[BypassSlowDivision] Do not bypass division of hash-like values
Disable bypassing if one of the operands looks like a hash value. Slow
division often occurs in hashtable implementations and fast division is
never taken there because a hash value is extremely unlikely to have
enough upper bits set to zero.
A value is considered to be hash-like if it is produced by
1) XOR operation
2) Multiplication by a constant wider than the shorter type
3) PHI node with all incoming values being hash-like
Differential Revision: https://reviews.llvm.org/D28200
llvm-svn: 299329