------- Comment #63 from dberlin at gcc dot gnu dot org 2007-05-14 16:38
-------
Subject: Re: [4.0/4.1/4.2/4.3 Regression] placement new does not change the
dynamic type as it should
On 14 May 2007 15:20:14 -0000, rguenth at gcc dot gnu dot org
<[EMAIL PROTECTED]> wrote:
>
>
> ------- Comment #62 from rguenth at gcc dot gnu dot org 2007-05-14 16:20
> -------
> We ICE with
>
> template <class T, class T2, int D>
> class Vector
> {
> public:
> Vector()
> {
> for (int i = 0; i < D; ++i)
> new (&x_m[i]) T2();
> }
> T2& operator[](int i) { return *reinterpret_cast<T2*>(&x_m[i]); }
>
> private:
> T x_m[D];
> };
>
> void foo(Vector<double, long, 3> *m)
> {
> Vector<double, long, 3> v;
> v[0] = 1;
> v[1] = 2;
> v[2] = 3;
> *m = v;
> }
>
> (adjust the storage type to be of same size for double/long):
>
> Program received signal SIGSEGV, Segmentation fault.
> 0x0000000000b11a5e in unmodifiable_var_p (var=0x0)
> at /space/rguenther/src/svn/trunk/gcc/tree-flow-inline.h:1598
> 1598 if (TREE_CODE (var) == SSA_NAME)
>
> #0 0x0000000000b11a5e in unmodifiable_var_p (var=0x0)
> at /space/rguenther/src/svn/trunk/gcc/tree-flow-inline.h:1598
> #1 0x0000000000b194c3 in may_alias_p (ptr=0x2b537d358210, mem_alias_set=2,
> var=0x2b537d359e00, var_alias_set=3, alias_set_only=0 '\0')
> at /space/rguenther/src/svn/trunk/gcc/tree-ssa-alias.c:2685
> #2 0x0000000000b17f2b in add_flow_insensitive_var_aliases (ai=0x14d7890,
> pvar=0x2b537d358210, set=2, tag=0x2b537d356ba0)
> at /space/rguenther/src/svn/trunk/gcc/tree-ssa-alias.c:2190
> #3 0x0000000000b184d3 in compute_change_dynamic_type_aliasing (
> vcdt=0x2b537d357a00, vai=0x14d7890)
> at /space/rguenther/src/svn/trunk/gcc/tree-ssa-alias.c:2242
> #4 0x000000000098a387 in pointer_set_traverse (pset=0x14e4e10,
> fn=0xb17f84 <compute_change_dynamic_type_aliasing>, data=0x14d7890)
> at /space/rguenther/src/svn/trunk/gcc/pointer-set.c:181
> #5 0x0000000000b18719 in compute_flow_insensitive_aliasing (ai=0x14d7890)
> at /space/rguenther/src/svn/trunk/gcc/tree-ssa-alias.c:2295
> #6 0x0000000000b15b17 in compute_may_aliases ()
>
> where in may_alias_p the ptr we passed does not have a symbol memory tag
> associated. (but var is SFT.3)
unmodifiable_var_p is not allowed to alias anything, so we don't
create SMT's for them.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29286
