[PATCH 13/14] perf clang: Pass fill path compiler

[Wang Nan]

If clang changes its working directory, filename passed to
perf_clang__compile_bpf() becomes invalid. Before running clang,
convert it to absolute path so file can be found even working directory
is different.

Signed-off-by: Wang Nan <wangn...@huawei.com>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Alexei Starovoitov <a...@fb.com>
Cc: He Kuang <heku...@huawei.com>
Cc: Jiri Olsa <jo...@kernel.org>
---
 tools/perf/util/c++/clang.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index 010b91e..812dd53 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -13,8 +13,10 @@
 #include "clang/Frontend/TextDiagnosticPrinter.h"
 #include "clang/Tooling/Tooling.h"
 #include "clang/CodeGen/CodeGenAction.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Option/Option.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetMachine.h"
@@ -164,7 +166,7 @@ void perf_clang__cleanup(void)
        llvm::llvm_shutdown();
 }
 
-int perf_clang__compile_bpf(const char *filename,
+int perf_clang__compile_bpf(const char *_filename,
                            void **p_obj_buf,
                            size_t *p_obj_buf_sz)
 {
@@ -173,8 +175,11 @@ int perf_clang__compile_bpf(const char *filename,
        if (!p_obj_buf || !p_obj_buf_sz)
                return -EINVAL;
 
+       llvm::SmallString<PATH_MAX> FileName(_filename);
+       llvm::sys::fs::make_absolute(FileName);
+
        llvm::opt::ArgStringList CFlags;
-       auto M = getModuleFromSource(std::move(CFlags), filename);
+       auto M = getModuleFromSource(std::move(CFlags), FileName.data());
        if (!M)
                return  -EINVAL;
        auto O = getBPFObjectFromModule(&*M);
-- 
1.8.3.4