tools build: Add feature detection for LLVM

Check if basic LLVM compiling environment is ready. Use llvm-config to detect include and library directories. Avoid using 'llvm-config --cxxflags' because its result contain some unwanted flags like --sysroot (if LLVM is built by yocto). Use '?=' to set LLVM_CONFIG, so explicitly passing LLVM_CONFIG to make would override it. Use 'llvm-config --libs BPF' to check if BPF backend is compiled in. Since now BPF bytecode is the only required backend, no need to waste time linking llvm and clang if BPF backend is missing. This also introduce an implicit requirement that LLVM should be new enough. Old LLVM doesn't support BPF backend. 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: Joe Stringer <joe@ovn.org> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/20161126070354.141764-8-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools build: Add feature detection for LLVM
Check if basic LLVM compiling environment is ready. Use llvm-config to detect include and library directories. Avoid using 'llvm-config --cxxflags' because its result contain some unwanted flags like --sysroot (if LLVM is built by yocto). Use '?=' to set LLVM_CONFIG, so explicitly passing LLVM_CONFIG to make would override it. Use 'llvm-config --libs BPF' to check if BPF backend is compiled in. Since now BPF bytecode is the only required backend, no need to waste time linking llvm and clang if BPF backend is missing. This also introduce an implicit requirement that LLVM should be new enough. Old LLVM doesn't support BPF backend. 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: Joe Stringer <joe@ovn.org> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/20161126070354.141764-8-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Wang Nan · Arnaldo Carvalho de Melo
1 parent 2bd42de0e1
Showing 2 changed files with 16 additions and 0 deletions Side-by-side Diff
tools/build/feature/Makefile
tools/build/feature/test-llvm.cpp
@@ -55,6 +55,7 @@
 CC := $(CROSS_COMPILE)gcc -MD
 CXX := $(CROSS_COMPILE)g++ -MD
 PKG_CONFIG := $(CROSS_COMPILE)pkg-config
+LLVM_CONFIG ?= llvm-config
  
 all: $(FILES)
  
@@ -228,6 +229,13 @@
  
 $(OUTPUT)test-jvmti.bin:
 	$(BUILD)
+
+$(OUTPUT)test-llvm.bin:
+	$(BUILDXX) -std=gnu++11 					\
+		-I$(shell $(LLVM_CONFIG) --includedir) 		\
+		-L$(shell $(LLVM_CONFIG) --libdir)		\
+		$(shell $(LLVM_CONFIG) --libs Core BPF)		\
+		$(shell $(LLVM_CONFIG) --system-libs)
  
 -include $(OUTPUT)*.d
  
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/raw_ostream.h"
+int main()
+{
+	llvm::errs() << "Hello World!\n";
+	llvm::llvm_shutdown();
+	return 0;
+}
...	...	@@ -55,6 +55,7 @@
55	55	CC := $(CROSS_COMPILE)gcc -MD
56	56	CXX := $(CROSS_COMPILE)g++ -MD
57	57	PKG_CONFIG := $(CROSS_COMPILE)pkg-config
	58	+LLVM_CONFIG ?= llvm-config
58	59
59	60	all: $(FILES)
60	61
...	...	@@ -228,6 +229,13 @@
228	229
229	230	$(OUTPUT)test-jvmti.bin:
230	231	$(BUILD)
	232	+
	233	+$(OUTPUT)test-llvm.bin:
	234	+ $(BUILDXX) -std=gnu++11 \
	235	+ -I$(shell $(LLVM_CONFIG) --includedir) \
	236	+ -L$(shell $(LLVM_CONFIG) --libdir) \
	237	+ $(shell $(LLVM_CONFIG) --libs Core BPF) \
	238	+ $(shell $(LLVM_CONFIG) --system-libs)
231	239
232	240	-include $(OUTPUT)*.d
233	241
	1	+#include "llvm/Support/ManagedStatic.h"
	2	+#include "llvm/Support/raw_ostream.h"
	3	+int main()
	4	+{
	5	+ llvm::errs() << "Hello World!\n";
	6	+ llvm::llvm_shutdown();
	7	+ return 0;
	8	+}