1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
From aa15fbe864f58be935154f76f8ebf144988e7746 Mon Sep 17 00:00:00 2001
From: jakub <jakub@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 25 May 2011 07:03:25 +0000
Subject: [PATCH] PR c++/49136
* semantics.c (cxx_eval_bit_field_ref): Handle the
case when BIT_FIELD_REF doesn't cover only a single field.
* g++.dg/cpp0x/constexpr-bitfield2.C: New test.
* g++.dg/cpp0x/constexpr-bitfield3.C: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_6-branch@174169 138bc75d-0d04-0410-961f-82ee72b054a4
index bd33bac..6207b12 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -6391,6 +6391,9 @@ cxx_eval_bit_field_ref (const constexpr_call *call, tree t,
bool *non_constant_p)
{
tree orig_whole = TREE_OPERAND (t, 0);
+ tree retval, fldval, utype, mask;
+ bool fld_seen = false;
+ HOST_WIDE_INT istart, isize;
tree whole = cxx_eval_constant_expression (call, orig_whole,
allow_non_constant, addr,
non_constant_p);
@@ -6411,12 +6414,47 @@ cxx_eval_bit_field_ref (const constexpr_call *call, tree t,
return t;
start = TREE_OPERAND (t, 2);
+ istart = tree_low_cst (start, 0);
+ isize = tree_low_cst (TREE_OPERAND (t, 1), 0);
+ utype = TREE_TYPE (t);
+ if (!TYPE_UNSIGNED (utype))
+ utype = build_nonstandard_integer_type (TYPE_PRECISION (utype), 1);
+ retval = build_int_cst (utype, 0);
FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole), i, field, value)
{
- if (bit_position (field) == start)
+ tree bitpos = bit_position (field);
+ if (bitpos == start && DECL_SIZE (field) == TREE_OPERAND (t, 1))
return value;
+ if (TREE_CODE (TREE_TYPE (field)) == INTEGER_TYPE
+ && TREE_CODE (value) == INTEGER_CST
+ && host_integerp (bitpos, 0)
+ && host_integerp (DECL_SIZE (field), 0))
+ {
+ HOST_WIDE_INT bit = tree_low_cst (bitpos, 0);
+ HOST_WIDE_INT sz = tree_low_cst (DECL_SIZE (field), 0);
+ HOST_WIDE_INT shift;
+ if (bit >= istart && bit + sz <= istart + isize)
+ {
+ fldval = fold_convert (utype, value);
+ mask = build_int_cst_type (utype, -1);
+ mask = fold_build2 (LSHIFT_EXPR, utype, mask,
+ size_int (TYPE_PRECISION (utype) - sz));
+ mask = fold_build2 (RSHIFT_EXPR, utype, mask,
+ size_int (TYPE_PRECISION (utype) - sz));
+ fldval = fold_build2 (BIT_AND_EXPR, utype, fldval, mask);
+ shift = bit - istart;
+ if (BYTES_BIG_ENDIAN)
+ shift = TYPE_PRECISION (utype) - shift - sz;
+ fldval = fold_build2 (LSHIFT_EXPR, utype, fldval,
+ size_int (shift));
+ retval = fold_build2 (BIT_IOR_EXPR, utype, retval, fldval);
+ fld_seen = true;
+ }
+ }
}
- gcc_unreachable();
+ if (fld_seen)
+ return fold_convert (TREE_TYPE (t), retval);
+ gcc_unreachable ();
return error_mark_node;
}
new file mode 100644
index 0000000..531bf31
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-bitfield2.C
@@ -0,0 +1,19 @@
+// PR c++/49136
+// { dg-do compile }
+// { dg-options "-std=c++0x" }
+
+struct day
+{
+ unsigned d : 5;
+ unsigned n : 3;
+ constexpr explicit day (int dd) : d(dd), n(7) {}
+};
+
+struct date {
+ int d;
+ constexpr date (day dd) : d(dd.n != 7 ? 7 : dd.d) {}
+};
+
+constexpr day d(0);
+constexpr date dt(d);
+static_assert (dt.d == 0, "Error");
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-bitfield3.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-bitfield3.C
new file mode 100644
index 0000000..b0ecbfb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-bitfield3.C
@@ -0,0 +1,33 @@
+// PR c++/49136
+// { dg-do compile }
+// { dg-options "-std=c++0x" }
+
+struct S
+{
+ unsigned : 1; unsigned s : 27; unsigned : 4;
+ constexpr S (unsigned int x) : s(x) {}
+};
+
+template <typename S>
+struct T
+{
+ unsigned int t;
+ constexpr T (S s) : t(s.s != 7 ? 0 : s.s) {}
+ constexpr T (S s, S s2) : t(s.s != s2.s ? 0 : s.s) {}
+};
+
+constexpr S s (7), s2 (7);
+constexpr T<S> t (s), t2 (s, s2);
+static_assert (t.t == 7, "Error");
+static_assert (t2.t == 7, "Error");
+
+struct U
+{
+ int a : 1; int s : 1;
+ constexpr U (int x, int y) : a (x), s (y) {}
+};
+
+constexpr U u (0, -1), u2 (-1, -1);
+constexpr T<U> t3 (u), t4 (u, u2);
+static_assert (t3.t == 0, "Error");
+static_assert (t4.t == -1, "Error");
--
1.7.0.4
|
