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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 {
namespace {
class State {
private:
CloneContext& ctx;
ProgramBuilder& b;
const sem::Info& 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>();
}
public:
/// Constructor
/// @param ctx_in the context
explicit State(CloneContext& ctx_in) : ctx(ctx_in), b(*ctx_in.dst), sem(ctx_in.src->Sem()) {}
/// Returns true if this transform should be run for the given program
static bool ShouldRun(const Program* program) {
for (auto* node : program->ASTNodes().Objects()) {
auto* stmt = node->As<ast::ContinueStatement>();
if (!stmt) {
continue;
}
if (GetParentSwitchInLoop(program->Sem(), stmt)) {
return true;
}
}
return false;
}
/// Runs the transform
void Run() {
for (auto* node : ctx.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;
}
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);
}
ctx.Clone();
}
};
} // namespace
RemoveContinueInSwitch::RemoveContinueInSwitch() = default;
RemoveContinueInSwitch::~RemoveContinueInSwitch() = default;
bool RemoveContinueInSwitch::ShouldRun(const Program* program, const DataMap& /*data*/) const {
return State::ShouldRun(program);
}
void RemoveContinueInSwitch::Run(CloneContext& ctx, const DataMap&, DataMap&) const {
State state(ctx);
state.Run();
}
} // namespace tint::transform