Merging r324039: (test case modified to work around r323886 et al.)

------------------------------------------------------------------------
r324039 | matze | 2018-02-02 01:08:19 +0100 (Fri, 02 Feb 2018) | 33 lines

SplitKit: Fix liveness recomputation in some remat cases.

Example situation:
```
BB0:
  %0 = ...
  use %0
  ; ...
  condjump BB1
  jmp BB2

BB1:
  %0 = ...   ; rematerialized def from above (from earlier split step)
  jmp BB2

BB2:
  ; ...
  use %0
```

%0 will have a live interval with 3 value numbers (for the BB0, BB1 and
BB2 parts). Now SplitKit tries and succeeds in rematerializing the value
number in BB2 (This only works because it is a secondary split so
SplitKit is can trace this back to a single original def).

We need to recompute all live ranges affected by a value number that we
rematerialize. The case that we missed before is that when the value
that is rematerialized is at a join (Phi VNI) then we also have to
recompute liveness for the predecessor VNIs.

rdar://35699130

Differential Revision: https://reviews.llvm.org/D42667
------------------------------------------------------------------------


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@324218 91177308-0d34-0410-b5e6-96231b3b80d8

0 files changed, 0 insertions, 0 deletions