[llvm-exegesis] Fix missing-headers build errors.

[oontvoo]

Summary

Switch all #includes to use <> because that is consistent with what happens in the cmake checks.
Otherwise, we could be in the situation where cmake checks see that headers exist at <perfmon/...>
but in llvm-exegesis code, we use "perfmon/...", which may not exist.

Related PR/revisions: D84076, PR51017+D105615

[courbet]

llvm/cmake/modules/FindLibpfm.cmake

18

I just looked at the code for check_include_file[1]: They are using #include <> and not #include "" - can we try that before giving up ? Because there should really be no difference between CHECK_CXX_SOURCE_COMPILES and this.

[1] https://gitlab.kitware.com/cmake/cmake/-/blob/master/Modules/CheckIncludeFile.c.in

[oontvoo]

updated code to use <> #include everywhere

[oontvoo]

llvm/cmake/modules/FindLibpfm.cmake

18

Done

[oontvoo]

clean up #ifdefs

[oontvoo]

rebase

llvm/cmake/modules/FindLibpfm.cmake

 # CMake module for finding libpfm4.
 #
 # If successful, the following variables will be defined:
 # HAVE_LIBPFM
 #
 # Libpfm can be disabled by setting LLVM_ENABLE_LIBPFM to 0.
 
 include(CheckIncludeFile)
 include(CheckLibraryExists)
 include(CheckCXXSourceCompiles)
 
 if (LLVM_ENABLE_LIBPFM)
   check_library_exists(pfm pfm_initialize "" HAVE_LIBPFM_INITIALIZE)
   if(HAVE_LIBPFM_INITIALIZE)
-    check_include_file(perfmon/perf_event.h HAVE_PERFMON_PERF_EVENT_H)
-    check_include_file(perfmon/pfmlib.h HAVE_PERFMON_PFMLIB_H)
-    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)
+    # Check to see if compilation with all libpfm headers succeed.
+    # Note: We do not use check_include_file() here because on some older
+    # libpfm versions, we have seen header-not-found errors
+    # while building, even though check_include_file() succeeded.
+    CHECK_CXX_SOURCE_COMPILES("
+      #include <perfmon/perf_event.h>
+      #include "perfmon/pfmlib.h"
+      #include "perfmon/pfmlib_perf_event.h"
+      int main() {
+        perf_branch_entry entry;
+        return 0;
+      }" COMPILE_WITH_HEADERS)
+    if(COMPILE_WITH_HEADERS)
       set(HAVE_LIBPFM 1)
       # Check to see if perf_branch_entry has the field 'cycles'.
       # We couldn't use CheckStructHasMember here because 'cycles' is a bit field which is not
       # supported by CheckStructHasMember.
       CHECK_CXX_SOURCE_COMPILES("
         #include <perfmon/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()
 
 

llvm/tools/llvm-exegesis/lib/X86/X86Counter.h

 /// Perf counter that reads the LBRs for measuring the benchmarked block's
 /// throughput.
 ///
 /// More info at: https://lwn.net/Articles/680985
 //===----------------------------------------------------------------------===//
 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_LIB_X86_X86COUNTER_H
 #define LLVM_TOOLS_LLVM_EXEGESIS_LIB_X86_X86COUNTER_H
 
-#include "../PerfHelper.h"
-#include "llvm/Support/Error.h"
-
 // FIXME: Use appropriate wrappers for poll.h and mman.h
 // to support Windows and remove this linux-only guard.
 #if defined(__linux__) && defined(HAVE_LIBPFM) &&                              \
     defined(LIBPFM_HAS_FIELD_CYCLES)
 
+#include "../PerfHelper.h"
+#include "llvm/Support/Error.h"
+
 namespace llvm {
 namespace exegesis {
 
 class X86LbrPerfEvent : public pfm::PerfEvent {
 public:
   X86LbrPerfEvent(unsigned SamplingPeriod);
 };
 

llvm/tools/llvm-exegesis/lib/X86/X86Counter.cpp

 #if defined(HAVE_LIBPFM) && defined(LIBPFM_HAS_FIELD_CYCLES)
 
 // FIXME: Use appropriate wrappers for poll.h and mman.h
 // to support Windows and remove this linux-only guard.
 #ifdef __linux__
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Errc.h"
 
-#ifdef HAVE_LIBPFM
 #include "perfmon/perf_event.h"
 #include "perfmon/pfmlib.h"
 #include "perfmon/pfmlib_perf_event.h"
-#endif // HAVE_LIBPFM
 
 #include <atomic>
 #include <chrono>
 #include <cstddef>
 #include <cstdint>
 #include <limits>
 #include <memory>
 #include <vector>