[PATCH] Fix nested function ICE with VLAs (PR middle-end/59011)

[Jakub Jelinek]

Hi!

tree-nested.c uses declare_vars with last argument true, which
relies on BLOCK_VARS of gimple_bind_block being a tail
of the gimple_bind_vars chain.  But unfortunately a debug info
improvement I've added to gimplify_var_or_parm_decl 4 years ago
violates this assumption, in that it adds some VAR_DECLs
at the head of BLOCK_VARS (DECL_INITIAL (current_function_decl))
chain, but doesn't adjust gimple_bind_vars chain correspondingly.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk/4.8?

2013-12-02  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/59011
        * gimplify.c (nonlocal_vla_vars): New variable.
        (gimplify_var_or_parm_decl): Put VAR_DECLs for VLAs into
        nonlocal_vla_vars chain.
        (gimplify_body): Call declare_vars on nonlocal_vla_vars chain
        if outer_bind has DECL_INITIAL (current_function_decl) block.

        * gcc.dg/pr59011.c: New test.

--- gcc/gimplify.c.jj   2013-12-02 14:33:34.000000000 +0100
+++ gcc/gimplify.c      2013-12-02 20:32:02.883491995 +0100
@@ -1689,6 +1689,9 @@ gimplify_conversion (tree *expr_p)
 /* Nonlocal VLAs seen in the current function.  */
 static struct pointer_set_t *nonlocal_vlas;
 
+/* The VAR_DECLs created for nonlocal VLAs for debug info purposes.  */
+static tree nonlocal_vla_vars;
+
 /* Gimplify a VAR_DECL or PARM_DECL.  Return GS_OK if we expanded a
    DECL_VALUE_EXPR, and it's worth re-examining things.  */
 
@@ -1737,14 +1740,13 @@ gimplify_var_or_parm_decl (tree *expr_p)
            ctx = ctx->outer_context;
          if (!ctx && !pointer_set_insert (nonlocal_vlas, decl))
            {
-             tree copy = copy_node (decl), block;
+             tree copy = copy_node (decl);
 
              lang_hooks.dup_lang_specific_decl (copy);
              SET_DECL_RTL (copy, 0);
              TREE_USED (copy) = 1;
-             block = DECL_INITIAL (current_function_decl);
-             DECL_CHAIN (copy) = BLOCK_VARS (block);
-             BLOCK_VARS (block) = copy;
+             DECL_CHAIN (copy) = nonlocal_vla_vars;
+             nonlocal_vla_vars = copy;
              SET_DECL_VALUE_EXPR (copy, unshare_expr (value_expr));
              DECL_HAS_VALUE_EXPR_P (copy) = 1;
            }
@@ -8562,6 +8564,21 @@ gimplify_body (tree fndecl, bool do_parm
 
   if (nonlocal_vlas)
     {
+      if (nonlocal_vla_vars)
+       {
+         /* tree-nested.c may later on call declare_vars (..., true);
+            which relies on BLOCK_VARS chain to be the tail of the
+            gimple_bind_vars chain.  Ensure we don't violate that
+            assumption.  */
+         if (gimple_bind_block (outer_bind)
+             == DECL_INITIAL (current_function_decl))
+           declare_vars (nonlocal_vla_vars, outer_bind, true);
+         else
+           BLOCK_VARS (DECL_INITIAL (current_function_decl))
+             = chainon (BLOCK_VARS (DECL_INITIAL (current_function_decl)),
+                        nonlocal_vla_vars);
+         nonlocal_vla_vars = NULL_TREE;
+       }
       pointer_set_destroy (nonlocal_vlas);
       nonlocal_vlas = NULL;
     }
--- gcc/testsuite/gcc.dg/pr59011.c.jj   2013-12-02 20:14:22.350702153 +0100
+++ gcc/testsuite/gcc.dg/pr59011.c      2013-12-02 20:15:10.902455660 +0100
@@ -0,0 +1,22 @@
+/* PR middle-end/59011 */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99" } */
+
+void
+foo (int m)
+{
+  int a[m];
+  void
+  bar (void)
+  {
+    {
+      int
+      baz (void)
+      {
+       return a[0];
+      }
+    }
+    a[0] = 42;
+  }
+  bar ();
+}

        Jakub