Allow whole program optimization to be switched off

cmake/Modules/UseOptimization.cmake

@@ -22,10 +22,13 @@ if (CMAKE_COMPILER_IS_GNUCXX)
   set (_opt_flags "")
 
   # link-time (a.k.a. global) optimizations
-  check_cxx_accepts_flag ("-flto" HAVE_LINK_OPTS)
-  if (HAVE_LINK_OPTS)
-	list (APPEND _opt_flags "-flto")
-  endif (HAVE_LINK_OPTS)
+  option (WHOLE_PROG_OPTIM "Whole program optimization (lto)" ON)
+  if (WHOLE_PROG_OPTIM)
+	check_cxx_accepts_flag ("-flto" HAVE_LINK_OPTS)
+	if (HAVE_LINK_OPTS)
+	  list (APPEND _opt_flags "-flto")
+	endif (HAVE_LINK_OPTS)
+  endif (WHOLE_PROG_OPTIM)
 
   # native instruction set tuning
   option (WITH_NATIVE "Use native instruction set" ON)

configure

@@ -18,6 +18,7 @@ Optional Features:
   --enable-static         build a static library [default=no]. Note: only one
                           of the options shared and static may be built.
   --disable-debug         build a release version of the library [default=no]
+  --disable-lto           do not use whole program optimization [default=yes]
   --disable-pch           do not use precompiled headers (if buggy compiler)
   --disable-silent-rules  print every compilation statement as executed
   --enable-system-debug   put .debug files in global GDB debug dir
@@ -101,6 +102,8 @@ use_mpi=
 silent_rules=
 #debug_loc=" -DSYSTEM_DEBUG=OFF"
 debug_loc=
+#use_lto=" -DWHOLE_PROG_OPTIM=ON"
+use_lto=
 
 # default is to warn for unknown options, but this can be disabled
 option_check=yes
@@ -232,6 +235,11 @@ for OPT in "$@"; do
               debug_loc=" -DSYSTEM_DEBUG=OFF"
               pkgname=""
               ;;
+            wpo  |\
+            lto  )
+              use_lto=" -DWHOLE_PROG_OPTIM=OFF"
+              pkgname=""
+              ;;
             openmp)
               use_openmp=" -DUSE_OPENMP=OFF"
               pkgname=""
@@ -333,7 +341,7 @@ for a in "${VARS[@]}"; do
 done
 
 # pass everything on to CMake
-CMDLINE="env ${ENVVARS} ${CMAKE_COMMAND} \"${srcdir}\" \"-DCMAKE_INSTALL_PREFIX=$prefix\" -DCMAKE_BUILD_TYPE=${buildtype}${pch_use}${silent_rules}${debug_loc}${use_openmp}${use_mpi} ${FEATURES}"
+CMDLINE="env ${ENVVARS} ${CMAKE_COMMAND} \"${srcdir}\" \"-DCMAKE_INSTALL_PREFIX=$prefix\" -DCMAKE_BUILD_TYPE=${buildtype}${pch_use}${silent_rules}${debug_loc}${use_openmp}${use_mpi}${use_lto} ${FEATURES}"
 echo --- calling CMake ---
 echo ${CMDLINE}
 eval exec ${CMDLINE}