https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68782
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jason at gcc dot gnu.org
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I think the problem is constexpr.c creates invalid trees, in particular
CONSTRUCTORs that have non-TREE_CONSTANT elements, yet they have TREE_CONSTANT
set on them (and possibly also TREE_SIDE_EFFECTS similarly).
build_constructor with NULL vals creates TREE_CONSTANT and !TREE_SIDE_EFFECTS
CONSTRUCTOR, and constexpr.c later modifies the elts without updating those
flags.
--- constexpr.c.jj4 2015-12-07 12:17:56.000000000 +0100
+++ constexpr.c 2015-12-14 19:40:24.054131253 +0100
@@ -2174,6 +2174,8 @@ cxx_eval_bare_aggregate (const constexpr
{
vec<constructor_elt, va_gc> *v = CONSTRUCTOR_ELTS (t);
bool changed = false;
+ bool constant_p = true;
+ bool side_effects_p = false;
gcc_assert (!BRACE_ENCLOSED_INITIALIZER_P (t));
verify_ctor_sanity (ctx, TREE_TYPE (t));
@@ -2222,7 +2224,13 @@ cxx_eval_bare_aggregate (const constexpr
(*p)->last().value = elt;
}
else
- CONSTRUCTOR_APPEND_ELT (*p, index, elt);
+ {
+ CONSTRUCTOR_APPEND_ELT (*p, index, elt);
+ if (!TREE_CONSTANT (elt))
+ constant_p = false;
+ if (TREE_SIDE_EFFECTS (elt))
+ side_effects_p = true;
+ }
}
if (*non_constant_p || !changed)
return t;
@@ -2230,6 +2238,10 @@ cxx_eval_bare_aggregate (const constexpr
/* We're done building this CONSTRUCTOR, so now we can interpret an
element without an explicit initializer as value-initialized. */
CONSTRUCTOR_NO_IMPLICIT_ZERO (t) = false;
+ if (!constant_p)
+ TREE_CONSTANT (t) = false;
+ if (side_effects_p)
+ TREE_SIDE_EFFECTS (t) = true;
if (VECTOR_TYPE_P (TREE_TYPE (t)))
t = fold (t);
return t;
@@ -2847,9 +2859,13 @@ cxx_eval_store_expression (const constex
/* The hash table might have moved since the get earlier. */
valp = ctx->values->get (object);
if (TREE_CODE (init) == CONSTRUCTOR)
- /* An outer ctx->ctor might be pointing to *valp, so just replace
- its contents. */
- CONSTRUCTOR_ELTS (*valp) = CONSTRUCTOR_ELTS (init);
+ {
+ /* An outer ctx->ctor might be pointing to *valp, so just replace
+ its contents. */
+ CONSTRUCTOR_ELTS (*valp) = CONSTRUCTOR_ELTS (init);
+ TREE_CONSTANT (*valp) = TREE_CONSTANT (init);
+ TREE_SIDE_EFFECTS (*valp) = TREE_SIDE_EFFECTS (init);
+ }
else
*valp = init;
}
is untested fix that cures this testcase, but the cxx_eval_bare_aggregate
changes are incomplete, there are other ways how a new elt is stored too. Or
perhaps it could just in another loop go over all elements and compute those
flags. Jason, any thoughts on this?
