Addresses of non-weak symbols are non-zero

Use this fact in some foldings of comparisons. See testcase.

Michael Matz committed 10 years ago

Commit d7208651 parent be6d8ff2 files · +13 −1Browse files

Unified · Split

2 files

@@ -4979,7 +4979,9 @@ static void expr_cond(void) · 4978 unmodified lines
4979	4979	expr_lor();
4980	4980	if (tok == '?') {
4981	4981	next();
4982		− if ((vtop->r & (VT_VALMASK \| VT_LVAL \| VT_SYM)) == VT_CONST) {
	4982	+ if ((vtop->r & (VT_VALMASK \| VT_LVAL)) == VT_CONST &&
	4983	+ (!(vtop->r & VT_SYM) \|\|
	4984	+ !(vtop->sym->type.t & VT_WEAK))) {
4983	4985	int saved_nocode_wanted = nocode_wanted;
4984	4986	CType boolean;
4985	4987	int c;

@@ -1470,6 +1470,10 @@ typedef int arrtype2[3]; · 1469 unmodified lines
1470	1470	arrtype2 sinit21 = {4};
1471	1471	arrtype2 sinit22 = {5,6,7};
1472	1472
	1473	+/* Address comparisons of non-weak symbols with zero can be const-folded */
	1474	+int sinit23[2] = { "astring" ? sizeof("astring") : -1,
	1475	+ &sinit23 ? 42 : -1 };
	1476	+
1473	1477	void init_test(void)
1474	1478	{
1475	1479	int linit1 = 2;
@@ -1484,6 +1488,9 @@ void init_test(void) · 8 unmodified lines
1484	1488	int linit15[10] = { linit1, linit1 + 1, [6] = linit1 + 2, };
1485	1489	struct linit16 { int a1, a2, a3, a4; } linit16 = { 1, .a3 = 2 };
1486	1490	int linit17 = sizeof(linit17);
	1491	+ int zero = 0;
	1492	+ /* Addresses on non-weak symbols are non-zero, but not the access itself */
	1493	+ int linit18[2] = {&zero ? 1 : -1, zero ? -1 : 1 };
1487	1494
1488	1495	printf("init_test:\n");
1489	1496
@@ -1577,6 +1584,9 @@ void init_test(void) · 87 unmodified lines
1577	1584	printf("arrtype4: %d %d %d\n", sinit22[0], sinit22[1], sinit22[2]);
1578	1585	printf("arrtype5: %d %d\n", sizeof(sinit21), sizeof(sinit22));
1579	1586	printf("arrtype6: %d\n", sizeof(arrtype2));
	1587	+
	1588	+ printf("sinit23= %d %d\n", sinit23[0], sinit23[1]);
	1589	+ printf("linit18= %d %d\n", linit18[0], linit18[1]);
1580	1590	}
1581	1591
1582	1592

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