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Re: [PATCH] Extend -fno-plt to normal non-PIC branches on x86
- From: Uros Bizjak <ubizjak at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 1 Jun 2015 20:07:25 +0200
- Subject: Re: [PATCH] Extend -fno-plt to normal non-PIC branches on x86
- Authentication-results: sourceware.org; auth=none
- References: <20150528173753 dot GA3377 at intel dot com> <20150528230244 dot GA14866 at intel dot com>
On Fri, May 29, 2015 at 1:02 AM, H.J. Lu <hongjiu.lu@intel.com> wrote:
> On Thu, May 28, 2015 at 10:37:53AM -0700, H.J. Lu wrote:
>> This patch extends -fno-plt to normal non-PIC calls on x86. -fno-plt
>> works in 64-bit mode with the existing binutils. For 32-bit, we need
>> the updated assembler and linker to support "call/jmp *foo@GOT" with
>> a new relocation different from R_386_GOT32 to indicate that this
>> relocation applies to indirect branches. A configure time check is
>> added to verify that 32-bit assembler generates a known relocation
>> which is different from R_386_GOT32. A new 32-bit relocaton is needed
>> since "call/jmp *foo@GOT" requires a different relocation from R_386_GOT32
>> which is used together with a GOT register in "call/jmp *foo@GOT(%reg)".
>>
>> OK for master?
>>
>> Thanks.
>>
>> H.J.
>> ---
>> * configure.ac (HAVE_AS_INDIRECT_BRANCH_VIA_GOT): New. Defined
>> if 32-bit assembler generates a known relocation which is
>> different from R_386_GOT32.
>> * config.in: Regenerated.
>> * configure: Likewise.
>> * config/i386/i386.c (ix86_output_call_insn): Extend -fno-plt
>> to normal non-PIC branches.
>
>
> Here is the updated patch to properly handle local functions with
> testcases.
Please get someone to review the functional aspect of the patch. I'm
not that familiar with all linker details to do any meaningful review
here.
Uros.