[all-commits] [llvm/llvm-project] 7558e9: [Attributor] Fix AANoUndef initialization

[Shinji Okumura via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 7558e9e5a2a90ee58792e3b1327f400e63054dfe
      https://github.com/llvm/llvm-project/commit/7558e9e5a2a90ee58792e3b1327f400e63054dfe
  Author: Shinji Okumura <okuraofvegetable at gmail.com>
  Date:   2020-09-02 (Wed, 02 Sep 2020)

  Changed paths:
    M llvm/lib/Transforms/IPO/AttributorAttributes.cpp

  Log Message:
  -----------
  [Attributor] Fix AANoUndef initialization

When the associated value is undef, we immediately forced to indicate a pessimistic fixpoint so far.
This patch changes the initialization to check the attribute given in IR at first and to indicate an optimistic fixpoint when it is given.
This change will enable us to catch , for example, the following case in AAUB.
```
call void @foo(i32 noundef undef)
```

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D86983