[appveyor] disable MSVC for now. mingw-w64 is almost there

[simgrid.git] / tools / cmake / Flags.cmake

diff --git a/tools/cmake/Flags.cmake b/tools/cmake/Flags.cmake
index 584434e..4bc9996 100644 (file)
--- a/tools/cmake/Flags.cmake
+++ b/tools/cmake/Flags.cmake
@@ -1,6 +1,8 @@
 ##
 ## This file is in charge of setting our paranoid flags with regard to warnings and optimization.
 ##
+##   It is only used for gcc and clang. MSVC builds don't load this file.
+##
 ##   These flags do break some classical CMake tests, so you don't
 ##   want to do so before the very end of the configuration.
 ## 
@@ -30,27 +32,67 @@ if(enable_compile_warnings)
   set(CMAKE_JAVA_COMPILE_FLAGS "-Xlint")
 endif()
 
+# Se the optimisation flags
+# NOTE, we should CMAKE_BUILD_TYPE for this
 if(enable_compile_optimizations)
   set(optCFLAGS "-O3 -funroll-loops -fno-strict-aliasing ")
-  if(CMAKE_COMPILER_IS_GNUCC AND (NOT enable_model-checking))
-    set(optCFLAGS "${optCFLAGS} -finline-functions ")
+else()
+  set(optCFLAGS "-O0 ")
+endif()
+if(enable_compile_optimizations AND CMAKE_COMPILER_IS_GNUCC
+    AND (NOT enable_model-checking))
+  # This is redundant (already in -03):
+  set(optCFLAGS "${optCFLAGS} -finline-functions ")
+endif()
+
+# Configure LTO
+# NOTE, cmake 3.0 has a INTERPROCEDURAL_OPTIMIZATION target
+#       property for this (http://www.cmake.org/cmake/help/v3.0/prop_tgt/INTERPROCEDURAL_OPTIMIZATION.html)
+if(enable_lto) # User wants LTO. Try if we can do that
+  set(enable_lto OFF)
+  if(enable_compile_optimizations
+      AND CMAKE_COMPILER_IS_GNUCC
+      AND (NOT enable_model-checking))
     if(WIN32)
       if (COMPILER_C_VERSION_MAJOR_MINOR STRGREATER "4.8")
-      # On windows, we need 4.8 or higher to enable lto because of http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50293
-      #
-      # We are experiencing assertion failures even with 4.8 on MinGW.
-      # Push the support forward: will see if 4.9 works when we test it.
-      set(optCFLAGS "${optCFLAGS} -flto ")
-      endif()
-    else()    
-      # On non-windows, 4.6 is enough for that
-      if(LINKER_VERSION STRGREATER "2.22")
-        set(optCFLAGS "${optCFLAGS} -flto ")
+        # On windows, we need 4.8 or higher to enable lto because of http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50293
+        #
+        # We are experiencing assertion failures even with 4.8 on MinGW.
+        # Push the support forward: will see if 4.9 works when we test it.
+        set(enable_lto ON)
       endif()
+    elseif(LINKER_VERSION STRGREATER "2.22")
+      set(enable_lto ON)
+    endif()
+  endif()
+  if(enable_lto)
+    message("-- LTO seems usable.")
+  else()
+    if(NOT enable_compile_optimizations)
+      message("-- LTO disabled: Compile-time optimizations turned off.")
+    else() 
+      if(enable_model-checking)
+        message("-- LTO disabled when compiling with model-checking.")
+      else()
+        message("-- LTO does not seem usable -- try updating your build chain.")
+      endif() 
     endif()
   endif()
 else()
-  set(optCFLAGS "-O0 ")
+  message("-- LTO disabled on the command line.")
+endif()
+if(enable_lto) # User wants LTO, and it seems usable. Go for it
+  set(optCFLAGS "${optCFLAGS} -flto ")
+  # See https://gcc.gnu.org/wiki/LinkTimeOptimizationFAQ#ar.2C_nm_and_ranlib:
+  # "Since version 4.9 gcc produces slim object files that only contain
+  # the intermediate representation. In order to handle archives of
+  # these objects you have to use the gcc wrappers:
+  # gcc-ar, gcc-nm and gcc-ranlib."
+  if(${CMAKE_C_COMPILER_ID} STREQUAL "GNU"
+      AND COMPILER_C_VERSION_MAJOR_MINOR STRGREATER "4.8")
+    set (CMAKE_AR gcc-ar)
+    set (CMAKE_RANLIB gcc-ranlib)
+  endif()
 endif()
 
 if(enable_model-checking AND enable_compile_optimizations)