From: Nathan I. <ningerso@d.umn.edu> - 2002-06-21 04:01:16
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On Thu, Jun 20, 2002 at 12:03:37PM -0400, Val...@vt... is quoted as saying: > > Well, a few minutes of UTSL found this in the GCC 3.1 source tree (in > gcc/toplev.c near line 337)): > > /* Nonzero means do optimizations. -O. > Particular numeric values stand for particular amounts of optimization; > thus, -O2 stores 2 here. However, the optimizations beyond the basic > ones are not controlled directly by this variable. Instead, they are > controlled by individual `flag_...' variables that are defaulted > based on this variable. */ > > int optimize = 0; > > and this near line 4724: > > if (optimize >= 3) > { > flag_inline_functions = 1; > flag_rename_registers = 1; > } > > So -O9 does the same as "-O3 -finline-functions -frename-registers". Most > likely, your added performance boost is due to one of those two. > > -- > Valdis Kletnieks > Computer Systems Senior Engineer > Virginia Tech > Erm, if that block of code was the difference why would -O9 be any different than -O3 (note the >= 3)? I know, I know, get off my ass and look into it myself. RbdPngn --------------------------------------------------------------------------- | Nathan Ingersoll | Computer Science/Mathematics | | mailto: ningerso@d.umn.edu | University of Minnesota-Duluth | | http://umn.edu/~ningerso | http://www.d.umn.edu | --------------------------------------------------------------------------- |