[Bug target/116856] Generated Code with unaligned uint32_t potentially hardfaults on ARM (due to LDRD)

[rearnsha at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116856

--- Comment #8 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
BTW, rewriting the code as:

#include <stdint.h>

typedef uint32_t __attribute__((aligned(1))) u32_u;

void f()
{
        static uint8_t array[64];
        for (uint8_t i = 0; i < sizeof(array); i++)
        {
                *(u32_u*) &array[i + 4] ^=
                                *(u32_u*)&array[i];
        }
}

Seems to address the problem, giving
f():
  ldr r3, .L5
  add r0, r3, #64
.L2:
  ldr r2, [r3, #-4] @ unaligned
  ldr r1, [r3] @ unaligned
  eors r2, r2, r1
  str r2, [r3], #1 @ unaligned
  cmp r0, r3
  bne .L2
  bx lr