[Bug middle-end/112830] internal compiler error: in convert_memory_address_addr_space_1, at explow.cc:302

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112830

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ebotcazou at gcc dot gnu.org

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
I'm struggling in creating test coverage for the *VLA = {} gimplification to
memset.  If I convince the C frontend to accept

void
bar (int n, __seg_fs void *p)
{
  typedef struct { char t[n]; } T;
  *(__seg_fs T *)p = (T) {};
}

with

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index df9a07928b5..a94270b6065 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -12223,12 +12223,7 @@ c_parser_postfix_expression_after_paren_type (c_parser
*parser,
               || (scspecs && scspecs->storage_class == csc_static)
               || constexpr_p), constexpr_p, &richloc);
   type = groktypename (type_name, &type_expr, &type_expr_const);
-  if (type != error_mark_node && C_TYPE_VARIABLE_SIZE (type))
-    {
-      error_at (type_loc, "compound literal has variable size");
-      type = error_mark_node;
-    }
-  else if (TREE_CODE (type) == FUNCTION_TYPE)
+  if (TREE_CODE (type) == FUNCTION_TYPE)
     {
       error_at (type_loc, "compound literal has function type");
       type = error_mark_node;
@@ -12257,6 +12252,13 @@ c_parser_postfix_expression_after_paren_type (c_parser
*parser,
   finish_init ();
   maybe_warn_string_init (type_loc, type, init);

+  if (type != error_mark_node
+      && C_TYPE_VARIABLE_SIZE (type)
+      && CONSTRUCTOR_NELTS (init.value) != 0)
+    {
+      error_at (type_loc, "compound literal has variable size");
+      type = error_mark_node;
+    }
   if (type != error_mark_node
       && !ADDR_SPACE_GENERIC_P (TYPE_ADDR_SPACE (type))
       && current_function_decl)

then I see the gimplifier fails to wrap the CONSTRUCTOR inside a WITH_SIZE_EXPR
which could be fixed with

diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
index a1d5ee28cbe..ae339c4a82a 100644
--- a/gcc/gimplify.cc
+++ b/gcc/gimplify.cc
@@ -5787,6 +5787,7 @@ gimplify_init_constructor (tree *expr_p, gimple_seq
*pre_p, gimple_seq *post_p,
       tree rhs = TREE_OPERAND (*expr_p, 1);
       if (want_value && object == lhs)
        lhs = unshare_expr (lhs);
+      maybe_with_size_expr (&rhs);
       gassign *init = gimple_build_assign (lhs, rhs);
       gimplify_seq_add_stmt (pre_p, init);
     }
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index a075fa38fba..e81b3f6ba72 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -3363,7 +3363,10 @@ verify_types_in_gimple_reference (tree expr, bool
require_lvalue)
     }

   if (!require_lvalue
-      && (is_gimple_reg (expr) || is_gimple_min_invariant (expr)))
+      && (is_gimple_reg (expr)
+         || is_gimple_min_invariant (expr)
+         || (TREE_CODE (expr) == CONSTRUCTOR
+             && CONSTRUCTOR_NELTS (expr) == 0)))
     return false;

   if (TREE_CODE (expr) != SSA_NAME && is_gimple_id (expr))

but then of course RTL expansion isn't prepared for this - we run into
store_expr expanding the CTOR but it would require special-casing such
RHS to eventually either call store_constructor or clear_storage_hints
directly.

Does Ada have support for address-spaces and is there a way to construct
a testcase that requires clearing of a VLA object in another address-space?