#include <stdint.h>
  #include <string.h>
	
  typedef struct {
      int32_t a;
      int32_t b;
  } Foo;
	
  int main(void)
  {
      uint8_t array[1024];
      memset(array, 1, sizeof(array));
	
      Foo *foo = (Foo*)(&array[0]);
      foo->a += 1;
  }

It appears that the array is aligned with the minimum ABI requirement 16 by default? May be a note of this in the standard, can't recall of the top of my head.

  %array = alloca [1024 x i8], align 16
  ...
  %6 = load i32, i32* %5, align 4
  ...
  store i32 %7, i32* %5, align 4

  #include <stdalign.h>
  #include <stdint.h>
  #include <string.h>

  typedef struct {
      int32_t a;
      int32_t b;
  } Foo;

  int main(void)
  {
      uint8_t alignas(alignof(Foo)) array[1024];
      memset(array, 1, sizeof(array));

      Foo *foo = (Foo*)(&array[0]);
      foo->a += 1;
  }

  %array = alloca [1024 x i8], align 4
  ...
  %6 = load i32, i32* %5, align 4
  ...
  store i32 %7, i32* %5, align 4