cmake+video: always use altivec.h header for detection + introduce SDL_ENABLE_ALTIVEC

CMakeLists.txt

@@ -856,23 +856,17 @@ if(SDL_ASSEMBLY)
       set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -maltivec")
       check_c_source_compiles("
           #include <altivec.h>
-          vector unsigned int vzero() {
-              return vec_splat_u32(0);
-          }
-          int main(int argc, char **argv) { return 0; }" HAVE_ALTIVEC_H_HDR)
-      check_c_source_compiles("
           vector unsigned int vzero() {
               return vec_splat_u32(0);
           }
           int main(int argc, char **argv) { return 0; }" CPU_SUPPORTS_ALTIVEC)
       cmake_pop_check_state()
-      if(CPU_SUPPORTS_ALTIVEC OR HAVE_ALTIVEC_H_HDR)
-        set(HAVE_ALTIVEC TRUE) # if only HAVE_ALTIVEC_H_HDR is set
-        target_compile_options(sdl-build-options INTERFACE "-maltivec")
+      if(CPU_SUPPORTS_ALTIVEC)
+        set(HAVE_ALTIVEC TRUE)
         set(SDL_ALTIVEC_BLITTERS 1)
-        if(HAVE_ALTIVEC_H_HDR)
-          set(HAVE_ALTIVEC_H 1)
-        endif()
+        target_compile_options(sdl-build-options INTERFACE "-maltivec")
+        set_property(SOURCE "${SDL3_SOURCE_DIR}/src/video/SDL_blit_N.c" APPEND PROPERTY COMPILE_DEFINITIONS "SDL_ENABLE_ALTIVEC")
+        set_property(SOURCE "${SDL3_SOURCE_DIR}/src/video/SDL_blit_N.c" APPEND PROPERTY SKIP_PRECOMPILE_HEADERS 1)
       endif()
     endif()
 

cmake/CheckCPUArchitecture.cmake

@@ -36,10 +36,10 @@ function(check_cpu_architecture ARCH VARIABLE)
     _internal_check_cpu_architecture("defined(__loongarch64)" loongarch64 ${VARIABLE})
   elseif(ARCH STREQUAL "emscripten")
     _internal_check_cpu_architecture("defined(__EMSCRIPTEN__)" emscripten ${VARIABLE})
-  elseif(ARCH STREQUAL "powerpc32")
-    _internal_check_cpu_architecture("defined(__PPC__) || defined(__powerpc__)" powerpc32 ${VARIABLE})
   elseif(ARCH STREQUAL "powerpc64")
     _internal_check_cpu_architecture("defined(__PPC64__) || defined(__powerpc64__)" powerpc64 ${VARIABLE})
+  elseif(ARCH STREQUAL "powerpc32")
+    _internal_check_cpu_architecture("(defined(__PPC__) || defined(__powerpc__)) && !defined(__powerpc64__)" powerpc32 ${VARIABLE})
   else()
     message(WARNING "Unknown CPU architectures (${ARCH}).")
     set("${VARIABLE}" FALSE)

cmake/sdlplatform.cmake

@@ -78,7 +78,7 @@ function(SDL_DetectCPUArchitecture)
     endforeach()
   endif()
 
-  set(sdl_known_archs x64 x86 arm64 arm32 emscripten powerpc32 powerpc64 loongarch64)
+  set(sdl_known_archs x64 x86 arm64 arm32 emscripten powerpc64 powerpc32 loongarch64)
   if(NOT sdl_cpu_names)
     set(found FALSE)
     foreach(sdl_known_arch ${sdl_known_archs})

include/SDL3/SDL_intrin.h

@@ -69,8 +69,8 @@ _m_prefetch(void *__P)
 #  include <arm_neon.h>
 #endif
 #else
-/* altivec.h redefining bool causes a number of problems, see bugs 3993 and 4392, so you need to explicitly define SDL_ENABLE_ALTIVEC_H to have it included. */
-#if defined(HAVE_ALTIVEC_H) && defined(__ALTIVEC__) && !defined(__APPLE_ALTIVEC__) && defined(SDL_ENABLE_ALTIVEC_H)
+/* altivec.h redefining bool causes a number of problems, see bugs 3993 and 4392, so you need to explicitly define SDL_ENABLE_ALTIVEC to have it included. */
+#if defined(__ALTIVEC__) && defined(SDL_ENABLE_ALTIVEC)
 #include <altivec.h>
 #endif
 #if !defined(SDL_DISABLE_NEON)

include/build_config/SDL_build_config.h.cmake

@@ -215,7 +215,6 @@
 #cmakedefine HAVE_FLOAT_H 1
 #endif /* HAVE_LIBC */
 
-#cmakedefine HAVE_ALTIVEC_H 1
 #cmakedefine HAVE_DBUS_DBUS_H 1
 #cmakedefine HAVE_FCITX 1
 #cmakedefine HAVE_IBUS_IBUS_H 1

src/SDL_internal.h

@@ -186,6 +186,10 @@
 #include <SDL3/SDL.h>
 #include <SDL3/SDL_intrin.h>
 
+#if defined(__ALTIVEC__) && defined(SDL_ENABLE_ALTIVEC)
+#define HAVE_ALTIVEC_INTRINSICS 1
+#endif
+
 #if defined(__ARM_NEON) && !defined(SDL_DISABLE_NEON)
 #define HAVE_NEON_INTRINSICS 1
 #endif

src/video/SDL_blit_N.c

@@ -46,9 +46,6 @@ enum blit_features
 };
 
 #if SDL_ALTIVEC_BLITTERS
-#ifdef HAVE_ALTIVEC_H
-#include <altivec.h>
-#endif
 #ifdef __MACOS__
 #include <sys/sysctl.h>
 static size_t