[PATCH] D14032: [RS4GC] Strip noalias attribute after statepoint rewrite

[Igor Laevsky via llvm-commits]

igor-laevsky created this revision.
igor-laevsky added a reviewer: sanjoy.
igor-laevsky added a subscriber: llvm-commits.
Herald added a subscriber: sanjoy.

We should remove noalias along with dereference and dereference_or_null attributes. Problem is that statepoint could potentially touch the entire heap including noalias objects. For example in this piece of code:
```
  %obj = call noalias %jObject* new_instance(...)
  store %val, %obj ; last use of %obj
  call gc.statepoint()
```
Llvm will consider that %obj and statepoint call do not alias and move store after the statepoint.

http://reviews.llvm.org/D14032

Files:
  include/llvm/IR/CallSite.h
  include/llvm/IR/Instructions.h
  lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
  test/Transforms/RewriteStatepointsForGC/deref-pointers.ll

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