arm-elf-as truncates branch offsets w/o warning

[Grant Edwards]

> I just noticed that a recent snapshot (000309) of the ARM
> assembler truncates branch offsets without warning.  I haven't
> had a chance yet to take look at the ARM assembler source.

There are two different (but related) problems:

  1) Legal, non-relocatible branch destinations >= 0x0400,00000
     are not handled correctly and bad code is generated with
     no error or warning messages.

  2) Illegal branches to non-relocatible branch destinations
     with offsets >= +/- 0x0200,00000 aren't detected and bad
     code is generated (also silently).

So far I've had a look at #1.  I can't see a way to fix it
easily, but I've attached a patch to gas/config/tc-arm.c that
will generate an error when a non-relocatible branch destination
is too large for gas to deal with.

I'll work on #2 next.

-- 
Grant Edwards
grante@visi.com