Re: [PATCH] Improve i?86 address delegitimization after 32-bit pic changes (PR target/63542)

["H.J. Lu" <hjl.tools@gmail.com>]

On Tue, Oct 21, 2014 at 9:03 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Mon, Sep 29, 2014 at 01:08:56PM +0200, Jakub Jelinek wrote:
>> I wonder if during/after reload we just couldn't look at
>> ORIGINAL_REGNO of hard regs if ix86_use_pseudo_pic_reg.  Or is that
>> the other case, where you don't have any PIC register replacement around,
>> and want to subtract something?  Perhaps in that case we could just
>> subtract the value of _GLOBAL_OFFSET_TABLE_ symbol if we have nothing better
>> around.
>
> Here is a patch that implements both of these ideas.
>
> The number of lines like:
> note: non-delegitimized UNSPEC UNSPEC_GOT (0) found in variable location
> note: non-delegitimized UNSPEC UNSPEC_GOTOFF (1) found in variable location
> during i686-linux bootstrap (not including regtest) went down from
> 14165 to 19.
>
> The patch trusts that a hard reg with ORIGINAL_REGNO containing the pic
> pseudo contains the _GLOBAL_OFFSET_TABLE_ value of the current shared
> library (or binary), I think that is reasonable assumption.
> And for ELF for the UNSPEC_GOTOFF it worse case can subtract
> _GLOBAL_OFFSET_TABLE_ symbol if it doesn't know what register to subtract.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2014-10-21  Jakub Jelinek  <jakub@redhat.com>
>
>         PR target/63542
>         * config/i386/i386.c (ix86_pic_register_p): Also return
>         true if x is a hard register with ORIGINAL_REGNO equal to
>         pic_offset_table_rtx pseudo REGNO.
>         (ix86_delegitimize_address): For ix86_use_pseudo_pic_reg ()
>         after reload, subtract GOT_SYMBOL_NAME symbol if possible.
>
>         * gcc.target/i386/pr63542-1.c: New test.
>         * gcc.target/i386/pr63542-2.c: New test.
>

This caused:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64025


-- 
H.J.