findReferencedRangeOfTemporaries() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/Optimization/InstructionReordering.ts lines 110–161

function findReferencedRangeOfTemporaries(fn: HIRFunction): References {
  const singleUseIdentifiers = new Map<IdentifierId, number>();
  const lastAssignments: LastAssignments = new Map();
  function reference(
    instr: InstructionId,
    place: Place,
    kind: ReferenceKind,
  ): void {
    if (
      place.identifier.name !== null &&
      place.identifier.name.kind === 'named'
    ) {
      if (kind === ReferenceKind.Write) {
        const name = place.identifier.name.value;
        const previous = lastAssignments.get(name);
        if (previous === undefined) {
          lastAssignments.set(name, instr);
        } else {
          lastAssignments.set(
            name,
            makeInstructionId(Math.max(previous, instr)),
          );
        }
      }
      return;
    } else if (kind === ReferenceKind.Read) {
      const previousCount = singleUseIdentifiers.get(place.identifier.id) ?? 0;
      singleUseIdentifiers.set(place.identifier.id, previousCount + 1);
    }
  }
  for (const [, block] of fn.body.blocks) {
    for (const instr of block.instructions) {
      for (const operand of eachInstructionValueLValue(instr.value)) {
        reference(instr.id, operand, ReferenceKind.Read);
      }
      for (const lvalue of eachInstructionLValue(instr)) {
        reference(instr.id, lvalue, ReferenceKind.Write);
      }
    }
    for (const operand of eachTerminalOperand(block.terminal)) {
      reference(block.terminal.id, operand, ReferenceKind.Read);
    }
  }
  return {
    singleUseIdentifiers: new Set(
      [...singleUseIdentifiers]
        .filter(([, count]) => count === 1)
        .map(([id]) => id),
    ),
    lastAssignments,
  };
}