kc3-lang/SDL

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• Hash : e4411505
  Author :
  Date : 2021-07-29T19:04:39
  

  Don't pack SDL_AudioCVT on CHERI architectures
  
  This is needed to support CHERI, and thus Arm's experimental Morello
  prototype, where pointers are implemented using unforgeable capabilities
  that include bounds and permissions metadata to provide fine-grained
  spatial and referential memory safety, as well as revocation by sweeping
  memory to provide heap temporal memory safety.
  
  The referential safety is enforced through the use of tagged memory, and
  there is only a single tag bit per capability-sized word, meaning it is
  impossible to store capabilities at unaligned locations, either getting
  a trap on load/store or the validity tag being stripped when
  round-tripepd through memory.
  
  Since this is a new ABI for which SDL has never been compiled before, we
  do not need to be concerned with this compatibility measure, so just
  don't pack the struct for CHERI architectures.
  
  This code is inherently rather dubious anyway; if MSVC and GCC disagree
  on struct layout when targeting Windows then that is a bug in GCC, but
  likely extends from the bogus #pragma pack directives for MSVC in
  begin_code.h, which will force types to be *underaligned* (and is
  attempting to work around something that is fundamentally a broken idea
  to be doing). In particular 8-byte-aligned types will be underaligned to
  4 bytes, but only on MSVC.  Since that code is not used for GCC that is
  probably the cause of the struct layout discrepancy, and there are
  likely other instances of that throughout SDL. Moreover, the supposed
  fix here is not in fact a fix, as now GCC will think SDL_AudioCVT is
  only 1-byte-aligned but MSVC will think it's 4-byte or 8-byte-aligned,
  meaning ABI incomatibility is introduced by this change. However,
  removing it would break ABI compatibility for purely-GCC-compiled code
  (as old binaries would see the struct as 1-byte-aligned and new binaries
  would see the struct as 8-byte-aligned) so SDL is stuck with this until
  it bumps its ABI.
  

• Files

• .github/
• .gitignore
• Android.mk
• BUGS.txt
• CMakeLists.txt
• CREDITS.txt
• INSTALL.txt
• LICENSE.txt
• Makefile.in
• Makefile.minimal
• Makefile.os2
• Makefile.pandora
• Makefile.psp
• Makefile.wiz
• README-SDL.txt
• README.md
• SDL2.spec.in
• SDL2Config.cmake
• TODO.txt
• VisualC-WinRT/
• VisualC/
• WhatsNew.txt
• Xcode-iOS/
• Xcode/
• acinclude/
• android-project-ant/
• android-project/
• autogen.sh
• build-scripts/
• cmake/
• cmake_uninstall.cmake.in
• configure
• configure.ac
• debian/
• docs/
• include/
• sdl2-config-version.cmake.in
• sdl2-config.cmake.in
• sdl2-config.in
• sdl2.m4
• sdl2.pc.in
• src/
• test/
• visualtest/
• wayland-protocols/

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