gas: add a means to programmatically determine the assembler version

It has been more than once that I would have wanted to have a way to
know the gas version in assembly sources, perhaps for use with .if. Add
such a pre-defined symbol, introducing the common pattern GAS(<symbol>)
for any such symbols. The use of parentheses is to keep the risk of
collisions with users' symbols as low as possible. (Possible future
arch-specific symbols may want to use GAS(<arch>:<symbol>).)

Similarly permit determining whether the assembler is a released
version. The exact value probably isn't of much use, it's more the
defined-ness that one might care about. Yet the symbol needs to have
some value anyway.

While by default pre-defined symbols won't be emitted to the symbol
table, introduce -emit-local-absolute to allow requesting this. Re-
purpose flag_strip_local_absolute to become tristate, with a negative
value indicating to also emit pre-defined symbols.

0 files changed, 0 insertions, 0 deletions