Date: Fri, 12 Aug 1994 18:42:03 -0400 (EDT)
From: Kimberley Burchett <OKRA AT max DOT tiac DOT net>
Subject: Re: Speed tuning programs
To: Olly Betts <olly AT mantis DOT co DOT uk>
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu



On Fri, 12 Aug 1994, Olly Betts wrote:

> What I'd like are any tips or suggestions for tweaking the performance
> of the DJGPP code to make it closer to the BCC code.  Either compiler
> options or coding suggestions.

  I made a batchfile called handcode.bat where you pass it the name of 
the program you want to hand code.  Then it stops compiling at the 
assembler level and you can edit the assembler.  I did it on one of my 
programs and cut out ten instructions from an inner inner loop and it 
goes about 46% faster now.  Once you change the assembler source, you 
then run finish.bat and it compiles it to a program.
  I had to make two finishing batch files - finish.bat and release.bat.  
finish.bat makes it so it produces profiling output while release.bat 
strips the a.out and doesn't produce profiling info.
  I included a %2 in the batchfile so you could include profiling 
information if you want.  You just type "handcode myprog -p" to get 
debugging info.  If you include debugging info, you have to use 
finish.bat to finish compiling because release.bat doesn't include the 
right libs.
  I also had to take out some of the command line options from 
handcode.bat that got passed to cpp because the command line was too 
long.  I took out some of the kindof repetetive defines that none of my 
programs use anyway.
  When you run the batch files, don't include the .c ending - it puts 
them there for you.
  What I like most is that most of the compile time is spent in cc1 so 
once you have assembler, tweaking the assembler takes _very_ little 
time.  At least until you crash it at which point you have to run 
handcode again - I make a backup of the assembler output just in case.

  So here are the batch files if you want to use them.

HANDCODE.BAT:

cpp -lang-c -D__GNUC__=2 -D__GNUC_MINOR__=5 -Dunix -Di386 -DGO32 -DMSDOS 
-D__OPTIMIZE__ %1.c D:/cca00051
cc1 D:/cca00051 -fno-builtin -quiet -dumpbase %1.c -O4 -version %2 -o %1.s

FINISH.BAT:

as -o D:/ccc00051 %1.s
ld c:\language\gcc/lib/gcrt0.o -Lc:\language\gcc/lib D:/ccc00051 -lm -lpc 
-lgcc -lc -lgcc
coff2exe a.out

RELEASE.BAT:

as -o D:/ccc00051 %1.s
ld c:\language\gcc/lib/crt0.o -Lc:\language\gcc/lib D:/ccc00051 -lm -lpc 
-lgcc -lc -lgcc
strip -s a.out
coff2exe a.out
mv a.exe %1.exe

							Kim