object-introspection/oi/CodeGen.h
Jake Hillion 55989a9156 oilgen: migrate to source parsing (#421)
Summary:
oilgen: migrate to source parsing

Using debug information generated from partial source (that is, not the final
binary) has been insufficient to generally generate OIL code.

A particular example is pointers to templates:
```cpp
#include <oi/oi.h>
template <typename T>
struct Foo {
  T t;
};
template <typename T>
struct Bar {
  Foo<T>& f;
};
void foo(const Bar<int>& b) {
  oi::introspect(b);
}
```

The pointer/reference to `Foo<int>` appears in DWARF with
`DW_AT_declaration(true)` because it could be specialised before its usage.
However, with OIL, we are creating an implicit usage site in the
`oi::introspect` call that the compiler is unable to see.

This change reworks OILGen to work from a Clang command line rather than debug
information. We setup and run a compiler on the source, giving us access to an
AST and Semantic Analyser. We then:
- Find the `oi::introspect` template.
- Iterate through each of its callsites for their type.
- Run `ClangTypeParser::parse` on each type.
- Run codegen.
- Compile into an object file.

Having access to the semantic analyser allows us to forcefully complete a type,
as it would be if it was used in the initial code.


Test Plan:
hope

`buck2 run fbcode//mode/opt fbcode//object-introspection/oil/examples/compile-time:compile-time`

Reviewed By: tyroguru

Differential Revision: D51854477

Pulled By: JakeHillion
2023-12-19 13:26:25 -08:00

110 lines
3.7 KiB
C++

/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* 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.
*/
#pragma once
#include <filesystem>
#include <functional>
#include <list>
#include <memory>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include "ContainerInfo.h"
#include "OICodeGen.h"
#include "type_graph/TypeGraph.h"
struct drgn_type;
namespace oi::detail {
class SymbolService;
}
namespace oi::detail::type_graph {
class Class;
class Member;
} // namespace oi::detail::type_graph
namespace oi::detail {
class CodeGen {
public:
CodeGen(const OICodeGen::Config& config);
CodeGen(const OICodeGen::Config& config, SymbolService& symbols)
: config_(config), symbols_(&symbols) {
}
struct ExactName {
std::string name;
};
struct HashedComponent {
std::string name;
};
using RootFunctionName = std::variant<ExactName, HashedComponent>;
/*
* Helper function to perform all the steps required for code generation for a
* single drgn_type.
*/
bool codegenFromDrgn(struct drgn_type* drgnType, std::string& code);
bool codegenFromDrgn(struct drgn_type* drgnType,
std::string linkageName,
std::string& code);
void exportDrgnTypes(TypeHierarchy& th,
std::list<drgn_type>& drgnTypes,
drgn_type** rootType) const;
bool registerContainers();
void registerContainer(std::unique_ptr<ContainerInfo> containerInfo);
void registerContainer(const std::filesystem::path& path);
void addDrgnRoot(struct drgn_type* drgnType,
type_graph::TypeGraph& typeGraph);
void transform(type_graph::TypeGraph& typeGraph);
void generate(type_graph::TypeGraph& typeGraph,
std::string& code,
RootFunctionName rootName);
private:
type_graph::TypeGraph typeGraph_;
const OICodeGen::Config& config_;
SymbolService* symbols_ = nullptr;
std::vector<std::unique_ptr<ContainerInfo>> containerInfos_;
std::unordered_set<const ContainerInfo*> definedContainers_;
std::unordered_map<const type_graph::Class*, const type_graph::Member*>
thriftIssetMembers_;
bool codegenFromDrgn(struct drgn_type* drgnType,
std::string& code,
RootFunctionName name);
void genDefsThrift(const type_graph::TypeGraph& typeGraph, std::string& code);
void addGetSizeFuncDefs(const type_graph::TypeGraph& typeGraph,
std::string& code);
void getClassSizeFuncDef(const type_graph::Class& c, std::string& code);
void getClassSizeFuncConcrete(std::string_view funcName,
const type_graph::Class& c,
std::string& code) const;
void addTypeHandlers(const type_graph::TypeGraph& typeGraph,
std::string& code);
void genClassTypeHandler(const type_graph::Class& c, std::string& code);
void genClassStaticType(const type_graph::Class& c, std::string& code);
void genClassTraversalFunction(const type_graph::Class& c, std::string& code);
void genClassTreeBuilderInstructions(const type_graph::Class& c,
std::string& code);
};
} // namespace oi::detail