Merge tree-ssa-20020619-branch into mainline.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@81764 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 1102 insertions, 0 deletions

diff --git a/gcc/c-simplify.c b/gcc/c-simplify.c
new file mode 100644
index 00000000000..bd50b5e025b
--- /dev/null
+++ b/gcc/c-simplify.c
@@ -0,0 +1,1102 @@
+/* Tree lowering pass.  This pass gimplifies the tree representation built
+   by the C-based front ends.  The structure of gimplified, or
+   language-independent, trees is dictated by the grammar described in this
+   file.
+   Copyright (C) 2002, 2003 Free Software Foundation, Inc.
+   Lowering of expressions contributed by Sebastian Pop <s.pop@laposte.net>
+   Re-written to support lowering of whole function trees, documentation
+   and miscellaneous cleanups by Diego Novillo <dnovillo@redhat.com>
+
+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 2, 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 COPYING.  If not, write to the Free
+Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+02111-1307, USA.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "tree.h"
+#include "errors.h"
+#include "varray.h"
+#include "c-tree.h"
+#include "c-common.h"
+#include "tree-simple.h"
+#include "hard-reg-set.h"
+#include "basic-block.h"
+#include "tree-flow.h"
+#include "tree-inline.h"
+#include "diagnostic.h"
+#include "langhooks.h"
+#include "langhooks-def.h"
+#include "flags.h"
+#include "rtl.h"
+#include "toplev.h"
+#include "tree-dump.h"
+#include "c-pretty-print.h"
+#include "cgraph.h"
+
+
+/*  The gimplification pass converts the language-dependent trees
+    (ld-trees) emitted by the parser into language-independent trees
+    (li-trees) that are the target of SSA analysis and transformations.
+
+    Language-independent trees are based on the SIMPLE intermediate
+    representation used in the McCAT compiler framework:
+
+    "Designing the McCAT Compiler Based on a Family of Structured
+    Intermediate Representations,"
+    L. Hendren, C. Donawa, M. Emami, G. Gao, Justiani, and B. Sridharan,
+    Proceedings of the 5th International Workshop on Languages and
+    Compilers for Parallel Computing, no. 757 in Lecture Notes in
+    Computer Science, New Haven, Connecticut, pp. 406-420,
+    Springer-Verlag, August 3-5, 1992.
+
+    http://www-acaps.cs.mcgill.ca/info/McCAT/McCAT.html
+
+    Basically, we walk down gimplifying the nodes that we encounter.  As we
+    walk back up, we check that they fit our constraints, and copy them
+    into temporaries if not.  */
+
+/* Local declarations.  */
+
+static enum gimplify_status gimplify_expr_stmt (tree *);
+static enum gimplify_status gimplify_decl_stmt (tree *);
+static enum gimplify_status gimplify_for_stmt (tree *, tree *);
+static enum gimplify_status gimplify_while_stmt (tree *);
+static enum gimplify_status gimplify_do_stmt (tree *);
+static enum gimplify_status gimplify_if_stmt (tree *);
+static enum gimplify_status gimplify_switch_stmt (tree *);
+static enum gimplify_status gimplify_return_stmt (tree *);
+static enum gimplify_status gimplify_stmt_expr (tree *);
+static enum gimplify_status gimplify_compound_literal_expr (tree *);
+#if defined ENABLE_CHECKING
+static int is_last_stmt_of_scope (tree);
+#endif
+static enum gimplify_status gimplify_block (tree *, tree *);
+static enum gimplify_status gimplify_cleanup (tree *, tree *);
+static tree gimplify_c_loop (tree, tree, tree, bool);
+static void push_context (void);
+static void pop_context (void);
+static tree c_build_bind_expr (tree, tree);
+static void add_block_to_enclosing (tree);
+static void gimplify_condition (tree *);
+
+enum bc_t { bc_break = 0, bc_continue = 1 };
+static tree begin_bc_block (enum bc_t);
+static tree finish_bc_block (tree, tree);
+static tree build_bc_goto (enum bc_t);
+
+static struct c_gimplify_ctx
+{
+  /* For handling break and continue.  */
+  tree current_bc_label;
+  tree bc_id[2];
+} *ctxp;
+
+static void
+push_context (void)
+{
+  if (ctxp)
+    abort ();
+  ctxp = (struct c_gimplify_ctx *) xcalloc (1, sizeof (struct c_gimplify_ctx));
+  ctxp->bc_id[bc_continue] = get_identifier ("continue");
+  ctxp->bc_id[bc_break] = get_identifier ("break");
+}
+
+static void
+pop_context (void)
+{
+  if (!ctxp || ctxp->current_bc_label)
+    abort ();
+  free (ctxp);
+  ctxp = NULL;
+}
+
+/* Gimplification of statement trees.  */
+
+/* Convert the tree representation of FNDECL from C frontend trees to
+   GENERIC.  */
+
+void
+c_genericize (tree fndecl)
+{
+  FILE *dump_file;
+  int local_dump_flags;
+  struct cgraph_node *cgn;
+
+  /* Dump the C-specific tree IR.  */
+  dump_file = dump_begin (TDI_original, &local_dump_flags);
+  if (dump_file)
+    {
+      fprintf (dump_file, "\n;; Function %s",
+	       (*lang_hooks.decl_printable_name) (fndecl, 2));
+      fprintf (dump_file, " (%s)\n",
+	       IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (fndecl)));
+      fprintf (dump_file, ";; enabled by -%s\n", dump_flag_name (TDI_original));
+      fprintf (dump_file, "\n");
+
+      if (local_dump_flags & TDF_RAW)
+	dump_node (DECL_SAVED_TREE (fndecl),
+		   TDF_SLIM | local_dump_flags, dump_file);
+      else
+	print_c_tree (dump_file, DECL_SAVED_TREE (fndecl));
+      fprintf (dump_file, "\n");
+
+      dump_end (TDI_original, dump_file);
+    }
+
+  /* Go ahead and gimplify for now.  */
+  push_context ();
+  gimplify_function_tree (fndecl);
+  pop_context ();
+
+  /* Dump the genericized tree IR.  */
+  dump_function (TDI_generic, fndecl);
+
+  /* Genericize all nested functions now.  We do things in this order so
+     that items like VLA sizes are expanded properly in the context of
+     the correct function.  */
+  cgn = cgraph_node (fndecl);
+  for (cgn = cgn->nested; cgn ; cgn = cgn->next_nested)
+    c_genericize (cgn->decl);
+}
+
+/*  Entry point for the tree lowering pass.  Recursively scan
+    *STMT_P and convert it to a GIMPLE tree.  */
+
+int
+c_gimplify_stmt (tree *stmt_p)
+{
+  tree stmt, next;
+  tree outer_pre = NULL_TREE;
+
+  /* PRE and POST are tree chains that contain the side-effects of the
+     gimplified tree.  For instance, given the expression tree:
+
+		c = ++a * 3 + b++;
+
+     After gimplification, the tree will be re-written as:
+
+		a = a + 1;
+		t1 = a * 3;	<-- PRE
+		c = t1 + b;
+		b = b + 1;	<-- POST  */
+
+  for (stmt = *stmt_p; stmt && stmt != error_mark_node; stmt = next)
+    {
+      tree pre, post;
+      int saved_stmts_are_full_exprs_p;
+      location_t stmt_locus;
+      enum gimplify_status ret;
+
+      /* Set up context appropriately for handling this statement.  */
+      saved_stmts_are_full_exprs_p = stmts_are_full_exprs_p ();
+      prep_stmt (stmt);
+      stmt_locus = input_location;
+
+      pre = NULL_TREE;
+      post = NULL_TREE;
+
+      next = TREE_CHAIN (stmt);
+
+      switch (TREE_CODE (stmt))
+	{
+	case COMPOUND_STMT:
+	  stmt = COMPOUND_BODY (stmt);
+	  ret = GS_OK;
+	  break;
+
+	case SCOPE_STMT:
+	  ret = gimplify_block (&stmt, &next);
+	  break;
+
+	case FOR_STMT:
+	  ret = gimplify_for_stmt (&stmt, &next);
+	  break;
+
+	case WHILE_STMT:
+	  ret = gimplify_while_stmt (&stmt);
+	  break;
+
+	case DO_STMT:
+	  ret = gimplify_do_stmt (&stmt);
+	  break;
+
+	case IF_STMT:
+	  ret = gimplify_if_stmt (&stmt);
+	  break;
+
+	case SWITCH_STMT:
+	  ret = gimplify_switch_stmt (&stmt);
+	  break;
+
+	case EXPR_STMT:
+	  ret = gimplify_expr_stmt (&stmt);
+	  break;
+
+	case RETURN_STMT:
+	  ret = gimplify_return_stmt (&stmt);
+	  break;
+
+	case DECL_STMT:
+	  ret = gimplify_decl_stmt (&stmt);
+	  break;
+
+	case LABEL_STMT:
+	  stmt = build1 (LABEL_EXPR, void_type_node, LABEL_STMT_LABEL (stmt));
+	  ret = GS_OK;
+	  break;
+
+	case GOTO_STMT:
+	  stmt = build1 (GOTO_EXPR, void_type_node, GOTO_DESTINATION (stmt));
+	  ret = GS_OK;
+	  break;
+
+	case CASE_LABEL:
+	  {
+	    tree label = create_artificial_label ();
+	    stmt = build (CASE_LABEL_EXPR, void_type_node,
+			  CASE_LOW (stmt), CASE_HIGH (stmt), label);
+	    ret = GS_OK;
+	  }
+	  break;
+
+	case CONTINUE_STMT:
+	  stmt = build_bc_goto (bc_continue);
+	  ret = GS_OK;
+	  break;
+
+	case BREAK_STMT:
+	  stmt = build_bc_goto (bc_break);
+	  ret = GS_OK;
+	  break;
+
+	case CLEANUP_STMT:
+	  ret = gimplify_cleanup (&stmt, &next);
+	  break;
+
+	case ASM_STMT:
+	  {
+	    tree new_stmt = build (ASM_EXPR, void_type_node, ASM_STRING (stmt),
+				   ASM_OUTPUTS (stmt), ASM_INPUTS (stmt),
+				   ASM_CLOBBERS (stmt));
+	    ASM_INPUT_P (new_stmt) = ASM_INPUT_P (stmt);
+	    ASM_VOLATILE_P (new_stmt) = ASM_VOLATILE_P (stmt);
+	    stmt = new_stmt;
+	    ret = GS_OK;
+	  }
+	  break;
+
+	default:
+	  if (lang_gimplify_stmt && (*lang_gimplify_stmt) (&stmt, &next))
+	    {
+	      ret = GS_OK;
+	      break;
+	    }
+
+	  fprintf (stderr, "unhandled statement node in c_gimplify_stmt:\n");
+	  debug_tree (stmt);
+	  abort ();
+	  break;
+	}
+
+      switch (ret)
+	{
+	case GS_ERROR:
+	  goto cont;
+	case GS_OK:
+          gimplify_stmt (&stmt);
+	  break;
+	case GS_ALL_DONE:
+	  break;
+	default:
+	  abort ();
+	}
+
+      /* PRE and POST now contain a list of statements for all the
+	 side-effects in STMT.  */
+
+      append_to_statement_list (stmt, &pre);
+      append_to_statement_list (post, &pre);
+      annotate_all_with_locus (&pre, stmt_locus);
+
+      append_to_statement_list (pre, &outer_pre);
+    cont:
+      /* Restore saved state.  */
+      current_stmt_tree ()->stmts_are_full_exprs_p
+	= saved_stmts_are_full_exprs_p;
+    }
+  append_to_statement_list (stmt, &outer_pre);
+  *stmt_p = outer_pre;
+
+  return GS_ALL_DONE;
+}
+
+static void
+add_block_to_enclosing (tree block)
+{
+  tree enclosing;
+
+  for (enclosing = gimple_current_bind_expr ();
+       enclosing; enclosing = TREE_CHAIN (enclosing))
+    if (BIND_EXPR_BLOCK (enclosing))
+      break;
+
+  enclosing = BIND_EXPR_BLOCK (enclosing);
+  BLOCK_SUBBLOCKS (enclosing) = chainon (BLOCK_SUBBLOCKS (enclosing), block);
+}
+
+/* Genericize a scope by creating a new BIND_EXPR.
+   BLOCK is either a BLOCK representing the scope or a chain of _DECLs.
+     In the latter case, we need to create a new BLOCK and add it to the
+     BLOCK_SUBBLOCKS of the enclosing block.
+   BODY is a chain of C _STMT nodes for the contents of the scope, to be
+     genericized.  */
+
+static tree
+c_build_bind_expr (tree block, tree body)
+{
+  tree decls, bind;
+
+  if (block == NULL_TREE)
+    decls = NULL_TREE;
+  else if (TREE_CODE (block) == BLOCK)
+    decls = BLOCK_VARS (block);
+  else
+    {
+      decls = block;
+      if (DECL_ARTIFICIAL (decls))
+	block = NULL_TREE;
+      else
+	{
+	  block = make_node (BLOCK);
+	  BLOCK_VARS (block) = decls;
+	  add_block_to_enclosing (block);
+	}
+    }
+
+  if (!body)
+    body = build_empty_stmt ();
+
+  bind = build (BIND_EXPR, void_type_node, decls, body, block);
+  TREE_SIDE_EFFECTS (bind) = 1;
+
+  return bind;
+}
+
+/* Genericize a syntactic block by removing the bracketing SCOPE_STMTs and
+   wrapping the intervening code in a BIND_EXPR.  This function assumes
+   that matching SCOPE_STMTs will always appear in the same statement
+   sequence.  */
+
+static enum gimplify_status
+gimplify_block (tree *stmt_p, tree *next_p)
+{
+  tree *p;
+  tree block;
+  tree bind;
+  int depth;
+  location_t stmt_locus;
+
+  if (!SCOPE_BEGIN_P (*stmt_p))
+    {
+      /* Can wind up mismatched with syntax errors.  */
+      if (!errorcount && !sorrycount)
+	abort ();
+      *stmt_p = NULL;
+      return GS_ERROR;
+    }
+
+  block = SCOPE_STMT_BLOCK (*stmt_p);
+
+  /* Find the matching ending SCOPE_STMT.  */
+  depth = 1;
+  for (p = &TREE_CHAIN (*stmt_p);; p = &TREE_CHAIN (*p))
+    {
+      if (*p == NULL)
+	break;
+      if (TREE_CODE (*p) == SCOPE_STMT)
+	{
+	  if (SCOPE_BEGIN_P (*p))
+	    ++depth;
+	  else if (--depth == 0)
+	    break;
+	}
+    }
+
+  stmt_locus = input_location;
+  if (*p)
+    {
+      if (SCOPE_STMT_BLOCK (*p) != block)
+	abort ();
+      if (EXPR_LOCUS (*p))
+	stmt_locus = *EXPR_LOCUS (*p);
+      *next_p = TREE_CHAIN (*p);
+      *p = NULL_TREE;
+    }
+  else
+    {
+      /* Can wind up mismatched with syntax errors.  */
+      if (!errorcount && !sorrycount)
+	abort ();
+    }
+
+  bind = c_build_bind_expr (block, TREE_CHAIN (*stmt_p));
+  *stmt_p = bind;
+  input_location = stmt_locus;
+
+  return GS_OK;
+}
+
+/* Genericize a CLEANUP_STMT.  Just wrap everything from here to the end of
+   the block in a TRY_FINALLY_EXPR.  Or a TRY_CATCH_EXPR, if it's an
+   EH-only cleanup.  */
+
+static enum gimplify_status
+gimplify_cleanup (tree *stmt_p, tree *next_p)
+{
+  tree stmt = *stmt_p;
+  tree body = TREE_CHAIN (stmt);
+  tree cleanup = CLEANUP_EXPR (stmt);
+  enum tree_code code
+    = (CLEANUP_EH_ONLY (stmt) ? TRY_CATCH_EXPR : TRY_FINALLY_EXPR);
+
+  if (!body)
+    body = build_empty_stmt ();
+  if (!cleanup)
+    cleanup = build_empty_stmt ();
+
+  *stmt_p = build (code, void_type_node, body, cleanup);
+  *next_p = NULL_TREE;
+
+  return GS_OK;
+}
+
+/*  Gimplify an EXPR_STMT node.
+
+    STMT is the statement node.
+
+    PRE_P points to the list where side effects that must happen before
+	STMT should be stored.
+
+    POST_P points to the list where side effects that must happen after
+	STMT should be stored.  */
+
+static enum gimplify_status
+gimplify_expr_stmt (tree *stmt_p)
+{
+  tree stmt = EXPR_STMT_EXPR (*stmt_p);
+
+  if (stmt == error_mark_node)
+    stmt = NULL;
+
+  /* Gimplification of a statement expression will nullify the
+     statement if all its side effects are moved to *PRE_P and *POST_P.
+
+     In this case we will not want to emit the gimplified statement.
+     However, we may still want to emit a warning, so we do that before
+     gimplification.  */
+  if (stmt && (extra_warnings || warn_unused_value))
+    {
+      if (!TREE_SIDE_EFFECTS (stmt))
+	{
+	  if (!IS_EMPTY_STMT (stmt)
+	      && !VOID_TYPE_P (TREE_TYPE (stmt))
+	      && !TREE_NO_WARNING (stmt))
+	    warning ("statement with no effect");
+	}
+      else if (warn_unused_value)
+	{
+	  /* Kludge for 20020220-2.c.  warn_if_unused_value shouldn't use
+	     the stmt file location info.  */
+	  set_file_and_line_for_stmt (input_location);
+	  warn_if_unused_value (stmt);
+	}
+    }
+
+  if (stmt == NULL_TREE)
+    stmt = build_empty_stmt ();
+  else if (stmts_are_full_exprs_p ())
+    stmt = build1 (CLEANUP_POINT_EXPR, void_type_node, stmt);
+
+  *stmt_p = stmt;
+
+  return GS_OK;
+}
+
+/* If the condition for a loop (or the like) is a decl, it will be a
+   TREE_LIST where the TREE_PURPOSE is a DECL_STMT and the TREE_VALUE is
+   a use of the decl.  Turn such a thing into a COMPOUND_EXPR.  */
+
+static void
+gimplify_condition (tree *cond_p)
+{
+  tree cond = *cond_p;
+  if (cond && TREE_CODE (cond) == TREE_LIST)
+    {
+      tree decl = TREE_PURPOSE (cond);
+      tree value = TREE_VALUE (cond);
+      c_gimplify_stmt (&decl);
+      *cond_p = build (COMPOUND_EXPR, TREE_TYPE (value), decl, value);
+    }
+}
+
+/* Begin a scope which can be exited by a break or continue statement.  BC
+   indicates which.
+
+   Just creates a label and pushes it into the current context.  */
+
+static tree
+begin_bc_block (enum bc_t bc)
+{
+  tree label = create_artificial_label ();
+  DECL_NAME (label) = ctxp->bc_id[bc];
+  TREE_CHAIN (label) = ctxp->current_bc_label;
+  ctxp->current_bc_label = label;
+  return label;
+}
+
+/* Finish a scope which can be exited by a break or continue statement.
+   LABEL was returned from the most recent call to begin_bc_block.  BODY is
+   an expression for the contents of the scope.
+
+   If we saw a break (or continue) in the scope, append a LABEL_EXPR to
+   body.  Otherwise, just forget the label.  */
+
+static tree
+finish_bc_block (tree label, tree body)
+{
+  if (label != ctxp->current_bc_label)
+    abort ();
+
+  if (TREE_USED (label))
+    {
+      tree t, sl = NULL;
+
+      /* Clear the name so flow can delete the label.  */
+      DECL_NAME (label) = NULL_TREE;
+      t = build1 (LABEL_EXPR, void_type_node, label);
+
+      append_to_statement_list (body, &sl);
+      append_to_statement_list (t, &sl);
+      body = sl;
+    }
+
+  ctxp->current_bc_label = TREE_CHAIN (label);
+  TREE_CHAIN (label) = NULL_TREE;
+  return body;
+}
+
+/* Build a GOTO_EXPR to represent a break or continue statement.  BC
+   indicates which.  */
+
+static tree
+build_bc_goto (enum bc_t bc)
+{
+  tree label;
+  tree target_name = ctxp->bc_id[bc];
+
+  /* Look for the appropriate type of label.  */
+  for (label = ctxp->current_bc_label;
+       label;
+       label = TREE_CHAIN (label))
+    if (DECL_NAME (label) == target_name)
+      break;
+
+  if (label == NULL_TREE)
+    {
+      if (bc == bc_break)
+	error ("break statement not within loop or switch");
+      else
+	error ("continue statement not within loop or switch");
+
+      return NULL_TREE;
+    }
+
+  /* Mark the label used for finish_bc_block.  */
+  TREE_USED (label) = 1;
+  return build1 (GOTO_EXPR, void_type_node, label);
+}
+
+/* Build a generic representation of one of the C loop forms.  COND is the
+   loop condition or NULL_TREE.  BODY is the (possibly compound) statement
+   controlled by the loop.  INCR is the increment expression of a for-loop,
+   or NULL_TREE.  COND_IS_FIRST indicates whether the condition is
+   evaluated before the loop body as in while and for loops, or after the
+   loop body as in do-while loops.  */
+
+static tree
+gimplify_c_loop (tree cond, tree body, tree incr, bool cond_is_first)
+{
+  tree top, entry, exit, cont_block, break_block, stmt_list, t;
+  location_t stmt_locus;
+
+  stmt_locus = input_location;
+
+  /* Detect do { ... } while (0) and don't generate loop construct.  */
+  if (!cond_is_first && cond && integer_zerop (cond))
+    top = cond = NULL;
+  else
+    {
+      /* If we use a LOOP_EXPR here, we have to feed the whole thing
+	 back through the main gimplifier to lower it.  Given that we
+	 have to gimplify the loop body NOW so that we can resolve
+	 break/continue stmts, seems easier to just expand to gotos.  */
+      top = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
+    }
+
+  break_block = begin_bc_block (bc_break);
+
+  if (top)
+    {
+      /* If we have an exit condition, then we build an IF with gotos either
+	 out of the loop, or to the top of it.  If there's no exit condition,
+	 then we just build a jump back to the top.  */
+      exit = build_and_jump (&LABEL_EXPR_LABEL (top));
+      if (cond)
+	{
+	  gimplify_condition (&cond);
+	  t = build_bc_goto (bc_break);
+	  exit = build (COND_EXPR, void_type_node, cond, exit, t);
+	  exit = fold (exit);
+	  gimplify_stmt (&exit);
+	}
+    }
+  else
+    exit = NULL_TREE;
+
+  cont_block = begin_bc_block (bc_continue);
+
+  gimplify_stmt (&body);
+  if (incr && stmts_are_full_exprs_p ())
+    incr = fold (build1 (CLEANUP_POINT_EXPR, void_type_node, incr));
+  gimplify_stmt (&incr);
+
+  body = finish_bc_block (cont_block, body);
+
+  stmt_list = NULL;
+
+  if (cond_is_first && cond)
+    {
+      entry = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
+      t = build_and_jump (&LABEL_EXPR_LABEL (entry));
+      append_to_statement_list (t, &stmt_list);
+    }
+  else
+    entry = NULL_TREE;
+
+  append_to_statement_list (top, &stmt_list);
+  append_to_statement_list (body, &stmt_list);
+  append_to_statement_list (incr, &stmt_list);
+  append_to_statement_list (entry, &stmt_list);
+  append_to_statement_list (exit, &stmt_list);
+
+  annotate_all_with_locus (&stmt_list, stmt_locus);
+
+  return finish_bc_block (break_block, stmt_list);
+}
+
+/* Gimplify a FOR_STMT node.  Move the stuff in the for-init-stmt into the
+   prequeue and hand off to gimplify_c_loop.  */
+
+static enum gimplify_status
+gimplify_for_stmt (tree *stmt_p, tree *next_p)
+{
+  tree stmt = *stmt_p;
+  tree init = FOR_INIT_STMT (stmt);
+
+  if (init)
+    {
+      /* Reorganize the statements so that we do the right thing with a
+	 CLEANUP_STMT.  We want the FOR_STMT and nothing else to be in the
+	 scope of the cleanup, so play with pointers to accomplish that. */
+      FOR_INIT_STMT (stmt) = NULL_TREE;
+      chainon (init, stmt);
+      *stmt_p = init;
+      *next_p = TREE_CHAIN (stmt);
+      TREE_CHAIN (stmt) = NULL_TREE;
+      c_gimplify_stmt (stmt_p);
+    }
+  else
+    *stmt_p = gimplify_c_loop (FOR_COND (stmt), FOR_BODY (stmt),
+			       FOR_EXPR (stmt), 1);
+
+  return GS_ALL_DONE;
+}
+
+/* Gimplify a WHILE_STMT node.  */
+
+static enum gimplify_status
+gimplify_while_stmt (tree *stmt_p)
+{
+  tree stmt = *stmt_p;
+  *stmt_p = gimplify_c_loop (WHILE_COND (stmt), WHILE_BODY (stmt),
+			     NULL_TREE, 1);
+  return GS_ALL_DONE;
+}
+
+/* Gimplify a DO_STMT node.  */
+
+static enum gimplify_status
+gimplify_do_stmt (tree *stmt_p)
+{
+  tree stmt = *stmt_p;
+  *stmt_p = gimplify_c_loop (DO_COND (stmt), DO_BODY (stmt),
+			     NULL_TREE, 0);
+  return GS_ALL_DONE;
+}
+
+/* Genericize an IF_STMT by turning it into a COND_EXPR.  */
+
+static enum gimplify_status
+gimplify_if_stmt (tree *stmt_p)
+{
+  tree stmt, then_, else_;
+
+  stmt = *stmt_p;
+ restart:
+  then_ = THEN_CLAUSE (stmt);
+  else_ = ELSE_CLAUSE (stmt);
+
+  if (!then_)
+    then_ = build_empty_stmt ();
+  if (!else_)
+    else_ = build_empty_stmt ();
+
+  stmt = build (COND_EXPR, void_type_node, IF_COND (stmt), then_, else_);
+  gimplify_condition (& TREE_OPERAND (stmt, 0));
+  *stmt_p = stmt;
+
+  /* Handle properly nested if-else chains via iteration instead of
+     mutual recursion between gimplify.c and c-simplify.c.  */
+  annotate_with_locus (stmt, input_location);
+  if (TREE_CODE (else_) == IF_STMT && !TREE_CHAIN (else_))
+    {
+      stmt_p = &COND_EXPR_ELSE (stmt);
+      stmt = else_;
+      prep_stmt (stmt);
+      goto restart;
+    }
+
+  return GS_OK;
+}
+
+/* Genericize a SWITCH_STMT by turning it into a SWITCH_EXPR.  */
+
+static enum gimplify_status
+gimplify_switch_stmt (tree *stmt_p)
+{
+  tree stmt = *stmt_p;
+  tree break_block, body;
+  location_t stmt_locus = input_location;
+
+  break_block = begin_bc_block (bc_break);
+
+  gimplify_condition (&SWITCH_COND (stmt));
+
+  body = SWITCH_BODY (stmt);
+  if (!body)
+    body = build_empty_stmt ();
+
+  *stmt_p = build (SWITCH_EXPR, SWITCH_TYPE (stmt), SWITCH_COND (stmt),
+		   body, NULL_TREE);
+  annotate_with_locus (*stmt_p, stmt_locus);
+  gimplify_stmt (stmt_p);
+
+  *stmt_p = finish_bc_block (break_block, *stmt_p);
+  return GS_ALL_DONE;
+}
+
+/* Genericize a RETURN_STMT by turning it into a RETURN_EXPR.  */
+
+static enum gimplify_status
+gimplify_return_stmt (tree *stmt_p)
+{
+  tree expr = RETURN_STMT_EXPR (*stmt_p);
+  expr = build1 (RETURN_EXPR, void_type_node, expr);
+  if (stmts_are_full_exprs_p ())
+    expr = build1 (CLEANUP_POINT_EXPR, void_type_node, expr);
+  *stmt_p = expr;
+  return GS_OK;
+}
+
+/* Gimplifies a DECL_STMT node T.
+
+   If a declaration V has an initial value I, create an expression 'V = I'
+   and insert it after the DECL_STMT.
+
+   PRE_P is a queue for effects that should happen before the DECL_STMT.
+
+   MID_P is a queue for effects that should happen after the DECL_STMT,
+   but before uses of the initialized decl.
+
+   POST_P is a queue for effects that should happen after uses of the
+   initialized decl.
+
+   Usually these last two will be the same, but they may need to be
+   different if the DECL_STMT is somehow embedded in an expression.  */
+
+static enum gimplify_status
+gimplify_decl_stmt (tree *stmt_p)
+{
+  tree stmt = *stmt_p;
+  tree decl = DECL_STMT_DECL (stmt);
+  tree pre = NULL_TREE;
+  tree post = NULL_TREE;
+
+  if (TREE_TYPE (decl) == error_mark_node)
+    {
+      *stmt_p = NULL;
+      return GS_ERROR;
+    }
+    
+  if (TREE_CODE (decl) == TYPE_DECL)
+    {
+      tree type = TREE_TYPE (decl);
+      if (TYPE_SIZE_UNIT (type)
+          && !TREE_CONSTANT (TYPE_SIZE_UNIT (type)))
+        {
+          /* This is a variable-sized array type.  Simplify its size.  */
+          tree temp = TYPE_SIZE_UNIT (type);
+          gimplify_expr (&temp, &pre, &post, is_gimple_val, fb_rvalue);
+        }
+    }
+
+  if (TREE_CODE (decl) == VAR_DECL && !DECL_EXTERNAL (decl))
+    {
+      tree init = DECL_INITIAL (decl);
+
+      if (!TREE_CONSTANT (DECL_SIZE (decl)))
+	{
+	  tree pt_type = build_pointer_type (TREE_TYPE (decl));
+	  tree alloc, size;
+
+	  /* This is a variable-sized decl.  Simplify its size and mark it
+	     for deferred expansion.  Note that mudflap depends on the format
+	     of the emitted code: see mx_register_decls().  */
+
+	  size = get_initialized_tmp_var (DECL_SIZE_UNIT (decl), &pre, &post);
+	  DECL_DEFER_OUTPUT (decl) = 1;
+	  alloc = build_function_call_expr
+	    (implicit_built_in_decls[BUILT_IN_STACK_ALLOC],
+	     tree_cons (NULL_TREE,
+			build1 (ADDR_EXPR, pt_type, decl),
+			tree_cons (NULL_TREE, size, NULL_TREE)));
+	  append_to_compound_expr (alloc, &pre);
+	}
+
+      if (init && init != error_mark_node)
+	{
+	  if (!TREE_STATIC (decl))
+	    {
+              /* Do not warn about int x = x; as it is a GCC extension
+                 to turn off this warning but only if warn_init_self
+		 is zero.  */
+              if (init == decl && !warn_init_self)
+                TREE_NO_WARNING (decl) = 1;
+              
+	      DECL_INITIAL (decl) = NULL_TREE;
+	      init = build (MODIFY_EXPR, void_type_node, decl, init);
+	      if (stmts_are_full_exprs_p ())
+		init = build1 (CLEANUP_POINT_EXPR, void_type_node, init);
+	      append_to_compound_expr (init, &pre);
+	    }
+	  else
+	    {
+	      /* We must still examine initializers for static variables
+		 as they may contain a label address.  */
+	      walk_tree (&init, force_labels_r, NULL, NULL);
+	    }
+	}
+
+      /* This decl isn't mentioned in the enclosing block, so add it to the
+	 list of temps.  FIXME it seems a bit of a kludge to say that
+	 anonymous artificial vars aren't pushed, but everything else is.  */
+      if (DECL_ARTIFICIAL (decl) && DECL_NAME (decl) == NULL_TREE)
+	gimple_add_tmp_var (decl);
+    }
+
+  append_to_compound_expr (post, &pre);
+  *stmt_p = pre;
+  return GS_OK;
+}
+
+/* Gimplification of expression trees.  */
+
+/* Gimplify a C99 compound literal expression.  This just means adding the
+   DECL_STMT before the current EXPR_STMT and using its anonymous decl
+   instead.  */
+
+static enum gimplify_status
+gimplify_compound_literal_expr (tree *expr_p)
+{
+  tree decl_s = COMPOUND_LITERAL_EXPR_DECL_STMT (*expr_p);
+  tree decl = DECL_STMT_DECL (decl_s);
+
+  /* This decl isn't mentioned in the enclosing block, so add it to the
+     list of temps.  FIXME it seems a bit of a kludge to say that
+     anonymous artificial vars aren't pushed, but everything else is.  */
+  if (DECL_NAME (decl) == NULL_TREE)
+    gimple_add_tmp_var (decl);
+
+  gimplify_decl_stmt (&decl_s);
+  *expr_p = decl_s ? decl_s : decl;
+  return GS_OK;
+}
+
+/* Do C-specific gimplification.  Args are as for gimplify_expr.  */
+
+int
+c_gimplify_expr (tree *expr_p, tree *pre_p ATTRIBUTE_UNUSED,
+		 tree *post_p ATTRIBUTE_UNUSED)
+{
+  enum tree_code code = TREE_CODE (*expr_p);
+
+  if (STATEMENT_CODE_P (code))
+    return c_gimplify_stmt (expr_p);
+
+  switch (code)
+    {
+    case COMPOUND_LITERAL_EXPR:
+      return gimplify_compound_literal_expr (expr_p);
+
+    case STMT_EXPR:
+      return gimplify_stmt_expr (expr_p);
+
+    default:
+      return GS_UNHANDLED;
+    }
+}
+
+/* Returns the final EXPR_STMT which represents the return value of a
+   STMT_EXPR, or NULL_TREE if none.  */
+
+tree
+stmt_expr_last_stmt (tree stmt_expr)
+{
+  tree body = STMT_EXPR_STMT (stmt_expr);
+  tree last_stmt, substmt;
+
+  /* Splice the last expression out of the STMT chain.  */
+  last_stmt = NULL_TREE;
+  for (substmt = COMPOUND_BODY (body); substmt;
+       substmt = TREE_CHAIN (substmt))
+    if (TREE_CODE (substmt) != SCOPE_STMT)
+      last_stmt = substmt;
+
+  if (last_stmt == NULL_TREE
+      || TREE_CODE (last_stmt) != EXPR_STMT
+      || (TREE_TYPE (last_stmt)
+	  && VOID_TYPE_P (TREE_TYPE (last_stmt))))
+    {
+      location_t loc;
+      if (last_stmt && EXPR_LOCUS (last_stmt))
+	loc = *EXPR_LOCUS (last_stmt);
+      else if (EXPR_LOCUS (stmt_expr))
+	loc = *EXPR_LOCUS (stmt_expr);
+      else
+	loc = input_location;
+      warning ("%Hstatement-expressions should end with a "
+	       "non-void expression", &loc);
+      last_stmt = NULL_TREE;
+    }
+
+#if defined ENABLE_CHECKING
+  if (last_stmt && !is_last_stmt_of_scope (last_stmt))
+    abort ();
+#endif
+
+  return last_stmt;
+}
+
+/* Gimplify a STMT_EXPR.  EXPR_P points to the expression to gimplify.
+   After gimplification, if the STMT_EXPR returns a value, EXPR_P will
+   point to a new temporary that holds that value; otherwise it will be
+   null.
+
+   PRE_P points to the list where side effects that must happen before
+     *EXPR_P should be stored.  */
+
+static enum gimplify_status
+gimplify_stmt_expr (tree *expr_p)
+{
+  tree body = STMT_EXPR_STMT (*expr_p);
+
+  if (VOID_TYPE_P (TREE_TYPE (*expr_p)))
+    {
+      *expr_p = body;
+      return c_gimplify_stmt (expr_p);
+    }
+  else
+    {
+      tree last_stmt = stmt_expr_last_stmt (*expr_p);
+      tree last_expr = NULL_TREE;
+
+      if (last_stmt)
+	{
+	  last_expr = EXPR_STMT_EXPR (last_stmt);
+
+	  if (stmts_are_full_exprs_p ())
+	    last_expr = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (last_expr),
+				last_expr);
+	  EXPR_STMT_EXPR (last_stmt) = NULL_TREE;
+	}
+
+      /* Genericize the block.  */
+      c_gimplify_stmt (&body);
+
+      /* Now retrofit that last expression into the BIND_EXPR.  */
+      if (last_expr)
+	{
+	  tree *sub_p;
+
+	  if (!STMT_EXPR_NO_SCOPE (*expr_p))
+	    {
+	      /* Our BIND_EXPR will always be hidden within
+		 a STATEMENT_LIST.  Discard that.  */
+	      body = expr_first (body);
+	      sub_p = &BIND_EXPR_BODY (body);
+
+	      /* Append the last expression to the end of the BIND_EXPR.
+		 We'll now re-process this, and let voidify_wrapper_expr
+		 do its job.  */
+	      append_to_statement_list_force (last_expr, sub_p);
+	      TREE_TYPE (body) = TREE_TYPE (last_expr);
+	    }
+	  else
+	    append_to_compound_expr (last_expr, &body);
+	}
+
+      *expr_p = body;
+      return GS_OK;
+    }
+}
+
+/* Code generation.  */
+
+/* Miscellaneous helpers.  */
+
+#if defined ENABLE_CHECKING
+/*  Return nonzero if STMT is the last statement of its scope.  */
+
+static int
+is_last_stmt_of_scope (tree stmt)
+{
+  return (TREE_CHAIN (stmt) == NULL_TREE
+	  || (TREE_CODE (TREE_CHAIN (stmt)) == SCOPE_STMT
+	      && SCOPE_END_P (TREE_CHAIN (stmt))));
+}
+#endif