fix: remove avx2 requirement for linux

Author: Julusian

BUILDING.md

@@ -96,7 +96,7 @@ If all goes to plan, a folder called 'staging' has been created with everything
 
 -DUSE_SYSTEM_CEF=OFF - (Linux only, default ON) use the version of CEF from your OS. This expects to be using builds from https://launchpad.net/~casparcg/+archive/ubuntu/ppa
 
--DENABLE_AVX2=ON (Linux only, default ON) Enable the AVX and AVX2 instruction sets (requires a CPU that supports it)
+-DENABLE_AVX2=ON (Linux only, default OFF) Enable the AVX and AVX2 instruction sets (requires a CPU that supports it)
 
 -DDIAG_FONT_PATH - Specify an alternate path/font to use for the DIAG window. On linux, this will often want to be set to an absolute path of a font
 

src/CMakeModules/Bootstrap_Linux.cmake

@@ -15,7 +15,7 @@ set(ENABLE_HTML ON CACHE BOOL "Enable CEF and HTML producer")
 set(USE_STATIC_BOOST OFF CACHE BOOL "Use shared library version of Boost")
 set(USE_SYSTEM_CEF ON CACHE BOOL "Use the version of cef from your OS (only tested with Ubuntu)")
 set(CASPARCG_BINARY_NAME "casparcg" CACHE STRING "Custom name of the binary to build (this disables some install files)")
-set(ENABLE_AVX2 ON CACHE BOOL "Enable the AVX2 instruction set (requires a CPU that supports it)")
+set(ENABLE_AVX2 OFF CACHE BOOL "Enable the AVX2 instruction set (requires a CPU that supports it)")
 
 # Determine build (target) platform
 SET (PLATFORM_FOLDER_NAME "linux")
@@ -131,11 +131,12 @@ IF (CMAKE_SYSTEM_PROCESSOR MATCHES "(i[3-6]86|x64|x86_64|amd64|e2k)")
         ADD_COMPILE_OPTIONS (-mavx)
         ADD_COMPILE_OPTIONS (-mavx2)
     ENDIF ()
+ELSE ()
+    ADD_COMPILE_DEFINITIONS (USE_SIMDE) # Enable OpenMP support in simde
+    ADD_COMPILE_DEFINITIONS (SIMDE_ENABLE_OPENMP) # Enable OpenMP support in simde
+    ADD_COMPILE_OPTIONS (-fopenmp-simd) # Enable OpenMP SIMD support
 ENDIF ()
 
-ADD_COMPILE_DEFINITIONS (USE_SIMDE) # Enable OpenMP support in simde
-ADD_COMPILE_DEFINITIONS (SIMDE_ENABLE_OPENMP) # Enable OpenMP support in simde
-ADD_COMPILE_OPTIONS (-fopenmp-simd) # Enable OpenMP SIMD support
 ADD_COMPILE_OPTIONS (-fnon-call-exceptions) # Allow signal handler to throw exception
 
 ADD_COMPILE_OPTIONS (-Wno-deprecated-declarations -Wno-write-strings -Wno-multichar -Wno-cpp -Werror)

src/modules/decklink/consumer/config.cpp

@@ -137,13 +137,16 @@ configuration parse_xml_config(const boost::property_tree::wptree&  ptree,
                                    << msg_info(L"The decklink consumer only supports rgba output on 8-bit channels"));
         }
 
+        if (config.pixel_format != configuration::pixel_format_t::rgba) {
 #ifdef WIN32
-        if (!CHECK_INSTRUCTION_SUPPORT(__IA_SUPPORT_VECTOR256, 0) &&
-            config.pixel_format != configuration::pixel_format_t::rgba) {
-            CASPAR_THROW_EXCEPTION(user_error()
-                                   << msg_info(L"You cpu does not support the features needed for yuv output"));
-        }
+            if (!CHECK_INSTRUCTION_SUPPORT(__IA_SUPPORT_VECTOR256, 0)) {
+#else
+            if (!__builtin_cpu_supports("avx2")) {
 #endif
+                CASPAR_THROW_EXCEPTION(user_error()
+                                       << msg_info(L"You cpu does not support the features needed for yuv output"));
+            }
+        }
     }
 
     config.primary = parse_output_config(ptree, format_repository);

src/modules/decklink/consumer/v210_strategies.cpp

@@ -21,6 +21,9 @@
 
 #include "../StdAfx.h"
 
+// Force this file to compile with avx2, as it has been crafted with intrinsics that require it.
+#pragma GCC target("avx2")
+
 #ifdef USE_SIMDE
 #define SIMDE_ENABLE_NATIVE_ALIASES
 #include <simde/x86/avx2.h>