We've found another bug in the code generation logic conditions for a
certain class of always-false conditions, those of the form
if ((a & 1) < 0)
These only reach the back end when compiling without optimization.
The bug was introduced by the choice of using TEST UNDER MASK
to implement a check for
if ((a & MASK) < VAL)
as
if ((a & MASK) == 0)
where VAL is less than the the lowest bit of MASK. This is correct
in all cases except for VAL == 0, in which case the original
condition is always false, but the replacement isn't.
Fixed by excluding that particular case.
llvm-svn: 259381
