1 #include <stdio.h> 2 #include "header.h" 3 4 void foo(union u *ptr, int flag) 5 { 6 union u local; 7 local.i = ptr->i; 8 9 printf("Calling printf to trash r0..r3\n"); 10 /* 11 * Clang 3.1 generates the following instructions to store flag into 12 * local.s.x. Because str is paired with ldrh, the high half-word in r0 is 13 * uninitialized and the corresponding positions in local.s.i will be 14 * clobbered. 15 * 16 * 1a: f8bd 0004 ldrh.w r0, [sp, #4] 17 * 1e: f005 0101 and.w r1, r5, #1 18 * 22: f020 0001 bic.w r0, r0, #1 19 * 26: 4308 orrs r0, r1 20 * 28: 9001 str r0, [sp, #4] 21 */ 22 local.s.x = flag; 23 ptr->i = local.i; 24 } 25
