https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97637
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Sometimes it may shrink the code a lot, it really depends on the code. Just that the question whether a particular transformation will make code faster or not is the primary question to ask, unless compiling with -Os or unless a particular code is e.g. through PGO determined to be cold.
