c - Are the effects of hand-optimization of code consistent across different gcc optimization levels? -


if run gcc -o0, , hand-optimize code using techniques such ones mentioned here, case optimized code run faster unoptimized code when run gcc -o3?

that is, if hand-optimize code under particular compiler optimization level, true these optimizations still productive (rather counterproductive) under different (higher or lower) compiler optimization level?

it might not same in different compiler. compiler can away hand optimization, mean ignore them. heavily depends implementation , behavior of compiler itself. of optimizations request compiler, can dropped @ time, (mostly without notification)


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