This re-commits r375152 which was pulled in r375233 because it broke
the EXPENSIVE_CHECKS bot on Windows.
The reason for the failure was a bug in the pass that the commit turned
on by default. This patch fixes that bug and turns the pass back on.
This patch has been verified on the buildbot that originally failed
thanks to Simon Pilgrim.
Differential revision: https://reviews.llvm.org/D52431
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375497 91177308-0d34-0410-b5e6-96231b3b80d8
Quite a while ago, we implemented a pass that will reduce the number of
CR-logical operations we emit. It does so by converting a CR-logical operation
into a branch. We have kept this off by default because it seemed to cause a
significant regression with one benchmark.
However, that regression turned out to be due to a completely unrelated
reason - AADB introducing a self-copy that is a priority-setting nop and it was
just exacerbated by this pass.
Now that we understand the reason for the only degradation, we can turn this
pass on by default. We have long since fixed the cause for the degradation.
Differential revision: https://reviews.llvm.org/D52431
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375152 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
A signed comparison of i1 values produces the opposite result to an unsigned one if the condition code
includes less-than or greater-than. This is so because 1 is the most negative signed i1 number and the
most positive unsigned i1 number. The CR-logical operations used for such comparisons are non-commutative
so for signed comparisons vs. unsigned ones, the input operands just need to be swapped.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D54825
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347831 91177308-0d34-0410-b5e6-96231b3b80d8
Nemanja Ivanovic