simplify operands of constant addresses with MINUSes

[Alexandre Oliva]

Joern has already approved the SH-specific part of an earlier version
of this patch, but I still need approval for the generic part.  Ok to
install?

On Nov  8, 2000, Alexandre Oliva <aoliva@redhat.com> wrote:

> It seems that some of the changes to introduce PIC support on sh-elf
> broke sh-hms.  The replacement output_addr_const wouldn't simplify
> MINUS expressions, which would cause GCC to sometimes output assembly
> constants such as `s + 5 - s', for which the assembler couldn't
> generate relocations, for not knowing in which segment `s' would live.

> Instead of moving the simplification over to
> sh.c:output_pic_addr_const(), I decided to make the generic
> output_addr_const() usable for SH PIC.  Since the PIC implementation
> on the SH uses a couple of unspecs within relatively complex
> expressions, I had to tweak the simplification machinery to accept
> those unspecs, and to add some means for output_addr_const() to
> call-back into machine-specific code.

> Here's the resulting patch.  No regressions on sh-elf, with and
> without -fPIC, and hundreds of fixes on sh-hms.  Ok to install?