Optimized compilation of tcl

MS I ran the tclbench suite on tclsh compiled with three different compilers and several optimisation combinations. This page summarizes the results.

These tests were run on a PIII/600Mhz/192MB laptop running linux RedHat7.2.

The compilers were:

Results

SPEED	SIZE	COMPILER	OPTIONS
1.00	1.00	gcc2.96	-O -march=pentiumpro
1.05	1.00	gcc2.96	-O -march=pentiumpro -fomit-frame-pointer
1.01	1.01	gcc2.96	-O2 -march=pentiumpro
1.07	1.02	gcc2.96	-O2 -march=pentiumpro -fomit-frame-pointer
1.01	0.97	gcc2.96	-Os -march=pentiumpro
1.05	0.98	gcc2.96	-Os -march=pentiumpro -fomit-frame-pointer
0.99	1.07	gcc3.1	-O -march=pentium3
1.03	1.08	gcc3.1	-O -march=pentium3 -fomit-frame-pointer
1.02	1.12	gcc3.1	-O2 -march=pentium3
1.06	1.13	gcc3.1	-O2 -march=pentium3 -fomit-frame-pointer
1.03	1.14	gcc3.1	-O3 -march=pentium3
1.08	1.15	gcc3.1	-O3 -march=pentium3 -fomit-frame-pointer
1.04	0.97	gcc3.1	-Os -march=pentium3
1.06	0.97	gcc3.1	-Os -march=pentium3 -fomit-frame-pointer
1.06	1.24	icc6.0	-O3 -xK
1.11	1.47	icc6.0	-O3 -xK -ip

Conclusions (?)

The "-fomit-frame-pointer" flag produces faster code with gcc. It is a question if it is worth the loss of a traceable core file - tcl shouldn't dump core
The default optimisation flag for gcc "-O" seems suboptimal; both GNU compilers produce faster and smaller code with "-Os"
The new gcc3.1 is not a big improvement on 2.96 for our purposes.
Intel's compiler with "-ip" produces slightly faster code than gcc (as measured by tclbench), but a much larger image. Otherwise, icc produces larger but not faster code.

Notes

These were all static builds of tclsh from the current (01-22-02) HEAD
The data presented is size/speed relative to the reference build "gcc2.96 -O". This produced a 702kB tclsh which ran the tclbench suite in 00:04:35.
All compilers were set to produce binaries exploiting the processors features ("-march" and "-x" flags).
I have not checked for the intel equivalent to gcc's "-Os" flag.
The "-fomit-frame-pointer" flag to gcc produces code that is non-debuggable - the stack trace in core files is not usable. This behaviour is also present (I think) in the optimised code produced by icc.