Author: Dieter Buerssner
Date: 15:36:14 09/11/00
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On September 11, 2000 at 18:22:13, Vincent Diepeveen wrote: >I compiled latest snapshot from the gcc compiler again, >and measured speed difference using -O9 -fexpensive-optimizations >-mcpu=pentiumpro -march=pentiumpro etcetera Have you tried gcc with -O or with -O2. All my programs, which I have checked for execution speed (chess program and numerical/quantum chemical simulations), run *slower*, when compiled with gcc and -O3 on x86. (I think -O9 is the same as -O3). Especially hurting seems to be the automatic inlining of gcc (that is not enabled by -O2). This can also be seen by looking at the assembler output. However, manual inlining of critical and fast functions by the inline keyword can help. Matters are quite different, when using a CPU with many registers (I think almost all contemporary CPUs other than x86 based). - Dieter
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