From 7981809f3639c6c323dbe7091b02c4ccf20d395a Mon Sep 17 00:00:00 2001
From: Erik Hofman <erik@ehofman.com>
Date: Tue, 15 Jan 2019 10:36:23 +0100
Subject: [PATCH] Split up SIMD support in ENABLE_SIMD which enables sse2
 support for the compiler and ENABLE_SIMD_CODE which enables the hand crafted
 SIMD math functions which defaults to OFF now since compilers have catched up
 on generating optimized vectorized SIMD code.

---
 CMakeLists.txt                    | 15 ++++++++++-----
 simgear/math/simd.hxx             |  4 ++--
 simgear/math/simd4x4.hxx          |  4 ++--
 simgear/simgear_config_cmake.h.in |  1 +
 4 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3562e791..8a2f59f1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -125,9 +125,14 @@ 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" ON)
 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)
+option(ENABLE_SIMD      "Enable SSE/SSE2 support for compilers" ON)
+option(ENABLE_SIMD_CODE	"Enable SSE/SSE2 support code for compilers" OFF)
 option(ENABLE_OPENMP    "Enable OpenMP compiler support" OFF)
 
+if (NOT ENABLE_SIMD AND ENABLE_SIMD_CODE)
+  set(ENABLE_SIMD_CODE OFF)
+endif()
+
 include (DetectArch)
 
 # until the fstream fix is applied and generally available in OSG,
@@ -412,8 +417,8 @@ if(CMAKE_COMPILER_IS_GNUCXX)
         "${CMAKE_CXX_FLAGS} -O0 -fno-omit-frame-pointer -fno-inline")
     elseif (ENABLE_SIMD)
       if (X86 OR X86_64)
-        set(CMAKE_C_FLAGS_RELEASE "-O3 -msse2 -mfpmath=sse")
-        set(CMAKE_CXX_FLAGS_RELEASE "-O3 -msse2 -mfpmath=sse")
+        set(CMAKE_C_FLAGS_RELEASE "-O3 -msse2 -mfpmath=sse -ftree-vectorize -ftree-slp-vectorize")
+        set(CMAKE_CXX_FLAGS_RELEASE "-O3 -msse2 -mfpmath=sse -ftree-vectorize -ftree-slp-vectorize")
       endif()
     endif()
 
@@ -440,8 +445,8 @@ if (CLANG)
         "${CMAKE_CXX_FLAGS} -O0 -fno-omit-frame-pointer -fno-inline-functions")
     elseif (ENABLE_SIMD)
       if (X86 OR X86_64)
-        set(CMAKE_C_FLAGS_RELEASE "-O3 -msse2 -mfpmath=sse")
-        set(CMAKE_CXX_FLAGS_RELEASE "-O3 -msse2 -mfpmath=sse")
+        set(CMAKE_C_FLAGS_RELEASE "-O3 -msse2 -mfpmath=sse -ftree-vectorize -ftree-slp-vectorize")
+        set(CMAKE_CXX_FLAGS_RELEASE "-O3 -msse2 -mfpmath=sse -ftree-vectorize -ftree-slp-vectorize")
       endif()
     endif()
 endif()
diff --git a/simgear/math/simd.hxx b/simgear/math/simd.hxx
index a2847775..162820ac 100644
--- a/simgear/math/simd.hxx
+++ b/simgear/math/simd.hxx
@@ -309,7 +309,7 @@ inline simd4_t<T,N> operator*(simd4_t<T,N> v, T f) {
     return v;
 }
 
-#ifdef ENABLE_SIMD
+#ifdef ENABLE_SIMD_CODE
 
 # ifdef __SSE__
 namespace simd4
@@ -1305,7 +1305,7 @@ inline simd4_t<int,N> max(simd4_t<int,N> v1, const simd4_t<int,N>& v2) {
 
 # endif
 
-#endif /* ENABLE_SIMD */
+#endif /* ENABLE_SIMD_CODE */
 
 #endif /* __SIMD_H__ */
 
diff --git a/simgear/math/simd4x4.hxx b/simgear/math/simd4x4.hxx
index 69203511..26db560f 100644
--- a/simgear/math/simd4x4.hxx
+++ b/simgear/math/simd4x4.hxx
@@ -289,7 +289,7 @@ inline simd4x4_t<T,N> operator*(const simd4x4_t<T,N>& m1, const simd4x4_t<T,N>&
 }
 
 
-#ifdef ENABLE_SIMD
+#ifdef ENABLE_SIMD_CODE
 
 # ifdef __SSE__
 template<>
@@ -1191,7 +1191,7 @@ inline simd4_t<int,3> transform<int>(const simd4x4_t<int,4>& m, const simd4_t<in
 } /* namespace simd4x */
 # endif
 
-#endif /* ENABLE_SIMD */
+#endif /* ENABLE_SIMD_CODE */
 
 #endif /* __SIMD4X4_H__ */
 
diff --git a/simgear/simgear_config_cmake.h.in b/simgear/simgear_config_cmake.h.in
index de1b69c6..89492869 100644
--- a/simgear/simgear_config_cmake.h.in
+++ b/simgear/simgear_config_cmake.h.in
@@ -27,4 +27,5 @@
 #cmakedefine ENABLE_SOUND
 #cmakedefine USE_AEONWAVE
 #cmakedefine ENABLE_SIMD
+#cmakedefine ENABLE_SIMD_CODE
 #cmakedefine ENABLE_GDAL