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Re: modified x86 ABI


Hello!

> At EMC we have a version of GCC which targets the x86 with a non
> standard ABI -- it produces code for 64 bit mode mode, but with types
> having the 32 bit ABI sizes.  So, ints, longs, and pointers are 32
> bits -- that is, it's ILP32 rather than LP64 -- but with the chip in
> 64 bit mode.

> If this set of changes was cleaned up, finished, and made relative to
> top of trunk rather than relative to 3.4.6, would people be interested
> in them?

Just recently, there was a discussion about memory consumpltion of
64bit x86 binaries [1], so your patch would address these issues.
Perhaps you should read a thread starting from [1], where some of the
issues regarding ABI change are already discussed.

> Put another way, should I bother to post them to gcc-patches (probably
> 3-6 months out) for possible inclusion into gcc?

If there are indeed ~50% memory savings from using ILP32 instead of
LP64, as speculated in [1], then I'm sure that  functionality that
brings goodies from 32bit (memory savings) and 64bit (new registers)
would find a lot of uses. We can introduce (for example) -mabi=32+
switch and experiment there.

OTOH, we are currently in development stage-3 and your proposed
timeline fits nicely in the time frame for new stage-1.

[1] http://gcc.gnu.org/ml/gcc/2007-10/msg00156.html

Uros.


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