[Tarantool-patches] [PATCH luajit 2/4] FFI: Fix sizeof expression in C parser for reference types.
Sergey Bronnikov
sergeyb at tarantool.org
Tue Jun 11 18:42:05 MSK 2024
Hi, Sergey
thanks for the patch! LGTM
On 03.06.2024 17:34, Sergey Kaplun wrote:
> From: Mike Pall <mike>
>
> (cherry picked from commit 899093a9e0fa5b16f27016381ef4b15529dadff2)
>
> According to C++ Standard, the `alignof()` (5.3.6.3) [1] and `sizeof()`
> (5.3.3.2) [2] for the reference should be the same as for the referenced
> type. This patch fixes the behaviour by following the reference to get a
> child id for `alignof()` and `sizeof()` while parsing C definitions via
> `ffi.cdef()`.
>
> Sergey Kaplun:
> * added the description and the test for the problem
>
> Part of tarantool/tarantool#9924
>
> [1]:https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4594.pdf#subsection.5.3.6
> [2]:https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4594.pdf#subsection.5.3.3
> ---
> src/lj_cparse.c | 2 +-
> .../lj-861-ctype-attributes.test.lua | 16 +++++++++++++++-
> 2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/src/lj_cparse.c b/src/lj_cparse.c
> index 01deb3bf..8506d719 100644
> --- a/src/lj_cparse.c
> +++ b/src/lj_cparse.c
> @@ -468,7 +468,7 @@ static void cp_expr_sizeof(CPState *cp, CPValue *k, int wantsz)
> } else {
> cp_expr_unary(cp, k);
> }
> - info = lj_ctype_info(cp->cts, k->id, &sz);
> + info = lj_ctype_info_raw(cp->cts, k->id, &sz);
> if (wantsz) {
> if (sz != CTSIZE_INVALID)
> k->u32 = sz;
> diff --git a/test/tarantool-tests/lj-861-ctype-attributes.test.lua b/test/tarantool-tests/lj-861-ctype-attributes.test.lua
> index d88045a5..e8b29d67 100644
> --- a/test/tarantool-tests/lj-861-ctype-attributes.test.lua
> +++ b/test/tarantool-tests/lj-861-ctype-attributes.test.lua
> @@ -7,7 +7,7 @@ local tap = require('tap')
> local test = tap.test('lj-861-ctype-attributes')
> local ffi = require('ffi')
>
> -test:plan(2)
> +test:plan(4)
>
> local EXPECTED_ALIGN = 4
>
> @@ -15,6 +15,15 @@ ffi.cdef([[
> struct __attribute__((aligned($))) s_aligned {
> uint8_t a;
> };
> +
> +struct test_parsing_sizeof {
> + char a[sizeof(struct s_aligned &)];
> +};
> +
> +struct test_parsing_alignof {
> + char a[__alignof__(struct s_aligned &)];
> +};
> +
> ]], EXPECTED_ALIGN)
>
> local ref_align = ffi.alignof(ffi.typeof('struct s_aligned &'))
> @@ -23,4 +32,9 @@ test:is(ref_align, EXPECTED_ALIGN, 'the reference alignment is correct')
> test:is(ref_align, ffi.alignof(ffi.typeof('struct s_aligned')),
> 'the alignment of a reference is the same as for the referenced type')
>
> +test:is(ffi.sizeof('struct test_parsing_sizeof'), EXPECTED_ALIGN,
> + 'correct sizeof during C parsing')
> +test:is(ffi.sizeof('struct test_parsing_alignof'), EXPECTED_ALIGN,
> + 'correct alignof during C parsing')
> +
> test:done(true)
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