porting GCC

["Krzysztof Matula" <km at taboo dot eu dot org>]

Hi!

I am extending one of GCC ports an I have the following problem:

I need to detect all references to to objects in data segment (SYMBOL_REF/v)
and modify rtx in such way, that the segment base address is added to the
offset (represented by the symbol itself). Generating such rtx is not a
problem, but I don't know where to connect this. In the code I am extending
such replacement is made in two "define_expand"-s. One of them looks like
this:

set(reg)(plus:SI((general_operand)(general_operand)))

As a result new rtx is generated that takes the segment base address and
adds a symbol offset:

set(reg)(plus:SI((reg)(SYMBOL_REF)))

...such rtl matches one of the "define_insn"-s.

The problm is that sometimes during optimizations GCC creates exactly the
same rtl, and it matches the same "define_insn" without going through
"define_expand". The rtl modification for proper data segment access is not
performed...

I think I have to flag the rtx generated in define_expand in some way and
setup the predicate used in define_insn to reject unflagged symbol refs...

Is that the right way??? If so, how can I flag the rtx??? Or, maybe I should
do this in a different way???

KM