re PR tree-optimization/17468 (Java garbage collector miscompiled at -O1 and higher)

	PR tree-optimization/17468
	* tree-ssa.c (verify_use, verify_phi_args, verify_ssa):  Verify that
	definition inside a block precede uses.
	* tree-tailcall.c (adjust_return_value): Emit statements in the
	correct order.

From-SVN: r87538

gcc/ChangeLog

+2004-09-15  Zdenek Dvorak  <rakdver@atrey.karlin.mff.cuni.cz>
+
+	PR tree-optimization/17468
+	* tree-ssa.c (verify_use, verify_phi_args, verify_ssa):  Verify that
+	definition inside a block precede uses.
+	* tree-tailcall.c (adjust_return_value): Emit statements in the
+	correct order.
+
 2004-09-15  Richard Sandiford  <rsandifo@redhat.com>
 
 	* config/mips/mips.h (POINTERS_EXTEND_UNSIGNED): Delete.

gcc/tree-ssa.c

@@ -207,11 +207,15 @@ err:
       arguments).
 
    IS_VIRTUAL is true if SSA_NAME is created by a V_MAY_DEF or a
-      V_MUST_DEF.  */
+      V_MUST_DEF.
+   
+   If NAMES_DEFINED_IN_BB is not NULL, it contains a bitmap of ssa names
+     that are defined before STMT in basic block BB.  */
 
 static bool
 verify_use (basic_block bb, basic_block def_bb, tree ssa_name,
-	    tree stmt, bool check_abnormal, bool is_virtual)
+	    tree stmt, bool check_abnormal, bool is_virtual,
+	    bitmap names_defined_in_bb)
 {
   bool err = false;
 
@@ -232,6 +236,13 @@ verify_use (basic_block bb, basic_block def_bb, tree ssa_name,
 	     def_bb->index, bb->index);
       err = true;
     }
+  else if (bb == def_bb
+	   && names_defined_in_bb != NULL
+	   && !bitmap_bit_p (names_defined_in_bb, SSA_NAME_VERSION (ssa_name)))
+    {
+      error ("Definition in block %i follows the use", def_bb->index);
+      err = true;
+    }
 
   if (check_abnormal
       && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (ssa_name))
@@ -281,7 +292,8 @@ verify_phi_args (tree phi, basic_block bb, basic_block *definition_block)
       if (TREE_CODE (op) == SSA_NAME)
 	err = verify_use (e->src, definition_block[SSA_NAME_VERSION (op)], op,
 			  phi, e->flags & EDGE_ABNORMAL,
-			  !is_gimple_reg (PHI_RESULT (phi)));
+			  !is_gimple_reg (PHI_RESULT (phi)),
+			  NULL);
 
       if (e->dest != bb)
 	{
@@ -506,6 +518,7 @@ verify_ssa (void)
   ssa_op_iter iter;
   tree op;
   enum dom_state orig_dom_state = dom_computed[CDI_DOMINATORS];
+  bitmap names_defined_in_bb = BITMAP_XMALLOC ();
 
   timevar_push (TV_TREE_SSA_VERIFY);
 
@@ -578,8 +591,12 @@ verify_ssa (void)
 
       /* Verify the arguments for every PHI node in the block.  */
       for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
-	if (verify_phi_args (phi, bb, definition_block))
-	  goto err;
+	{
+	  if (verify_phi_args (phi, bb, definition_block))
+	    goto err;
+	  bitmap_set_bit (names_defined_in_bb,
+			  SSA_NAME_VERSION (PHI_RESULT (phi)));
+	}
 
       /* Now verify all the uses and vuses in every statement of the block.  */
       for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
@@ -589,17 +606,44 @@ verify_ssa (void)
 	  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_VIRTUAL_USES)
 	    {
 	      if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)],
-			      op, stmt, false, true))
+			      op, stmt, false, true,
+			      names_defined_in_bb))
 		goto err;
 	    }
 
 	  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE)
 	    {
 	      if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)],
-			      op, stmt, false, false))
+			      op, stmt, false, false,
+			      names_defined_in_bb))
 		goto err;
 	    }
+
+	  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS)
+	    {
+	      bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (op));
+	    }
 	}
+
+      /* Verify the uses in arguments of PHI nodes at the exits from the
+	 block.  */
+      for (e = bb->succ; e; e = e->succ_next)
+	{
+	  for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
+	    {
+	      bool virtual = !is_gimple_reg (PHI_RESULT (phi));
+	      op = PHI_ARG_DEF_FROM_EDGE (phi, e);
+	      if (TREE_CODE (op) != SSA_NAME)
+		continue;
+
+	      if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)],
+			      op, phi, false, virtual,
+			      names_defined_in_bb))
+		goto err;
+	    }
+	}
+
+      bitmap_clear (names_defined_in_bb);
     }
 
   /* Finally, verify alias information.  */
@@ -613,6 +657,7 @@ verify_ssa (void)
   else
     dom_computed[CDI_DOMINATORS] = orig_dom_state;
   
+  BITMAP_XFREE (names_defined_in_bb);
   timevar_pop (TV_TREE_SSA_VERIFY);
   return;
 

gcc/tree-tailcall.c

@@ -624,7 +624,7 @@ adjust_return_value (basic_block bb, tree m, tree a)
 
       var = make_ssa_name (tmp, stmt);
       TREE_OPERAND (stmt, 0) = var;
-      bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
+      bsi_insert_before (&bsi, stmt, BSI_SAME_STMT);
     }
   else
     var = ret_var;
@@ -639,7 +639,7 @@ adjust_return_value (basic_block bb, tree m, tree a)
 
       var = make_ssa_name (tmp, stmt);
       TREE_OPERAND (stmt, 0) = var;
-      bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
+      bsi_insert_before (&bsi, stmt, BSI_SAME_STMT);
     }
 
   TREE_OPERAND (ret_stmt, 0) = var;