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// Copyright 2022 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/tint/transform/remove_continue_in_switch.h"
#include <string>
#include <unordered_map>
#include <utility>
#include "src/tint/ast/continue_statement.h"
#include "src/tint/ast/switch_statement.h"
#include "src/tint/program_builder.h"
#include "src/tint/sem/block_statement.h"
#include "src/tint/sem/for_loop_statement.h"
#include "src/tint/sem/loop_statement.h"
#include "src/tint/sem/switch_statement.h"
#include "src/tint/sem/while_statement.h"
#include "src/tint/transform/utils/get_insertion_point.h"
#include "src/tint/utils/map.h"
TINT_INSTANTIATE_TYPEINFO(tint::transform::RemoveContinueInSwitch);
namespace tint::transform {
/// PIMPL state for the transform
struct RemoveContinueInSwitch::State {
/// Constructor
/// @param program the source program
explicit State(const Program* program) : src(program) {}
/// Runs the transform
/// @returns the new program or SkipTransform if the transform is not required
ApplyResult Run() {
bool made_changes = false;
for (auto* node : src->ASTNodes().Objects()) {
auto* cont = node->As<ast::ContinueStatement>();
if (!cont) {
continue;
}
// If first parent is not a switch within a loop, skip
auto* switch_stmt = GetParentSwitchInLoop(sem, cont);
if (!switch_stmt) {
continue;
}
made_changes = true;
auto cont_var_name =
tint::utils::GetOrCreate(switch_to_cont_var_name, switch_stmt, [&]() {
// Create and insert 'var tint_continue : bool = false;' before the
// switch.
auto var_name = b.Symbols().New("tint_continue");
auto* decl = b.Decl(b.Var(var_name, b.ty.bool_(), b.Expr(false)));
auto ip = utils::GetInsertionPoint(ctx, switch_stmt);
ctx.InsertBefore(ip.first->Declaration()->statements, ip.second, decl);
// Create and insert 'if (tint_continue) { continue; }' after
// switch.
auto* if_stmt = b.If(b.Expr(var_name), b.Block(b.Continue()));
ctx.InsertAfter(ip.first->Declaration()->statements, ip.second, if_stmt);
// Return the new var name
return var_name;
});
// Replace 'continue;' with '{ tint_continue = true; break; }'
auto* new_stmt = b.Block( //
b.Assign(b.Expr(cont_var_name), true), //
b.Break());
ctx.Replace(cont, new_stmt);
}
if (!made_changes) {
return SkipTransform;
}
ctx.Clone();
return Program(std::move(b));
}
private:
/// The source program
const Program* const src;
/// The target program builder
ProgramBuilder b;
/// The clone context
CloneContext ctx = {&b, src, /* auto_clone_symbols */ true};
/// Alias to src->sem
const sem::Info& sem = src->Sem();
// Map of switch statement to 'tint_continue' variable.
std::unordered_map<const ast::SwitchStatement*, Symbol> switch_to_cont_var_name;
// If `cont` is within a switch statement within a loop, returns a pointer to
// that switch statement.
static const ast::SwitchStatement* GetParentSwitchInLoop(const sem::Info& sem,
const ast::ContinueStatement* cont) {
// Find whether first parent is a switch or a loop
auto* sem_stmt = sem.Get(cont);
auto* sem_parent = sem_stmt->FindFirstParent<sem::SwitchStatement, sem::LoopBlockStatement,
sem::ForLoopStatement, sem::WhileStatement>();
if (!sem_parent) {
return nullptr;
}
return sem_parent->Declaration()->As<ast::SwitchStatement>();
}
};
RemoveContinueInSwitch::RemoveContinueInSwitch() = default;
RemoveContinueInSwitch::~RemoveContinueInSwitch() = default;
Transform::ApplyResult RemoveContinueInSwitch::Apply(const Program* src,
const DataMap&,
DataMap&) const {
State state(src);
return state.Run();
}
} // namespace tint::transform