tarantool / luajit / 26639774283

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tarantool/master: 93%

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github

Committed by Buristan

Commit Message

FFI: Various ABI and calling convention fixes.

Thanks to Sergey Kaplun.

(cherry picked from commit 5b2e51db2)

This patch fixes several issues at once:

1) On x64, the structure pass-by-value on the stack for the small
   argument size lacks the alignment check. This patch fixes that.

2 ) According to the AAPCS64, the alignment of the argument to be passed
    by value is determined by its natural alignment [1] instead of the
    alignment of the type (see B.6 [2]). Not applicable to OSX. For
    fixing this, we need to store the field alignment for `CT_FIELD`
    ctype since field alignment determines natural alignment.

    On OSX the "packed" stack rules [3] applied for non-variadic
    functions too. This patch fixes that.

3) The x64 ABI allows reordering of arguments. The structures that
   should be passed on the stack due to lack of the corresponding check
   may be placed in registers anyway. This patch fixes that by adding
   the corresponding flag in `ccall_set_args()`.

4) Also, this patch fixes the zero-sized bitfield behaviour to be intact
   with GCC (after 12.1 [4]) and Clang. Be aware that the alignment of
   zero-sized fields is not applied to each field of the structure.

5) It fixes handling for multidimensional HFA structures on arm64.
   Structures with zero-sized arrays are considered non-HFA.

Also, this commit adds tests for vector arguments and empty structures
to be sure that their behaviour still valid after changes.

[1]: https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#510composite-types
[2]: https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#682parameter-passing-rules
[3]: https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms#Pass-arguments-to-functions-correctly
[4]: https://gcc.gnu.org/gcc-12/changes.html

Sergey Kaplun:
* added the description and the test for the problem

Part of tarantool/tarantool#12480

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