[PATCH] D77076: [InstSimplify] Allow some arithmetic optimizations for add/sub/div/rem look through freeze

[Juneyoung Lee via Phabricator via llvm-commits]

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================
Comment at: llvm/test/Transforms/InstSimplify/add.ll:26
+  ret void
+}
+
----------------
I wrote tests in a way that the result is passed to `call f()` rather than being returned, for brevity of tests.


This is a patch to relieve possible performance degradation after D76483 <https://reviews.llvm.org/D76483>.
I picked a few optimizations for add/sub/div/rem in InstSimplify and made them look through freeze.
For example, `X - X => 0` can be expanded so `X - freeze(X)` and `freeze(X) - X` are also converted.

`m_Specific` takes an additional bool parameter `IgnoreFreeze` which makes it match the value after stripping freeze operations.
This expansion is helpful for expanding InstSimplify to support freeze operations without duplicating code.

Proofs:

X + (Y - freeze(X)) -> Y
http://volta.cs.utah.edu:8080/z/yn2mcx

freeze(X) + (Y - X) -> Y
http://volta.cs.utah.edu:8080/z/EmNlwy

freeze(X) - X -> 0
http://volta.cs.utah.edu:8080/z/JVRhLa

freeze(X) div X -> 1, freeze(X) rem X -> 0
http://volta.cs.utah.edu:8080/z/5F6yCt

(X * freeze(Y)) / Y -> X
http://volta.cs.utah.edu:8080/z/MlbJgN

(X % freeze(Y)) / Y -> 0
http://volta.cs.utah.edu:8080/z/CQNyVN


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77076

Files:
  llvm/include/llvm/IR/PatternMatch.h
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/test/Transforms/InstSimplify/add.ll
  llvm/test/Transforms/InstSimplify/div.ll
  llvm/test/Transforms/InstSimplify/rem.ll
  llvm/test/Transforms/InstSimplify/sub.ll

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