build: Add local build option on Linux; compiler fixups (#1756)

> [!IMPORTANT]
> This alters default behavior for configuration on Linux that
maintainers should be aware of.

Introduces `ARES_BUILD_LOCAL` on Linux, enabled by default, that will
pass `-march=native` if enabled. Maintainers will probably want to
disable this. Also adds `ARES_ENABLE_MINIMUM_CPU`, `ON` by default, that
compiles with the previously enforced `x86-64-v2` minimum on x86_64.
Maintainers should do whatever they want with this option.

(@bsdcode @Mastergatto)

These changes are intended to give Linux users building from source a
better experience. Enabling x86-64-v2 compared to compiling without any
SSE functionality is a 10%+ performance loss locally in the N64 core,
and may be higher on actual x86_64 machines.

> [!NOTE]
> It is worth noting that even though we do not explicitly define a
minimum SSE functionality on arm64, in practice nall will still [define
`__SSE4_1__`](https://github.com/ares-emulator/ares/blob/e808d2c5ab5be91d3e1035063892e8c5115d25e2/nall/intrinsics.hpp#L232)
and take advantage of SIMD on that platform via sse2neon.

### Other changes

* Adds `-march=native` on macOS builds under the control of
`ARES_BUILD_LOCAL`, and fixes `ARES_BUILD_LOCAL` on Windows so that
`-march=native` is added under gcc and not just clang.

* Removes warning in the N64 core related to the issue caused by strict
aliasing under GCC.

* Fixed an issue where macOS would always generate for arm64 rather than
the host architecture.

* Ran a formatter pass that was previously missed on the CMake code, so
there are a couple miscellaneous formatting changes.

ares/n64/CMakeLists.txt

@@ -36,13 +36,6 @@ elseif(OS_LINUX OR OS_FREEBSD OR OS_OPENBSD)
   include(cmake/os-linux.cmake)
 endif()
 
-if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-  message(WARNING "
-Building N64 with optimizations under GCC currently results in broken graphical output, see \
-https://github.com/ares-emulator/ares/issues/1737 . Building with clang instead will work around this issue. \
-")
-endif()
-
 ares_add_sources(
   CORE #
     n64

cmake/common/compiler_common.cmake

@@ -100,11 +100,7 @@ set(
   -Wno-delete-non-abstract-non-virtual-dtor
 )
 
-set(
-  _ares_gcc_common_options
-  -fwrapv
-  -fno-strict-aliasing
-)
+set(_ares_gcc_common_options -fwrapv -fno-strict-aliasing -Wno-unused-result)
 
 if(NOT DEFINED CMAKE_COMPILE_WARNING_AS_ERROR)
   set(CMAKE_COMPILE_WARNING_AS_ERROR OFF)

cmake/linux/compilerconfig.cmake

@@ -3,6 +3,17 @@ include_guard(GLOBAL)
 option(ENABLE_COMPILER_TRACE "Enable clang time-trace" OFF)
 mark_as_advanced(ENABLE_COMPILER_TRACE)
 
+option(
+  ARES_BUILD_LOCAL
+  "Allows the compiler to generate code optimized for the target machine; increases performance."
+  ON
+)
+option(
+  ARES_ENABLE_MINIMUM_CPU
+  "Defines a project minimum instruction set version in order to expose advanced SSE functionality to the compiler. Currently x86-64-v2 on x86_64; not defined on arm64."
+  ON
+)
+
 include(ccache)
 include(compiler_common)
 
@@ -14,7 +25,16 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
     -fwrapv
   )
 elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-  add_compile_options(
-    ${_ares_gcc_common_options}
-  )
+  add_compile_options(${_ares_gcc_common_options})
+endif()
+
+if(ARES_BUILD_LOCAL)
+  add_compile_options($<$<NOT:$<CONFIG:Debug>>:-march=native>)
+else()
+  if(ARES_ENABLE_MINIMUM_CPU)
+    string(TOLOWER ${CMAKE_SYSTEM_PROCESSOR} LOWERCASE_CMAKE_SYSTEM_PROCESSOR)
+    if(LOWERCASE_CMAKE_SYSTEM_PROCESSOR MATCHES "(i[3-6]86|x86|x64|x86_64|amd64|e2k)")
+      add_compile_options($<$<NOT:$<CONFIG:Debug>>:-march=x86-64-v2>)
+    endif()
+  endif()
 endif()

cmake/macos/compilerconfig.cmake

@@ -5,12 +5,18 @@ include_guard(GLOBAL)
 option(ENABLE_COMPILER_TRACE "Enable clang time-trace" OFF)
 mark_as_advanced(ENABLE_COMPILER_TRACE)
 
+option(
+  ARES_BUILD_LOCAL
+  "Allows the compiler to generate code optimized for the target machine; increases performance. Also disables certain entitlements and runtime options that interfere with debugging but are required for notarization and distribution."
+  ON
+)
+
 include(ccache)
 include(compiler_common)
 
 # Enable selection between arm64 and x86_64 targets
 if(NOT CMAKE_OSX_ARCHITECTURES)
-  set(CMAKE_OSX_ARCHITECTURES arm64 CACHE STRING "Build architectures for macOS" FORCE)
+  set(CMAKE_OSX_ARCHITECTURES ${CMAKE_SYSTEM_PROCESSOR} CACHE STRING "Build architectures for macOS" FORCE)
 endif()
 set_property(CACHE CMAKE_OSX_ARCHITECTURES PROPERTY STRINGS arm64 x86_64)
 
@@ -38,6 +44,16 @@ string(APPEND CMAKE_CXX_FLAGS_RELEASE " -g")
 string(APPEND CMAKE_OBJC_FLAGS_RELEASE " -g")
 string(APPEND CMAKE_OBJCXX_FLAGS_RELEASE " -g")
 
+if(ARES_BUILD_LOCAL)
+  add_compile_options($<$<NOT:$<CONFIG:Debug>>:-march=native>)
+else()
+  if(CMAKE_OSX_ARCHITECTURES MATCHES arm64)
+    #
+  else()
+    add_compile_options($<$<NOT:$<CONFIG:Debug>>:-march=x86-64-v2>)
+  endif()
+endif()
+
 if(ENABLE_COMPILER_TRACE)
   add_compile_options(-ftime-trace)
   add_link_options(LINKER:-print_statistics)

cmake/macos/defaults.cmake

@@ -2,6 +2,7 @@
 
 include_guard(GLOBAL)
 
+# Required to avoid us finding a system SDL2.framework before our provided SDL2.dylib
 set(CMAKE_FIND_FRAMEWORK LAST)
 
 # Set empty codesigning team if not specified as cache variable

cmake/windows/compilerconfig.cmake

@@ -4,6 +4,12 @@ endif()
 
 include_guard(GLOBAL)
 
+option(
+  ARES_BUILD_LOCAL
+  "Allows the compiler to generate code optimized for the target machine; increases performance."
+  ON
+)
+
 include(ccache)
 include(compiler_common)
 
@@ -53,7 +59,6 @@ set(
 
 set(
   _ares_clang_cl_c_cxx_options
-  -Wno-unused-function
   -Wno-reorder-ctor
   -Wno-missing-braces
   -Wno-char-subscripts
@@ -69,30 +74,36 @@ if(MSVC)
   string(REPLACE "/Ob1" "/Ob2" CMAKE_C_FLAGS_RELWITHDEBINFO ${CMAKE_C_FLAGS_RELWITHDEBINFO})
 endif()
 
-# add compiler flags
+# add general compiler flags and optimizations
 if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
   # we are on either msys2/mingw clang, or clang-cl
   # add common options
   add_compile_options(
     "$<$<COMPILE_LANGUAGE:C>:${_ares_clang_c_options}>"
     "$<$<COMPILE_LANGUAGE:CXX>:${_ares_clang_cxx_options}>"
-    "$<$<COMPILE_LANGUAGE:C,CXX>:${_ares_clang_cl_c_cxx_options}>"
   )
   if(NOT MSVC)
     # we are on msys2 clang
     # statically link libc++
     add_link_options(-static-libstdc++)
+
     # msys2/mingw-specific invocations to make clang emit debug symbols
     set(_ares_mingw_clang_debug_compile_options -g -gcodeview)
     set(_ares_mingw_clang_debug_link_options -fuse-ld=lld -g -Wl,--pdb=)
     add_compile_options("$<$<CONFIG:Debug,RelWithDebInfo>:${_ares_mingw_clang_debug_compile_options}>")
     add_link_options("$<$<CONFIG:Debug,RelWithDebInfo>:${_ares_mingw_clang_debug_link_options}>")
-    # clang-cl does not understand -fwrapv, but we do want it on msys2 clang
+
     add_compile_options(-fwrapv)
   else()
+    # we are on clang-cl
     # generate PDBs rather than embed debug symbols
     set(CMAKE_MSVC_DEBUG_INFORMATION_FORMAT ProgramDatabase)
-    add_compile_options("$<$<COMPILE_LANGUAGE:CXX>:${_ares_msvc_cxx_options}>")
+
+    add_compile_options(
+      "$<$<COMPILE_LANGUAGE:CXX>:${_ares_msvc_cxx_options}>"
+      "$<$<COMPILE_LANGUAGE:C,CXX>:${_ares_clang_cl_c_cxx_options}>"
+    )
+
     # work around https://gitlab.kitware.com/cmake/cmake/-/issues/26559
     add_compile_options($<$<AND:$<BOOL:${ENABLE_IPO}>,$<NOT:$<CONFIG:Debug>>>:-flto=thin>)
     add_link_options(
@@ -102,29 +113,34 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
       $<$<NOT:$<CONFIG:Debug>>:/OPT:REF>
       $<$<NOT:$<CONFIG:Debug>>:/OPT:ICF>
     )
-    # add -fwrapv
-    add_compile_options(
-      "$<$<COMPILE_LANGUAGE:C,CXX>:/clang:-fwrapv>"
-    )
-  endif()
 
-  # optimizations
-  if(ARES_BUILD_LOCAL)
-    add_compile_options(-march=native)
-  else()
-    if(${arch} STREQUAL x64)
-      add_compile_options("$<$<COMPILE_LANGUAGE:C,CXX>:-march=x86-64-v2>")
-    endif()
+    # add -fwrapv
+    add_compile_options("$<$<COMPILE_LANGUAGE:C,CXX>:/clang:-fwrapv>")
   endif()
 elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
   add_compile_options("$<$<COMPILE_LANGUAGE:C,CXX>:${_ares_msvc_cxx_options}>")
   if(CMAKE_COMPILE_WARNING_AS_ERROR)
     add_link_options(/WX)
   endif()
 elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-  add_compile_options(
-    ${_ares_gcc_common_options}
-  )
+  add_compile_options(${_ares_gcc_common_options})
+endif()
+
+# arch/machine-specific optimizations
+if(ARES_BUILD_LOCAL)
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    add_compile_options($<$<NOT:$<CONFIG:Debug>>:-march=native>)
+  else()
+    # todo: arch optimizations on msvc
+  endif()
+else()
+  if(${arch} STREQUAL x64)
+    if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+      add_compile_options("$<$<COMPILE_LANGUAGE:C,CXX>:-march=x86-64-v2>")
+    endif()
+  else()
+    # todo: arm64 arch baseline
+  endif()
 endif()
 
 if(NOT MINGW)

desktop-ui/cmake/os-windows.cmake

@@ -3,10 +3,7 @@ target_sources(desktop-ui PRIVATE resource/ares.rc resource/ares.Manifest)
 set_property(DIRECTORY ${CMAKE_SOURCE_DIR} PROPERTY VS_STARTUP_PROJECT desktop-ui)
 
 if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-  target_link_libraries(
-    desktop-ui
-    PRIVATE mingw32
-  )
+  target_link_libraries(desktop-ui PRIVATE mingw32)
 endif()
 
 if(ARES_ENABLE_LIBRASHADER)

mia/CMakeLists.txt

@@ -129,10 +129,7 @@ if(ARES_BUILD_OPTIONAL_TARGETS)
 
   if(OS_WINDOWS)
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-      target_link_libraries(
-        mia-ui
-        PRIVATE nall
-      )
+      target_link_libraries(mia-ui PRIVATE nall)
     endif()
   endif()