On Wed, Mar 14, 2001 at 02:05:29PM -0500, Daniel Jacobowitz wrote: > OK, so that needs to change. That's pretty easy to do, at least in our > local toolchains. If it's only in your local toolchains, it's lost. Send your changes to the FSF! > > > I worked back in time in gcc, binutils, and kernel sources and I > > > couldn't figure out what's changed - I'm sure this worked at some > > > point. > > > > You'll have to go back far in time. I introduced the use of -mmad for > > Nevada-class CPUs in late summor '97. > > > > As a second bug which makes this one even more annoying something like > > > > .set mips3 > > sdc1 $f2, (a0) > > .set mips0 > > > > also doesn't work - the assembler will still throw an "opcode not supported > > on this processor" message. After all MIPS III means double precission fp. > > And passing additional assembler options with -Wa,foo doesn't help either > > in this case so without the necessary gcc / assembler changes this > > optimization is lost for now. > > Does -mmad make a sufficient difference on these processors to bother > fixing it? Not for the kernel but it's a sufficiently important optimization for some specialised applications (signal processing type etc.) that it should be fixed. > If it does, I can probably whip up a -mmad patch to binutils to allow > those opcodes - or I could introduce -mnevada, or whatever the > appropriate term would be, to mean "r8000 with the mad* extensions". > In fact, that would probably be easiest, and sounds like the most > correct. Don't think of the r8000; the kernel only uses the -mcpu=r8000 option because the Nevada CPUs have _somewhat_ similar scheduling properties to the R8000. This of it as an independant ISA expension which can be used with an arbitrary MIPS processor - even a R3000 processor. Ralf
