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cmake: don't auto vectorize with AltiVec on PPC #13321

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cmake: don't auto vectorize with AltiVec on PPC #13321

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1 change: 1 addition & 0 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -893,6 +893,7 @@ if(SDL_ASSEMBLY)
set(HAVE_ALTIVEC TRUE)
set(SDL_ALTIVEC_BLITTERS 1)
sdl_compile_options(PRIVATE "-maltivec")
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If altivec is not always available on powerpc platforms, then this option must go.
Instead, we should use -maltivec for only those sources that can contain altivec implementations and/or use the SDL_TARGETING("altivec") macro (gcc supports it).

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Oh yes: We allow that macro for gcc >= 4.9, and it does seem to support it: https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Function-Attributes.html#Function-Attributes

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This line might be a deal-breaker:

In 32-bit code, you cannot enable AltiVec instructions unless -mabi=altivec is used on the command line

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This line might be a deal-breaker:

In 32-bit code, you cannot enable AltiVec instructions unless -mabi=altivec is used on the command line

Isn't that required in combination with -maltivec? (Or I remember wrong..)

sdl_compile_options(PRIVATE "-fno-tree-vectorize")
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" PROPERTY SKIP_PRECOMPILE_HEADERS 1)
endif()
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