Hi,
I have a question related to using the O1 option in gcc C to optimize the
code.
With the compile option of -O1, my program takes 1.5 units to run.
However, when I compile the program with all the flags* for O1 instead of
-O1 itself, my program takes 3 units to run.
Can anybody tell me why is this difference? Is there more to what O1 does
than just turning the specified flags on?
I am primarily interested to know which optimizations where effective for
my code.
P.S.
*Flags include all -O1 flags specified in the GCC manual for GCC 4.0.2 -
http://gcc.gnu.org/onlinedocs/gcc-4.0.2/gcc/Optimize-Options.html.
-fdefer-pop -fdelayed-branch -fguess-branch-probability -fcprop-registers
-floop-optimize -fif-conversion -fif-conversion2 -ftree-ccp -ftree-dce
-ftree-dominator-opts -ftree-dse -ftree-ter -ftree-lrs -ftree-sra
-ftree-copyrename -ftree-fre -ftree-ch -fmerge-constants
