[all-commits] [llvm/llvm-project] b75609: [AAPointerInfo] refactor how offsets and Access ob...

[Sameer Sahasrabuddhe via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b756096b0cbef0918394851644649b3c28a886e2
      https://github.com/llvm/llvm-project/commit/b756096b0cbef0918394851644649b3c28a886e2
  Author: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>
  Date:   2022-11-01 (Tue, 01 Nov 2022)

  Changed paths:
    M llvm/include/llvm/Transforms/IPO/Attributor.h
    M llvm/lib/Transforms/IPO/Attributor.cpp
    M llvm/lib/Transforms/IPO/AttributorAttributes.cpp
    M llvm/test/Transforms/Attributor/call-simplify-pointer-info.ll
    M llvm/test/Transforms/Attributor/value-simplify-pointer-info.ll

  Log Message:
  -----------
  [AAPointerInfo] refactor how offsets and Access objects are tracked

AAPointerInfo now maintains a list of all Access objects that it owns, along
with the following maps:

- OffsetBins: OffsetAndSize -> { Access }
- InstTupleMap: RemoteI x LocalI -> Access

A RemoteI is any instruction that accesses memory. RemoteI is different from
LocalI if and only if LocalI is a call; then RemoteI is some instruction in the
callgraph starting from LocalI.

Motivation: When AAPointerInfo recomputes the offset for an instruction, it sets
the value to Unknown if the new offset is not the same as the old offset. The
instruction must now be moved from its current bin to the bin corresponding to
the new offset. This happens for example, when:

- A PHINode has operands that result in different offsets.
- The same remote inst is reachable from the same local inst via different paths
  in the callgraph:

```
               A (local inst)
               |
               B
              / \
             C1  C2
              \ /
               D (remote inst)

```
This fixes a bug where a store is incorrectly eliminated in a lit test.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D136526