perf build: Add clang and llvm compile and linking support

Add necessary c++ flags and link libraries to support builtin clang and
LLVM. Add all llvm and clang libraries, so don't need to worry about
clang changes its libraries setting. However, linking perf would take
much longer than usual.

Signed-off-by: Wang Nan <[e-mail]>
Cc: Alexei Starovoitov <[e-mail]>
Cc: He Kuang <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Joe Stringer <[e-mail]>
Cc: Zefan Li <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Makefile.config

···
 # Treat warnings as errors unless directed not to
 ifneq ($(WERROR),0)
   CFLAGS += -Werror
+  CXXFLAGS += -Werror
 endif
 
 ifndef DEBUG
···
 CFLAGS += -Wall
 CFLAGS += -Wextra
 CFLAGS += -std=gnu99
+
+CXXFLAGS += -std=gnu++11 -fno-exceptions -fno-rtti
+CXXFLAGS += -Wall
+CXXFLAGS += -fno-omit-frame-pointer
+CXXFLAGS += -ggdb3
+CXXFLAGS += -funwind-tables
+CXXFLAGS += -Wno-strict-aliasing
 
 # Enforce a non-executable stack, as we may regress (again) in the future by
 # adding assembler files missing the .GNU-stack linker note.
···
   else
     $(warning No openjdk development package found, please install JDK package)
     NO_JVMTI := 1
+  endif
+endif
+
+USE_CXX = 0
+USE_CLANGLLVM = 0
+ifdef LIBCLANGLLVM
+  $(call feature_check,cxx)
+  ifneq ($(feature-cxx), 1)
+    msg := $(warning No g++ found, disable clang and llvm support. Please install g++)
+  else
+    $(call feature_check,llvm)
+    ifneq ($(feature-llvm), 1)
+      msg := $(warning No libLLVM found, disable clang and llvm support. Please install llvm-dev)
+    else
+      $(call feature_check,clang)
+      ifneq ($(feature-clang), 1)
+        msg := $(warning No libclang found, disable clang and llvm support. Please install libclang-dev)
+      else
+        CFLAGS += -DHAVE_LIBCLANGLLVM_SUPPORT
+        CXXFLAGS += -DHAVE_LIBCLANGLLVM_SUPPORT -I$(shell $(LLVM_CONFIG) --includedir)
+        $(call detected,CONFIG_CXX)
+        $(call detected,CONFIG_CLANGLLVM)
+	USE_CXX = 1
+	USE_LLVM = 1
+	USE_CLANG = 1
+      endif
+    endif
   endif
 endif
 

tools/perf/Makefile.perf

···
 # and bypass the feature detection
 #
 # Define NO_JVMTI if you do not want jvmti agent built
+#
+# Define LIBCLANGLLVM if you DO want builtin clang and llvm support.
+# When selected, pass LLVM_CONFIG=/path/to/llvm-config to `make' if
+# llvm-config is not in $PATH.
 
 # As per kernel Makefile, avoid funny character set dependencies
 unexport LC_ALL
···
 $(call allow-override,CC,$(CROSS_COMPILE)gcc)
 $(call allow-override,AR,$(CROSS_COMPILE)ar)
 $(call allow-override,LD,$(CROSS_COMPILE)ld)
+$(call allow-override,CXX,$(CROSS_COMPILE)g++)
 
 LD += $(EXTRA_LDFLAGS)
 
···
 HOSTAR  ?= ar
 
 PKG_CONFIG = $(CROSS_COMPILE)pkg-config
+LLVM_CONFIG ?= llvm-config
 
 RM      = rm -f
 LN      = ln -f
···
 
 LIBS = -Wl,--whole-archive $(PERFLIBS) -Wl,--no-whole-archive -Wl,--start-group $(EXTLIBS) -Wl,--end-group
 
+ifeq ($(USE_CLANG), 1)
+  CLANGLIBS_LIST = AST Basic CodeGen Driver Frontend Lex Tooling Edit Sema Analysis Parse Serialization
+  LIBCLANG = $(foreach l,$(CLANGLIBS_LIST),$(wildcard $(shell $(LLVM_CONFIG) --libdir)/libclang$(l).a))
+  LIBS += -Wl,--start-group $(LIBCLANG) -Wl,--end-group
+endif
+
+ifeq ($(USE_LLVM), 1)
+  LIBLLVM = $(shell $(LLVM_CONFIG) --libs all) $(shell $(LLVM_CONFIG) --system-libs)
+  LIBS += -L$(shell $(LLVM_CONFIG) --libdir) $(LIBLLVM)
+endif
+
+ifeq ($(USE_CXX), 1)
+  LIBS += -lstdc++
+endif
+
 export INSTALL SHELL_PATH
 
 ### Build rules
···
 
 PERF_IN := $(OUTPUT)perf-in.o
 
-export srctree OUTPUT RM CC LD AR CFLAGS V BISON FLEX AWK
+export srctree OUTPUT RM CC CXX LD AR CFLAGS CXXFLAGS V BISON FLEX AWK
 export HOSTCC HOSTLD HOSTAR
 include $(srctree)/tools/build/Makefile.include
 

tools/perf/tests/make

···
 make_no_libcrypto   := NO_LIBCRYPTO=1
 make_with_babeltrace:= LIBBABELTRACE=1
 make_no_sdt	    := NO_SDT=1
+make_with_clangllvm := LIBCLANGLLVM=1
 make_tags           := tags
 make_cscope         := cscope
 make_help           := help
···
 run += make_no_auxtrace
 run += make_no_libbpf
 run += make_with_babeltrace
+run += make_with_clangllvm
 run += make_help
 run += make_doc
 run += make_perf_o