Class: Kumi::IR::Loop::Passes::LoopFusion

Inherits:
Passes::Base show all
Defined in:
lib/kumi/ir/loop/passes/loop_fusion.rb

Overview

Merges sibling loops over the same axis and source into one pass.

The lowerer emits one loop per statement group, so loop-invariant scalar work between two vector statements splits what could be a single traversal. Fusion hoists the independent scalar barrier above the first loop and appends the second loop’s body, renaming its element/index registers.

A pair fuses only when it is provably safe:

  • both loops iterate the same source register on the same axis

  • every instruction between them depends on nothing the first loop defines, no array it pushes to, and no accumulator it steps

  • the second loop touches arrays the first loop pushes to only via index_read at its own loop index (the value produced in the same fused iteration); shifts, lengths, or re-iteration of a partially built array block fusion (stencils legitimately need two passes)

Instance Method Summary collapse

Instance Method Details

#run(graph:, context: {}) ⇒ Object

rubocop:disable Lint/UnusedMethodArgument



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# File 'lib/kumi/ir/loop/passes/loop_fusion.rb', line 24

def run(graph:, context: {}) # rubocop:disable Lint/UnusedMethodArgument
  functions = graph.functions.values.map { |fn| process_function(fn) }
  Loop::Module.new(name: graph.name, functions: functions)
end