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Re: [PATCH i386] Allow sibcalls in no-PLT PIC
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Jan Hubicka <hubicka at ucw dot cz>
- Cc: Rich Felker <dalias at libc dot org>, Alexander Monakov <amonakov at ispras dot ru>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Uros Bizjak <ubizjak at gmail dot com>
- Date: Fri, 15 May 2015 16:30:20 -0700
- Subject: Re: [PATCH i386] Allow sibcalls in no-PLT PIC
- Authentication-results: sourceware.org; auth=none
- References: <1430757479-14241-1-git-send-email-amonakov at ispras dot ru> <1430757479-14241-5-git-send-email-amonakov at ispras dot ru> <alpine dot LNX dot 2 dot 11 dot 1505151927170 dot 22867 at monopod dot intra dot ispras dot ru> <CAMe9rOq+gfTcCoY4AKefkZgysHr_XXOaCtOFWDro8OeT+mBUWQ at mail dot gmail dot com> <20150515194824 dot GB14415 at kam dot mff dot cuni dot cz> <CAMe9rOr3yQv-+cJxwp_YfNY=9G+FnV6=JdYh_T6kPDJtSA0fzg at mail dot gmail dot com> <20150515202319 dot GE17573 at brightrain dot aerifal dot cx> <CAMe9rOqRBz7L6Fr1nxDVrTEh3EQ-AVV0dMCC0-xdpq87k=e4EQ at mail dot gmail dot com> <20150515204237 dot GF17573 at brightrain dot aerifal dot cx> <CAMe9rOp1ibVzf0KOt+1boOxb5ag85fe2Rv2Rst=CgAtOTGFBxA at mail dot gmail dot com> <20150515230810 dot GA73210 at kam dot mff dot cuni dot cz> <CAMe9rOr1_r0tvi_JdsCL8w-MMAqhSeVpA6sbksnn1yP224zn_A at mail dot gmail dot com>
On Fri, May 15, 2015 at 4:14 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> My relax branch proposal works even without LTO.
>
I will borrow GOTPCREL from x86-64 and do
[hjl@gnu-6 relax-4]$ cat b.S
call *foo@GOTPCREL(%eax)
[hjl@gnu-6 relax-4]$ ./as -32 -o b.o b.S
[hjl@gnu-6 relax-4]$ ./objdump -dwr b.o
b.o: file format elf32-i386
Disassembly of section .text:
00000000 <.text>:
0: ff 90 fc ff ff ff call *-0x4(%eax) 2: R_386_RELAX_GOT32 foo
[hjl@gnu-6 relax-4]$
And linker can turn it into
relax call foo
if foo is defined locally.
--
H.J.