enterSSAImpl() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/SSA/EnterSSA.ts lines 245–329

function enterSSAImpl(
  func: HIRFunction,
  builder: SSABuilder,
  rootEntry: BlockId,
): void {
  const visitedBlocks: Set<BasicBlock> = new Set();
  for (const [blockId, block] of func.body.blocks) {
    CompilerError.invariant(!visitedBlocks.has(block), {
      reason: `found a cycle! visiting bb${block.id} again`,
      loc: GeneratedSource,
    });

    visitedBlocks.add(block);

    builder.startBlock(block);

    if (blockId === rootEntry) {
      // NOTE: func.context should be empty for the root function
      CompilerError.invariant(func.context.length === 0, {
        reason: `Expected function context to be empty for outer function declarations`,
        loc: func.loc,
      });
      func.params = func.params.map(param => {
        if (param.kind === 'Identifier') {
          return builder.definePlace(param);
        } else {
          return {
            kind: 'Spread',
            place: builder.definePlace(param.place),
          };
        }
      });
    }

    for (const instr of block.instructions) {
      mapInstructionOperands(instr, place => builder.getPlace(place));
      mapInstructionLValues(instr, lvalue => builder.definePlace(lvalue));

      if (
        instr.value.kind === 'FunctionExpression' ||
        instr.value.kind === 'ObjectMethod'
      ) {
        const loweredFunc = instr.value.loweredFunc.func;
        const entry = loweredFunc.body.blocks.get(loweredFunc.body.entry)!;
        CompilerError.invariant(entry.preds.size === 0, {
          reason:
            'Expected function expression entry block to have zero predecessors',
          loc: GeneratedSource,
        });
        entry.preds.add(blockId);
        builder.defineFunction(loweredFunc);
        builder.enter(() => {
          loweredFunc.params = loweredFunc.params.map(param => {
            if (param.kind === 'Identifier') {
              return builder.definePlace(param);
            } else {
              return {
                kind: 'Spread',
                place: builder.definePlace(param.place),
              };
            }
          });
          enterSSAImpl(loweredFunc, builder, rootEntry);
        });
        entry.preds.clear();
      }
    }

    mapTerminalOperands(block.terminal, place => builder.getPlace(place));
    for (const outputId of eachTerminalSuccessor(block.terminal)) {
      const output = func.body.blocks.get(outputId)!;
      let count;
      if (builder.unsealedPreds.has(output)) {
        count = builder.unsealedPreds.get(output)! - 1;
      } else {
        count = output.preds.size - 1;
      }
      builder.unsealedPreds.set(output, count);

      if (count === 0 && visitedBlocks.has(output)) {
        builder.fixIncompletePhis(output);