3 ms·

> Compilers don't do clever masking tricks to avoid branches, in general They actually do a lot of such tricks. Check out the GCC sources, for example tree-ssa

> Compilers don't do clever masking tricks to avoid branches, in general They actually do a lot of such tricks. Check out the GCC sources, for example tree-ssa-phiopt.c[1] and ifcvt.c[2] [1] https://github.com/gcc-mirror/gcc/blob/master/gcc/tree-ssa-phiopt.c https://github.com/gcc-mirror/gcc/blob/master/gcc/tree-ssa-p... [2] https://github.com/gcc-mirror/gcc/blob/master/gcc/ifcvt.c https://github.com/gcc-mirror/gcc/blob/master/gcc/ifcvt.c

jleahy 7y ago
Well I was thinking of ifcvt when I mentioned a few special cases. Particularly things like minmax and abs are very specific.
ncmncm 7y ago
They do it a bit, but they leave a very great deal on the table. Clang will convert a = (b&m)|(c&~m) into cmov, but gcc won't.