optimizations flags that are equivalent to -O3

Little little369@gmail.com
Sun Feb 14 22:34:00 GMT 2010


According to GCC 4.3.3 manuals, -O3 turns on the following optimization
flags. However, I tested with 4.5.0 snapshot, -O3 produced a binary 3x
faster than the one produced by the following optimization flags. It seems
-O3 turns on optimization flags that are not in the following list. Any
info... Thanks.

-falign-functions  -falign-jumps 
-falign-loops  -falign-labels 
-fcse-follow-jumps  -fcse-skip-blocks 
-fgcse  -fgcse-lm  
-freorder-blocks  -freorder-functions 
-fsched-interblock  -fsched-spec 
-fschedule-insns  -fschedule-insns2 
-fstrict-aliasing -fstrict-overflow 

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