From 8a6bb4c00ae292a877aee872687452457e8d7ab5 Mon Sep 17 00:00:00 2001
From: Drake Arconis <drake@alchemyviewer.org>
Date: Sun, 17 Jan 2016 08:19:17 -0500
Subject: [PATCH] Add options for LTO and Incremental Linking for windows

---
 indra/cmake/00-Common.cmake            | 33 ++++++++++++++++++++++++--
 indra/cmake/Variables.cmake            |  2 ++
 indra/llplugin/slplugin/CMakeLists.txt |  2 +-
 3 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/indra/cmake/00-Common.cmake b/indra/cmake/00-Common.cmake
index f6d570c3f..ba900d1d5 100644
--- a/indra/cmake/00-Common.cmake
+++ b/indra/cmake/00-Common.cmake
@@ -49,7 +49,7 @@ if (WINDOWS)
       "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} /Od /Zi /MD /MP"
       CACHE STRING "C++ compiler release-with-debug options" FORCE)
   set(CMAKE_CXX_FLAGS_RELEASE
-      "${CMAKE_CXX_FLAGS_RELEASE} ${LL_CXX_FLAGS} /O2 /Zi /MD /MP /fp:fast -D_SECURE_STL=0 -D_HAS_ITERATOR_DEBUGGING=0"
+      "${CMAKE_CXX_FLAGS_RELEASE} ${LL_CXX_FLAGS} /O2 /Zi /Zo /MD /MP /Ob2 /Zc:inline /fp:fast -D_ITERATOR_DEBUG_LEVEL=0"
       CACHE STRING "C++ compiler release options" FORCE)
   set(CMAKE_C_FLAGS_RELEASE
       "${CMAKE_C_FLAGS_RELEASE} ${LL_C_FLAGS} /O2 /Zi /MD /MP /fp:fast"
@@ -59,6 +59,27 @@ if (WINDOWS)
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /LARGEADDRESSAWARE")
   endif (WORD_SIZE EQUAL 32)
 
+  if (USE_LTO)
+    if(INCREMENTAL_LINK)
+      set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /LTCG:INCREMENTAL")
+      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} /LTCG:INCREMENTAL")
+      set(CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} /LTCG:INCREMENTAL")
+    else(INCREMENTAL_LINK)
+      set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /LTCG")
+      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} /LTCG")
+      set(CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} /LTCG")
+    endif(INCREMENTAL_LINK)
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /OPT:REF /OPT:ICF /LTCG")
+    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} /OPT:REF /OPT:ICF /LTCG")
+    set(CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} /LTCG")
+  elseif (INCREMENTAL_LINK)
+    set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "${CMAKE_SHARED_LINKER_FLAGS} /INCREMENTAL /VERBOSE:INCR")
+    set(CMAKE_EXE_LINKER_FLAGS_RELEASE "${CMAKE_EXE_LINKER_FLAGS} /INCREMENTAL /VERBOSE:INCR")
+  else ()
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /OPT:REF /INCREMENTAL:NO")
+    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} /OPT:REF /INCREMENTAL:NO")
+  endif ()
+
   set(CMAKE_CXX_STANDARD_LIBRARIES "")
   set(CMAKE_C_STANDARD_LIBRARIES "")
 
@@ -78,9 +99,17 @@ if (WINDOWS)
       /Oy-
       /Zm140
       /wd4267
-	  /wd4244
+      /wd4244
       )
 
+  if (USE_LTO)
+    add_compile_options(
+        /GL
+        /Gy
+        /Gw
+        )
+  endif (USE_LTO)
+
   if (WORD_SIZE EQUAL 32)
     add_compile_options(/arch:SSE2)
   endif (WORD_SIZE EQUAL 32)
diff --git a/indra/cmake/Variables.cmake b/indra/cmake/Variables.cmake
index 015dfb162..016fdd10f 100644
--- a/indra/cmake/Variables.cmake
+++ b/indra/cmake/Variables.cmake
@@ -29,6 +29,8 @@ set(LL_TESTS OFF CACHE BOOL "Build and run unit and integration tests (disable f
 # Compiler and toolchain options
 set(DISABLE_TCMALLOC OFF CACHE BOOL "Disable linkage of TCMalloc. (64bit builds automatically disable TCMalloc)")
 set(DISABLE_FATAL_WARNINGS TRUE CACHE BOOL "Set this to FALSE to enable fatal warnings.")
+option(INCREMENTAL_LINK "Use incremental linking or incremental LTCG for LTO on win32 builds (enable for faster links on some machines)" OFF)
+option(USE_LTO "Enable Whole Program Optimization and related folding and binary reduction routines" OFF)
 
 if(LIBS_CLOSED_DIR)
   file(TO_CMAKE_PATH "${LIBS_CLOSED_DIR}" LIBS_CLOSED_DIR)
diff --git a/indra/llplugin/slplugin/CMakeLists.txt b/indra/llplugin/slplugin/CMakeLists.txt
index 9020b85ca..f2596a1a6 100644
--- a/indra/llplugin/slplugin/CMakeLists.txt
+++ b/indra/llplugin/slplugin/CMakeLists.txt
@@ -57,7 +57,7 @@ set_target_properties(SLPlugin
 if (WINDOWS)
   set_target_properties(SLPlugin
     PROPERTIES
-    LINK_FLAGS "/OPT:NOREF"
+    LINK_FLAGS_DEBUG "/NODEFAULTLIB:\"LIBCMTD\""
   )
   EMBED_MANIFEST(SLPlugin 1)
 endif()