Hi Eljay Thanks for your quick reply. > -O0 > Performs no optimizations. It disables (bypasses) all the optimization > machinery. Should make compile time faster, and easier to debug (-g), > but may hide certain bad (language non-compliant) bugs at runtime (which > may give a false impression that the code is correct), and won't > generate a few warnings from -Wall -Wextra which depend on optimization > analysis. > > -O1 -fno-yadayada... > Enables many optimizations, and the mentioned -fno-yadayada... flags > will disable that handful of specific optimizations. (Most of the > optimizations have no independently twiddle-able flags.) > > I like this trick to see which twiddle-able flags were enabled: > > gcc -O1 -S -fverbose-asm -x c <(echo '') -o O1.s > cat O1.s > > (Your command-line may differ, depending on your platform.) Do you (or someone else) know how to enable only constant propagation + constant folding in an -O0 optimization setting? I guess it's necessary to tweak the code, isn't it? If so, how much effort would it be? Cheers, Thomas
