perf(ssa): avoid repeated operand scans

[Automaat]

Repeated operands add the same instruction to a value's referrer list once per operand. replaceAll currently rescans all operands for every entry, making Phi nodes and similar instructions quadratic.

Group adjacent entries for the same instruction, scan its operands once, and append the original group so referrer multiplicity remains unchanged.

A focused correctness test and benchmark are included. Hosted results (2 CPUs, 1 GiB RAM; median of 3):

Repeated operands	Before	After	Speedup
16	1,396 ns/op	294 ns/op	4.7x
64	17,436 ns/op	940 ns/op	18.5x
256	266,416 ns/op	3,489 ns/op	76x
1024	4,157,267 ns/op	15,995 ns/op	260x

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Patch Set 1:

(1 comment)

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Message from Alan Donovan:

Patch Set 1:

(1 comment)

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