for  gcc/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR debug/48866
	* cfgexpand.c (def_expansions): New.
	(def_expansion_recent_tree, def_expansion_recent_rtx): New.
	(def_expansions_init, def_expansions_fini): New.
	(def_has_expansion_ptr, def_get_expansion_ptr): New.
	(expand_debug_expr): Use recorded expansion if available.
	(expand_gimple_basic_block): Prepare to record expansion of
	replaceable defs.  Change return type to void.
	(gimple_expand_cfg): Initialize and finalize expansions cache.
	Expand dominator blocks before dominated.
	* expr.c (expand_expr_real_1): Use recorded expansion of
	replaceable defs.
	* expr.h (def_has_expansion_ptr): Declare.

Index: gcc/cfgexpand.c
===================================================================
--- gcc/cfgexpand.c.orig	2011-06-01 20:39:58.244953408 -0300
+++ gcc/cfgexpand.c	2011-06-01 21:44:38.005879125 -0300
@@ -2337,6 +2337,42 @@ convert_debug_memory_address (enum machi
   return x;
 }
 
+/* Map replaceable SSA_NAMEs to their RTL expansions.  */
+static rtx *def_expansions;
+
+/* Initialize the def_expansions data structure.  This is to be called
+   before expansion of a function starts.  */
+
+static void
+def_expansions_init (void)
+{
+  gcc_checking_assert (!def_expansions);
+  def_expansions = XCNEWVEC (rtx, num_ssa_names);
+}
+
+/* Finalize the def_expansions data structure.  This is to be called
+   at the end of the expansion of a function.  */
+
+static void
+def_expansions_fini (void)
+{
+  gcc_checking_assert (def_expansions);
+  XDELETEVEC (def_expansions);
+  def_expansions = NULL;
+}
+
+/* Return a pointer to the rtx expanded from EXP.  EXP must be a
+   replaceable SSA_NAME.  */
+
+rtx *
+def_get_expansion_ptr (tree exp)
+{
+  gcc_checking_assert (def_expansions);
+  gcc_checking_assert (TREE_CODE (exp) == SSA_NAME);
+  gcc_checking_assert (bitmap_bit_p (SA.values, SSA_NAME_VERSION (exp)));
+  return &def_expansions[SSA_NAME_VERSION (exp)];
+}
+
 /* Return an RTX equivalent to the value of the tree expression
    EXP.  */
 
@@ -3131,7 +3167,16 @@ expand_debug_expr (tree exp)
 	gimple g = get_gimple_for_ssa_name (exp);
 	if (g)
 	  {
-	    op0 = expand_debug_expr (gimple_assign_rhs_to_tree (g));
+	    rtx *xp = def_get_expansion_ptr (exp);
+
+	    if (xp)
+	      op0 = copy_rtx (*xp);
+	    else
+	      op0 = NULL;
+
+	    if (!op0)
+	      op0 = expand_debug_expr (gimple_assign_rhs_to_tree (g));
+
 	    if (!op0)
 	      return NULL;
 	  }
@@ -3618,20 +3663,38 @@ expand_gimple_basic_block (basic_block b
 	    }
 	  else
 	    {
+	      rtx *xp = NULL;
 	      def_operand_p def_p;
 	      def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_DEF);
 
-	      if (def_p != NULL)
+	      /* Ignore this stmt if it is in the list of
+		 replaceable expressions.  */
+	      if (def_p != NULL
+		  && SA.values
+		  && bitmap_bit_p (SA.values,
+				   SSA_NAME_VERSION (DEF_FROM_PTR (def_p))))
 		{
-		  /* Ignore this stmt if it is in the list of
-		     replaceable expressions.  */
-		  if (SA.values
-		      && bitmap_bit_p (SA.values,
-				       SSA_NAME_VERSION (DEF_FROM_PTR (def_p))))
-		    continue;
+		  tree def = DEF_FROM_PTR (def_p);
+		  gimple g = get_gimple_for_ssa_name (def);
+		  rtx retval;
+
+		  last = get_last_insn ();
+
+		  retval = expand_expr (gimple_assign_rhs_to_tree (g),
+					NULL_RTX, VOIDmode, EXPAND_SUM);
+
+		  xp = def_get_expansion_ptr (def);
+		  gcc_checking_assert (!*xp);
+		  *xp = retval;
 		}
-	      last = expand_gimple_stmt (stmt);
+	      else
+		last = expand_gimple_stmt (stmt);
 	      maybe_dump_rtl_for_gimple_stmt (stmt, last);
+	      if (xp && dump_file && (dump_flags & TDF_DETAILS))
+		{
+		  fprintf (dump_file, "\n=> ");
+		  print_rtl (dump_file, *xp);
+		}
 	    }
 	}
     }
@@ -4112,11 +4175,14 @@ gimple_expand_cfg (void)
     e->flags &= ~EDGE_EXECUTABLE;
 
   lab_rtx_for_bb = pointer_map_create ();
+  def_expansions_init ();
+
   FOR_BB_BETWEEN (bb, init_block->next_bb, EXIT_BLOCK_PTR, next_bb)
     bb = expand_gimple_basic_block (bb);
 
   if (MAY_HAVE_DEBUG_INSNS)
     expand_debug_locations ();
+  def_expansions_fini ();
 
   execute_free_datastructures ();
   timevar_push (TV_OUT_OF_SSA);
Index: gcc/expr.c
===================================================================
--- gcc/expr.c.orig	2011-06-01 20:39:58.604953351 -0300
+++ gcc/expr.c	2011-06-01 22:44:52.659524628 -0300
@@ -8424,10 +8424,40 @@ expand_expr_real_1 (tree exp, rtx target
 	  && !SSA_NAME_IS_DEFAULT_DEF (exp)
 	  && (optimize || DECL_IGNORED_P (SSA_NAME_VAR (exp)))
 	  && stmt_is_replaceable_p (SSA_NAME_DEF_STMT (exp)))
-	g = SSA_NAME_DEF_STMT (exp);
+	{
+	  g = SSA_NAME_DEF_STMT (exp);
+	  if (g)
+	    return expand_expr_real (gimple_assign_rhs_to_tree (g),
+				     target, tmode, modifier, NULL);
+	}
       if (g)
-	return expand_expr_real (gimple_assign_rhs_to_tree (g), target, tmode,
-				 modifier, NULL);
+	{
+	  rtx retval = *def_get_expansion_ptr (exp);
+
+	  gcc_assert (retval);
+
+	  switch (modifier)
+	    {
+	    case EXPAND_SUM:
+	      return retval;
+
+	    case EXPAND_STACK_PARM:
+	    case EXPAND_NORMAL:
+	      if (!target || !REG_P (target) || GET_MODE (target) != mode
+		  || !general_operand (retval, mode))
+		return force_reg (mode, retval);
+
+	      emit_move_insn (target, retval);
+	      return target;
+
+	    case EXPAND_MEMORY:
+	    case EXPAND_CONST_ADDRESS:
+	    case EXPAND_INITIALIZER:
+	    case EXPAND_WRITE:
+	    default:
+	      gcc_unreachable ();
+	    }
+	}
 
       ssa_name = exp;
       decl_rtl = get_rtx_for_ssa_name (ssa_name);
Index: gcc/expr.h
===================================================================
--- gcc/expr.h.orig	2011-06-01 20:39:58.742953327 -0300
+++ gcc/expr.h	2011-06-01 20:47:22.640844048 -0300
@@ -693,4 +693,7 @@ extern tree build_libfunc_function (cons
 /* Get the personality libfunc for a function decl.  */
 rtx get_personality_function (tree);
 
+/* In cfgexpand.c.  */
+rtx *def_get_expansion_ptr (tree);
+
 #endif /* GCC_EXPR_H */