1 /* $NetBSD: msg_309.c,v 1.7 2023/07/07 19:45:22 rillig Exp $ */
2 # 3 "msg_309.c"
3
4 // Test for message: extra bits set to 0 in conversion of '%s' to '%s', op '%s' [309]
5
6 /* lint1-extra-flags: -X 351 */
7
8 int
scale(unsigned long long x)9 scale(unsigned long long x) {
10
11 /*
12 * Both operands of '&' have the same type, therefore no conversion
13 * is necessary and no bits can get lost.
14 */
15 if ((x & 0xffffffff00000000ULL) != 0)
16 return 32;
17
18 /*
19 * The constant has type 'unsigned 32-bit'. The usual arithmetic
20 * conversions of '&' convert this constant to unsigned 64-bit.
21 * The programmer may or may not have intended to sign-extend the
22 * bit mask here. This situation may occur during migration from a
23 * 32-bit to a 64-bit platform.
24 */
25 /* expect+1: warning: extra bits set to 0 in conversion of 'unsigned int' to 'unsigned long long', op '&' [309] */
26 if ((x & 0xffff0000) != 0)
27 return 16;
28
29 /*
30 * The integer constant is explicitly unsigned. Even in this case,
31 * the code may have originated on a platform where 'x' had 32 bits
32 * originally, and the intention may have been to clear the lower 16
33 * bits.
34 */
35 /* expect+1: warning: extra bits set to 0 in conversion of 'unsigned int' to 'unsigned long long', op '&' [309] */
36 if ((x & 0xffff0000U) != 0)
37 return 16;
38
39 /*
40 * Even if the expression is written as '& ~', which makes the
41 * intention of clearing the lower 16 bits clear, on a 32-bit
42 * platform the integer constant stays at 32 bits, and when porting
43 * the code to a 64-bit platform, the upper 32 bits are preserved.
44 */
45 /* expect+1: warning: extra bits set to 0 in conversion of 'unsigned int' to 'unsigned long long', op '&' [309] */
46 if ((x & ~0xffffU) != 0)
47 return 16;
48
49 /*
50 * Casting the integer constant to the proper type removes all
51 * ambiguities about the programmer's intention.
52 */
53 if ((x & (unsigned long long)~0xffffU) != 0)
54 return 16;
55
56 /*
57 * In the remaining cases, the constant does not have its most
58 * significant bit set, therefore there is no ambiguity.
59 */
60 if ((x & 0xff00) != 0)
61 return 8;
62 if ((x & 0xf0) != 0)
63 return 4;
64 if ((x & 0xc) != 0)
65 return 2;
66 if ((x & 0x2) != 0)
67 return 1;
68 return (int)(x & 0x1);
69 }
70