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gcc_attribute_label.c revision 1.3
      1  1.3  rillig /*	$NetBSD: gcc_attribute_label.c,v 1.3 2022/04/28 21:38:38 rillig Exp $	*/
      2  1.1  rillig # 3 "gcc_attribute_label.c"
      3  1.1  rillig 
      4  1.1  rillig /*
      5  1.1  rillig  * Tests for the GCC __attribute__ for labels.
      6  1.1  rillig  *
      7  1.1  rillig  * https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html
      8  1.1  rillig  */
      9  1.1  rillig 
     10  1.1  rillig void dead(void);
     11  1.1  rillig 
     12  1.1  rillig void
     13  1.1  rillig test(int i)
     14  1.1  rillig {
     15  1.1  rillig 	if (i < 1000)
     16  1.1  rillig 		goto hot;
     17  1.1  rillig error:
     18  1.1  rillig 	__attribute__((__cold__));
     19  1.1  rillig 	dead();
     20  1.1  rillig 
     21  1.1  rillig hot:
     22  1.1  rillig 	__attribute__((__hot__));
     23  1.1  rillig 	if (i < 0)
     24  1.1  rillig 		goto error;
     25  1.1  rillig }
     26  1.3  rillig 
     27  1.3  rillig /* GCC allows a label to be marked as (possibly) unused. */
     28  1.3  rillig void
     29  1.3  rillig unused_labels(int x)
     30  1.3  rillig {
     31  1.3  rillig 	switch (x) {
     32  1.3  rillig 	case 3:
     33  1.3  rillig 		__attribute__((__unused__))
     34  1.3  rillig 		break;
     35  1.3  rillig 	case 4:
     36  1.3  rillig 		goto label;
     37  1.3  rillig 	label:
     38  1.3  rillig 		__attribute__((__unused__))
     39  1.3  rillig 		return;
     40  1.3  rillig 	}
     41  1.3  rillig 
     42  1.3  rillig 	/*
     43  1.3  rillig 	 * The GCC attributes may only occur after a label; they cannot occur
     44  1.3  rillig 	 * before an arbitrary statement.
     45  1.3  rillig 	 */
     46  1.3  rillig 	__attribute__((__unused__))
     47  1.3  rillig 	/* expect+1: error: syntax error 'return' [249] */
     48  1.3  rillig 	return;
     49  1.3  rillig }
     50