Optimization and flags for making a static library with g++

Question

I am just starting with g++ compiler on Linux and got some questions on the compiler flags. Here are they

Optimizations

I read about optimizatio

Answer 1

Regarding when to use what optimization option - there is no single correct answer.

Certain optimization levels may, at times, decrease performance. It depends on the kind of code you are writing and the execution pattern it has, and depends on the specific CPU you are running on.

(To give a simple canonical example - the compiler may decide to use an optimization that makes your code slightly larger than before. This may cause a certain part of the code to no longer fit into the instruction cache, at which point many more accesses to memory would be required - in a loop, for example).

It is best to measure and optimize for whatever you need. Try, measure and decide.

One important rule of thumb - the more optimizations are performed on your code, the harder it is to debug it using a debugger (or read its disassembly), because the C/C++ source view gets further away from the generated binary. It is a good rule of thumb to work with fewer optimizations when developing / debugging for this reason.