On Sat, 2021-05-08 at 20:07 +0800, 172060045@xxxxxxxxxx wrote: > > Hi all, > > Recently I noticed that gcc -O2 didn't turn on vectorization > optimization， > which it turns on in clang -O2. > > Does GCC think it involves the trade-off of space speed, or other > considerations? > > Thanks in advance. > > Yancheng It's just a decision I think. The "original" reason may be that vectorization can make code *slower* on some cases. There was some discussion about enabling -ftree-loop-vectorization at - O2 for x86, but that was too late (for GCC 9): https://gcc.gnu.org/pipermail/gcc/2019-January/228102.html CC Jan: would this be reconsidered for GCC 12? -- Xi Ruoyao <xry111@xxxxxxxxxxxxxxxx> School of Aerospace Science and Technology, Xidian University
