GCC 4.9.2 -O/O1
          -fauto-inc-dec 
          -fcompare-elim 
          -fcprop-registers 
          -fdce 
          -fdefer-pop 
          -fdelayed-branch 
          -fdse 
          -fguess-branch-probability 
          -fif-conversion2 
          -fif-conversion 
          -fipa-pure-const 
          -fipa-profile 
          -fipa-reference 
          -fmerge-constants
          -fsplit-wide-types 
          -ftree-bit-ccp 
          -ftree-builtin-call-dce 
          -ftree-ccp 
          -ftree-ch 
          -ftree-copyrename 
          -ftree-dce 
          -ftree-dominator-opts 
          -ftree-dse 
          -ftree-forwprop 
          -ftree-fre 
          -ftree-phiprop 
          -ftree-slsr 
          -ftree-sra 
          -ftree-pta 
          -ftree-ter 
          -funit-at-a-time
          -fomit-frame-pointer (maybe)
GCC 4.9.2 -O2
          -fthread-jumps 
          -falign-functions  -falign-jumps 
          -falign-loops  -falign-labels 
          -fcaller-saves 
          -fcrossjumping 
          -fcse-follow-jumps  -fcse-skip-blocks 
          -fdelete-null-pointer-checks 
          -fdevirtualize -fdevirtualize-speculatively 
          -fexpensive-optimizations 
          -fgcse  -fgcse-lm  
          -fhoist-adjacent-loads 
          -finline-small-functions 
          -findirect-inlining 
          -fipa-sra 
          -fisolate-erroneous-paths-dereference 
          -foptimize-sibling-calls 
          -fpartial-inlining 
          -fpeephole2 
          -freorder-blocks  -freorder-functions 
          -frerun-cse-after-loop  
          -fsched-interblock  -fsched-spec 
          -fschedule-insns  -fschedule-insns2 
          -fstrict-aliasing -fstrict-overflow 
          -ftree-switch-conversion -ftree-tail-merge 
          -ftree-pre 
          -ftree-vrp