Re: RFA: Fix FRV switch table generation in PIC mode

[Richard Henderson <rth at gcc dot gnu dot org>]

On Fri, Feb 23, 2007 at 03:56:06PM +0000, Nick Clifton wrote:
> I tried that - it did not work.  You still end up with the jump table in 
> the .rodata section.  This then fails to assemble because the entries in 
> the jump table are computed as the difference between the table's label 
> (in .rodata) and the jump destination (in .text).

We want one of these things, in order of preference:

(1) Constant jump tables outside the text section.  This mostly makes
    for nice disassembly, but also can avoid code/data cache pollution,
    depending on the cpu.

(2) Constant jump tables inside the text section.  Constant tables are
    much preferable to non-constant jump tables, no matter where we 
    have to put them.

I'm a bit confused that the assembler rejects the difference, since
that should in fact be a fixed displacement at link time.  I poked
around the assembler, and there doesn't seem to be a way to generate
the GPREL32 relocation, which would be another good choice, though
it would require a slightly different insn sequence to use it.

So, failing all that, there *is* a good reason to use 
JUMP_TABLES_IN_TEXT_SECTION, and that is that the assembler is lame.
So I think you should go back to that patch.


r~