[PATCH v2 18/18] perf clang: Define PERF_BUILTIN_CLANG for builtin clang compiling

[Wang Nan]

By this macro BPF script knows what compiler it is being built with.
Scripts prefer external clang can force fall back to it by:

 #ifdef PERF_BUILTIN_CLANG
 # error I prefer external clang compiler
 #endif

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 tools/perf/util/c++/clang.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index a2de788..dd32f5d 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -62,6 +62,7 @@ createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
 		"-vectorize-slp",
 		"-Wno-unused-value",
 		"-Wno-pointer-sign",
+		"-DPERF_BUILTIN_CLANG=1"
 		"-x", "c"};
 
 	CCArgs.append(CFlags.begin(), CFlags.end());
-- 
1.8.3.4