object-introspection/tools/OILGen.cpp
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

94 lines
3.0 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.
*/
#include <clang/Tooling/CommonOptionsParser.h>
#include <gflags/gflags.h>
#include <glog/logging.h>
#include <cstdlib>
#include <filesystem>
#include <iostream>
#include <range/v3/range/conversion.hpp>
#include <range/v3/view/transform.hpp>
#include <vector>
#include "oi/OICodeGen.h"
#include "oi/OIGenerator.h"
namespace fs = std::filesystem;
using namespace oi::detail;
static llvm::cl::OptionCategory OilgenCategory("oilgen options");
static llvm::cl::list<std::string> ConfigFiles(
"config-file",
llvm::cl::desc(R"(</path/to/oid.toml>)"),
llvm::cl::cat(OilgenCategory));
static llvm::cl::opt<std::string> OutputFile(
"output",
llvm::cl::desc(R"(Write output to this file.)"),
llvm::cl::init("a.o"),
llvm::cl::cat(OilgenCategory));
static llvm::cl::opt<int> DebugLevel(
"debug-level",
llvm::cl::desc(R"(Verbose level for logging.)"),
llvm::cl::init(-1),
llvm::cl::cat(OilgenCategory));
static llvm::cl::opt<std::string> DumpJit(
"dump-jit",
llvm::cl::desc(R"(Write the generated code to a file.)"),
llvm::cl::init("jit.cpp"),
llvm::cl::cat(OilgenCategory));
int main(int argc, const char* argv[]) {
google::InitGoogleLogging(argv[0]);
FLAGS_minloglevel = 0;
FLAGS_stderrthreshold = 0;
auto expectedParser =
clang::tooling::CommonOptionsParser::create(argc, argv, OilgenCategory);
if (!expectedParser) {
llvm::errs() << expectedParser.takeError();
return -1;
}
clang::tooling::CommonOptionsParser& options = expectedParser.get();
auto& compilations = options.getCompilations();
if (DebugLevel.getNumOccurrences()) {
google::LogToStderr();
google::SetStderrLogging(google::INFO);
google::SetVLOGLevel("*", DebugLevel);
// Upstream glog defines `GLOG_INFO` as 0 https://fburl.com/ydjajhz0,
// but internally it's defined as 1 https://fburl.com/code/9fwams75
gflags::SetCommandLineOption("minloglevel", "0");
}
OIGenerator oigen;
oigen.setConfigFilePaths(ConfigFiles |
ranges::views::transform([](const auto& p) {
return std::filesystem::path(p);
}) |
ranges::to<std::vector>());
if (DumpJit.getNumOccurrences())
oigen.setSourceFileDumpPath(DumpJit.getValue());
oigen.setOutputPath(OutputFile.getValue());
oigen.setFailIfNothingGenerated(true);
return oigen.generate(compilations, options.getSourcePathList());
}