jwf@dewey.UUCP (Jim Franklin) (11/04/83)
Green Hills Software of Pasadena, CA claims to have an optimizing C compiler
for the Motorola 68000. It runs as a cross-compiler on Berkeley 4.1 UNIX.
From literature we received from Green Hills (GH), the compiler appears to
generate excellent code when the optimizer switches are turned on.
About a month ago we sent a tape to GH with some C benchmark programs and
asked them to compile them (invoking the optimizer) and send us back the
assembly language output (.s) files. GH compiled the programs and sent us
back the .s files, but they didn't invoke their optimizer. They told us that
they don't recommend invoking the optimizer unless the programs are loop
bound. Incidentally, most of our C benchmarks were loop bound.
If their optimizer really worked, then we assume that they would have compiled
our benchmark using the optimizer. After all, they are trying to sell a
product and they should show us the best they can do. We are suspicious that
either (1) their compiler crashed with the optimizer turned on (e.g., bus
error - core dumped), or (2) it ran fine but generated bogus code.
At this point we don't know what to make of GH and their compiler. Does
anyone out there know
(1) if Green Hills is real -- i.e., does their compiler really work?
(2) does their optimizer generate correct code in most cases? if it doesn't
always work, does it know when it doesn't work or does it just generate
mysteriously incorrect code? Can you tell the compiler not to optimize
sections of a file?
(3) is anyone using the GH VAX to 68000 cross-compiler for large projects
(say 100,000 lines of C)?