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// 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/tint/transform/unshadow.h"
#include <memory>
#include <unordered_map>
#include <utility>
#include "src/tint/program_builder.h"
#include "src/tint/sem/block_statement.h"
#include "src/tint/sem/function.h"
#include "src/tint/sem/statement.h"
#include "src/tint/sem/variable.h"
TINT_INSTANTIATE_TYPEINFO(tint::transform::Unshadow);
namespace tint::transform {
/// PIMPL state for the transform
struct Unshadow::State {
/// The source program
const Program* const src;
/// The target program builder
ProgramBuilder b;
/// The clone context
CloneContext ctx = {&b, src, /* auto_clone_symbols */ true};
/// 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
Transform::ApplyResult Run() {
auto& sem = src->Sem();
// Maps a variable to its new name.
utils::Hashmap<const sem::Variable*, Symbol, 8> renamed_to;
auto rename = [&](const sem::Variable* v) -> const ast::Variable* {
auto* decl = v->Declaration();
auto name = src->Symbols().NameFor(decl->symbol);
auto symbol = b.Symbols().New(name);
renamed_to.Add(v, symbol);
auto source = ctx.Clone(decl->source);
auto* type = ctx.Clone(decl->type);
auto* initializer = ctx.Clone(decl->initializer);
auto attributes = ctx.Clone(decl->attributes);
return Switch(
decl, //
[&](const ast::Var* var) {
return b.Var(source, symbol, type, var->declared_address_space,
var->declared_access, initializer, attributes);
},
[&](const ast::Let*) {
return b.Let(source, symbol, type, initializer, attributes);
},
[&](const ast::Const*) {
return b.Const(source, symbol, type, initializer, attributes);
},
[&](const ast::Parameter*) { //
return b.Param(source, symbol, type, attributes);
},
[&](Default) {
TINT_ICE(Transform, b.Diagnostics())
<< "unexpected variable type: " << decl->TypeInfo().name;
return nullptr;
});
};
bool made_changes = false;
for (auto* node : ctx.src->SemNodes().Objects()) {
Switch(
node, //
[&](const sem::LocalVariable* local) {
if (local->Shadows()) {
ctx.Replace(local->Declaration(), [&, local] { return rename(local); });
made_changes = true;
}
},
[&](const sem::Parameter* param) {
if (param->Shadows()) {
ctx.Replace(param->Declaration(), [&, param] { return rename(param); });
made_changes = true;
}
});
}
if (!made_changes) {
return SkipTransform;
}
ctx.ReplaceAll(
[&](const ast::IdentifierExpression* ident) -> const tint::ast::IdentifierExpression* {
if (auto* sem_ident = sem.Get(ident)) {
if (auto* user = sem_ident->UnwrapLoad()->As<sem::VariableUser>()) {
if (auto renamed = renamed_to.Find(user->Variable())) {
return b.Expr(*renamed);
}
}
}
return nullptr;
});
ctx.Clone();
return Program(std::move(b));
}
};
Unshadow::Unshadow() = default;
Unshadow::~Unshadow() = default;
Transform::ApplyResult Unshadow::Apply(const Program* src, const DataMap&, DataMap&) const {
return State(src).Run();
}
} // namespace tint::transform