From: Hans-Bernhard Broeker Newsgroups: comp.os.msdos.djgpp Subject: Re: -O6 optimizations Date: 13 May 2001 14:20:21 GMT Organization: Aachen University of Technology (RWTH) Lines: 34 Message-ID: <9dm575$sqh$1@nets3.rz.RWTH-Aachen.DE> References: <2rVK6.20535$z01 DOT 3117219 AT carnaval DOT risq DOT qc DOT ca> NNTP-Posting-Host: acp3bf.physik.rwth-aachen.de X-Trace: nets3.rz.RWTH-Aachen.DE 989763621 29521 137.226.32.75 (13 May 2001 14:20:21 GMT) X-Complaints-To: abuse AT rwth-aachen DOT de NNTP-Posting-Date: 13 May 2001 14:20:21 GMT Originator: broeker@ To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com Patrick Mitran wrote: > I'm using gcc 2.95.3. I was wondering where I could get a list of all the > optimizations that are turned on by -O6. About the most complete description of this can be had by asking GCC itself to show it: redir -eo O6.txt gcc -c -v -Q -O6 hello.c Look into the O6.txt file, right after the banner line from 'cc1'. There's a list of all single options in effect in this GCC run. An example from a very old Linux box: GNU C version 2.7.2 (i386 Linux/ELF) compiled by GNU C version 2.7.2. enabled: -fdefer-pop -fcse-follow-jumps -fcse-skip-blocks \ -fexpensive-optimizations -fthread-jumps -fstrength-reduce -fpeephole -fforce-mem -ffunction-cse -finline-functions -finline -fcaller-saves -fpcc-struct-return -frerun-cse-after-loop -fcommon -fgnu-linker -m80387 -mhard-float -mno-soft-float -mno-386 -m486 -mieee-fp -mfp-ret-in-387 > Also, do I have to add the -mpentium switch too or is this inclused > in -O6. No. "Optimization" should have different effects for different processor types. Otherwise, -mpentium and friends would be pointless. Architecture or CPU type settings are thus independent from optimization flags. -- Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de) Even if all the snow were burnt, ashes would remain.