src/ast/ExpressionManipulator.cpp

/*
 * Copyright 2017 WebAssembly Community Group participants
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "ast_utils.h"
#include "support/hash.h"

namespace wasm {

Expression* ExpressionManipulator::flexibleCopy(Expression* original, Module& wasm, CustomCopier custom) {
  struct Copier : public Visitor<Copier, Expression*> {
    Module& wasm;
    CustomCopier custom;

    Builder builder;

    Copier(Module& wasm, CustomCopier custom) : wasm(wasm), custom(custom), builder(wasm) {}

    Expression* copy(Expression* curr) {
      if (!curr) return nullptr;
      auto* ret = custom(curr);
      if (ret) return ret;
      return Visitor<Copier, Expression*>::visit(curr);
    }

    Expression* visitBlock(Block *curr) {
      auto* ret = builder.makeBlock();
      for (Index i = 0; i < curr->list.size(); i++) {
        ret->list.push_back(copy(curr->list[i]));
      }
      ret->name = curr->name;
      ret->finalize(curr->type);
      return ret;
    }
    Expression* visitIf(If *curr) {
      return builder.makeIf(copy(curr->condition), copy(curr->ifTrue), copy(curr->ifFalse));
    }
    Expression* visitLoop(Loop *curr) {
      return builder.makeLoop(curr->name, copy(curr->body));
    }
    Expression* visitBreak(Break *curr) {
      return builder.makeBreak(curr->name, copy(curr->value), copy(curr->condition));
    }
    Expression* visitSwitch(Switch *curr) {
      return builder.makeSwitch(curr->targets, curr->default_, copy(curr->condition), copy(curr->value));
    }
    Expression* visitCall(Call *curr) {
      auto* ret = builder.makeCall(curr->target, {}, curr->type);
      for (Index i = 0; i < curr->operands.size(); i++) {
        ret->operands.push_back(copy(curr->operands[i]));
      }
      return ret;
    }
    Expression* visitCallImport(CallImport *curr) {
      auto* ret = builder.makeCallImport(curr->target, {}, curr->type);
      for (Index i = 0; i < curr->operands.size(); i++) {
        ret->operands.push_back(copy(curr->operands[i]));
      }
      return ret;
    }
    Expression* visitCallIndirect(CallIndirect *curr) {
      auto* ret = builder.makeCallIndirect(curr->fullType, copy(curr->target), {}, curr->type);
      for (Index i = 0; i < curr->operands.size(); i++) {
        ret->operands.push_back(copy(curr->operands[i]));
      }
      return ret;
    }
    Expression* visitGetLocal(GetLocal *curr) {
      return builder.makeGetLocal(curr->index, curr->type);
    }
    Expression* visitSetLocal(SetLocal *curr) {
      if (curr->isTee()) {
        return builder.makeTeeLocal(curr->index, copy(curr->value));
      } else {
        return builder.makeSetLocal(curr->index, copy(curr->value));
      }
    }
    Expression* visitGetGlobal(GetGlobal *curr) {
      return builder.makeGetGlobal(curr->name, curr->type);
    }
    Expression* visitSetGlobal(SetGlobal *curr) {
      return builder.makeSetGlobal(curr->name, copy(curr->value));
    }
    Expression* visitLoad(Load *curr) {
      return builder.makeLoad(curr->bytes, curr->signed_, curr->offset, curr->align, copy(curr->ptr), curr->type);
    }
    Expression* visitStore(Store *curr) {
      return builder.makeStore(curr->bytes, curr->offset, curr->align, copy(curr->ptr), copy(curr->value), curr->valueType);
    }
    Expression* visitConst(Const *curr) {
      return builder.makeConst(curr->value);
    }
    Expression* visitUnary(Unary *curr) {
      return builder.makeUnary(curr->op, copy(curr->value));
    }
    Expression* visitBinary(Binary *curr) {
      return builder.makeBinary(curr->op, copy(curr->left), copy(curr->right));
    }
    Expression* visitSelect(Select *curr) {
      return builder.makeSelect(copy(curr->condition), copy(curr->ifTrue), copy(curr->ifFalse));
    }
    Expression* visitDrop(Drop *curr) {
      return builder.makeDrop(copy(curr->value));
    }
    Expression* visitReturn(Return *curr) {
      return builder.makeReturn(copy(curr->value));
    }
    Expression* visitHost(Host *curr) {
      assert(curr->operands.size() == 0);
      return builder.makeHost(curr->op, curr->nameOperand, {});
    }
    Expression* visitNop(Nop *curr) {
      return builder.makeNop();
    }
    Expression* visitUnreachable(Unreachable *curr) {
      return builder.makeUnreachable();
    }
  };

  Copier copier(wasm, custom);
  return copier.copy(original);
}


// Splice an item into the middle of a block's list
void ExpressionManipulator::spliceIntoBlock(Block* block, Index index, Expression* add) {
  auto& list = block->list;
  if (index == list.size()) {
    list.push_back(add); // simple append
  } else {
    // we need to make room
    list.push_back(nullptr);
    for (Index i = list.size() - 1; i > index; i--) {
      list[i] = list[i - 1];
    }
    list[index] = add;
  }
}

} // namespace wasm