tcd@vax5.cit.cornell.edu (01/08/91)
I am using MPW C (v. 3.0) to write a program that involves a lot of floating point calculation. The code that is generated appears incredibly inefficient (although I'll admit that I have never looked at the output from another compiler before, so I don't have much basis for comparison). I have learned to use a lot of temporary variables and eliminate explicit subscripting of arrays, but some things appear impossible to get around. A typical section of code that really bothers me is something like the following: FMOVE FP7,FP0 FADD.X (A3),FP0 FMOVE FP0,FP7 when FADD.X (A3),FP7 would produce the desired result. What I am wondering is the following: 1) Does version 3.1 of MPW offer any improvement in this regard? 2) How do other Macintosh compilers (C or otherwise) compare? 3) Does anyone know of a book or other source that describes tips, techniques, pitfalls, etc. for a Macintosh programmer interested in execution speed for floating point calculations? Thanks, Tim Dorcey
torrie@cs.stanford.edu (Evan J Torrie) (01/08/91)
tcd@vax5.cit.cornell.edu writes: > I am using MPW C (v. 3.0) to write a program that involves >a lot of floating point calculation. The code that is generated >appears incredibly inefficient (although I'll admit that I have >never looked at the output from another compiler before, so I >don't have much basis for comparison). I have learned to use a lot >of temporary variables and eliminate explicit subscripting of arrays, >but some things appear impossible to get around. A typical section of >code that really bothers me is something like the following: > FMOVE FP7,FP0 > FADD.X (A3),FP0 > FMOVE FP0,FP7 You might want to try looking at Apple's recently released (and fairly much unsupported) GCC for MPW. GCC produces fairly efficient code for the 6888x series, certainly much better than MPW C has ever produced for me (factors of 2 or 3 times faster in some cases). -- ------------------------------------------------------------------------------ Evan Torrie. Stanford University, Class of 199? torrie@cs.stanford.edu Where can a nation lie when it hides its organic minds in a cellar dark and grim? They must be ... very dim.