Re: [tree-ssa] Bootstrap broken on x86_64-linux-gnu

[Andreas Jaeger <aj at suse dot de>]

Daniel Berlin <dberlin@dberlin.org> writes:

> I think I hit this bug yesterday when making load PRE work.
> Another fun "we have to resize an array when we split an edge" problem.
>
> Please try this patch.
>
> Hopefully, it'll apply. I have some other changes in the same tree, so
> i had to do some hand editing on the diff.

It does not apply but it does not look ok either, see below.


> If not, it should be easy to see what i'm trying to do anyway (prevent
> us from accessing a non existent array member).
>
>
> Index: tree-ssa-pre.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/Attic/tree-ssa-pre.c,v
> retrieving revision 1.1.4.94
> diff -u -3 -p -r1.1.4.94 tree-ssa-pre.c
> --- tree-ssa-pre.c	24 Oct 2003 07:41:31 -0000	1.1.4.94
> +++ tree-ssa-pre.c	29 Oct 2003 15:03:21 -0000
> @@ -323,7 +323,8 @@ struct expr_info
>  
>  /* Cache of expressions generated for given phi operand, to avoid
>     recomputation and wasting memory.  */
> -tree *phi_pred_cache;
> +static tree *phi_pred_cache;
> +static int n_phi_preds;
>  
>  /* Trying to lookup ephi pred operand indexes takes forever on graphs
>     that have high connectivity because it's an O(n) linked list
> @@ -1193,7 +1224,6 @@
>  /* Make a copy of Z as it would look in BB j, using the PHIs in BB.  */
>  
>  static tree
>  subst_phis (struct expr_info *ei, tree Z, basic_block j, basic_block bb)
>  {
>    tree stmt_copy;
> -  if (phi_pred_cache[j->index] != NULL_TREE)

This line looks broken.  Do you really intend this?

> @@ -1200,6 +1232,12 @@
> +
> +  /* Return the cached version, if we have one. */
> +  if (j->index < n_phi_preds 
> +      && phi_pred_cache[j->index] != NULL_TREE)
>      return phi_pred_cache[j->index];
> +
> +  /* Otherwise, generate a new expression.  */
>    pre_stats.exprs_generated++;
>    stmt_copy = unshare_expr (Z);
>    create_stmt_ann (stmt_copy);
>    modify_stmt (stmt_copy);
>    get_stmt_operands (stmt_copy);
> @@ -1210,1 +1248,0 @@
> -  phi_pred_cache[j->index] = stmt_copy;
> @@ -1211,3 +1273,6 @@
> +
> +  if (j->index < n_phi_preds)
> +    phi_pred_cache[j->index] = stmt_copy;
>    return stmt_copy;
>  }
>  
> @@ -3045,6 +3129,7 @@ pre_expression (struct expr_info *slot, 
>    bitmap_clear (created_phi_preds);
>    ephi_pindex_htab = htab_create (500, ephi_pindex_hash, ephi_pindex_eq, free);
>    phi_pred_cache = xcalloc (last_basic_block, sizeof (tree));
> +  n_phi_preds = last_basic_block;
>  
>    if (!expr_phi_insertion ((bitmap *)data, ei))
>      goto cleanup;  

Andreas
-- 
 Andreas Jaeger, aj@suse.de, http://www.suse.de/~aj
  SuSE Linux AG, Deutschherrnstr. 15-19, 90429 Nürnberg, Germany
   GPG fingerprint = 93A3 365E CE47 B889 DF7F  FED1 389A 563C C272 A126

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