Class: Kumi::Core::Analyzer::Passes::LoadInputCSE

Inherits:
PassBase
  • Object
show all
Defined in:
lib/kumi/core/analyzer/passes/load_input_cse.rb

Overview

Load Input Common Subexpression Elimination Pass

Eliminates redundant load_input operations by reusing loads that were already stored by earlier declarations.

OPTIMIZATION STRATEGY:

  • Cross-declaration load reuse: If a load_input with the same (plan_id, scope, is_scalar, has_idx) was already stored by an earlier declaration, rewrite later identical loads to ref the stored value instead of re-loading.

  • Only reuses producers that appear earlier in module order (no reordering/hoisting).

  • Safe because interpreter’s outputs persist across declarations and ref operations resolve previously stored values.

REQUIREMENTS:

  • Must run after LowerToIR pass

  • IR module must be available in state

DEBUG:

  • Set DEBUG_LOAD_CSE=1 to see optimization decisions

Instance Method Summary collapse

Methods inherited from PassBase

#debug, #debug_enabled?, #initialize

Methods included from ErrorReporting

#inferred_location, #raise_localized_error, #raise_syntax_error, #raise_type_error, #report_enhanced_error, #report_error, #report_semantic_error, #report_syntax_error, #report_type_error

Constructor Details

This class inherits a constructor from Kumi::Core::Analyzer::Passes::PassBase

Instance Method Details

#run(_errors) ⇒ Object 



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# File 'lib/kumi/core/analyzer/passes/load_input_cse.rb', line 29

def run(_errors)
  ir = get_state(:ir_module, required: true)
  return state unless ir&.decls

  debug = ENV.fetch("DEBUG_LOAD_CSE", nil)

  # Map: key -> { name:, decl_index: }
  producers = {}

  puts "LOAD_CSE: Analyzing #{ir.decls.length} declarations" if debug

  # First pass: find canonical producers (earliest decl that stores a given load)
  ir.decls.each_with_index do |decl, di|
    decl.ops.each_with_index do |op, oi|
      next unless op.tag == :load_input

      key = load_key(op)
      # Does this decl store that slot under a name?
      store_name = name_storing_slot(decl.ops, oi)
      next unless store_name

      # Keep earliest producer only
      unless producers.key?(key)
        producers[key] = { name: store_name, decl_index: di }
        puts "LOAD_CSE: Found producer #{store_name} in decl #{di} for key #{key.inspect}" if debug
      end
    end
  end

  puts "LOAD_CSE: Found #{producers.size} unique load patterns" if debug

  # Second pass: rewrite later identical loads to refs
  optimizations = 0
  new_decls = ir.decls.each_with_index.map do |decl, di|
    new_ops = decl.ops.each_with_index.map do |op, oi|
      next op unless op.tag == :load_input

      key = load_key(op)
      prod = producers[key]

      # Only rewrite if producer is in an earlier decl
      if prod && prod[:decl_index] < di
        optimizations += 1
        puts "LOAD_CSE: Replacing load_input in #{decl.name}[#{oi}] with ref to #{prod[:name]}" if debug
        Kumi::Core::IR::Ops.Ref(prod[:name])
      else
        op
      end
    end

    Kumi::Core::IR::Decl.new(
      name: decl.name,
      kind: decl.kind,
      shape: decl.shape,
      ops: new_ops
    )
  end

  puts "LOAD_CSE: Applied #{optimizations} optimizations" if debug

  new_ir = Kumi::Core::IR::Module.new(inputs: ir.inputs, decls: new_decls)
  state.with(:ir_module, new_ir)
end