Check for IPO

CMakeLists.txt

@@ -18,6 +18,9 @@ option (SFIZZ_BENCHMARKS "Enable benchmarks build [default: OFF]" OFF)
 option (SFIZZ_TESTS      "Enable tests build [default: OFF]" OFF)
 option (SFIZZ_SHARED     "Enable shared library build [default: ON]" ON)
 
+# Don't use IPO in non Release builds
+include (CheckIPO)
+
 # Add Abseil
 add_subdirectory (external/abseil-cpp EXCLUDE_FROM_ALL)
 

cmake/CheckIPO.cmake

@@ -0,0 +1,14 @@
+# Added in CMake 3.9
+include (CheckIPOSupported)
+check_ipo_supported (RESULT result OUTPUT output)
+
+if (result AND ENABLE_LTO AND ${CMAKE_BUILD_TYPE} MATCHES Release)
+    message (STATUS "\nLTO enabled.")
+else()
+    if (${output})
+        message (WARNING "\nIPO disabled: ${output}")
+    else()
+        message (WARNING "\nIPO was disabled, not in a Release build?")
+    endif()
+    set (ENABLE_LTO OFF)
+endif()