OK.
On Wed, Apr 5, 2017 at 2:48 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> The testcase in the PR (GC related, so not easily reduceable) ICEs
> because two TEMPLATE_TYPE_PARMs that comptypes returns true on have
> different TYPE_CANONICAL (each has itself).
> The problem is that
> comptypes->structural_comptypes->comp_template_parms_position
> compares not just idx and level, but also the
> TEMPLATE_PARM_PARAMETER_PACK bit, and rewrite_template_parm first
> computes the TYPE_CANONICAL (with the bit still unset) and then copies
> over the TEMPLATE_PARM_PARAMETER_PACK bit. This means that it can for
> TYPE_CANONICAL comparison compare unequal when it will compare equal later
> or maybe vice versa.
>
> Fixed thusly (the rewrite_template_parm changes), additionally while
> debugging I've noticed an inefficiency, vec_safe_grow_cleared is certainly
> more efficient than vec_safe_push of NULL in a loop - e.g. the latter
> might reallocate multiple times and really can't beat one growing and
> one memset, and two minor formatting nits.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2017-04-05 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/80309
> * pt.c (canonical_type_parameter): Use vec_safe_grow_cleared instead
> of a loop doing vec_safe_push of NULL. Formatting fixes.
> (rewrite_template_parm): Copy TEMPLATE_PARM_PARAMETER_PACK from oldidx
> to newidx before calling canonical_type_parameter on newtype.
>
> --- gcc/cp/pt.c.jj 2017-04-04 07:32:53.000000000 +0200
> +++ gcc/cp/pt.c 2017-04-05 13:43:18.883690743 +0200
> @@ -3997,10 +3997,10 @@ canonical_type_parameter (tree type)
> tree list;
> int idx = TEMPLATE_TYPE_IDX (type);
> if (!canonical_template_parms)
> - vec_alloc (canonical_template_parms, idx+1);
> + vec_alloc (canonical_template_parms, idx + 1);
>
> - while (canonical_template_parms->length () <= (unsigned)idx)
> - vec_safe_push (canonical_template_parms, NULL_TREE);
> + if (canonical_template_parms->length () <= (unsigned) idx)
> + vec_safe_grow_cleared (canonical_template_parms, idx + 1);
>
> list = (*canonical_template_parms)[idx];
> while (list && !comptypes (type, TREE_VALUE (list), COMPARE_STRUCTURAL))
> @@ -4011,8 +4011,7 @@ canonical_type_parameter (tree type)
> else
> {
> (*canonical_template_parms)[idx]
> - = tree_cons (NULL_TREE, type,
> - (*canonical_template_parms)[idx]);
> + = tree_cons (NULL_TREE, type, (*canonical_template_parms)[idx]);
> return type;
> }
> }
> @@ -24955,6 +24954,8 @@ rewrite_template_parm (tree olddecl, uns
> newidx = TEMPLATE_TYPE_PARM_INDEX (newtype)
> = build_template_parm_index (index, level, level,
> newdecl, newtype);
> + TEMPLATE_PARM_PARAMETER_PACK (newidx)
> + = TEMPLATE_PARM_PARAMETER_PACK (oldidx);
> TYPE_STUB_DECL (newtype) = TYPE_NAME (newtype) = newdecl;
> TYPE_CANONICAL (newtype) = canonical_type_parameter (newtype);
>
> @@ -25002,11 +25003,11 @@ rewrite_template_parm (tree olddecl, uns
> SET_DECL_TEMPLATE_PARM_P (newconst);
> newidx = build_template_parm_index (index, level, level,
> newconst, newtype);
> + TEMPLATE_PARM_PARAMETER_PACK (newidx)
> + = TEMPLATE_PARM_PARAMETER_PACK (oldidx);
> DECL_INITIAL (newdecl) = DECL_INITIAL (newconst) = newidx;
> }
>
> - TEMPLATE_PARM_PARAMETER_PACK (newidx)
> - = TEMPLATE_PARM_PARAMETER_PACK (oldidx);
> return newdecl;
> }
>
>
> Jakub
