[PATCH 1/2] perf build: Autodetect minimum required llvm-dev version

[James Clark]

The new LLVM addr2line feature requires a minimum version of 13 to
compile. Add a feature check for the version so that NO_LLVM=1 doesn't
need to be explicitly added. Leave the existing llvm feature check
intact because it's used by tools other than Perf.

This fixes the following compilation error when the llvm-dev version
doesn't match:

  util/llvm-c-helpers.cpp: In function 'char* llvm_name_for_code(dso*, const char*, u64)':
  util/llvm-c-helpers.cpp:178:21: error: 'std::remove_reference_t<llvm::DILineInfo>' {aka 'struct llvm::DILineInfo'} has no member named 'StartAddress'
    178 |   addr, res_or_err->StartAddress ? *res_or_err->StartAddress : 0);

Fixes: c3f8644c21df ("perf report: Support LLVM for addr2line()")
Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
---
 tools/build/Makefile.feature           |  2 +-
 tools/build/feature/Makefile           |  9 +++++++++
 tools/build/feature/test-llvm-perf.cpp | 14 ++++++++++++++
 tools/perf/Makefile.config             |  6 +++---
 4 files changed, 27 insertions(+), 4 deletions(-)
 create mode 100644 tools/build/feature/test-llvm-perf.cpp

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 0717e96d6a0e..427a9389e26c 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -136,7 +136,7 @@ FEATURE_DISPLAY ?=              \
          libunwind              \
          libdw-dwarf-unwind     \
          libcapstone            \
-         llvm                   \
+         llvm-perf              \
          zlib                   \
          lzma                   \
          get_cpuid              \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 12796808f07a..d6a98b3854f8 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -73,6 +73,7 @@ FILES=                                          \
          test-libopencsd.bin			\
          test-clang.bin				\
          test-llvm.bin				\
+         test-llvm-perf.bin   \
          test-llvm-version.bin			\
          test-libaio.bin			\
          test-libzstd.bin			\
@@ -388,6 +389,14 @@ $(OUTPUT)test-llvm.bin:
 		$(shell $(LLVM_CONFIG) --system-libs)		\
 		> $(@:.bin=.make.output) 2>&1
 
+$(OUTPUT)test-llvm-perf.bin:
+	$(BUILDXX) -std=gnu++17 				\
+		-I$(shell $(LLVM_CONFIG) --includedir) 		\
+		-L$(shell $(LLVM_CONFIG) --libdir)		\
+		$(shell $(LLVM_CONFIG) --libs Core BPF)		\
+		$(shell $(LLVM_CONFIG) --system-libs)		\
+		> $(@:.bin=.make.output) 2>&1
+
 $(OUTPUT)test-llvm-version.bin:
 	$(BUILDXX) -std=gnu++17					\
 		-I$(shell $(LLVM_CONFIG) --includedir)		\
diff --git a/tools/build/feature/test-llvm-perf.cpp b/tools/build/feature/test-llvm-perf.cpp
new file mode 100644
index 000000000000..a8cbb67e335e
--- /dev/null
+++ b/tools/build/feature/test-llvm-perf.cpp
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/raw_ostream.h"
+
+#if LLVM_VERSION_MAJOR < 13
+# error "Perf requires llvm-devel/llvm-dev version 13 or greater"
+#endif
+
+int main()
+{
+	llvm::errs() << "Hello World!\n";
+	llvm::llvm_shutdown();
+	return 0;
+}
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 7888c932b1b4..37e3eee2986e 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -981,8 +981,8 @@ ifdef BUILD_NONDISTRO
 endif
 
 ifndef NO_LIBLLVM
-  $(call feature_check,llvm)
-  ifeq ($(feature-llvm), 1)
+  $(call feature_check,llvm-perf)
+  ifeq ($(feature-llvm-perf), 1)
     CFLAGS += -DHAVE_LIBLLVM_SUPPORT
     CFLAGS += $(shell $(LLVM_CONFIG) --cflags)
     CXXFLAGS += -DHAVE_LIBLLVM_SUPPORT
@@ -992,7 +992,7 @@ ifndef NO_LIBLLVM
     EXTLIBS += -lstdc++
     $(call detected,CONFIG_LIBLLVM)
   else
-    $(warning No libllvm found, slower source file resolution, please install llvm-devel/llvm-dev)
+    $(warning No libllvm 13+ found, slower source file resolution, please install llvm-devel/llvm-dev)
     NO_LIBLLVM := 1
   endif
 endif
-- 
2.34.1