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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/single_entry_point.h"
#include <unordered_set>
#include <utility>
#include "src/tint/program_builder.h"
#include "src/tint/sem/function.h"
#include "src/tint/sem/variable.h"
TINT_INSTANTIATE_TYPEINFO(tint::transform::SingleEntryPoint);
TINT_INSTANTIATE_TYPEINFO(tint::transform::SingleEntryPoint::Config);
namespace tint::transform {
SingleEntryPoint::SingleEntryPoint() = default;
SingleEntryPoint::~SingleEntryPoint() = default;
Transform::ApplyResult SingleEntryPoint::Apply(const Program* src,
const DataMap& inputs,
DataMap&) const {
ProgramBuilder b;
CloneContext ctx{&b, src, /* auto_clone_symbols */ true};
auto* cfg = inputs.Get<Config>();
if (cfg == nullptr) {
b.Diagnostics().add_error(diag::System::Transform,
"missing transform data for " + std::string(TypeInfo().name));
return Program(std::move(b));
}
// Find the target entry point.
const ast::Function* entry_point = nullptr;
for (auto* f : src->AST().Functions()) {
if (!f->IsEntryPoint()) {
continue;
}
if (src->Symbols().NameFor(f->symbol) == cfg->entry_point_name) {
entry_point = f;
break;
}
}
if (entry_point == nullptr) {
b.Diagnostics().add_error(diag::System::Transform,
"entry point '" + cfg->entry_point_name + "' not found");
return Program(std::move(b));
}
auto& sem = src->Sem();
auto& referenced_vars = sem.Get(entry_point)->TransitivelyReferencedGlobals();
// Clone any module-scope variables, types, and functions that are statically referenced by the
// target entry point.
for (auto* decl : src->AST().GlobalDeclarations()) {
Switch(
decl, //
[&](const ast::TypeDecl* ty) {
// Strip aliases that reference unused override declarations.
if (auto* arr = sem.Get(ty)->As<type::Array>()) {
auto* refs = sem.TransitivelyReferencedOverrides(arr);
if (refs) {
for (auto* o : *refs) {
if (!referenced_vars.Contains(o)) {
return;
}
}
}
}
// TODO(jrprice): Strip other unused types.
b.AST().AddTypeDecl(ctx.Clone(ty));
},
[&](const ast::Override* override) {
if (referenced_vars.Contains(sem.Get(override))) {
if (!ast::HasAttribute<ast::IdAttribute>(override->attributes)) {
// If the override doesn't already have an @id() attribute, add one
// so that its allocated ID so that it won't be affected by other
// stripped away overrides
auto* global = sem.Get(override);
const auto* id = b.Id(global->OverrideId());
ctx.InsertFront(override->attributes, id);
}
b.AST().AddGlobalVariable(ctx.Clone(override));
}
},
[&](const ast::Var* var) {
if (referenced_vars.Contains(sem.Get<sem::GlobalVariable>(var))) {
b.AST().AddGlobalVariable(ctx.Clone(var));
}
},
[&](const ast::Const* c) {
// Always keep 'const' declarations, as these can be used by attributes and array
// sizes, which are not tracked as transitively used by functions. They also don't
// typically get emitted by the backend unless they're actually used.
b.AST().AddGlobalVariable(ctx.Clone(c));
},
[&](const ast::Function* func) {
if (sem.Get(func)->HasAncestorEntryPoint(entry_point->symbol)) {
b.AST().AddFunction(ctx.Clone(func));
}
},
[&](const ast::Enable* ext) { b.AST().AddEnable(ctx.Clone(ext)); },
[&](Default) {
TINT_UNREACHABLE(Transform, b.Diagnostics())
<< "unhandled global declaration: " << decl->TypeInfo().name;
});
}
// Clone the entry point.
b.AST().AddFunction(ctx.Clone(entry_point));
return Program(std::move(b));
}
SingleEntryPoint::Config::Config(std::string entry_point) : entry_point_name(entry_point) {}
SingleEntryPoint::Config::Config(const Config&) = default;
SingleEntryPoint::Config::~Config() = default;
SingleEntryPoint::Config& SingleEntryPoint::Config::operator=(const Config&) = default;
} // namespace tint::transform