Subreg-byte patches (was: Branching for GCC 3.0)

[Richard Henderson]

On Tue, Jan 09, 2001 at 12:08:58PM -0500, Jakub Jelinek wrote:
> But this would not work for SPARC v9 ABI, because some values are
> specifically passed in even and some values in odd SFmode registers...

Yes, that is the reason we can't simply hide the SFmode regs.
And by not hiding them we get into troubles with the FP->DImode
conversion instructions, when gcc starts taking subregs of the
DImode result.

This could also be fixed in a different way for 3.0 if necessary,
by using CLASS_CANNOT_CHANGE_MODE, though we would generate worse
code on some common cases because of it.

Long-term, SUBREG_BYTE is the correct solution.


r~