Register variables

utzoo!decvax!decwrl!sun!megatest!fortune!hpda!hplabs!hao!kpno!stevens utzoo!decvax!decwrl!sun!megatest!fortune!hpda!hplabs!hao!kpno!stevens
Mon Mar 28 06:36:19 AEST 1983

   Until a few years ago Yourdon, Inc. was in the C compiler business.
I am aware of a compiler they sold for the PDP-11 (Unix and RSX-11 versions)
and they also developed one for IBM for their Series/1 (under the EDX
operating system, I believe - IBM never released it since they changed the
OS under Yourdon's feet during developement and when the compiler was
completed it wouldn't work under the new version of EDX!).
   Anyway, Yourdon's PDP-11 compiler allowed longs to be assigned to two
of the three available registers on the PDP-11 and also allowed floats and
doubles to be assigned to two of the 4 FP registers.  I consider that
quite amazing since the Ritchie compiler, PCC and Whitesmiths don't go
that far with register variables on the 11.  PCC on the VAX doesn't even allow
floats or doubles in registers either.
   Is anyone aware of any other C compilers that allow either floats/doubles
to be assigned to registers or allow multi-register register assignments
(longs on the PDP-11, for example)?
	Richard Stevens

More information about the Comp.lang.c mailing list