tree-ssa-strlen.c (get_string_length): Change assertion to STPCPY.

2011-10-24  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>

	* tree-ssa-strlen.c (get_string_length): Change assertion to STPCPY.
	(zero_length_string): Change assertion to accept strinfo without
	length but with stmt instead.
	Set the endptr pointer also if starting a new chain.
	(adjust_related_strinfos): Ignore strinfos marked for delayed
	length computation.
	(handle_builtin_strcpy): Mark earlier strinfo elements also for
	delayed length computation.

2011-10-24  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>

	* gcc.dg/strlenopt-22.c: New testcase.
	* gcc.dg/strlenopt-4.c: Change scan value for s390(x).

From-SVN: r180402

1 files changed, 38 insertions, 8 deletions

diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index 697340f..72da15e 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -397,7 +397,7 @@ get_string_length (strinfo si)
       callee = gimple_call_fndecl (stmt);
       gcc_assert (callee && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL);
       lhs = gimple_call_lhs (stmt);
-      gcc_assert (builtin_decl_implicit_p (BUILT_IN_STRCPY));
+      gcc_assert (builtin_decl_implicit_p (BUILT_IN_STPCPY));
       /* unshare_strinfo is intentionally not called here.  The (delayed)
 	 transformation of strcpy or strcat into stpcpy is done at the place
 	 of the former strcpy/strcat call and so can affect all the strinfos
@@ -588,13 +588,13 @@ zero_length_string (tree ptr, strinfo chainsi)
 		  || si->prev != chainsi->idx)
 		break;
 	    }
-	  gcc_assert (chainsi->length);
+	  gcc_assert (chainsi->length || chainsi->stmt);
 	  if (chainsi->endptr == NULL_TREE)
 	    {
 	      chainsi = unshare_strinfo (chainsi);
 	      chainsi->endptr = ptr;
 	    }
-	  if (integer_zerop (chainsi->length))
+	  if (chainsi->length && integer_zerop (chainsi->length))
 	    {
 	      if (chainsi->next)
 		{
@@ -626,6 +626,8 @@ zero_length_string (tree ptr, strinfo chainsi)
       if (chainsi->first == 0)
 	chainsi->first = chainsi->idx;
       chainsi->next = idx;
+      if (chainsi->endptr == NULL_TREE)
+	chainsi->endptr = ptr;
       si->prev = chainsi->idx;
       si->first = chainsi->first;
       si->writable = chainsi->writable;
@@ -654,11 +656,19 @@ adjust_related_strinfos (location_t loc, strinfo origsi, tree adj)
 	  tree tem;
 
 	  si = unshare_strinfo (si);
-	  gcc_assert (si->length);
-	  tem = fold_convert_loc (loc, TREE_TYPE (si->length), adj);
-	  si->length = fold_build2_loc (loc, PLUS_EXPR,
-					TREE_TYPE (si->length), si->length,
-					tem);
+	  if (si->length)
+	    {
+	      tem = fold_convert_loc (loc, TREE_TYPE (si->length), adj);
+	      si->length = fold_build2_loc (loc, PLUS_EXPR,
+					    TREE_TYPE (si->length), si->length,
+					    tem);
+	    }
+	  else if (si->stmt != NULL)
+	    /* Delayed length computation is unaffected.  */
+	    ;
+	  else
+	    gcc_unreachable ();
+
 	  si->endptr = NULL_TREE;
 	  si->dont_invalidate = true;
 	}
@@ -1117,10 +1127,30 @@ handle_builtin_strcpy (enum built_in_function bcode, gimple_stmt_iterator *gsi)
 
   if (dsi->length == NULL_TREE)
     {
+      strinfo chainsi;
+
       /* If string length of src is unknown, use delayed length
 	 computation.  If string lenth of dst will be needed, it
 	 can be computed by transforming this strcpy call into
 	 stpcpy and subtracting dst from the return value.  */
+
+      /* Look for earlier strings whose length could be determined if
+	 this strcpy is turned into an stpcpy.  */
+
+      if (dsi->prev != 0 && (chainsi = verify_related_strinfos (dsi)) != NULL)
+	{
+	  for (; chainsi && chainsi != dsi; chainsi = get_strinfo (chainsi->next))
+	    {
+	      /* When setting a stmt for delayed length computation
+		 prevent all strinfos through dsi from being
+		 invalidated.  */
+	      chainsi = unshare_strinfo (chainsi);
+	      chainsi->stmt = stmt;
+	      chainsi->length = NULL_TREE;
+	      chainsi->endptr = NULL_TREE;
+	      chainsi->dont_invalidate = true;
+	    }
+	}
       dsi->stmt = stmt;
       return;
     }