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From: Wang Nan <wangnan0@huawei.com>
To: <acme@redhat.com>, <ast@fb.com>
CC: <lizefan@huawei.com>, <hekuang@huawei.com>,
        <linux-kernel@vger.kernel.org>, <pi3orama@163.com>,
        Wang Nan <wangnan0@huawei.com>, Jiri Olsa <jolsa@kernel.org>
Subject: [PATCH 12/34] tools build: Add feature detection for clang
Date: Tue, 15 Nov 2016 04:05:55 +0000
Message-ID: <20161115040617.69788-13-wangnan0@huawei.com>
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Check if basic clang compiling environment is ready.

Doesn't like 'llvm-config --libs' which can returns llvm libraries in
right order and duplicates some libraries if necessary, there's no
correspondence for clang libraries (-lclangxxx). to avoid extra
complexity and to avoid new clang breaking libraries ordering, use
--start-group and --end-group.

In this test case, manually identify required clang libs and hope it to
be stable. Putting all clang libraries here is possible (use make's
wildcard), but then feature checking becomes very slow.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1474874832-134786-5-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/build/feature/Makefile       | 10 ++++++++++
 tools/build/feature/test-clang.cpp | 21 +++++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 tools/build/feature/test-clang.cpp

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index c09de59..871d553 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -237,6 +237,16 @@ $(OUTPUT)test-llvm.bin:
 		$(shell $(LLVM_CONFIG) --libs Core BPF)		\
 		$(shell $(LLVM_CONFIG) --system-libs)
 
+$(OUTPUT)test-clang.bin:
+	$(BUILDXX) -std=gnu++11 					\
+		-I$(shell $(LLVM_CONFIG) --includedir) 		\
+		-L$(shell $(LLVM_CONFIG) --libdir)		\
+		-Wl,--start-group -lclangBasic -lclangDriver	\
+		  -lclangFrontend -lclangEdit -lclangLex	\
+		  -lclangAST -Wl,--end-group 			\
+		$(shell $(LLVM_CONFIG) --libs Core option)	\
+		$(shell $(LLVM_CONFIG) --system-libs)
+
 -include $(OUTPUT)*.d
 
 ###############################
diff --git a/tools/build/feature/test-clang.cpp b/tools/build/feature/test-clang.cpp
new file mode 100644
index 0000000..e23c1b1
--- /dev/null
+++ b/tools/build/feature/test-clang.cpp
@@ -0,0 +1,21 @@
+#include "clang/Basic/VirtualFileSystem.h"
+#include "clang/Driver/Driver.h"
+#include "clang/Frontend/TextDiagnosticPrinter.h"
+#include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+using namespace clang::driver;
+
+int main()
+{
+	IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
+	IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
+
+	DiagnosticsEngine Diags(DiagID, &*DiagOpts);
+	Driver TheDriver("test", "bpf-pc-linux", Diags);
+
+	llvm::llvm_shutdown();
+	return 0;
+}
-- 
2.10.1