feat[perf]: optimize optimizer

[charles-cooper]

What I did

improve compilation-time by 10-15%, but it's a little gross

How I did it

How to verify it

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.88889% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 85.03%. Comparing base (a0d9b1f) to head (c597129).

❗ Current head c597129 differs from pull request most recent head 7fcd302

Please upload reports for the commit 7fcd302 to get more accurate results.

Files	Patch %	Lines
vyper/codegen/ir_node.py	83.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3782      +/-   ##
==========================================
- Coverage   91.08%   85.03%   -6.06%     
==========================================
  Files         106       92      -14     
  Lines       15315    13722    -1593     
  Branches     3368     3081     -287     
==========================================
- Hits        13950    11668    -2282     
- Misses        928     1566     +638     
- Partials      437      488      +51     

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[charles-cooper]

i checked whether caching _optimized is safe, and i think it is. the concern is that IRnodes are mutable (and the metadata on them is sometimes mutated, but those aren't used in optimization). there aren't really any places where IRnode args are written to - they are in rewrite_return_sequences as part of assembly emission, but that happens after optimization. the only other places where they are in the constructor and in deepcopy.

(vyper) ~/vyper $ git grep "\.args\[.* = "
vyper/ir/compile_ir.py:            ir_node.args[0].value = "pass"
vyper/ir/compile_ir.py:            ir_node.args[1].value = "pass"
vyper/ir/compile_ir.py:        withargs[code.args[0].value] = height
vyper/ir/compile_ir.py:            withargs[code.args[0].value] = old

(vyper) ~/vyper $ git grep "\.args ="
tests/functional/codegen/features/test_logging_from_call.py:    assert logs[0].args == logs[1].args
tests/functional/codegen/features/test_logging_from_call.py:    assert logs[0].args == logs[1].args
vyper/ast/parse.py:        fn_node.args = python_ast.arguments(defaults=[])
vyper/codegen/ir_node.py:        self.args = args
vyper/codegen/ir_node.py:        ret.args = [copy.deepcopy(arg) for arg in ret.args]
vyper/codegen/ir_node.py:            and self.args == other.args
vyper/ir/compile_ir.py:            ir_node.args = IRnode.from_list(_t, source_pos=ir_node.source_pos).args
vyper/ir/optimizer.py:        return x.args == y.args == [] and x.value == y.value and not x.is_complex_ir
vyper/venom/function.py:        self.args = []

[harkal]

I like explicit caching where you can see easily that things get cached and clearly when caches are/need to be invalidated. @cachedproperty scares me :)

[charles-cooper]

closing this, we are planning to axe the old IR pipeline anyway so we don't really need to focus on improvements to it.