https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114955
--- Comment #3 from hanwei (K) <hanwei62 at huawei dot com> ---
Yeap, press return too soon.
Code like:
#include <stdio.h>
#pragma pack(1)
char a_global[2] = {0,0};
int g_int[3] = {1, 2, 4};
char b_global[2] = {0, 0};
struct A {
char c;
long long a;
int i;
};
#pragma pack()
struct TMP g_struct = {0};
---
We set pragma pack(1) hope the address of variable (also first member of
struct) with struct A type align to 1.
https://github.com/gcc-mirror/gcc/blame/ce343444c019f34172320d0873cc993d43750f41/gcc/config/aarch64/aarch64.h#L128
#define AARCH64_EXPAND_ALIGNMENT(COND, EXP, ALIGN) \
(((COND) && ((ALIGN) < BITS_PER_WORD) \
&& (TREE_CODE (EXP) == ARRAY_TYPE \
|| TREE_CODE (EXP) == UNION_TYPE \
|| TREE_CODE (EXP) == RECORD_TYPE)) ? BITS_PER_WORD : (ALIGN))
force the mininal align of arrays, unions and structures (in aarch64 is 8) even
if we set pragma pack for it.
The address of global variable and static variable is implementation-defined,
but the data align behavior of GCC seem conflict with pragma pack?
