From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17400 invoked by alias); 14 Sep 2014 09:35:37 -0000 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 Received: (qmail 17389 invoked by uid 89); 14 Sep 2014 09:35:35 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL,BAYES_00 autolearn=no version=3.3.2 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sun, 14 Sep 2014 09:35:33 +0000 Received: from svr-orw-fem-04.mgc.mentorg.com ([147.34.97.41]) by relay1.mentorg.com with esmtp id 1XT6DS-0004Pz-6s from Yao_Qi@mentor.com for gdb-patches@sourceware.org; Sun, 14 Sep 2014 02:35:30 -0700 Received: from GreenOnly (147.34.91.1) by svr-orw-fem-04.mgc.mentorg.com (147.34.97.41) with Microsoft SMTP Server id 14.3.181.6; Sun, 14 Sep 2014 02:35:29 -0700 From: Yao Qi To: Subject: Re: [PATCH] Fix gdb.dwarf2/dwz.exp for thumb mode References: <1409706936-11220-1-git-send-email-yao@codesourcery.com> Date: Sun, 14 Sep 2014 09:35:00 -0000 In-Reply-To: <1409706936-11220-1-git-send-email-yao@codesourcery.com> (Yao Qi's message of "Wed, 3 Sep 2014 09:15:36 +0800") Message-ID: <87k356lfa8.fsf@codesourcery.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes X-SW-Source: 2014-09/txt/msg00480.txt.bz2 Yao Qi writes: > +asm (".section \".text\""); > +asm (".balign 8"); > +asm ("main_start: .globl main_start"); > + > int > main() Doug expressed the concern that this approach is fragile to clang, because clang will move the label after function main. After some experiments, I find a reliable approach: define a label main_label inside function main, so neither gcc or clang moves it out of function. We can get the address of main by main_label minus the offset of main_label to main. In this updated patch, we compile main.c to object, and gets main_label's offset to main. Then, we can produce the correct address of main in the debug information. --=20 Yao (=E9=BD=90=E5=B0=A7) From: Yao Qi Subject: [PATCH] Fix gdb.dwarf2/dwz.exp for thumb mode We see the fail in gdb.dwarf2/dwz.exp in thumb mode, p the_int^M $2 =3D 99^M (gdb) FAIL: gdb.dwarf2/dwz.exp: p the_int In thumb mode, the lsb of references to 'main' in the assembly (produced by dwarf assember) is set, so the generated debug information is incorrect. in this patch, we add a label main_label inside function main. Linker doesn't set its lsb in thumb mode, and we can get function main's address by 'main_label - $main_label_offset'. This label isn't moved out of function main in both gcc and clang. gdb/testsuite: 2014-09-13 Yao Qi * gdb.dwarf2/main.c (main): New lable main_label. * gdb.dwarf2/dwz.exp: Get the offset of main_label to main. Return early if $main_label_offset is unknown. Get address of main by "main_label - $main_label_offset". diff --git a/gdb/testsuite/gdb.dwarf2/dwz.exp b/gdb/testsuite/gdb.dwarf2/dw= z.exp index 9175f9e..229f512 100644 --- a/gdb/testsuite/gdb.dwarf2/dwz.exp +++ b/gdb/testsuite/gdb.dwarf2/dwz.exp @@ -27,8 +27,9 @@ if {[gdb_compile ${srcdir}/${subdir}/${srcfile} ${binfil= e}1.o \ return -1 } =20 -# Start GDB and load object file, compute the function length which is -# needed in the Dwarf Assembler below. +# Start GDB and load object file, compute the function length and the +# offset from main to main_label which are needed in the Dwarf Assembler +# below. clean_restart ${testfile}1.o =20 set main_length "" @@ -59,9 +60,17 @@ gdb_test_multiple $test $test { } } =20 -if { $main_length =3D=3D "" } { +set main_label_offset "" +set test "p main_label" +gdb_test_multiple $test $test { + -re ".* =3D {.*} $hex .*\r\n$gdb_prompt $" { + set main_label_offset $expect_out(1,string) + } +} + +if { $main_length =3D=3D "" || $main_label_offset =3D=3D "" } { # Bail out here, because we can't do the following tests if - # $main_length is unknown. + # $main_length or $main_label_offset is unknown. return -1 } =20 @@ -71,7 +80,7 @@ gdb_exit set asm_file [standard_output_file $srcfile2] Dwarf::assemble $asm_file { declare_labels partial_label int_label int_label2 - global main_length + global main_length main_label_offset =20 extern main =20 @@ -79,8 +88,8 @@ Dwarf::assemble $asm_file { partial_label: partial_unit {} { subprogram { {name main} - {low_pc main addr} - {high_pc "main + $main_length" addr} + {low_pc "main_label - $main_label_offset" addr} + {high_pc "main_label - $main_label_offset + $main_length" addr} } } } diff --git a/gdb/testsuite/gdb.dwarf2/main.c b/gdb/testsuite/gdb.dwarf2/mai= n.c index 3ddd194..e6d4715 100644 --- a/gdb/testsuite/gdb.dwarf2/main.c +++ b/gdb/testsuite/gdb.dwarf2/main.c @@ -20,5 +20,6 @@ int main() { + asm ("main_label: .globl main_label"); return 0; }