http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55434
Bug #: 55434
Summary: const array with elements initialized by constructor
marked non-const in debug info
Classification: Unclassified
Product: gcc
Version: 4.7.3
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: t56xjcu...@snkmail.com
Created attachment 28758
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28758
C++ source file
In this code:
struct s
{
int i1, i2;
};
const s c1 = { 1, 2 };
const s ca1[] = { { 1, 2} };
const s c2 = c1;
const s ca2[] = { c1 };
int main(void)
{
return 0;
}
gdb sees all variables as const except for ca2:
(gdb) ptype ca1
type = const struct s {
int i1;
int i2;
} [1]
(gdb) ptype ca2
type = struct s {
int i1;
int i2;
} [1]
The problem seems to be in split_nonconstant_init() in cp/typeck2.c; when
TREE_READONLY (dest) is set to zero, the information that it was ever read-only
is lost before the DWARF record is written.
The following patch seems to fix the problem. I would not be surprised if
there were a more elegant way of doing this.
(You might be wondering: How did I find this, and why do I care? I've been
working on something to read object files and then flag variables that raise
thread-safety issues because they are (1) global or static and (2) not const.
Reading DWARF records works really well, except for this particular problem.)
Index: gcc/cp/typeck2.c
===================================================================
--- gcc/cp/typeck2.c (revision 193640)
+++ gcc/cp/typeck2.c (working copy)
@@ -633,6 +633,7 @@
init = NULL_TREE;
code = pop_stmt_list (code);
DECL_INITIAL (dest) = init;
+ TREE_WASREADONLY (dest) = TREE_READONLY (dest);
TREE_READONLY (dest) = 0;
}
else
Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c (revision 193640)
+++ gcc/dwarf2out.c (working copy)
@@ -18031,7 +18031,9 @@
if (decl_by_reference_p (decl_or_origin))
add_type_attribute (var_die, TREE_TYPE (type), 0, 0, context_die);
else
- add_type_attribute (var_die, type, TREE_READONLY (decl_or_origin),
+ add_type_attribute (var_die, type,
+ TREE_READONLY (decl_or_origin) ||
+ TREE_WASREADONLY (decl_or_origin),
TREE_THIS_VOLATILE (decl_or_origin), context_die);
}
Index: gcc/tree.h
===================================================================
--- gcc/tree.h (revision 193640)
+++ gcc/tree.h (working copy)
@@ -464,8 +464,9 @@
unsigned packed_flag : 1;
unsigned user_align : 1;
unsigned nameless_flag : 1;
+ unsigned wasreadonly_flag : 1;
- unsigned spare : 12;
+ unsigned spare : 11;
/* This field is only used with type nodes; the only reason it is present
in tree_base instead of tree_type is to save space. The size of the
@@ -1344,6 +1345,7 @@
Nonzero in a FUNCTION_DECL means this function should be treated
as "const" function (can only read its arguments). */
#define TREE_READONLY(NODE) (NON_TYPE_CHECK (NODE)->base.readonly_flag)
+#define TREE_WASREADONLY(NODE) (NON_TYPE_CHECK (NODE)->base.wasreadonly_flag)
/* Value of expression is constant. Always on in all ..._CST nodes. May
also appear in an expression or decl where the value is constant. */
