Commit Graph

2 Commits

Author SHA1 Message Date
David Majnemer 1bacc0abc9 InstCombine: Ensure select condition types are identical before merging
Selection conditions may be vectors or scalars.  Make sure InstCombine
doesn't indiscriminately assume that a select which is value dependent
on another select have identical select condition types.

This fixes PR22773.

llvm-svn: 231156
2015-03-03 22:40:36 +00:00
Owen Anderson 883b5add8e Remove a very old instcombine where we would turn sequences of selects into
logical operations on the i1's driving them.  This is a bad idea for every
target I can think of (confirmed with micro tests on all of: x86-64, ARM,
AArch64, Mips, and PowerPC) because it forces the i1 to be materialized into
a general purpose register, whereas consuming it directly into a select generally
allows it to exist only transiently in a predicate or flags register.

Chandler ran a set of performance tests with this change, and reported no
measurable change on x86-64.

llvm-svn: 201275
2014-02-12 23:54:07 +00:00