public inbox for gcc-prs@sourceware.org help / color / mirror / Atom feed
From: Adrian von Bidder <avbidder@atlas.acter.ch> To: gcc-gnats@gcc.gnu.org Subject: target/5399: arm/thumb: pointer indirections when using -fpic Date: Wed, 16 Jan 2002 02:26:00 -0000 [thread overview] Message-ID: <200201161022.g0GAMAi07550@atlas.acter.ch> (raw) [-- Warning: decoded text below may be mangled, UTF-8 assumed --] [-- Attachment #1: Type: text/plain, Size: 1894 bytes --] >Number: 5399 >Category: target >Synopsis: arm/thumb: pointer indirections when using -fpic >Confidential: no >Severity: critical >Priority: medium >Responsible: unassigned >State: open >Class: wrong-code >Submitter-Id: net >Arrival-Date: Wed Jan 16 02:26:00 PST 2002 >Closed-Date: >Last-Modified: >Originator: avbidder@acter.ch (Adrian von Bidder) >Release: 3.1 20020115 (experimental) >Organization: acter ag, zürich >Environment: System: Linux atlas 2.4.16 #4 Fri Dec 7 07:58:59 CET 2001 i686 unknown Architecture: i686 binutils are cvs from 20010115 also. Same config opts as for gcc. host: i686-pc-linux-gnu build: i686-pc-linux-gnu target: arm-unknown-elf configured with: ../gcc-HEAD/configure --enable-checking --enable-languages=c --prefix=/home/avbidder/hacking-toolchain/inst --target=arm-elf --with-cpu=arm7tdmi >Description: The simple C program main(){ foo("hello george!\n"); } compiled with -mthumb -fpic (other options don't matter. I use -O3 -mpic-register=r6 -msingle-pic-base as this is what I really use and I find the asm output is more readable, too). creates asm output: ===== ... .section .rodata ... .LC0: .ascii "hello george!\n\000" .align 2 .LC1: .word .LC0 ... [main:] ldr r0, .L2 ldr r1, [r6, r0] ldr r0, [r1] bl foo ... .L2: .word .LC1(GOTOFF) ... ==== The problem is - afaics - the GOTOFF (instead of GOT). In the linked binary, .L2 contains the offset of .LC1 from start of GOT, which is start of data, too, and not the offset of a GOT entry for .LC1. So the first load loads .L2, the second load already loads the string pointer .LC1 and the third load then loads the first four bytes of the string itself... >How-To-Repeat: see above >Fix: >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2002-01-16 10:26 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2002-01-16 2:26 Adrian von Bidder [this message] 2002-01-16 3:16 Phil Blundell 2002-01-18 9:35 pb
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=200201161022.g0GAMAi07550@atlas.acter.ch \ --to=avbidder@atlas.acter.ch \ --cc=gcc-gnats@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).