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Re: Patch to correct x86 FP extend splits


On Wed, Apr 14, 1999 at 01:52:52PM -0400, John Wehle wrote:
> This should address the issues raised by you and Zack.
> It passes bootstrap and make check on x86 FreeBSD 3.1
> configured for aout.

Yesterday I've played with change forcing all constant to be stored
in smallest possible mode (to reduce code size and avoid XF mode
drawbacks).
Needless to say that this introduced tons of extend patterns.
I think there are two quite improtant problem with them.
First is unnecesary stack slot allocation (that is quite large) and the
stack slot is not freed even when it is unused. There is probably nothing
we can do with this, except using push/pop pair in such cases.
But I think we can at least reduce it by allocating only the larger slot and use it
in both cases.
BTW it was increasing stack by 80 bytes, that seems to be that the slot is not
resused even it ought to be...

second problem is, that there is full pattern with the clobber and second pattern
w/o them doing the actual extension. The full pattern is translated to
second one by split. But combine during canonization pass removes those clobbers
as well, so we probably need to ensure, that second pattern will not match before reload.

Honza


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