[PATCH v4 01/18 -cleanup] perf build: Check LLVM version in feature check

[Wang Nan]

Cancel builtin llvm and clang support when LLVM version is
less than 3.9.0: following commits uses newer API.

Since Clang/LLVM's API is not guaranteed to be stable,
add a test-llvm-version.cpp feature checker, issue warning if
LLVM found in compiling environment is not tested yet.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Joe Stringer <joe@xxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
 tools/build/feature/Makefile              |  8 ++++++--
 tools/build/feature/test-llvm-version.cpp | 11 +++++++++++
 tools/build/feature/test-llvm.cpp         |  5 +++++
 tools/perf/Makefile.config                |  8 ++++++--
 4 files changed, 28 insertions(+), 4 deletions(-)
 create mode 100644 tools/build/feature/test-llvm-version.cpp

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 303196c..b564a2e 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -231,14 +231,18 @@ $(OUTPUT)test-jvmti.bin:
 	$(BUILD)
 
 $(OUTPUT)test-llvm.bin:
-	$(BUILDXX) -std=gnu++11 					\
+	$(BUILDXX) -std=gnu++11 				\
 		-I$(shell $(LLVM_CONFIG) --includedir) 		\
 		-L$(shell $(LLVM_CONFIG) --libdir)		\
 		$(shell $(LLVM_CONFIG) --libs Core BPF)		\
 		$(shell $(LLVM_CONFIG) --system-libs)
 
+$(OUTPUT)test-llvm-version.bin:
+	$(BUILDXX) -std=gnu++11 				\
+		-I$(shell $(LLVM_CONFIG) --includedir)
+
 $(OUTPUT)test-clang.bin:
-	$(BUILDXX) -std=gnu++11 					\
+	$(BUILDXX) -std=gnu++11 				\
 		-I$(shell $(LLVM_CONFIG) --includedir) 		\
 		-L$(shell $(LLVM_CONFIG) --libdir)		\
 		-Wl,--start-group -lclangBasic -lclangDriver	\
diff --git a/tools/build/feature/test-llvm-version.cpp b/tools/build/feature/test-llvm-version.cpp
new file mode 100644
index 0000000..896d317
--- /dev/null
+++ b/tools/build/feature/test-llvm-version.cpp
@@ -0,0 +1,11 @@
+#include <cstdio>
+#include "llvm/Config/llvm-config.h"
+
+#define NUM_VERSION (((LLVM_VERSION_MAJOR) << 16) + (LLVM_VERSION_MINOR << 8) + LLVM_VERSION_PATCH)
+#define pass int main() {printf("%x\n", NUM_VERSION); return 0;}
+
+#if NUM_VERSION >= 0x030900
+pass
+#else
+# error This LLVM is not tested yet.
+#endif
diff --git a/tools/build/feature/test-llvm.cpp b/tools/build/feature/test-llvm.cpp
index d8d2cee..455a332 100644
--- a/tools/build/feature/test-llvm.cpp
+++ b/tools/build/feature/test-llvm.cpp
@@ -1,5 +1,10 @@
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/raw_ostream.h"
+#define NUM_VERSION (((LLVM_VERSION_MAJOR) << 16) + (LLVM_VERSION_MINOR << 8) + LLVM_VERSION_PATCH)
+
+#if NUM_VERSION < 0x030900
+# error "LLVM version too low"
+#endif
 int main()
 {
 	llvm::errs() << "Hello World!\n";
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 09c2a98..2f4d5b0 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -802,12 +802,13 @@ ifdef LIBCLANGLLVM
     msg := $(warning No g++ found, disable clang and llvm support. Please install g++)
   else
     $(call feature_check,llvm)
+    $(call feature_check,llvm-version)
     ifneq ($(feature-llvm), 1)
-      msg := $(warning No libLLVM found, disable clang and llvm support. Please install llvm-dev)
+      msg := $(warning No libLLVM found, disable clang and llvm support. Please install llvm-dev (>= 3.9.0))
     else
       $(call feature_check,clang)
       ifneq ($(feature-clang), 1)
-        msg := $(warning No libclang found, disable clang and llvm support. Please install libclang-dev)
+        msg := $(warning No libclang found, disable clang and llvm support. Please install libclang-dev (>= 3.9.0))
       else
         CFLAGS += -DHAVE_LIBCLANGLLVM_SUPPORT
         CXXFLAGS += -DHAVE_LIBCLANGLLVM_SUPPORT -I$(shell $(LLVM_CONFIG) --includedir)
@@ -816,6 +817,9 @@ ifdef LIBCLANGLLVM
 	USE_CXX = 1
 	USE_LLVM = 1
 	USE_CLANG = 1
+        ifneq ($(feature-llvm-version),1)
+          msg := $(warning This version of llvm is not tested. May cause building error)
+        endif
       endif
     endif
   endif
-- 
2.10.1