* GAS relaxation: estimation in md_relax_frag() do not match md_apply_fix()
@ 2020-03-04 4:03 William Tambe
2020-03-05 0:49 ` Alan Modra
0 siblings, 1 reply; 2+ messages in thread
From: William Tambe @ 2020-03-04 4:03 UTC (permalink / raw)
To: Binutils
In our Binutils port, GAS relaxing is done implementing md_relax_frag()
such that the displacement used to generate the growth amount to return
is computed using:
((S_GET_VALUE (symbolP) + fragP->fr_offset) -
(fragP->fr_address + fragP->fr_fix));
However, during md_apply_fix(), the same displacement value is greatly
different, causing it not to fit in the relocation fix estimated
during md_relax_frag().
Any idea what could explain it ?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: GAS relaxation: estimation in md_relax_frag() do not match md_apply_fix()
2020-03-04 4:03 GAS relaxation: estimation in md_relax_frag() do not match md_apply_fix() William Tambe
@ 2020-03-05 0:49 ` Alan Modra
0 siblings, 0 replies; 2+ messages in thread
From: Alan Modra @ 2020-03-05 0:49 UTC (permalink / raw)
To: William Tambe; +Cc: Binutils
On Tue, Mar 03, 2020 at 11:02:55PM -0500, William Tambe wrote:
> In our Binutils port, GAS relaxing is done implementing md_relax_frag()
> such that the displacement used to generate the growth amount to return
> is computed using:
> ((S_GET_VALUE (symbolP) + fragP->fr_offset) -
> (fragP->fr_address + fragP->fr_fix));
>
> However, during md_apply_fix(), the same displacement value is greatly
> different, causing it not to fit in the relocation fix estimated
> during md_relax_frag().
>
> Any idea what could explain it ?
A debugger is a great learning tool. Especially one with watchpoints.
Use gdb to see where and how parts of fragP change.
--
Alan Modra
Australia Development Lab, IBM
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