Method SplitBasicBlock

source/opt/basic_block.cpp:245–289

}

BasicBlock* BasicBlock::SplitBasicBlock(IRContext* context, uint32_t label_id,
                                        iterator iter) {
  assert(!insts_.empty());

  std::unique_ptr<BasicBlock> new_block_temp = MakeUnique<BasicBlock>(
      MakeUnique<Instruction>(context, spv::Op::OpLabel, 0, label_id,
                              std::initializer_list<Operand>{}));
  BasicBlock* new_block = new_block_temp.get();
  function_->InsertBasicBlockAfter(std::move(new_block_temp), this);

  new_block->insts_.Splice(new_block->end(), &insts_, iter, end());
  assert(new_block->GetParent() == GetParent() &&
         "The parent should already be set appropriately.");

  context->AnalyzeDefUse(new_block->GetLabelInst());

  // Update the phi nodes in the successor blocks to reference the new block id.
  const_cast<const BasicBlock*>(new_block)->ForEachSuccessorLabel(
      [new_block, this, context](const uint32_t label) {
        BasicBlock* target_bb = context->get_instr_block(label);
        target_bb->ForEachPhiInst(
            [this, new_block, context](Instruction* phi_inst) {
              bool changed = false;
              for (uint32_t i = 1; i < phi_inst->NumInOperands(); i += 2) {
                if (phi_inst->GetSingleWordInOperand(i) == this->id()) {
                  changed = true;
                  phi_inst->SetInOperand(i, {new_block->id()});
                }
              }

              if (changed) {
                context->UpdateDefUse(phi_inst);
              }
            });
      });

  if (context->AreAnalysesValid(IRContext::kAnalysisInstrToBlockMapping)) {
    context->set_instr_block(new_block->GetLabelInst(), new_block);
    new_block->ForEachInst([new_block, context](Instruction* inst) {
      context->set_instr_block(inst, new_block);
    });
  }

  return new_block;
}

}  // namespace opt
}  // namespace spvtools