--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/gimple-low.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,960 @@
+/* GIMPLE lowering pass.  Converts High GIMPLE into Low GIMPLE.
+
+   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008
+   Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "tree.h"
+#include "rtl.h"
+#include "varray.h"
+#include "gimple.h"
+#include "tree-iterator.h"
+#include "tree-inline.h"
+#include "diagnostic.h"
+#include "langhooks.h"
+#include "langhooks-def.h"
+#include "tree-flow.h"
+#include "timevar.h"
+#include "except.h"
+#include "hashtab.h"
+#include "flags.h"
+#include "function.h"
+#include "expr.h"
+#include "toplev.h"
+#include "tree-pass.h"
+
+/* The differences between High GIMPLE and Low GIMPLE are the
+   following:
+
+   1- Lexical scopes are removed (i.e., GIMPLE_BIND disappears).
+
+   2- GIMPLE_TRY and GIMPLE_CATCH are converted to abnormal control
+      flow and exception regions are built as an on-the-side region
+      hierarchy (See tree-eh.c:lower_eh_constructs).
+
+   3- Multiple identical return statements are grouped into a single
+      return and gotos to the unique return site.  */
+
+/* Match a return statement with a label.  During lowering, we identify
+   identical return statements and replace duplicates with a jump to
+   the corresponding label.  */
+struct return_statements_t
+{
+  tree label;
+  gimple stmt;
+};
+typedef struct return_statements_t return_statements_t;
+
+DEF_VEC_O(return_statements_t);
+DEF_VEC_ALLOC_O(return_statements_t,heap);
+
+struct lower_data
+{
+  /* Block the current statement belongs to.  */
+  tree block;
+
+  /* A vector of label and return statements to be moved to the end
+     of the function.  */
+  VEC(return_statements_t,heap) *return_statements;
+
+  /* True if the function calls __builtin_setjmp.  */
+  bool calls_builtin_setjmp;
+};
+
+static void lower_stmt (gimple_stmt_iterator *, struct lower_data *);
+static void lower_gimple_bind (gimple_stmt_iterator *, struct lower_data *);
+static void lower_gimple_return (gimple_stmt_iterator *, struct lower_data *);
+static void lower_builtin_setjmp (gimple_stmt_iterator *);
+
+
+/* Lower the body of current_function_decl from High GIMPLE into Low
+   GIMPLE.  */
+
+static unsigned int
+lower_function_body (void)
+{
+  struct lower_data data;
+  gimple_seq body = gimple_body (current_function_decl);
+  gimple_seq lowered_body;
+  gimple_stmt_iterator i;
+  gimple bind;
+  tree t;
+  gimple x;
+
+  /* The gimplifier should've left a body of exactly one statement,
+     namely a GIMPLE_BIND.  */
+  gcc_assert (gimple_seq_first (body) == gimple_seq_last (body)
+	      && gimple_code (gimple_seq_first_stmt (body)) == GIMPLE_BIND);
+
+  memset (&data, 0, sizeof (data));
+  data.block = DECL_INITIAL (current_function_decl);
+  BLOCK_SUBBLOCKS (data.block) = NULL_TREE;
+  BLOCK_CHAIN (data.block) = NULL_TREE;
+  TREE_ASM_WRITTEN (data.block) = 1;
+  data.return_statements = VEC_alloc (return_statements_t, heap, 8);
+
+  bind = gimple_seq_first_stmt (body);
+  lowered_body = NULL;
+  gimple_seq_add_stmt (&lowered_body, bind);
+  i = gsi_start (lowered_body);
+  lower_gimple_bind (&i, &data);
+
+  /* Once the old body has been lowered, replace it with the new
+     lowered sequence.  */
+  gimple_set_body (current_function_decl, lowered_body);
+
+  i = gsi_last (lowered_body);
+
+  /* If the function falls off the end, we need a null return statement.
+     If we've already got one in the return_statements vector, we don't
+     need to do anything special.  Otherwise build one by hand.  */
+  if (gimple_seq_may_fallthru (lowered_body)
+      && (VEC_empty (return_statements_t, data.return_statements)
+	  || gimple_return_retval (VEC_last (return_statements_t,
+			           data.return_statements)->stmt) != NULL))
+    {
+      x = gimple_build_return (NULL);
+      gimple_set_location (x, cfun->function_end_locus);
+      gimple_set_block (x, DECL_INITIAL (current_function_decl));
+      gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
+    }
+
+  /* If we lowered any return statements, emit the representative
+     at the end of the function.  */
+  while (!VEC_empty (return_statements_t, data.return_statements))
+    {
+      return_statements_t t;
+
+      /* Unfortunately, we can't use VEC_pop because it returns void for
+	 objects.  */
+      t = *VEC_last (return_statements_t, data.return_statements);
+      VEC_truncate (return_statements_t,
+	  	    data.return_statements,
+	  	    VEC_length (return_statements_t,
+		      		data.return_statements) - 1);
+
+      x = gimple_build_label (t.label);
+      gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
+
+      /* Remove the line number from the representative return statement.
+	 It now fills in for many such returns.  Failure to remove this
+	 will result in incorrect results for coverage analysis.  */
+      gimple_set_location (t.stmt, UNKNOWN_LOCATION);
+      gsi_insert_after (&i, t.stmt, GSI_CONTINUE_LINKING);
+    }
+
+  /* If the function calls __builtin_setjmp, we need to emit the computed
+     goto that will serve as the unique dispatcher for all the receivers.  */
+  if (data.calls_builtin_setjmp)
+    {
+      tree disp_label, disp_var, arg;
+
+      /* Build 'DISP_LABEL:' and insert.  */
+      disp_label = create_artificial_label ();
+      /* This mark will create forward edges from every call site.  */
+      DECL_NONLOCAL (disp_label) = 1;
+      cfun->has_nonlocal_label = 1;
+      x = gimple_build_label (disp_label);
+      gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
+
+      /* Build 'DISP_VAR = __builtin_setjmp_dispatcher (DISP_LABEL);'
+	 and insert.  */
+      disp_var = create_tmp_var (ptr_type_node, "setjmpvar");
+      arg = build_addr (disp_label, current_function_decl);
+      t = implicit_built_in_decls[BUILT_IN_SETJMP_DISPATCHER];
+      x = gimple_build_call (t, 1, arg);
+      gimple_call_set_lhs (x, disp_var);
+
+      /* Build 'goto DISP_VAR;' and insert.  */
+      gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
+      x = gimple_build_goto (disp_var);
+      gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
+    }
+
+  gcc_assert (data.block == DECL_INITIAL (current_function_decl));
+  BLOCK_SUBBLOCKS (data.block)
+    = blocks_nreverse (BLOCK_SUBBLOCKS (data.block));
+
+  clear_block_marks (data.block);
+  VEC_free(return_statements_t, heap, data.return_statements);
+  return 0;
+}
+
+struct gimple_opt_pass pass_lower_cf = 
+{
+ {
+  GIMPLE_PASS,
+  "lower",				/* name */
+  NULL,					/* gate */
+  lower_function_body,			/* execute */
+  NULL,					/* sub */
+  NULL,					/* next */
+  0,					/* static_pass_number */
+  0,					/* tv_id */
+  PROP_gimple_any,			/* properties_required */
+  PROP_gimple_lcf,			/* properties_provided */
+  0,					/* properties_destroyed */
+  0,					/* todo_flags_start */
+  TODO_dump_func			/* todo_flags_finish */
+ }
+};
+
+
+/* Verify if the type of the argument matches that of the function
+   declaration.  If we cannot verify this or there is a mismatch,
+   mark the call expression so it doesn't get inlined later.  */
+
+static void
+check_call_args (gimple stmt)
+{
+  tree fndecl, parms, p;
+  unsigned int i, nargs;
+
+  if (gimple_call_cannot_inline_p (stmt))
+    return;
+
+  nargs = gimple_call_num_args (stmt);
+
+  /* Get argument types for verification.  */
+  fndecl = gimple_call_fndecl (stmt);
+  parms = NULL_TREE;
+  if (fndecl)
+    parms = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
+  else if (POINTER_TYPE_P (TREE_TYPE (gimple_call_fn (stmt))))
+    parms = TYPE_ARG_TYPES (TREE_TYPE (TREE_TYPE (gimple_call_fn (stmt))));
+
+  /* Verify if the type of the argument matches that of the function
+     declaration.  If we cannot verify this or there is a mismatch,
+     mark the call expression so it doesn't get inlined later.  */
+  if (fndecl && DECL_ARGUMENTS (fndecl))
+    {
+      for (i = 0, p = DECL_ARGUMENTS (fndecl);
+	   i < nargs;
+	   i++, p = TREE_CHAIN (p))
+	{
+	  /* We cannot distinguish a varargs function from the case
+	     of excess parameters, still deferring the inlining decision
+	     to the callee is possible.  */
+	  if (!p)
+	    break;
+	  if (p == error_mark_node
+	      || gimple_call_arg (stmt, i) == error_mark_node
+	      || !fold_convertible_p (DECL_ARG_TYPE (p),
+				      gimple_call_arg (stmt, i)))
+	    {
+	      gimple_call_set_cannot_inline (stmt, true);
+	      break;
+	    }
+	}
+    }
+  else if (parms)
+    {
+      for (i = 0, p = parms; i < nargs; i++, p = TREE_CHAIN (p))
+	{
+	  /* If this is a varargs function defer inlining decision
+	     to callee.  */
+	  if (!p)
+	    break;
+	  if (TREE_VALUE (p) == error_mark_node
+	      || gimple_call_arg (stmt, i) == error_mark_node
+	      || TREE_CODE (TREE_VALUE (p)) == VOID_TYPE
+	      || !fold_convertible_p (TREE_VALUE (p),
+				      gimple_call_arg (stmt, i)))
+	    {
+	      gimple_call_set_cannot_inline (stmt, true);
+	      break;
+	    }
+	}
+    }
+  else
+    {
+      if (nargs != 0)
+	gimple_call_set_cannot_inline (stmt, true);
+    }
+}
+
+
+/* Lower sequence SEQ.  Unlike gimplification the statements are not relowered
+   when they are changed -- if this has to be done, the lowering routine must
+   do it explicitly.  DATA is passed through the recursion.  */
+
+static void
+lower_sequence (gimple_seq seq, struct lower_data *data)
+{
+  gimple_stmt_iterator gsi;
+
+  for (gsi = gsi_start (seq); !gsi_end_p (gsi); )
+    lower_stmt (&gsi, data);
+}
+
+
+/* Lower the OpenMP directive statement pointed by GSI.  DATA is
+   passed through the recursion.  */
+
+static void
+lower_omp_directive (gimple_stmt_iterator *gsi, struct lower_data *data)
+{
+  gimple stmt;
+  
+  stmt = gsi_stmt (*gsi);
+
+  lower_sequence (gimple_omp_body (stmt), data);
+  gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
+  gsi_insert_seq_before (gsi, gimple_omp_body (stmt), GSI_SAME_STMT);
+  gimple_omp_set_body (stmt, NULL);
+  gsi_remove (gsi, false);
+}
+
+
+/* Lower statement GSI.  DATA is passed through the recursion.  */
+
+static void
+lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
+{
+  gimple stmt = gsi_stmt (*gsi);
+
+  gimple_set_block (stmt, data->block);
+
+  switch (gimple_code (stmt))
+    {
+    case GIMPLE_BIND:
+      lower_gimple_bind (gsi, data);
+      return;
+
+    case GIMPLE_COND:
+      /* The gimplifier has already lowered this into gotos.  */
+      break;
+
+    case GIMPLE_RETURN:
+      lower_gimple_return (gsi, data);
+      return;
+
+    case GIMPLE_TRY:
+      lower_sequence (gimple_try_eval (stmt), data);
+      lower_sequence (gimple_try_cleanup (stmt), data);
+      break;
+
+    case GIMPLE_CATCH:
+      lower_sequence (gimple_catch_handler (stmt), data);
+      break;
+
+    case GIMPLE_EH_FILTER:
+      lower_sequence (gimple_eh_filter_failure (stmt), data);
+      break;
+
+    case GIMPLE_NOP:
+    case GIMPLE_ASM:
+    case GIMPLE_ASSIGN:
+    case GIMPLE_GOTO:
+    case GIMPLE_PREDICT:
+    case GIMPLE_LABEL:
+    case GIMPLE_SWITCH:
+    case GIMPLE_CHANGE_DYNAMIC_TYPE:
+    case GIMPLE_OMP_FOR:
+    case GIMPLE_OMP_SECTIONS:
+    case GIMPLE_OMP_SECTIONS_SWITCH:
+    case GIMPLE_OMP_SECTION:
+    case GIMPLE_OMP_SINGLE:
+    case GIMPLE_OMP_MASTER:
+    case GIMPLE_OMP_ORDERED:
+    case GIMPLE_OMP_CRITICAL:
+    case GIMPLE_OMP_RETURN:
+    case GIMPLE_OMP_ATOMIC_LOAD:
+    case GIMPLE_OMP_ATOMIC_STORE:
+    case GIMPLE_OMP_CONTINUE:
+      break;
+
+    case GIMPLE_CALL:
+      {
+	tree decl = gimple_call_fndecl (stmt);
+
+	if (decl
+	    && DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
+	    && DECL_FUNCTION_CODE (decl) == BUILT_IN_SETJMP)
+	  {
+	    data->calls_builtin_setjmp = true;
+	    lower_builtin_setjmp (gsi);
+	    return;
+	  }
+	check_call_args (stmt);
+      }
+      break;
+
+    case GIMPLE_OMP_PARALLEL:
+    case GIMPLE_OMP_TASK:
+      lower_omp_directive (gsi, data);
+      return;
+
+    default:
+      gcc_unreachable ();
+    }
+
+  gsi_next (gsi);
+}
+
+/* Lower a bind_expr TSI.  DATA is passed through the recursion.  */
+
+static void
+lower_gimple_bind (gimple_stmt_iterator *gsi, struct lower_data *data)
+{
+  tree old_block = data->block;
+  gimple stmt = gsi_stmt (*gsi);
+  tree new_block = gimple_bind_block (stmt);
+
+  if (new_block)
+    {
+      if (new_block == old_block)
+	{
+	  /* The outermost block of the original function may not be the
+	     outermost statement chain of the gimplified function.  So we
+	     may see the outermost block just inside the function.  */
+	  gcc_assert (new_block == DECL_INITIAL (current_function_decl));
+	  new_block = NULL;
+	}
+      else
+	{
+	  /* We do not expect to handle duplicate blocks.  */
+	  gcc_assert (!TREE_ASM_WRITTEN (new_block));
+	  TREE_ASM_WRITTEN (new_block) = 1;
+
+	  /* Block tree may get clobbered by inlining.  Normally this would
+	     be fixed in rest_of_decl_compilation using block notes, but
+	     since we are not going to emit them, it is up to us.  */
+	  BLOCK_CHAIN (new_block) = BLOCK_SUBBLOCKS (old_block);
+	  BLOCK_SUBBLOCKS (old_block) = new_block;
+	  BLOCK_SUBBLOCKS (new_block) = NULL_TREE;
+	  BLOCK_SUPERCONTEXT (new_block) = old_block;
+
+	  data->block = new_block;
+	}
+    }
+
+  record_vars (gimple_bind_vars (stmt));
+  lower_sequence (gimple_bind_body (stmt), data);
+
+  if (new_block)
+    {
+      gcc_assert (data->block == new_block);
+
+      BLOCK_SUBBLOCKS (new_block)
+	= blocks_nreverse (BLOCK_SUBBLOCKS (new_block));
+      data->block = old_block;
+    }
+
+  /* The GIMPLE_BIND no longer carries any useful information -- kill it.  */
+  gsi_insert_seq_before (gsi, gimple_bind_body (stmt), GSI_SAME_STMT);
+  gsi_remove (gsi, false);
+}
+
+/* Try to determine whether a TRY_CATCH expression can fall through.
+   This is a subroutine of block_may_fallthru.  */
+
+static bool
+try_catch_may_fallthru (const_tree stmt)
+{
+  tree_stmt_iterator i;
+
+  /* If the TRY block can fall through, the whole TRY_CATCH can
+     fall through.  */
+  if (block_may_fallthru (TREE_OPERAND (stmt, 0)))
+    return true;
+
+  i = tsi_start (TREE_OPERAND (stmt, 1));
+  switch (TREE_CODE (tsi_stmt (i)))
+    {
+    case CATCH_EXPR:
+      /* We expect to see a sequence of CATCH_EXPR trees, each with a
+	 catch expression and a body.  The whole TRY_CATCH may fall
+	 through iff any of the catch bodies falls through.  */
+      for (; !tsi_end_p (i); tsi_next (&i))
+	{
+	  if (block_may_fallthru (CATCH_BODY (tsi_stmt (i))))
+	    return true;
+	}
+      return false;
+
+    case EH_FILTER_EXPR:
+      /* The exception filter expression only matters if there is an
+	 exception.  If the exception does not match EH_FILTER_TYPES,
+	 we will execute EH_FILTER_FAILURE, and we will fall through
+	 if that falls through.  If the exception does match
+	 EH_FILTER_TYPES, the stack unwinder will continue up the
+	 stack, so we will not fall through.  We don't know whether we
+	 will throw an exception which matches EH_FILTER_TYPES or not,
+	 so we just ignore EH_FILTER_TYPES and assume that we might
+	 throw an exception which doesn't match.  */
+      return block_may_fallthru (EH_FILTER_FAILURE (tsi_stmt (i)));
+
+    default:
+      /* This case represents statements to be executed when an
+	 exception occurs.  Those statements are implicitly followed
+	 by a RESX_EXPR to resume execution after the exception.  So
+	 in this case the TRY_CATCH never falls through.  */
+      return false;
+    }
+}
+
+
+/* Same as above, but for a GIMPLE_TRY_CATCH.  */
+
+static bool
+gimple_try_catch_may_fallthru (gimple stmt)
+{
+  gimple_stmt_iterator i;
+
+  /* We don't handle GIMPLE_TRY_FINALLY.  */
+  gcc_assert (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH);
+
+  /* If the TRY block can fall through, the whole TRY_CATCH can
+     fall through.  */
+  if (gimple_seq_may_fallthru (gimple_try_eval (stmt)))
+    return true;
+
+  i = gsi_start (gimple_try_cleanup (stmt));
+  switch (gimple_code (gsi_stmt (i)))
+    {
+    case GIMPLE_CATCH:
+      /* We expect to see a sequence of GIMPLE_CATCH stmts, each with a
+	 catch expression and a body.  The whole try/catch may fall
+	 through iff any of the catch bodies falls through.  */
+      for (; !gsi_end_p (i); gsi_next (&i))
+	{
+	  if (gimple_seq_may_fallthru (gimple_catch_handler (gsi_stmt (i))))
+	    return true;
+	}
+      return false;
+
+    case GIMPLE_EH_FILTER:
+      /* The exception filter expression only matters if there is an
+	 exception.  If the exception does not match EH_FILTER_TYPES,
+	 we will execute EH_FILTER_FAILURE, and we will fall through
+	 if that falls through.  If the exception does match
+	 EH_FILTER_TYPES, the stack unwinder will continue up the
+	 stack, so we will not fall through.  We don't know whether we
+	 will throw an exception which matches EH_FILTER_TYPES or not,
+	 so we just ignore EH_FILTER_TYPES and assume that we might
+	 throw an exception which doesn't match.  */
+      return gimple_seq_may_fallthru (gimple_eh_filter_failure (gsi_stmt (i)));
+
+    default:
+      /* This case represents statements to be executed when an
+	 exception occurs.  Those statements are implicitly followed
+	 by a GIMPLE_RESX to resume execution after the exception.  So
+	 in this case the try/catch never falls through.  */
+      return false;
+    }
+}
+
+
+/* Try to determine if we can fall out of the bottom of BLOCK.  This guess
+   need not be 100% accurate; simply be conservative and return true if we
+   don't know.  This is used only to avoid stupidly generating extra code.
+   If we're wrong, we'll just delete the extra code later.  */
+
+bool
+block_may_fallthru (const_tree block)
+{
+  /* This CONST_CAST is okay because expr_last returns its argument
+     unmodified and we assign it to a const_tree.  */
+  const_tree stmt = expr_last (CONST_CAST_TREE(block));
+
+  switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
+    {
+    case GOTO_EXPR:
+    case RETURN_EXPR:
+    case RESX_EXPR:
+      /* Easy cases.  If the last statement of the block implies 
+	 control transfer, then we can't fall through.  */
+      return false;
+
+    case SWITCH_EXPR:
+      /* If SWITCH_LABELS is set, this is lowered, and represents a
+	 branch to a selected label and hence can not fall through.
+	 Otherwise SWITCH_BODY is set, and the switch can fall
+	 through.  */
+      return SWITCH_LABELS (stmt) == NULL_TREE;
+
+    case COND_EXPR:
+      if (block_may_fallthru (COND_EXPR_THEN (stmt)))
+	return true;
+      return block_may_fallthru (COND_EXPR_ELSE (stmt));
+
+    case BIND_EXPR:
+      return block_may_fallthru (BIND_EXPR_BODY (stmt));
+
+    case TRY_CATCH_EXPR:
+      return try_catch_may_fallthru (stmt);
+
+    case TRY_FINALLY_EXPR:
+      /* The finally clause is always executed after the try clause,
+	 so if it does not fall through, then the try-finally will not
+	 fall through.  Otherwise, if the try clause does not fall
+	 through, then when the finally clause falls through it will
+	 resume execution wherever the try clause was going.  So the
+	 whole try-finally will only fall through if both the try
+	 clause and the finally clause fall through.  */
+      return (block_may_fallthru (TREE_OPERAND (stmt, 0))
+	      && block_may_fallthru (TREE_OPERAND (stmt, 1)));
+
+    case MODIFY_EXPR:
+      if (TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR)
+	stmt = TREE_OPERAND (stmt, 1);
+      else
+	return true;
+      /* FALLTHRU */
+
+    case CALL_EXPR:
+      /* Functions that do not return do not fall through.  */
+      return (call_expr_flags (stmt) & ECF_NORETURN) == 0;
+    
+    case CLEANUP_POINT_EXPR:
+      return block_may_fallthru (TREE_OPERAND (stmt, 0));
+
+    default:
+      return true;
+    }
+}
+
+
+/* Try to determine if we can continue executing the statement
+   immediately following STMT.  This guess need not be 100% accurate;
+   simply be conservative and return true if we don't know.  This is
+   used only to avoid stupidly generating extra code. If we're wrong,
+   we'll just delete the extra code later.  */
+
+bool
+gimple_stmt_may_fallthru (gimple stmt)
+{
+  if (!stmt)
+    return true;
+
+  switch (gimple_code (stmt))
+    {
+    case GIMPLE_GOTO:
+    case GIMPLE_RETURN:
+    case GIMPLE_RESX:
+      /* Easy cases.  If the last statement of the seq implies 
+	 control transfer, then we can't fall through.  */
+      return false;
+
+    case GIMPLE_SWITCH:
+      /* Switch has already been lowered and represents a
+	 branch to a selected label and hence can not fall through.  */
+      return true;
+
+    case GIMPLE_COND:
+      /* GIMPLE_COND's are already lowered into a two-way branch.  They
+	 can't fall through.  */
+      return false;
+
+    case GIMPLE_BIND:
+      return gimple_seq_may_fallthru (gimple_bind_body (stmt));
+
+    case GIMPLE_TRY:
+      if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH)
+        return gimple_try_catch_may_fallthru (stmt);
+
+      /* It must be a GIMPLE_TRY_FINALLY.  */
+
+      /* The finally clause is always executed after the try clause,
+	 so if it does not fall through, then the try-finally will not
+	 fall through.  Otherwise, if the try clause does not fall
+	 through, then when the finally clause falls through it will
+	 resume execution wherever the try clause was going.  So the
+	 whole try-finally will only fall through if both the try
+	 clause and the finally clause fall through.  */
+      return (gimple_seq_may_fallthru (gimple_try_eval (stmt))
+	      && gimple_seq_may_fallthru (gimple_try_cleanup (stmt)));
+
+    case GIMPLE_ASSIGN:
+      return true;
+
+    case GIMPLE_CALL:
+      /* Functions that do not return do not fall through.  */
+      return (gimple_call_flags (stmt) & ECF_NORETURN) == 0;
+    
+    default:
+      return true;
+    }
+}
+
+
+/* Same as gimple_stmt_may_fallthru, but for the gimple sequence SEQ.  */
+
+bool
+gimple_seq_may_fallthru (gimple_seq seq)
+{
+  return gimple_stmt_may_fallthru (gimple_seq_last_stmt (seq));
+}
+
+
+/* Lower a GIMPLE_RETURN GSI.  DATA is passed through the recursion.  */
+
+static void
+lower_gimple_return (gimple_stmt_iterator *gsi, struct lower_data *data)
+{
+  gimple stmt = gsi_stmt (*gsi);
+  gimple t;
+  int i;
+  return_statements_t tmp_rs;
+
+  /* Match this up with an existing return statement that's been created.  */
+  for (i = VEC_length (return_statements_t, data->return_statements) - 1;
+       i >= 0; i--)
+    {
+      tmp_rs = *VEC_index (return_statements_t, data->return_statements, i);
+
+      if (gimple_return_retval (stmt) == gimple_return_retval (tmp_rs.stmt))
+	goto found;
+    }
+
+  /* Not found.  Create a new label and record the return statement.  */
+  tmp_rs.label = create_artificial_label ();
+  tmp_rs.stmt = stmt;
+  VEC_safe_push (return_statements_t, heap, data->return_statements, &tmp_rs);
+
+  /* Generate a goto statement and remove the return statement.  */
+ found:
+  t = gimple_build_goto (tmp_rs.label);
+  gimple_set_location (t, gimple_location (stmt));
+  gimple_set_block (t, gimple_block (stmt));
+  gsi_insert_before (gsi, t, GSI_SAME_STMT);
+  gsi_remove (gsi, false);
+}
+
+/* Lower a __builtin_setjmp TSI.
+
+   __builtin_setjmp is passed a pointer to an array of five words (not
+   all will be used on all machines).  It operates similarly to the C
+   library function of the same name, but is more efficient.
+
+   It is lowered into 3 other builtins, namely __builtin_setjmp_setup,
+   __builtin_setjmp_dispatcher and __builtin_setjmp_receiver, but with
+   __builtin_setjmp_dispatcher shared among all the instances; that's
+   why it is only emitted at the end by lower_function_body.
+
+   After full lowering, the body of the function should look like:
+
+    {
+      void * setjmpvar.0;
+      int D.1844;
+      int D.2844;
+
+      [...]
+
+      __builtin_setjmp_setup (&buf, &<D1847>);
+      D.1844 = 0;
+      goto <D1846>;
+      <D1847>:;
+      __builtin_setjmp_receiver (&<D1847>);
+      D.1844 = 1;
+      <D1846>:;
+      if (D.1844 == 0) goto <D1848>; else goto <D1849>;
+
+      [...]
+
+      __builtin_setjmp_setup (&buf, &<D2847>);
+      D.2844 = 0;
+      goto <D2846>;
+      <D2847>:;
+      __builtin_setjmp_receiver (&<D2847>);
+      D.2844 = 1;
+      <D2846>:;
+      if (D.2844 == 0) goto <D2848>; else goto <D2849>;
+
+      [...]
+
+      <D3850>:;
+      return;
+      <D3853>: [non-local];
+      setjmpvar.0 = __builtin_setjmp_dispatcher (&<D3853>);
+      goto setjmpvar.0;
+    }
+
+   The dispatcher block will be both the unique destination of all the
+   abnormal call edges and the unique source of all the abnormal edges
+   to the receivers, thus keeping the complexity explosion localized.  */
+
+static void
+lower_builtin_setjmp (gimple_stmt_iterator *gsi)
+{
+  gimple stmt = gsi_stmt (*gsi);
+  tree cont_label = create_artificial_label ();
+  tree next_label = create_artificial_label ();
+  tree dest, t, arg;
+  gimple g;
+
+  /* NEXT_LABEL is the label __builtin_longjmp will jump to.  Its address is
+     passed to both __builtin_setjmp_setup and __builtin_setjmp_receiver.  */
+  FORCED_LABEL (next_label) = 1;
+
+  dest = gimple_call_lhs (stmt);
+
+  /* Build '__builtin_setjmp_setup (BUF, NEXT_LABEL)' and insert.  */
+  arg = build_addr (next_label, current_function_decl);
+  t = implicit_built_in_decls[BUILT_IN_SETJMP_SETUP];
+  g = gimple_build_call (t, 2, gimple_call_arg (stmt, 0), arg);
+  gimple_set_location (g, gimple_location (stmt));
+  gimple_set_block (g, gimple_block (stmt));
+  gsi_insert_before (gsi, g, GSI_SAME_STMT);
+
+  /* Build 'DEST = 0' and insert.  */
+  if (dest)
+    {
+      g = gimple_build_assign (dest, fold_convert (TREE_TYPE (dest),
+						   integer_zero_node));
+      gimple_set_location (g, gimple_location (stmt));
+      gimple_set_block (g, gimple_block (stmt));
+      gsi_insert_before (gsi, g, GSI_SAME_STMT);
+    }
+
+  /* Build 'goto CONT_LABEL' and insert.  */
+  g = gimple_build_goto (cont_label);
+  gsi_insert_before (gsi, g, TSI_SAME_STMT);
+
+  /* Build 'NEXT_LABEL:' and insert.  */
+  g = gimple_build_label (next_label);
+  gsi_insert_before (gsi, g, GSI_SAME_STMT);
+
+  /* Build '__builtin_setjmp_receiver (NEXT_LABEL)' and insert.  */
+  arg = build_addr (next_label, current_function_decl);
+  t = implicit_built_in_decls[BUILT_IN_SETJMP_RECEIVER];
+  g = gimple_build_call (t, 1, arg);
+  gimple_set_location (g, gimple_location (stmt));
+  gimple_set_block (g, gimple_block (stmt));
+  gsi_insert_before (gsi, g, GSI_SAME_STMT);
+
+  /* Build 'DEST = 1' and insert.  */
+  if (dest)
+    {
+      g = gimple_build_assign (dest, fold_convert (TREE_TYPE (dest),
+						   integer_one_node));
+      gimple_set_location (g, gimple_location (stmt));
+      gimple_set_block (g, gimple_block (stmt));
+      gsi_insert_before (gsi, g, GSI_SAME_STMT);
+    }
+
+  /* Build 'CONT_LABEL:' and insert.  */
+  g = gimple_build_label (cont_label);
+  gsi_insert_before (gsi, g, GSI_SAME_STMT);
+
+  /* Remove the call to __builtin_setjmp.  */
+  gsi_remove (gsi, false);
+}
+
+
+/* Record the variables in VARS into function FN.  */
+
+void
+record_vars_into (tree vars, tree fn)
+{
+  if (fn != current_function_decl)
+    push_cfun (DECL_STRUCT_FUNCTION (fn));
+
+  for (; vars; vars = TREE_CHAIN (vars))
+    {
+      tree var = vars;
+
+      /* BIND_EXPRs contains also function/type/constant declarations
+         we don't need to care about.  */
+      if (TREE_CODE (var) != VAR_DECL)
+	continue;
+
+      /* Nothing to do in this case.  */
+      if (DECL_EXTERNAL (var))
+	continue;
+
+      /* Record the variable.  */
+      cfun->local_decls = tree_cons (NULL_TREE, var,
+					     cfun->local_decls);
+    }
+
+  if (fn != current_function_decl)
+    pop_cfun ();
+}
+
+
+/* Record the variables in VARS into current_function_decl.  */
+
+void
+record_vars (tree vars)
+{
+  record_vars_into (vars, current_function_decl);
+}
+
+
+/* Mark BLOCK used if it has a used variable in it, then recurse over its
+   subblocks.  */
+
+static void
+mark_blocks_with_used_vars (tree block)
+{
+  tree var;
+  tree subblock;
+
+  if (!TREE_USED (block))
+    {
+      for (var = BLOCK_VARS (block);
+	   var;
+	   var = TREE_CHAIN (var))
+	{
+	  if (TREE_USED (var))
+	    {
+	      TREE_USED (block) = true;
+	      break;
+	    }
+	}
+    }
+  for (subblock = BLOCK_SUBBLOCKS (block);
+       subblock;
+       subblock = BLOCK_CHAIN (subblock))
+    mark_blocks_with_used_vars (subblock);
+}
+
+/* Mark the used attribute on blocks correctly.  */
+  
+static unsigned int
+mark_used_blocks (void)
+{  
+  mark_blocks_with_used_vars (DECL_INITIAL (current_function_decl));
+  return 0;
+}
+
+
+struct gimple_opt_pass pass_mark_used_blocks = 
+{
+ {
+  GIMPLE_PASS,
+  "blocks",				/* name */
+  NULL,					/* gate */
+  mark_used_blocks,			/* execute */
+  NULL,					/* sub */
+  NULL,					/* next */
+  0,					/* static_pass_number */
+  0,					/* tv_id */
+  0,					/* properties_required */
+  0,					/* properties_provided */
+  0,					/* properties_destroyed */
+  0,					/* todo_flags_start */
+  TODO_dump_func			/* todo_flags_finish */
+ }
+};