Max Kazantsev 34ae308c73 [SCEV] Use context to strengthen flags of BinOps
Sometimes SCEV cannot infer nuw/nsw from something as simple as
```
  len in [0, MAX_INT]
...
  iv = phi(0, iv.next)
  guard(iv <s len)
  guard(iv <u len)
  iv.next = iv + 1
```
just because flag strenthening only relies on definition and does not use local facts.
This patch adds support for the simplest case: inference of flags of `add(x, constant)`
if we can contextually prove that `x <= max_int - constant`.

In case if it has negative CT impact, we can add an option to switch it off. I woudln't
expect that though.

Differential Revision: https://reviews.llvm.org/D129643
Reviewed By: apilipenko
2022-08-03 14:08:57 +07:00
..
2022-07-19 09:57:28 +02:00
2021-05-19 10:25:31 -07:00
2021-01-11 10:19:26 +07:00