[all-commits] [llvm/llvm-project] 376d04: [AAPointerInfo] refactor how offsets and Access ob...

[Sameer Sahasrabuddhe via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 376d0469b917a889139f23e199a5d52c87c7a5bb
      https://github.com/llvm/llvm-project/commit/376d0469b917a889139f23e199a5d52c87c7a5bb
  Author: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>
  Date:   2022-11-15 (Tue, 15 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

This restores commit b756096b0cbef0918394851644649b3c28a886e2, which was
originally reverted in 00b09a7b18abb253d36b3d3e1c546007288f6e89.

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, ye-luo

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