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Subject[PATCH v2 10/18] perf clang: Support compile IR to BPF object and add testcase
Date
getBPFObjectFromModule() is introduced to use LLVM to convert Module
(LLVM IR) to BPF object code. Add new testcase for it.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
---
tools/perf/tests/clang.c | 6 ++++-
tools/perf/util/c++/clang-c.h | 1 +
tools/perf/util/c++/clang-test.cpp | 31 ++++++++++++++++++++-----
tools/perf/util/c++/clang.cpp | 46 ++++++++++++++++++++++++++++++++++++++
tools/perf/util/c++/clang.h | 3 +++
5 files changed, 80 insertions(+), 7 deletions(-)

diff --git a/tools/perf/tests/clang.c b/tools/perf/tests/clang.c
index 57ee160..2964c06 100644
--- a/tools/perf/tests/clang.c
+++ b/tools/perf/tests/clang.c
@@ -12,6 +12,10 @@ static struct {
.func = test__clang_to_IR,
.desc = "Test builtin clang compile C source to IR",
},
+ {
+ .func = test__clang_to_obj,
+ .desc = "Test builtin clang compile C source to ELF object",
+ },
#endif
};

@@ -33,7 +37,7 @@ int test__clang(int i __maybe_unused)
return TEST_SKIP;
}
#else
-int test__clang(int i __maybe_unused)
+int test__clang(int i)
{
if (i < 0 || i >= (int)ARRAY_SIZE(clang_testcase_table))
return TEST_FAIL;
diff --git a/tools/perf/util/c++/clang-c.h b/tools/perf/util/c++/clang-c.h
index dcde4b5..22b3936 100644
--- a/tools/perf/util/c++/clang-c.h
+++ b/tools/perf/util/c++/clang-c.h
@@ -9,6 +9,7 @@ extern void perf_clang__init(void);
extern void perf_clang__cleanup(void);

extern int test__clang_to_IR(void);
+extern int test__clang_to_obj(void);

#ifdef __cplusplus
}
diff --git a/tools/perf/util/c++/clang-test.cpp b/tools/perf/util/c++/clang-test.cpp
index c5546fd..473fe63 100644
--- a/tools/perf/util/c++/clang-test.cpp
+++ b/tools/perf/util/c++/clang-test.cpp
@@ -13,15 +13,13 @@ public:
~perf_clang_scope() {perf_clang__cleanup();}
};

-extern "C" {
-
-int test__clang_to_IR(void)
+static std::unique_ptr<llvm::Module>
+__test__clang_to_IR(void)
{
- perf_clang_scope _scope;
unsigned int kernel_version;

if (fetch_kernel_version(&kernel_version, NULL, 0))
- return -1;
+ return std::unique_ptr<llvm::Module>(nullptr);

std::string cflag_kver("-DLINUX_VERSION_CODE=" +
std::to_string(kernel_version));
@@ -30,14 +28,35 @@ int test__clang_to_IR(void)
perf::getModuleFromSource({cflag_kver.c_str()},
"perf-test.c",
test_llvm__bpf_base_prog);
+ return M;
+}
+
+extern "C" {
+int test__clang_to_IR(void)
+{
+ perf_clang_scope _scope;

+ auto M = __test__clang_to_IR();
if (!M)
return -1;
-
for (llvm::Function& F : *M)
if (F.getName() == "bpf_func__SyS_epoll_wait")
return 0;
return -1;
}

+int test__clang_to_obj(void)
+{
+ perf_clang_scope _scope;
+
+ auto M = __test__clang_to_IR();
+ if (!M)
+ return -1;
+
+ auto Buffer = perf::getBPFObjectFromModule(&*M);
+ if (!Buffer)
+ return -1;
+ return 0;
+}
+
}
diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index 715ca0a..ab3a47c 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -13,10 +13,15 @@
#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"
@@ -105,6 +110,47 @@ getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
return getModuleFromSource(std::move(CFlags), Path, VFS);
}

+std::unique_ptr<llvm::SmallVectorImpl<char>>
+getBPFObjectFromModule(llvm::Module *Module)
+{
+ using namespace llvm;
+
+ LLVMInitializeBPFTargetInfo();
+ LLVMInitializeBPFTarget();
+ LLVMInitializeBPFTargetMC();
+ LLVMInitializeBPFAsmPrinter();
+
+ 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" {
diff --git a/tools/perf/util/c++/clang.h b/tools/perf/util/c++/clang.h
index b4fc2a9..dd8b042 100644
--- a/tools/perf/util/c++/clang.h
+++ b/tools/perf/util/c++/clang.h
@@ -19,5 +19,8 @@ std::unique_ptr<Module>
getModuleFromSource(opt::ArgStringList CFlags,
StringRef Path);

+std::unique_ptr<llvm::SmallVectorImpl<char>>
+getBPFObjectFromModule(llvm::Module *Module);
+
}
#endif
--
1.8.3.4
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