https://gcc.gnu.org/bugzilla/show_bug.cgi?id=20517
Roger Sayle <roger at nextmovesoftware dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |roger at nextmovesoftware dot
com
Resolution|--- |FIXED
Target Milestone|--- |4.6.4
--- Comment #8 from Roger Sayle <roger at nextmovesoftware dot com> ---
GCC generates code without shifts for all the examples in comment #4, since
around version 4.6.4. The "((x&0xf0)>>4) == 1" of the original, is now
canonicalized to "((x>>4)&0xf) == 1" at the tree-level (to minimize the size of
immediate constants). Whether ((x>>C1)&C2)==C3 is more/less efficient than
(x&C4)==C5, where C4=C2<<C1 and C5=C3<<C1, depends upon the target, so this
decision is made in the RTL optimizers, as explained in the PR's comments.
