/* $NetBSD: gcc_attribute_aligned.c,v 1.8 2024/05/01 10:30:56 rillig Exp $ */
# 3 "gcc_attribute_aligned.c"
/*
* Test size computations on aligned and packed structs.
*/
/* lint1-extra-flags: -X 351 */
typedef unsigned short uint16_t;
typedef unsigned int uint32_t;
typedef unsigned long long uint64_t;
/* from sys/arch/x86/include/cpu_extended_state.h */
union fp_addr {
uint64_t fa_64;
struct {
uint32_t fa_off;
uint16_t fa_seg;
uint16_t fa_opcode;
} fa_32;
} __attribute__((packed)) __attribute__((aligned(4)));
/* Each variant of the union has size 8. */
/* expect+1: error: negative array dimension (-8) [20] */
typedef int sizeof_fp_addr[-(int)sizeof(union fp_addr)];
struct fpacc87 {
uint64_t f87_mantissa;
uint16_t f87_exp_sign;
} __attribute__((packed)) __attribute__((aligned(2)));
/*
* Due to the 'packed', the uint64_t does not need to be aligned on an 8-byte
* boundary, which allows the struct to have the minimal required size of 10.
*/
/* expect+1: error: negative array dimension (-10) [20] */
typedef int sizeof_fpacc87[-(int)sizeof(struct fpacc87)];
struct save87 {
uint16_t s87_cw __attribute__((aligned(4)));
uint16_t s87_sw __attribute__((aligned(4)));
uint16_t s87_tw __attribute__((aligned(4)));
union fp_addr s87_ip;
union fp_addr s87_dp;
struct fpacc87 s87_ac[8];
};
/* @4 2 + @4 2 + @4 2 + @4 8 + @4 8 + @2 (8 * 10) == 108 */
/* expect+1: error: negative array dimension (-108) [20] */
typedef int sizeof_save87[-(int)sizeof(struct save87)];
void
aligned_struct_member(void)
{
struct aligned {
int first;
int second __attribute__((__aligned__(16)));
};
/*
* Aligning 'second' to a 16-bytes boundary not only aligns the member
* inside the structure, it also affects the alignment requirement of
* the whole structure. Due to this struct alignment, the size of the
* structure gets rounded up to 32 instead of using the minimally
* necessary storage of 20.
*
*
https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html
*/
/* expect+1: error: negative array dimension (-32) [20] */
typedef int ctassert[-(int)sizeof(struct aligned)];
}
void
alignment_larger_than_size(void)
{
struct s {
unsigned u32 __attribute__((__aligned__(32)));
} _Alignas(4096);
/* expect+1: error: negative array dimension (-4096) [20] */
typedef int size[-(int)sizeof(struct s)];
}
