feat: common simplifications

[avik-pal]

• a + (-b) => a - b if -b isn't used anywhere
• <op>(transpose(a), transpose(b)) => transpose(<op>(a, b)) if only use
• <op>(transpose(a), cst) => transpose(<op>(a, transposed_cst))
• no_nan simplifications
  • a - a => 0
  • c = a + b; d = c - b => d = a
  • c = a + b; d = b - c => d = -a

[avik-pal]

@wsmoses is a - a to 0 for floats not a valid transform? There is a is integer check in SubSimplify

    if (isa<IntegerType>(op.getType().getElementType()) &&
        op.getLhs() == op.getRhs()) {

[wsmoses]

To be compliant it might also require checking it isn't nan (or enabling the equivalent of fast math)

[avik-pal]

does stablehlo provide fast math flags? arith seems to provide but can't find anything in stablehlo specs

[wsmoses]

No we've usually been just parameterizing the canonicalizations here where relevant (eg search for like using or something)

[wsmoses]

Enzyme-JAX/src/enzyme_ad/jax/Passes/Passes.td

Line 49 in 52e1454

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