [10.20.94.141]) by jupiter.vmware.com (Postfix) with ESMTP id D6597DC05C; Thu, 20 Aug 2009 10:42:30 -0700 (PDT) Message-ID: <4A8D8A26.7010303@vmware.com> Date: Thu, 20 Aug 2009 17:58:00 -0000 From: Michael Snyder User-Agent: Thunderbird 1.5.0.12 (X11/20080411) MIME-Version: 1.0 To: "tromey@redhat.com" CC: "gdb-patches@sourceware.org" Subject: Re: RFC: allow breakpoints on labels References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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: 2009-08/txt/msg00324.txt.bz2 Tom Tromey wrote: > This patch fixes PR 8357. > > The bug is that while gcc emits dwarf for labels appearing in the user's > source, there is no way to refer to these labels from gdb. This patch > changes the dwarf reader to put labels in the symbol table, and it > changes linespecs to let the user specify a label in the current > function. > > Built and regtested on x86-64 (compile farm). > > I'd appreciate comments. This also needs a doc review. Questions: 1) Labels will be in a separate name-space from other symbols (functions)? 2) The search order will find functions first, and only if there is no conflicting function, find a label? What if there's a function and a label of the same name, and user wants to specify the label? 3) There's no danger of our confusing a label with a function somewhere downstream, and doing something silly such as applying prologue_skip or skip_trampoline to a label? > 2009-08-20 Tom Tromey > > PR breakpoints/8357: > * symtab.h (domain_enum_tag) : Update comment. > * linespec.c (decode_line_1): Update comment. Call decode_label. > (decode_label): New function. > (symbol_found): Handle LOC_LABEL. > * dwarf2read.c (new_symbol) : Set symbol's type and > domain. Call add_symbol_to_list. > > 2009-08-20 Tom Tromey > > * gdb.texinfo (Specify Location): Document labels. > > 2009-08-20 Tom Tromey > > * gdb.base/label.exp: New file. > * gdb.base/label.c: New file. > > diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo > index 4016acc..7dcf51c 100644 > --- a/gdb/doc/gdb.texinfo > +++ b/gdb/doc/gdb.texinfo > @@ -5783,6 +5783,13 @@ in the file @var{filename}. You only need the file name with a > function name to avoid ambiguity when there are identically named > functions in different source files. > > +@item @var{label} > +Specifies the line at which the label named @var{label} appears. > +@value{GDBN} searches for the label in the function corresponding to > +the currently selected stack frame. If there is no current selected > +stack frame (for instance, if the inferior is not running), then > +@value{GDBN} will not search for a label. > + > @item *@var{address} > Specifies the program address @var{address}. For line-oriented > commands, such as @code{list} and @code{edit}, this specifies a source > diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c > index 445bab8..21d6f9b 100644 > --- a/gdb/dwarf2read.c > +++ b/gdb/dwarf2read.c > @@ -8327,7 +8327,10 @@ new_symbol (struct die_info *die, struct type *type, struct dwarf2_cu *cu) > { > SYMBOL_VALUE_ADDRESS (sym) = DW_ADDR (attr) + baseaddr; > } > + SYMBOL_TYPE (sym) = objfile_type (objfile)->builtin_core_addr; > + SYMBOL_DOMAIN (sym) = LABEL_DOMAIN; > SYMBOL_CLASS (sym) = LOC_LABEL; > + add_symbol_to_list (sym, cu->list_in_scope); > break; > case DW_TAG_subprogram: > /* SYMBOL_BLOCK_VALUE (sym) will be filled in later by > diff --git a/gdb/linespec.c b/gdb/linespec.c > index 3e943a1..4f7e797 100644 > --- a/gdb/linespec.c > +++ b/gdb/linespec.c > @@ -123,6 +123,9 @@ static struct symtabs_and_lines decode_dollar (char *copy, > char ***canonical, > struct symtab *file_symtab); > > +static int decode_label (char *copy, char ***canonical, > + struct symtabs_and_lines *result); > + > static struct symtabs_and_lines decode_variable (char *copy, > int funfirstline, > char ***canonical, > @@ -640,6 +643,7 @@ See set/show multiple-symbol.")); > FILE:LINENUM -- that line in that file. PC returned is 0. > FUNCTION -- line number of openbrace of that function. > PC returned is the start of the function. > + LABEL -- a label in the current scope > VARIABLE -- line number of definition of that variable. > PC returned is 0. > FILE:FUNCTION -- likewise, but prefer functions in that file. > @@ -873,6 +877,16 @@ decode_line_1 (char **argptr, int funfirstline, struct symtab *default_symtab, > return decode_dollar (copy, funfirstline, default_symtab, > canonical, file_symtab); > > + /* Try the token as a label, but only if no file was specified, > + because we can only really find labels in the current scope. */ > + > + if (!file_symtab) > + { > + struct symtabs_and_lines label_result; > + if (decode_label (copy, canonical, &label_result)) > + return label_result; > + } > + > /* Look up that token as a variable. > If file specified, use that file's per-file block to start with. */ > > @@ -1708,6 +1722,27 @@ decode_dollar (char *copy, int funfirstline, struct symtab *default_symtab, > > > > +/* A helper for decode_line_1 that tries to find a label. The label > + is searched for in the current block. > + COPY is the name of the label to find. > + CANONICAL is the same as the "canonical" argument to decode_line_1. > + RESULT is a pointer to a symtabs_and_lines structure which will be > + filled in on success. > + This function returns 1 if a label was found, 0 otherwise. */ > + > +static int > +decode_label (char *copy, char ***canonical, struct symtabs_and_lines *result) > +{ > + struct symbol *sym; > + > + sym = lookup_symbol (copy, get_selected_block (0), LABEL_DOMAIN, 0); > + > + if (sym != NULL) > + *result = symbol_found (0, canonical, copy, sym, NULL); > + > + return sym != NULL; > +} > + > /* Decode a linespec that's a variable. If FILE_SYMTAB is non-NULL, > look in that symtab's static variables first. If NOT_FOUND_PTR is not NULL and > the function cannot be found, store boolean true in the location pointed to > @@ -1787,7 +1822,7 @@ symbol_found (int funfirstline, char ***canonical, char *copy, > } > else > { > - if (funfirstline) > + if (funfirstline && SYMBOL_CLASS (sym) != LOC_LABEL) > error (_("\"%s\" is not a function"), copy); > else if (SYMBOL_LINE (sym) != 0) > { > diff --git a/gdb/symtab.h b/gdb/symtab.h > index 740d4e0..d425d6e 100644 > --- a/gdb/symtab.h > +++ b/gdb/symtab.h > @@ -378,8 +378,7 @@ typedef enum domain_enum_tag > > STRUCT_DOMAIN, > > - /* LABEL_DOMAIN may be used for names of labels (for gotos); > - currently it is not used and labels are not recorded at all. */ > + /* LABEL_DOMAIN may be used for names of labels (for gotos). */ > > LABEL_DOMAIN, > > diff --git a/gdb/testsuite/gdb.base/label.c b/gdb/testsuite/gdb.base/label.c > new file mode 100644 > index 0000000..f9cd8c3 > --- /dev/null > +++ b/gdb/testsuite/gdb.base/label.c > @@ -0,0 +1,21 @@ > +#include > + > +int > +main (int argc, char *argv) > +{ > + int i = 0; > + goto there; > + > +here: > + printf("not here\n"); > + i = 1; > + > +there: > + printf("but here\n"); > + if (i == 0) > + goto here; > + > +done: > + return 0; > +} > + > diff --git a/gdb/testsuite/gdb.base/label.exp b/gdb/testsuite/gdb.base/label.exp > new file mode 100644 > index 0000000..9c4532c > --- /dev/null > +++ b/gdb/testsuite/gdb.base/label.exp > @@ -0,0 +1,66 @@ > +# 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 . > + > +if $tracelevel then { > + strace $tracelevel > +} > + > + > +if [is_remote target] then { > + return 0 > +} > + > + > +# > +# test running programs > +# > +set prms_id 0 > +set bug_id 0 > + > +set testfile "label" > +set srcfile ${testfile}.c > +set binfile ${objdir}/${subdir}/${testfile} > + > +if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug nowarnings}] != "" } { > + untested label.exp > + return -1 > +} > + > + > +gdb_exit > +gdb_start > +gdb_reinitialize_dir $srcdir/$subdir > +gdb_load ${binfile} > + > +if {![runto_main]} { > + fail "label tests suppressed" > + return -1 > +} > + > +gdb_test "break here" \ > + "Breakpoint.*at.*" \ > + "breakpoint here" > + > +gdb_test "break there" \ > + "Breakpoint.*at.*" \ > + "breakpoint there" > + > +gdb_test "cont" \ > + "Breakpoint 3,.*" \ > + "continue to 'there'" > + > +gdb_test "cont" \ > + "Breakpoint 2,.*" \ > + "continue to 'here'"