Good non-coprocessor compiler for 80386 Unix V.3

cg-atlas!mikkel (Carl Mikkelson X5220)
Tue, 7 Jul 87 20:17:17 edt

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Good non-coprocessor compiler for 80386 Unix V.3 cg-atlas!mikkel (1987-07-07)
Re: Good non-coprocessor compiler for 80386 Unix V.3 dougl@ism780c (Doug Leavitt) (1987-07-15)
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Date: Tue, 7 Jul 87 20:17:17 edt
From: cg-atlas!mikkel (Carl Mikkelson X5220)

We are investigating compilers for the 80386 to be alternatives for the
compiler supplied with the Intel/Interactive V.3 Unix port.
Metaware and GreenHills have been suggested, however they generate code
for the floating-point coprocessor, which is emulated through a system
of traps in the Unix kernel.

As a point of benchmark reference, the floating point performance of a
coprocessorless 386 is less than one-third that of a co-processorless
68010 (not even a 68020). Our suspicion is that the extra time is being
spent in trap processing.

We would like to purchase a good quality compiler that will generate code
to use a floating point library, directly called. Ideally, it would also
support the equivalent of a "-F" switch (using only single precision in all

Any leads?

Thanks -- Carl

[The PC/IX C compiler for the 8088 also used floating point traps, but the
overhead there seemed to be small. I worked for Interactive at the time, and
the thinking was that people who care about FP performance will appreciate
the in-line FP code, and people who don't will appreciate that the same
binaries run either way. Given the relatively low cost of an 80287 compared
to the rest of the system, it still seems sound to me. I'd be interested in
hearing about other compilers, though. It's not hard to generate better code
than PCC does. -John]

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