H8300S ld Relax

[Ian Lance Taylor]

   Date: Wed, 01 Mar 2000 07:44:55 +0000
   From: Paul Clarke <paulc@senet.com.au>

   A dig into the bfd sources shows that there is 32->16->8 relax mode for
   move instructions but I could not determine which of the other relax
   howto's
   apply for the bit op case.

The HOWTOs describe the various relocations supported for H8/300
COFF.  They are dumped by objdump -r.  You can use objdump -r to see
what the bit operations are using in the .o files.  Look at
h8300_reloc16_estimate to see how those relocations are used.

   If anyone is familar with the h8300 bfd code would they mind either
   adding
   an 8 bit operation relax and/or throwing some more comments around the
   code so that myself and others can follow whats going on. There seem to
   be plenty of comments in the coff-h8300 about the following function
   contains position references to the howto struct this must change, so I
   guess that
   the h8300 port is not regarded as a good reference design.  What other
   target(s)
   would provide a better foundation for understanding relaxing or a
   starting
   point for a new h8300 relax function.

I doubt that anybody is familiar with the H8/300 code.  There
unfortunately is no good reference for relaxing.  Relaxing tends to be
highly processor specific.  The H8/300 does share some code with the
H8/500 and the W65.

I don't really recommend rewriting the H8/300 relaxing support
wholesale.  It looks reasonable to me.  The reliance on the ordering
of the howtos is pretty ugly, but that ordering can not be easily
changed.  In any case, the code could be changed to use appropriate
conditions and switches to choose the new howto, rather than the
additions that it does use.

Ian