From 203db3d09519d5ed0ee36dd9669f418c1f0ee82d Mon Sep 17 00:00:00 2001
From: Erik Hofman <erik@ehofman.com>
Date: Fri, 16 Dec 2016 10:49:44 +0100
Subject: [PATCH] Enable SSE and SSE2 by default

---
 CMakeLists.txt                | 14 +++++++++++++
 CMakeModules/DetectArch.cmake | 37 +++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)
 create mode 100644 CMakeModules/DetectArch.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c476a5de..cd0f695a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -114,6 +114,9 @@ option(ENABLE_SOUND     "Set to OFF to disable building SimGear's sound support"
 option(USE_AEONWAVE     "Set to ON to use AeonWave instead of OpenAL" OFF)
 option(ENABLE_PKGUTIL   "Set to ON to build the sg_pkgutil application (default)" ON)
 option(ENABLE_DNS       "Set to ON to use udns library and DNS service resolver" ON)
+option(ENABLE_SIMD      "Enable SSE/SSE2 support for x86 compilers" ON)
+
+include (DetectArch)
 
 # until the fstream fix is applied and generally available in OSG,
 # keep the compatability link option as the default
@@ -332,6 +335,12 @@ if(CMAKE_COMPILER_IS_GNUCXX)
       message(WARNING "GCC 4.4 will be required soon, please upgrade")
     endif()
 
+    if(ENABLE_SIMD)
+      if (X86 OR X86_64)
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse3 -mfpmath=sse")
+      endif()
+    endif()
+
     # certain GCC versions don't provide the atomic builds, and hence
     # require is to provide them in SGAtomic.cxx
     set(CMAKE_REQUIRED_INCLUDES ${CMAKE_INCLUDE_PATH})
@@ -369,6 +378,11 @@ if(WIN32)
 
     if(MSVC)
         set(MSVC_FLAGS "-DWIN32 -DNOMINMAX -D_USE_MATH_DEFINES -D_CRT_SECURE_NO_WARNINGS -D__CRT_NONSTDC_NO_WARNINGS /MP")
+        if(ENABLE_SIMD)
+          if (X86 OR X86_64)
+            set(MSVC_FLAGS "${MSVC_FLAGS} /arch:SSE /arch:SSE2 /Ox")
+          endif()
+        endif()
 
         if (NOT OSG_FSTREAM_EXPORT_FIXED)
           message(STATUS "For better linking performance, use OSG with patched fstream header")
diff --git a/CMakeModules/DetectArch.cmake b/CMakeModules/DetectArch.cmake
new file mode 100644
index 00000000..33849d1a
--- /dev/null
+++ b/CMakeModules/DetectArch.cmake
@@ -0,0 +1,37 @@
+IF(CMAKE_SYSTEM_PROCESSOR MATCHES amd64.*|x86_64.* OR CMAKE_GENERATOR MATCHES "Visual Studio.*Win64")
+  IF(CMAKE_C_FLAGS MATCHES -m32 OR CMAKE_CXX_FLAGS MATCHES -m32)
+    SET(X86 1)
+  ELSE(CMAKE_C_FLAGS MATCHES -m32 OR CMAKE_CXX_FLAGS MATCHES -m32)
+    SET(X86_64 1)
+  ENDIF(CMAKE_C_FLAGS MATCHES -m32 OR CMAKE_CXX_FLAGS MATCHES -m32)
+ELSEIF(CMAKE_SYSTEM_PROCESSOR MATCHES i686.*|i386.*|x86.* OR WIN32)
+  IF(CMAKE_C_FLAGS MATCHES -m64 OR CMAKE_CXX_FLAGS MATCHES -m64)
+    SET(X86_64 1)
+  ELSE(CMAKE_C_FLAGS MATCHES -m64 OR CMAKE_CXX_FLAGS MATCHES -m64)
+    SET(X86 1)
+  ENDIF(CMAKE_C_FLAGS MATCHES -m64 OR CMAKE_CXX_FLAGS MATCHES -m64)
+ELSEIF(CMAKE_SYSTEM_PROCESSOR MATCHES arm.* AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    SET(ARM 1)
+ELSEIF(CMAKE_SYSTEM_PROCESSOR MATCHES mips)
+    SET(MIPS 1)
+ENDIF()
+
+IF ("${CMAKE_C_COMPILER_ID}" STREQUAL "Clang")
+  # using Clang
+  SET(CLANG 1)
+ELSEIF ("${CMAKE_C_COMPILER_ID}" STREQUAL "TinyCC")
+  # using TinyCC
+  SET(TINYCC 1)
+ELSEIF ("${CMAKE_C_COMPILER_ID}" STREQUAL "GNU")
+  # using GCC
+  SET(GCC 1)
+ELSEIF ("${CMAKE_C_COMPILER_ID}" STREQUAL "Intel")
+  # using Intel C++
+  SET(INTELCC 1)
+ELSEIF ("${CMAKE_C_COMPILER_ID}" STREQUAL "MSVC")
+  # using Visual Studio C++
+  SET(MSVC 1)
+ELSEIF ("${CMAKE_C_COMPILER_ID}" STREQUAL "MIPSpro")
+  # using SGI MIPSpro
+  SET(MIPSPRO 1)
+ENDIF()