Compiler Optimization with GCC

[mas027]

Does anyone know where I could get any information on how to know which specific GCC compiler optimizations were used during compilation (and a little more specific than the O1, O2, O3 optimizations)??


thanks a bunch!

 

[Salem]

Did you try the manual page?
Eg.
-O turns on the following optimization flags:


--
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.

 

[mas027]

Thanks...Yeah I checked out the manual page, but I want to know what the "optimization flags" actually do. Like what do these flags do?... -fthread-jumps
-fcrossjumping
-foptimize-sibling-calls
-fcse-follow-jumps -fcse-skip-blocks
-fgcse -fgcse-lm
-fexpensive-optimizations
-frerun-cse-after-loop
-fcaller-saves
-fpeephole2
-fschedule-insns -fschedule-insns2
-fsched-interblock -fsched-spec
-fregmove


I cant seem to find any information on these.
thanks a lot!

 

[Salem]

How about scrolling down the page of the very link I posted?

-fthread-jumps
Perform optimizations where we check to see if a jump branches to a location where another comparison subsumed by the first is found. If so, the first branch is redirected to either the destination of the second branch or a point immediately following it, depending on whether the condition is known to be true or false.

Enabled at levels -O2, -O3, -Os.

--
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.