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// SPDX-License-Identifier: GPL-2.0
/*
* llvm C frontend for perf. Support dynamically compile C file
*
* Inspired by clang example code:
* http://llvm.org/svn/llvm-project/cfe/trunk/examples/clang-interpreter/main.cpp
*
* Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
* Copyright (C) 2016 Huawei Inc.
*/
#include "clang/Basic/Version.h"
#include "clang/CodeGen/CodeGenAction.h"
#include "clang/Frontend/CompilerInvocation.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/TextDiagnosticPrinter.h"
#include "clang/Tooling/Tooling.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/Option/Option.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <memory>
#include "clang.h"
#include "clang-c.h"
namespace perf {
static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
using namespace clang;
static CompilerInvocation *
createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
DiagnosticsEngine& Diags)
{
llvm::opt::ArgStringList CCArgs {
"-cc1",
"-triple", "bpf-pc-linux",
"-fsyntax-only",
"-ferror-limit", "19",
"-fmessage-length", "127",
"-O2",
"-nostdsysteminc",
"-nobuiltininc",
"-vectorize-loops",
"-vectorize-slp",
"-Wno-unused-value",
"-Wno-pointer-sign",
"-x", "c"};
CCArgs.append(CFlags.begin(), CFlags.end());
CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs);
FrontendOptions& Opts = CI->getFrontendOpts();
Opts.Inputs.clear();
Opts.Inputs.emplace_back(Path,
FrontendOptions::getInputKindForExtension("c"));
return CI;
}
static std::unique_ptr<llvm::Module>
getModuleFromSource(llvm::opt::ArgStringList CFlags,
StringRef Path, IntrusiveRefCntPtr<vfs::FileSystem> VFS)
{
CompilerInstance Clang;
Clang.createDiagnostics();
Clang.setVirtualFileSystem(&*VFS);
#if CLANG_VERSION_MAJOR < 4
IntrusiveRefCntPtr<CompilerInvocation> CI =
createCompilerInvocation(std::move(CFlags), Path,
Clang.getDiagnostics());
Clang.setInvocation(&*CI);
#else
std::shared_ptr<CompilerInvocation> CI(
createCompilerInvocation(std::move(CFlags), Path,
Clang.getDiagnostics()));
Clang.setInvocation(CI);
#endif
std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
if (!Clang.ExecuteAction(*Act))
return std::unique_ptr<llvm::Module>(nullptr);
return Act->takeModule();
}
std::unique_ptr<llvm::Module>
getModuleFromSource(llvm::opt::ArgStringList CFlags,
StringRef Name, StringRef Content)
{
using namespace vfs;
llvm::IntrusiveRefCntPtr<OverlayFileSystem> OverlayFS(
new OverlayFileSystem(getRealFileSystem()));
llvm::IntrusiveRefCntPtr<InMemoryFileSystem> MemFS(
new InMemoryFileSystem(true));
/*
* pushOverlay helps setting working dir for MemFS. Must call
* before addFile.
*/
OverlayFS->pushOverlay(MemFS);
MemFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
return getModuleFromSource(std::move(CFlags), Name, OverlayFS);
}
std::unique_ptr<llvm::Module>
getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
{
IntrusiveRefCntPtr<vfs::FileSystem> VFS(vfs::getRealFileSystem());
return getModuleFromSource(std::move(CFlags), Path, VFS);
}
std::unique_ptr<llvm::SmallVectorImpl<char>>
getBPFObjectFromModule(llvm::Module *Module)
{
using namespace llvm;
std::string TargetTriple("bpf-pc-linux");
std::string Error;
const Target* Target = TargetRegistry::lookupTarget(TargetTriple, Error);
if (!Target) {
llvm::errs() << Error;
return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
}
llvm::TargetOptions Opt;
TargetMachine *TargetMachine =
Target->createTargetMachine(TargetTriple,
"generic", "",
Opt, Reloc::Static);
Module->setDataLayout(TargetMachine->createDataLayout());
Module->setTargetTriple(TargetTriple);
std::unique_ptr<SmallVectorImpl<char>> Buffer(new SmallVector<char, 0>());
raw_svector_ostream ostream(*Buffer);
legacy::PassManager PM;
if (TargetMachine->addPassesToEmitFile(PM, ostream,
TargetMachine::CGFT_ObjectFile)) {
llvm::errs() << "TargetMachine can't emit a file of this type\n";
return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);;
}
PM.run(*Module);
return std::move(Buffer);
}
}
extern "C" {
void perf_clang__init(void)
{
perf::LLVMCtx.reset(new llvm::LLVMContext());
LLVMInitializeBPFTargetInfo();
LLVMInitializeBPFTarget();
LLVMInitializeBPFTargetMC();
LLVMInitializeBPFAsmPrinter();
}
void perf_clang__cleanup(void)
{
perf::LLVMCtx.reset(nullptr);
llvm::llvm_shutdown();
}
int perf_clang__compile_bpf(const char *filename,
void **p_obj_buf,
size_t *p_obj_buf_sz)
{
using namespace perf;
if (!p_obj_buf || !p_obj_buf_sz)
return -EINVAL;
llvm::opt::ArgStringList CFlags;
auto M = getModuleFromSource(std::move(CFlags), filename);
if (!M)
return -EINVAL;
auto O = getBPFObjectFromModule(&*M);
if (!O)
return -EINVAL;
size_t size = O->size_in_bytes();
void *buffer;
buffer = malloc(size);
if (!buffer)
return -ENOMEM;
memcpy(buffer, O->data(), size);
*p_obj_buf = buffer;
*p_obj_buf_sz = size;
return 0;
}
}
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