[PATCH][GAS/ARM] Better handling of difference between a symbol and an undefined symbol.

[=?big5?b?RG91ZyBLd2FuICjD9q62vHcp?= <dougkwan at google dot com>]

Hi,

   This patch handles difference expression between a symbol and an
undefined symbol better so that we can assemble something like:


        .section        .data.i,"a"
i:
        .long   0

        .section        .data.j,"a"
j:
        .long   i - (. - .L1)
.L1:


The problem with the above code is that .L1 in "i - (. - L1)" is a
forward reference.  The current code in expr() evaluate this to
something belonging to section .data.j,  That causes a subsequent
failure in segment check because i is defined in another section.

-Doug

gas/ChangeLog:
2010-09-27  Doug Kwan  <dougkwan@google.com>

        * expr.c (expr): Handle difference between a symbol and an undefined
        symbol specially.

gas/testsuite/ChangeLog:

2010-09-27  Doug Kwan  <dougkwan@google.com>

        * gas/arm/got_prel2.d: New.
        * gas/arm/got_prel2.s: New.

Attachment: patch-und-diff.txt
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