* tree-phinode.c (resize_phi_node): Abort when LEN is strictly

	greater than PHI_ARG_CAPACITY.
	(reserve_phi_args_for_new_edge): Initialize the new PHI
	argument to NULL_TREE.  Increment PHI_NUM_ARGS.
	(add_phi_arg): Add a PHI argument to the slot given by
	E->dest_idx.
	(remove_phi_arg_num): Do not write to PHI_ARG_EDGE.
	* tree-flow-inline (phi_arg_from_edge): Return E->dest_idx.
	* tree-ssa.c (ssa_redirect_edge): Check for a missing PHI
	argument by looking at PHI_ARG_DEF.
	(verify_phi_args): Check for a missing PHI argument.  Remove
	the check for duplicate PHI arguments.
	* tree.h (PHI_ARG_EDGE): Redefine in terms of EDGE_PRED.
	(phi_arg_d): Remove e.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@91097 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 59 insertions, 43 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 01ecb442b8d..2fa744f46d6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,20 @@
+2004-11-23  Kazu Hirata  <kazu@cs.umass.edu>
+
+	* tree-phinode.c (resize_phi_node): Abort when LEN is strictly
+	greater than PHI_ARG_CAPACITY.
+	(reserve_phi_args_for_new_edge): Initialize the new PHI
+	argument to NULL_TREE.  Increment PHI_NUM_ARGS.
+	(add_phi_arg): Add a PHI argument to the slot given by
+	E->dest_idx.
+	(remove_phi_arg_num): Do not write to PHI_ARG_EDGE.
+	* tree-flow-inline (phi_arg_from_edge): Return E->dest_idx.
+	* tree-ssa.c (ssa_redirect_edge): Check for a missing PHI
+	argument by looking at PHI_ARG_DEF.
+	(verify_phi_args): Check for a missing PHI argument.  Remove
+	the check for duplicate PHI arguments.
+	* tree.h (PHI_ARG_EDGE): Redefine in terms of EDGE_PRED.
+	(phi_arg_d): Remove e.
+
 2004-11-23  Andreas Krebbel  <krebbel1@de.ibm.com>
 
 	* config/s390/s390.c (s390_backchain_string): Removed.
diff --git a/gcc/tree-flow-inline.h b/gcc/tree-flow-inline.h
index e3c955e8c26..ea5e741ae12 100644
--- a/gcc/tree-flow-inline.h
+++ b/gcc/tree-flow-inline.h
@@ -393,15 +393,9 @@ set_phi_nodes (basic_block bb, tree l)
 static inline int
 phi_arg_from_edge (tree phi, edge e)
 {
-  int i;
   gcc_assert (phi);
   gcc_assert (TREE_CODE (phi) == PHI_NODE);
-
-  for (i = 0; i < PHI_NUM_ARGS (phi); i++)
-    if (PHI_ARG_EDGE (phi, i) == e)
-      return i;
-
-  return -1;
+  return e->dest_idx;
 }
 
 /* Mark VAR as used, so that it'll be preserved during rtl expansion.  */
diff --git a/gcc/tree-phinodes.c b/gcc/tree-phinodes.c
index c8c811c6f1c..eec2fa3ed4f 100644
--- a/gcc/tree-phinodes.c
+++ b/gcc/tree-phinodes.c
@@ -212,13 +212,13 @@ make_phi_node (tree var, int len)
 
   phi = allocate_phi_node (capacity);
 
-  /* We do not have to clear a part of the PHI node that stores PHI
-     arguments, which is safe because we tell the garbage collector to
-     scan up to num_args elements in the array of PHI arguments.  In
-     other words, the garbage collector will not follow garbage
-     pointers in the unused portion of the array.  */
-  memset (phi, 0, sizeof (struct tree_phi_node) - sizeof (struct phi_arg_d));
+  /* We need to clear the entire PHI node, including the argument
+     portion, because we represent a "missing PHI argument" by placing
+     NULL_TREE in PHI_ARG_DEF.  */
+  memset (phi, 0, (sizeof (struct tree_phi_node) - sizeof (struct phi_arg_d)
+		   + sizeof (struct phi_arg_d) * len));
   TREE_SET_CODE (phi, PHI_NODE);
+  PHI_NUM_ARGS (phi) = len;
   PHI_ARG_CAPACITY (phi) = capacity;
   TREE_TYPE (phi) = TREE_TYPE (var);
   if (TREE_CODE (var) == SSA_NAME)
@@ -253,7 +253,7 @@ resize_phi_node (tree *phi, int len)
   int old_size;
   tree new_phi;
 
-  gcc_assert (len >= PHI_ARG_CAPACITY (*phi));
+  gcc_assert (len > PHI_ARG_CAPACITY (*phi));
 
   /* The garbage collector will not look at the PHI node beyond the
      first PHI_NUM_ARGS elements.  Therefore, all we have to copy is a
@@ -294,6 +294,17 @@ reserve_phi_args_for_new_edge (basic_block bb)
 
 	  release_phi_node (old_phi);
 	}
+
+      /* We represent a "missing PHI argument" by placing NULL_TREE in
+	 the corresponding slot.  If PHI arguments were added
+	 immediately after an edge is created, this zeroing would not
+	 be necessary, but unfortunately this is not the case.  For
+	 example, the loop optimizer duplicates several basic blocks,
+	 redirects edges, and then fixes up PHI arguments later in
+	 batch.  */
+      SET_PHI_ARG_DEF (*loc, len - 1, NULL_TREE);
+
+      PHI_NUM_ARGS (*loc)++;
     }
 }
 
@@ -326,13 +337,16 @@ void
 add_phi_arg (tree *phi, tree def, edge e)
 {
   basic_block bb = e->dest;
-  int i = PHI_NUM_ARGS (*phi);
 
   gcc_assert (bb == bb_for_stmt (*phi));
 
   /* We resize PHI nodes upon edge creation.  We should always have
      enough room at this point.  */
-  gcc_assert (PHI_NUM_ARGS (*phi) < PHI_ARG_CAPACITY (*phi));
+  gcc_assert (PHI_NUM_ARGS (*phi) <= PHI_ARG_CAPACITY (*phi));
+
+  /* We resize PHI nodes upon edge creation.  We should always have
+     enough room at this point.  */
+  gcc_assert (e->dest_idx < (unsigned int) PHI_NUM_ARGS (*phi));
 
   /* Copy propagation needs to know what object occur in abnormal
      PHI nodes.  This is a convenient place to record such information.  */
@@ -342,10 +356,8 @@ add_phi_arg (tree *phi, tree def, edge e)
       SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (*phi)) = 1;
     }
 
-  SET_PHI_ARG_DEF (*phi, i, def);
-  PHI_ARG_EDGE (*phi, i) = e;
-  PHI_ARG_NONZERO (*phi, i) = false;
-  PHI_NUM_ARGS (*phi)++;
+  SET_PHI_ARG_DEF (*phi, e->dest_idx, def);
+  PHI_ARG_NONZERO (*phi, e->dest_idx) = false;
 }
 
 /* Remove the Ith argument from PHI's argument list.  This routine assumes
@@ -365,14 +377,13 @@ remove_phi_arg_num (tree phi, int i)
   if (i != num_elem - 1)
     {
       SET_PHI_ARG_DEF (phi, i, PHI_ARG_DEF (phi, num_elem - 1));
-      PHI_ARG_EDGE (phi, i) = PHI_ARG_EDGE (phi, num_elem - 1);
       PHI_ARG_NONZERO (phi, i) = PHI_ARG_NONZERO (phi, num_elem - 1);
     }
 
   /* Shrink the vector and return.  Note that we do not have to clear
-     PHI_ARG_DEF, PHI_ARG_EDGE, or PHI_ARG_NONZERO because the garbage
-     collector will not look at those elements beyond the first
-     PHI_NUM_ARGS elements of the array.  */
+     PHI_ARG_DEF or PHI_ARG_NONZERO because the garbage collector will
+     not look at those elements beyond the first PHI_NUM_ARGS elements
+     of the array.  */
   PHI_NUM_ARGS (phi)--;
 }
 
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index 67129771904..e2b23f01844 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -64,7 +64,7 @@ ssa_redirect_edge (edge e, basic_block dest)
       next = PHI_CHAIN (phi);
 
       i = phi_arg_from_edge (phi, e);
-      if (i < 0)
+      if (PHI_ARG_DEF (phi, i) == NULL_TREE)
 	continue;
 
       src = PHI_ARG_DEF (phi, i);
@@ -277,7 +277,6 @@ verify_phi_args (tree phi, basic_block bb, basic_block *definition_block)
   edge e;
   bool err = false;
   unsigned i, phi_num_args = PHI_NUM_ARGS (phi);
-  edge_iterator ei;
 
   if (EDGE_COUNT (bb->preds) != phi_num_args)
     {
@@ -286,22 +285,27 @@ verify_phi_args (tree phi, basic_block bb, basic_block *definition_block)
       goto error;
     }
 
-  /* Mark all the incoming edges.  */
-  FOR_EACH_EDGE (e, ei, bb->preds)
-    e->aux = (void *) 1;
-
   for (i = 0; i < phi_num_args; i++)
     {
       tree op = PHI_ARG_DEF (phi, i);
 
+      e = PHI_ARG_EDGE (phi, i);
+
+      if (op == NULL_TREE)
+	{
+	  error ("PHI argument is missing for edge %d->%d\n",
+	         e->src->index,
+		 e->dest->index);
+	  err = true;
+	  goto error;
+	}
+
       if (TREE_CODE (op) != SSA_NAME && !is_gimple_min_invariant (op))
 	{
 	  error ("PHI argument is not SSA_NAME, or invariant");
 	  err = true;
 	}
 
-      e = PHI_ARG_EDGE (phi, i);
-
       if (TREE_CODE (op) == SSA_NAME)
 	err = verify_use (e->src, definition_block[SSA_NAME_VERSION (op)], op,
 			  phi, e->flags & EDGE_ABNORMAL,
@@ -315,21 +319,12 @@ verify_phi_args (tree phi, basic_block bb, basic_block *definition_block)
 	  err = true;
 	}
 
-      if (e->aux == (void *) 0)
-	{
-	  error ("PHI argument flowing through dead or duplicated edge %d->%d\n",
-	         e->src->index, e->dest->index);
-	  err = true;
-	}
-
       if (err)
 	{
 	  fprintf (stderr, "PHI argument\n");
 	  print_generic_stmt (stderr, op, TDF_VOPS);
 	  goto error;
 	}
-
-      e->aux = (void *) 0;
     }
 
 error:
diff --git a/gcc/tree.h b/gcc/tree.h
index c95c84d0afa..dc4a9d44ec8 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1374,7 +1374,7 @@ struct tree_ssa_name GTY(())
 #define PHI_NUM_ARGS(NODE)		PHI_NODE_CHECK (NODE)->phi.num_args
 #define PHI_ARG_CAPACITY(NODE)		PHI_NODE_CHECK (NODE)->phi.capacity
 #define PHI_ARG_ELT(NODE, I)		PHI_NODE_ELT_CHECK (NODE, I)
-#define PHI_ARG_EDGE(NODE, I)		PHI_NODE_ELT_CHECK (NODE, I).e
+#define PHI_ARG_EDGE(NODE, I) 		(EDGE_PRED (PHI_BB ((NODE)), (I)))
 #define PHI_ARG_NONZERO(NODE, I) 	PHI_NODE_ELT_CHECK (NODE, I).nonzero
 #define PHI_BB(NODE)			PHI_NODE_CHECK (NODE)->phi.bb
 #define PHI_DF(NODE)			PHI_NODE_CHECK (NODE)->phi.df
@@ -1384,7 +1384,6 @@ struct edge_def;
 struct phi_arg_d GTY(())
 {
   tree def;
-  struct edge_def * GTY((skip (""))) e;
   bool nonzero;
 };