[all-commits] [llvm/llvm-project] 7bdba9: [mlir][arith] Fix `arith.select` canonicalization ...

[Fehr Mathieu via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7bdba956efae81f111f0cc6c7aaa92f9712444ba
      https://github.com/llvm/llvm-project/commit/7bdba956efae81f111f0cc6c7aaa92f9712444ba
  Author: Fehr Mathieu <mathieu.fehr at gmail.com>
  Date:   2024-03-13 (Wed, 13 Mar 2024)

  Changed paths:
    M mlir/lib/Dialect/Arith/IR/ArithCanonicalization.td
    M mlir/lib/Dialect/Arith/IR/ArithOps.cpp
    M mlir/test/Dialect/Arith/canonicalize.mlir

  Log Message:
  -----------
  [mlir][arith] Fix `arith.select` canonicalization patterns (#84685)

Because `arith.select` does not propagate poison of the second or third
operand depending on the condition, some canonicalization patterns are
currently incorrect. This patch removes these incorrect patterns, and
adds a new pattern to fix the case of `i1` select with constants.

Patterns that are removed:
* select(predA, select(predB, x, y), y) => select(and(predA, predB), x,
y)
* select(predA, select(predB, y, x), y) => select(and(predA,
not(predB)), x, y)
* select(predA, x, select(predB, x, y)) => select(or(predA, predB), x,
y)
* select(predA, x, select(predB, y, x)) => select(or(predA, not(predB)),
x, y)
* arith.select %arg, %x, %y : i1 => and(%arg, %x) or and(!%arg, %y)
  
Pattern that is added:
* select(pred, false, true) => not(pred) for i1

The first two patterns are incorrect when `predB` is poison and `predA`
is false, as a non-poison `y` gets compiled to `poison`. The next two
patterns are incorrect when `predB` is poison and `predA` is true, as a
non-poison `x` gets compiled to `poison`. The last pattern is incorrect
as it propagates poison from all operands afer compilation.



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