Simplify binary operations where one operand is a select instruction.
The simplifications performed here never create new instructions, they
only return existing instructions (or a constant), and so are always a
win.  In theory they should transform (for example)
  %z = and i32 %x, %y
  %s = select i1 %cond, i32 %y, i32 %z
  %r = and i32 %x, %s
into
  %r = and i32 %x, y
but in practice they get into a fight with instcombine, and lose.
Unfortunately instcombine does a poor job in this case.  Nonetheless
I'm committing this transform to make it easier to discuss what to
do to make peace with instcombine.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118679 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed