Nikolai Bozhenov fca527af5c [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

2017-04-02 13:14:30 +00:00

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