[PATCH] D84076: [llvm-exegesis] Unset HAVE_LIBPFM if the kernel is too old.

[Vy Nguyen via Phabricator via llvm-commits]

oontvoo updated this revision to Diff 280262.
oontvoo added a comment.

CheckStructHasMember didn't work (because cycles is a bit field) so updated it to just compile a small program that accesses .cycles.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D84076/new/

https://reviews.llvm.org/D84076

Files:
  llvm/cmake/modules/FindLibpfm.cmake
  llvm/include/llvm/Config/config.h.cmake


Index: llvm/include/llvm/Config/config.h.cmake
===================================================================
--- llvm/include/llvm/Config/config.h.cmake
+++ llvm/include/llvm/Config/config.h.cmake
@@ -97,6 +97,9 @@
 /* Define to 1 if you have the `pfm' library (-lpfm). */
 #cmakedefine HAVE_LIBPFM ${HAVE_LIBPFM}
 
+/* Define to 1 if perf_branch_entry struct  has field cycles */
+#cmakedefine LIBPFM_HAS_FIELD_CYCLES ${LIBPFM_HAS_FIELD_CYCLES}
+
 /* Define to 1 if you have the `psapi' library (-lpsapi). */
 #cmakedefine HAVE_LIBPSAPI ${HAVE_LIBPSAPI}
 
Index: llvm/cmake/modules/FindLibpfm.cmake
===================================================================
--- llvm/cmake/modules/FindLibpfm.cmake
+++ llvm/cmake/modules/FindLibpfm.cmake
@@ -7,6 +7,7 @@
 
 include(CheckIncludeFile)
 include(CheckLibraryExists)
+include(CheckCXXSourceCompiles)
 
 if (LLVM_ENABLE_LIBPFM)
   check_library_exists(pfm pfm_initialize "" HAVE_LIBPFM_INITIALIZE)
@@ -16,6 +17,19 @@
     check_include_file(perfmon/pfmlib_perf_event.h HAVE_PERFMON_PFMLIB_PERF_EVENT_H)
     if(HAVE_PERFMON_PERF_EVENT_H AND HAVE_PERFMON_PFMLIB_H AND HAVE_PERFMON_PFMLIB_PERF_EVENT_H)
       set(HAVE_LIBPFM 1)
+      # Check to see if perf_branch_entry has field cycle.
+      # We couldn't use CheckStructHasMember here because 'cycles' is a bit field.
+      CHECK_CXX_SOURCE_COMPILES("
+#include <linux/perf_event.h>
+int main() {
+  perf_branch_entry entry;
+  entry.cycles = 2;
+  return 0;
+}
+" COMPILE_WITH_CYCLES)
+      if(COMPILE_WITH_CYCLES)
+        set(LIBPFM_HAS_FIELD_CYCLES 1)
+      endif()
     endif()
   endif()
 endif()


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