From 3a29ba795d38c9d17de687d22752f9c94b395d49 Mon Sep 17 00:00:00 2001
From: Kornel Benko <kornel@lyx.org>
Date: Tue, 17 Dec 2019 13:59:52 +0100
Subject: [PATCH] Cmake build: Select use of interprocedural optimization

New cmake-option to explicit select/deselect the IPO
---
 3rdparty/hunspell/CMakeLists.txt |  7 +++----
 3rdparty/libiconv/CMakeLists.txt |  7 +++----
 3rdparty/mythes/CMakeLists.txt   |  8 ++++----
 3rdparty/zlib/CMakeLists.txt     |  7 +++----
 CMakeLists.txt                   | 30 +++++++++++++++++++-----------
 5 files changed, 32 insertions(+), 27 deletions(-)

diff --git a/3rdparty/hunspell/CMakeLists.txt b/3rdparty/hunspell/CMakeLists.txt
index 9921d6d88a..90dae464f9 100644
--- a/3rdparty/hunspell/CMakeLists.txt
+++ b/3rdparty/hunspell/CMakeLists.txt
@@ -3,10 +3,9 @@ cmake_minimum_required(VERSION 3.1)
 
 set(LYX_IPO_SUPPORTED FALSE)
 if (POLICY CMP0069)
-  if (NOT LYX_DEBUG)
-    cmake_policy(SET CMP0069 NEW)
-    include(CheckIPOSupported)
-    check_ipo_supported(RESULT LYX_IPO_SUPPORTED)
+  cmake_policy(SET CMP0069 NEW)
+  if (LYX_USE_IPO MATCHES "ON")
+    set(LYX_IPO_SUPPORTED YES)
   endif()
 endif()
 
diff --git a/3rdparty/libiconv/CMakeLists.txt b/3rdparty/libiconv/CMakeLists.txt
index 6261b3cb30..39beb96fbf 100644
--- a/3rdparty/libiconv/CMakeLists.txt
+++ b/3rdparty/libiconv/CMakeLists.txt
@@ -9,10 +9,9 @@ cmake_minimum_required(VERSION 3.1)
 
 set(LYX_IPO_SUPPORTED FALSE)
 if (POLICY CMP0069)
-  if (NOT LYX_DEBUG)
-    cmake_policy(SET CMP0069 NEW)
-    include(CheckIPOSupported)
-    check_ipo_supported(RESULT LYX_IPO_SUPPORTED)
+  cmake_policy(SET CMP0069 NEW)
+  if (LYX_USE_IPO MATCHES "ON")
+    set(LYX_IPO_SUPPORTED YES)
   endif()
 endif()
 
diff --git a/3rdparty/mythes/CMakeLists.txt b/3rdparty/mythes/CMakeLists.txt
index 1b224a9d4c..869bee7c93 100644
--- a/3rdparty/mythes/CMakeLists.txt
+++ b/3rdparty/mythes/CMakeLists.txt
@@ -2,13 +2,13 @@ cmake_minimum_required(VERSION 3.1)
 
 set(LYX_IPO_SUPPORTED FALSE)
 if (POLICY CMP0069)
-  if (NOT LYX_DEBUG)
-    cmake_policy(SET CMP0069 NEW)
-    include(CheckIPOSupported)
-    check_ipo_supported(RESULT LYX_IPO_SUPPORTED)
+  cmake_policy(SET CMP0069 NEW)
+  if (LYX_USE_IPO MATCHES "ON")
+    set(LYX_IPO_SUPPORTED YES)
   endif()
 endif()
 
+
 set(VERSION "1.2.5")
 set(SRCDIR ${CMAKE_CURRENT_SOURCE_DIR}/${VERSION})
 
diff --git a/3rdparty/zlib/CMakeLists.txt b/3rdparty/zlib/CMakeLists.txt
index b14776ef45..9bc1d0dbee 100644
--- a/3rdparty/zlib/CMakeLists.txt
+++ b/3rdparty/zlib/CMakeLists.txt
@@ -2,10 +2,9 @@ cmake_minimum_required(VERSION 3.1)
 
 set(LYX_IPO_SUPPORTED FALSE)
 if (POLICY CMP0069)
-  if (NOT LYX_DEBUG)
-    cmake_policy(SET CMP0069 NEW)
-    include(CheckIPOSupported)
-    check_ipo_supported(RESULT LYX_IPO_SUPPORTED)
+  cmake_policy(SET CMP0069 NEW)
+  if (LYX_USE_IPO MATCHES "ON")
+    set(LYX_IPO_SUPPORTED YES)
   endif()
 endif()
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index ca9895dadd..fbcc460de7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -81,15 +81,6 @@ if(NOT help AND NOT HELP)
       message(FATAL_ERROR "Exiting")
     endif()
   endif()
-  # Enable LTO if supported and not debugging
-  set(LYX_IPO_SUPPORTED FALSE)
-  if (POLICY CMP0069)
-    if (NOT LYX_DEBUG)
-      cmake_policy(SET CMP0069 NEW)
-      include(CheckIPOSupported)
-      check_ipo_supported(RESULT LYX_IPO_SUPPORTED)
-    endif()
-  endif()
 endif()
 
 if(UNIX)
@@ -151,6 +142,7 @@ LYX_OPTION(ENABLE_KEYTESTS  "Enable for keytests" OFF ALL)
 LYX_OPTION(ASAN             "Use address sanitizer" OFF ALL)
 LYX_COMBO(USE_FILEDIALOG    "Use native or QT file dialog" QT NATIVE)
 LYX_COMBO(USE_QT            "Use Qt version as frontend" AUTO QT4 QT5)
+LYX_COMBO(USE_IPO           "Interprocedural optimization" OFF AUTO ON)
 #LYX_OPTION(3RDPARTY_BUILD   "Build 3rdparty libs" OFF ALL)
 LYX_OPTION(DISABLE_CALLSTACK_PRINTING "do not print a callstack when crashing" OFF ALL)
 LYX_OPTION(EXTERNAL_Z       "OFF := Build 3rdparty lib zlib" ON ALL)
@@ -250,8 +242,6 @@ if(LYX_DEPENDENCIES_DOWNLOAD)
 	endforeach()
 endif()
 
-
-
 message(STATUS)
 
 set(EXECUTABLE_OUTPUT_PATH  ${TOP_BINARY_DIR}/bin)
@@ -261,6 +251,24 @@ else()
 	set(LIBRARY_OUTPUT_PATH  ${TOP_BINARY_DIR}/lib)
 endif()
 
+set(LYX_IPO_SUPPORTED OFF)
+if (POLICY CMP0069)
+  cmake_policy(SET CMP0069 NEW)
+  if(LYX_USE_IPO MATCHES "AUTO")
+    # Enable LTO if supported and not debugging
+    if (NOT LYX_DEBUG)
+      include(CheckIPOSupported)
+      check_ipo_supported(RESULT LYX_IPO_SUPPORTED)
+    endif()
+  else()
+    set(LYX_IPO_SUPPORTED ${LYX_USE_IPO})
+  endif()
+endif()
+if (LYX_IPO_SUPPORTED)
+  set(LYX_USE_IPO "ON" CACHE STRING "Use interprocedural optimization" FORCE)
+else()
+  set(LYX_USE_IPO "OFF" CACHE STRING "Use interprocedural optimization" FORCE)
+endif()
 
 # Set to some meaningful default
 find_package(CXX11Compiler)