src/transform/for_loop_to_loop.cc

// Copyright 2021 The Tint Authors.
//
// 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 "src/transform/for_loop_to_loop.h"

#include "src/ast/break_statement.h"
#include "src/program_builder.h"

TINT_INSTANTIATE_TYPEINFO(tint::transform::ForLoopToLoop);

namespace tint {
namespace transform {
ForLoopToLoop::ForLoopToLoop() = default;

ForLoopToLoop::~ForLoopToLoop() = default;

void ForLoopToLoop::Run(CloneContext& ctx, const DataMap&, DataMap&) {
  ctx.ReplaceAll([&](ast::ForLoopStatement* for_loop) -> ast::Statement* {
    ast::StatementList stmts;
    if (auto* cond = for_loop->condition()) {
      // !condition
      auto* not_cond = ctx.dst->create<ast::UnaryOpExpression>(
          ast::UnaryOp::kNot, ctx.Clone(cond));

      // { break; }
      auto* break_body = ctx.dst->Block(ctx.dst->create<ast::BreakStatement>());

      // if (!condition) { break; }
      stmts.emplace_back(ctx.dst->If(not_cond, break_body));
    }
    for (auto* stmt : for_loop->body()->statements()) {
      stmts.emplace_back(ctx.Clone(stmt));
    }

    ast::BlockStatement* continuing = nullptr;
    if (auto* cont = for_loop->continuing()) {
      continuing = ctx.dst->Block(ctx.Clone(cont));
    }

    auto* body = ctx.dst->Block(stmts);
    auto* loop = ctx.dst->create<ast::LoopStatement>(body, continuing);

    if (auto* init = for_loop->initializer()) {
      return ctx.dst->Block(ctx.Clone(init), loop);
    }

    return loop;
  });

  ctx.Clone();
}

}  // namespace transform
}  // namespace tint