 gfortran.h        |    5 -
 intrinsic.c       |    3
 invoke.texi       |    6 +
 iresolve.c        |   10 ++-
 libgfortran.h     |    3
 options.c         |    2
 simplify.c        |    6 +
 trans-decl.c      |  118 +++++++++++++++++++++++++++++++++++++
 trans-intrinsic.c |   22 ++++++
 trans-stmt.c      |  172 +++++++++++++++++++++++++++++++++++++++++++++++-------
 trans.h           |   19 +++++
 11 files changed, 340 insertions(+), 26 deletions(-)

diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index b64fa20..9a6907e 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -458,7 +458,7 @@ enum gfc_isym_id
   GFC_ISYM_NORM2,
   GFC_ISYM_NOT,
   GFC_ISYM_NULL,
-  GFC_ISYM_NUMIMAGES,
+  GFC_ISYM_NUM_IMAGES,
   GFC_ISYM_OR,
   GFC_ISYM_PACK,
   GFC_ISYM_PARITY,
@@ -572,7 +572,8 @@ init_local_integer;
 typedef enum
 {
   GFC_FCOARRAY_NONE = 0,
-  GFC_FCOARRAY_SINGLE
+  GFC_FCOARRAY_SINGLE,
+  GFC_FCOARRAY_LIB
 }
 gfc_fcoarray;
 
diff --git a/gcc/fortran/intrinsic.c b/gcc/fortran/intrinsic.c
index 80dbaa8..0fea078 100644
--- a/gcc/fortran/intrinsic.c
+++ b/gcc/fortran/intrinsic.c
@@ -2358,7 +2358,8 @@ add_functions (void)
 
   make_generic ("null", GFC_ISYM_NULL, GFC_STD_F95);
 
-  add_sym_0 ("num_images", GFC_ISYM_NUMIMAGES, CLASS_INQUIRY, ACTUAL_NO, BT_INTEGER, di, GFC_STD_F2008,
+  add_sym_0 ("num_images", GFC_ISYM_NUM_IMAGES, CLASS_INQUIRY, ACTUAL_NO,
+	     BT_INTEGER, di, GFC_STD_F2008,
 	     NULL, gfc_simplify_num_images, NULL);
 
   add_sym_3 ("pack", GFC_ISYM_PACK, CLASS_TRANSFORMATIONAL, ACTUAL_NO, BT_REAL, dr, GFC_STD_F95,
diff --git a/gcc/fortran/invoke.texi b/gcc/fortran/invoke.texi
index 291d1e7..f934015 100644
--- a/gcc/fortran/invoke.texi
+++ b/gcc/fortran/invoke.texi
@@ -166,7 +166,7 @@ and warnings}.
 -fwhole-file -fsecond-underscore @gol
 -fbounds-check -fcheck-array-temporaries  -fmax-array-constructor =@var{n} @gol
 -fcheck=@var{<all|array-temps|bounds|do|mem|pointer|recursion>} @gol
--fcoarray=@var{<none|single>} -fmax-stack-var-size=@var{n} @gol
+-fcoarray=@var{<none|single|lib>} -fmax-stack-var-size=@var{n} @gol
 -fpack-derived  -frepack-arrays  -fshort-enums  -fexternal-blas @gol
 -fblas-matmul-limit=@var{n} -frecursive -finit-local-zero @gol
 -finit-integer=@var{n} -finit-real=@var{<zero|inf|-inf|nan|snan>} @gol
@@ -1248,6 +1248,10 @@ statements will produce a compile-time error. (Default)
 
 @item @samp{single}
 Single-image mode, i.e. @code{num_images()} is always one.
+
+@item @samp{lib}
+Library-based coarray parallelization; a suitable GNU Fortran coarray
+library needs to be linked.
 @end table
 
 
diff --git a/gcc/fortran/iresolve.c b/gcc/fortran/iresolve.c
index d8309d2..f023544 100644
--- a/gcc/fortran/iresolve.c
+++ b/gcc/fortran/iresolve.c
@@ -2556,7 +2556,15 @@ gfc_resolve_image_index (gfc_expr *f, gfc_expr *array ATTRIBUTE_UNUSED,
 void
 gfc_resolve_this_image (gfc_expr *f, gfc_expr *array, gfc_expr *dim)
 {
-  resolve_bound (f, array, dim, NULL, "__this_image", true);
+  static char this_image[] = "__this_image";
+  if (array)
+    resolve_bound (f, array, dim, NULL, "__this_image", true);
+  else
+    {
+      f->ts.type = BT_INTEGER;
+      f->ts.kind = gfc_default_integer_kind;
+      f->value.function.name = this_image;
+    }
 }
 
 
diff --git a/gcc/fortran/libgfortran.h b/gcc/fortran/libgfortran.h
index 85a73d8..a87a057 100644
--- a/gcc/fortran/libgfortran.h
+++ b/gcc/fortran/libgfortran.h
@@ -98,12 +98,13 @@ typedef enum
 }
 libgfortran_error_codes;
 
+/* Must kept in sync with libgfortrancaf.h.  */
 typedef enum
 {
   GFC_STAT_UNLOCKED = 0,
   GFC_STAT_LOCKED,
   GFC_STAT_LOCKED_OTHER_IMAGE,
-  GFC_STAT_STOPPED_IMAGE
+  GFC_STAT_STOPPED_IMAGE /* See LIBERROR_INQUIRE_INTERNAL_UNIT above. */
 }
 libgfortran_stat_codes;
 
diff --git a/gcc/fortran/options.c b/gcc/fortran/options.c
index c116103..d81be4c 100644
--- a/gcc/fortran/options.c
+++ b/gcc/fortran/options.c
@@ -515,6 +515,8 @@ gfc_handle_coarray_option (const char *arg)
     gfc_option.coarray = GFC_FCOARRAY_NONE;
   else if (strcmp (arg, "single") == 0)
     gfc_option.coarray = GFC_FCOARRAY_SINGLE;
+  else if (strcmp (arg, "lib") == 0)
+    gfc_option.coarray = GFC_FCOARRAY_LIB;
   else
     gfc_fatal_error ("Argument to -fcoarray is not valid: %s", arg);
 }
diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
index bb8b575..69edad8 100644
--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -4591,6 +4591,9 @@ gfc_simplify_num_images (void)
       return &gfc_bad_expr;
     }
 
+  if (gfc_option.coarray != GFC_FCOARRAY_SINGLE)
+    return NULL;
+
   /* FIXME: gfc_current_locus is wrong.  */
   result = gfc_get_constant_expr (BT_INTEGER, gfc_default_integer_kind,
 				  &gfc_current_locus);
@@ -6313,6 +6316,9 @@ gfc_simplify_this_image (gfc_expr *coarray, gfc_expr *dim)
   gfc_array_spec *as;
   int d;
 
+  if (gfc_option.coarray != GFC_FCOARRAY_SINGLE)
+    return NULL;
+
   if (coarray == NULL)
     {
       gfc_expr *result;
diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
index 08207e0..3e63de5 100644
--- a/gcc/fortran/trans-decl.c
+++ b/gcc/fortran/trans-decl.c
@@ -111,6 +111,22 @@ tree gfor_fndecl_in_unpack;
 tree gfor_fndecl_associated;
 
 
+/* Coarray run-time library function decls.  */
+tree gfor_fndecl_caf_init;
+tree gfor_fndecl_caf_finalize;
+tree gfor_fndecl_caf_critical;
+tree gfor_fndecl_caf_end_critical;
+tree gfor_fndecl_caf_sync_all;
+tree gfor_fndecl_caf_sync_images;
+tree gfor_fndecl_caf_error_stop;
+tree gfor_fndecl_caf_error_stop_str;
+
+/* Coarray global variables for num_images/this_image.  */
+
+tree gfort_gvar_caf_num_images;
+tree gfort_gvar_caf_this_image;
+
+
 /* Math functions.  Many other math functions are handled in
    trans-intrinsic.c.  */
 
@@ -3003,6 +3019,50 @@ gfc_build_builtin_function_decls (void)
   DECL_PURE_P (gfor_fndecl_associated) = 1;
   TREE_NOTHROW (gfor_fndecl_associated) = 1;
 
+  /* Coarray library calls.  */
+  if (gfc_option.coarray == GFC_FCOARRAY_LIB)
+    {
+      tree pint_type, pppchar_type;
+
+      pint_type = build_pointer_type (integer_type_node);
+      pppchar_type
+	= build_pointer_type (build_pointer_type (pchar_type_node));
+
+      gfor_fndecl_caf_init = gfc_build_library_function_decl (
+		   get_identifier (PREFIX("caf_init")),  void_type_node,
+		   4, pint_type, pppchar_type, pint_type, pint_type);
+
+      gfor_fndecl_caf_finalize = gfc_build_library_function_decl (
+	get_identifier (PREFIX("caf_finalize")), void_type_node, 0);
+
+      gfor_fndecl_caf_critical = gfc_build_library_function_decl (
+	get_identifier (PREFIX("caf_critical")), void_type_node, 0);
+
+      gfor_fndecl_caf_end_critical = gfc_build_library_function_decl (
+	get_identifier (PREFIX("caf_end_critical")), void_type_node, 0);
+
+      gfor_fndecl_caf_sync_all = gfc_build_library_function_decl_with_spec (
+	get_identifier (PREFIX("caf_sync_all")), ".W", integer_type_node,
+	2, build_pointer_type (pchar_type_node), integer_type_node);
+
+      gfor_fndecl_caf_sync_images = gfc_build_library_function_decl_with_spec (
+	get_identifier (PREFIX("caf_sync_images")), ".RRW", integer_type_node,
+	4, integer_type_node, pint_type, build_pointer_type (pchar_type_node),
+	integer_type_node);
+
+      gfor_fndecl_caf_error_stop = gfc_build_library_function_decl (
+	get_identifier (PREFIX("caf_error_stop")),
+	void_type_node, 1, gfc_int4_type_node);
+      /* CAF's ERROR STOP doesn't return.  */
+      TREE_THIS_VOLATILE (gfor_fndecl_caf_error_stop) = 1;
+
+      gfor_fndecl_caf_error_stop_str = gfc_build_library_function_decl_with_spec (
+	get_identifier (PREFIX("caf_error_stop_str")), ".R.",
+	void_type_node, 2, pchar_type_node, gfc_int4_type_node);
+      /* CAF's ERROR STOP doesn't return.  */
+      TREE_THIS_VOLATILE (gfor_fndecl_caf_error_stop_str) = 1;
+    }
+
   gfc_build_intrinsic_function_decls ();
   gfc_build_intrinsic_lib_fndecls ();
   gfc_build_io_library_fndecls ();
@@ -4405,6 +4465,40 @@ add_argument_checking (stmtblock_t *block, gfc_symbol *sym)
 }
 
 
+void
+gfc_init_coarray_decl (void)
+{
+  tree save_fn_decl = current_function_decl;
+
+  if (gfc_option.coarray != GFC_FCOARRAY_LIB)
+    return;
+
+  if (gfort_gvar_caf_this_image || gfort_gvar_caf_num_images)
+    return;
+
+  save_fn_decl = current_function_decl;
+  current_function_decl = NULL_TREE;
+  push_cfun (cfun);
+
+  gfort_gvar_caf_this_image = gfc_create_var (integer_type_node,
+					      PREFIX("caf_this_image"));
+  DECL_ARTIFICIAL (gfort_gvar_caf_this_image) = 1;
+  TREE_USED (gfort_gvar_caf_this_image) = 1;
+  TREE_PUBLIC (gfort_gvar_caf_this_image) = 1;
+  TREE_STATIC (gfort_gvar_caf_this_image) = 1;
+
+  gfort_gvar_caf_num_images = gfc_create_var (integer_type_node,
+					      PREFIX("caf_num_images"));
+  DECL_ARTIFICIAL (gfort_gvar_caf_num_images) = 1;
+  TREE_USED (gfort_gvar_caf_num_images) = 1;
+  TREE_PUBLIC (gfort_gvar_caf_num_images) = 1;
+  TREE_STATIC (gfort_gvar_caf_num_images) = 1;
+
+  pop_cfun ();
+  current_function_decl = save_fn_decl;
+}
+
+
 static void
 create_main_function (tree fndecl)
 {
@@ -4484,6 +4578,23 @@ create_main_function (tree fndecl)
 
   /* Call some libgfortran initialization routines, call then MAIN__(). */
 
+  /* Call _gfortran_caf_init (*argc, ***argv, *this_image, *num_images).  */
+  if (gfc_option.coarray == GFC_FCOARRAY_LIB)
+    {
+      tree pint_type, pppchar_type;
+      pint_type = build_pointer_type (integer_type_node);
+      pppchar_type
+	= build_pointer_type (build_pointer_type (pchar_type_node));
+
+      gfc_init_coarray_decl ();
+      tmp = build_call_expr_loc (input_location, gfor_fndecl_caf_init, 4,
+		gfc_build_addr_expr (pint_type, argc),
+		gfc_build_addr_expr (pppchar_type, argv),
+		gfc_build_addr_expr (pint_type, gfort_gvar_caf_this_image),
+		gfc_build_addr_expr (pint_type, gfort_gvar_caf_num_images));
+      gfc_add_expr_to_block (&body, tmp);
+    }
+
   /* Call _gfortran_set_args (argc, argv).  */
   TREE_USED (argc) = 1;
   TREE_USED (argv) = 1;
@@ -4601,6 +4712,13 @@ create_main_function (tree fndecl)
   /* Mark MAIN__ as used.  */
   TREE_USED (fndecl) = 1;
 
+  /* Coarray: Call _gfortran_caf_finalize(void).  */
+  if (gfc_option.coarray == GFC_FCOARRAY_LIB)
+    {
+      tmp = build_call_expr_loc (input_location, gfor_fndecl_caf_finalize, 0);
+      gfc_add_expr_to_block (&body, tmp);
+    }
+
   /* "return 0".  */
   tmp = fold_build2_loc (input_location, MODIFY_EXPR, integer_type_node,
 			 DECL_RESULT (ftn_main),
diff --git a/gcc/fortran/trans-intrinsic.c b/gcc/fortran/trans-intrinsic.c
index 502a815..100620d 100644
--- a/gcc/fortran/trans-intrinsic.c
+++ b/gcc/fortran/trans-intrinsic.c
@@ -918,6 +918,20 @@ gfc_conv_intrinsic_exponent (gfc_se *se, gfc_expr *expr)
   se->expr = fold_convert (type, res);
 }
 
+static void
+trans_this_image (gfc_se * se, gfc_expr *expr ATTRIBUTE_UNUSED)
+{
+  gfc_init_coarray_decl ();
+  se->expr = gfort_gvar_caf_this_image;
+}
+
+static void
+trans_num_images (gfc_se * se)
+{
+  gfc_init_coarray_decl ();
+  se->expr = gfort_gvar_caf_num_images;
+}
+
 /* Evaluate a single upper or lower bound.  */
 /* TODO: bound intrinsic generates way too much unnecessary code.  */
 
@@ -6111,6 +6125,14 @@ gfc_conv_intrinsic_function (gfc_se * se, gfc_expr * expr)
       gfc_conv_intrinsic_loc (se, expr);
       break;
 
+    case GFC_ISYM_THIS_IMAGE:
+      trans_this_image (se, expr);
+      break;
+
+    case GFC_ISYM_NUM_IMAGES:
+      trans_num_images (se);
+      break;
+
     case GFC_ISYM_ACCESS:
     case GFC_ISYM_CHDIR:
     case GFC_ISYM_CHMOD:
diff --git a/gcc/fortran/trans-stmt.c b/gcc/fortran/trans-stmt.c
index 98fb74c..4de490c8 100644
--- a/gcc/fortran/trans-stmt.c
+++ b/gcc/fortran/trans-stmt.c
@@ -599,11 +599,20 @@ gfc_trans_stop (gfc_code *code, bool error_stop)
   gfc_init_se (&se, NULL);
   gfc_start_block (&se.pre);
 
+  if (gfc_option.coarray == GFC_FCOARRAY_LIB && !error_stop)
+    {
+      tmp = build_call_expr_loc (input_location, gfor_fndecl_caf_finalize, 0);
+      gfc_add_expr_to_block (&se.pre, tmp);
+    }
+
   if (code->expr1 == NULL)
     {
       tmp = build_int_cst (gfc_int4_type_node, 0);
       tmp = build_call_expr_loc (input_location,
-				 error_stop ? gfor_fndecl_error_stop_string
+				 error_stop
+				 ? (gfc_option.coarray == GFC_FCOARRAY_LIB
+				    ? gfor_fndecl_caf_error_stop_str
+				    : gfor_fndecl_error_stop_string)
 				 : gfor_fndecl_stop_string,
 				 2, build_int_cst (pchar_type_node, 0), tmp);
     }
@@ -611,7 +620,10 @@ gfc_trans_stop (gfc_code *code, bool error_stop)
     {
       gfc_conv_expr (&se, code->expr1);
       tmp = build_call_expr_loc (input_location,
-				 error_stop ? gfor_fndecl_error_stop_numeric
+				 error_stop
+				 ? (gfc_option.coarray == GFC_FCOARRAY_LIB
+				    ? gfor_fndecl_caf_error_stop
+				    : gfor_fndecl_error_stop_numeric)
 				 : gfor_fndecl_stop_numeric_f08, 1, 
 				 fold_convert (gfc_int4_type_node, se.expr));
     }
@@ -619,7 +631,10 @@ gfc_trans_stop (gfc_code *code, bool error_stop)
     {
       gfc_conv_expr_reference (&se, code->expr1);
       tmp = build_call_expr_loc (input_location,
-				 error_stop ? gfor_fndecl_error_stop_string
+				 error_stop
+				 ? (gfc_option.coarray == GFC_FCOARRAY_LIB
+				    ? gfor_fndecl_caf_error_stop_str
+				    : gfor_fndecl_error_stop_string)
 				 : gfor_fndecl_stop_string,
 				 2, se.expr, se.string_length);
     }
@@ -633,14 +648,55 @@ gfc_trans_stop (gfc_code *code, bool error_stop)
 
 
 tree
-gfc_trans_sync (gfc_code *code, gfc_exec_op type __attribute__ ((unused)))
+gfc_trans_sync (gfc_code *code, gfc_exec_op type)
 {
-  gfc_se se;
+  gfc_se se, argse;
+  tree tmp;
+  tree images = NULL_TREE, stat = NULL_TREE,
+       errmsg = NULL_TREE, errmsglen = NULL_TREE;
+
+  /* Short cut: For single images without bound checking or without STAT=,
+     return early. (ERRMSG= is always untouched for -fcoarray=single.)  */
+  if (!code->expr1 && !(gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)
+      && gfc_option.coarray != GFC_FCOARRAY_LIB)
+    return NULL_TREE; 
 
-  if ((code->expr1 && (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)) || code->expr2)
+  gfc_init_se (&se, NULL);
+  gfc_start_block (&se.pre);
+
+  if (code->expr1 && code->expr1->rank == 0)
     {
-      gfc_init_se (&se, NULL);
-      gfc_start_block (&se.pre);
+      gfc_init_se (&argse, NULL);
+      gfc_conv_expr_val (&argse, code->expr1);
+      images = argse.expr;
+    }
+
+  /* FIXME: Handle the case that STAT= or ERRMSG= variable
+     is an absent dummy argument. ERRMSG might be OK, but
+     LOCAL STAT might have an issue. */
+
+  if (code->expr2)
+    {
+      gcc_assert (code->expr2->expr_type == EXPR_VARIABLE);
+      gfc_init_se (&argse, NULL);
+      gfc_conv_expr_val (&argse, code->expr2);
+      stat = argse.expr;
+    }
+
+  if (code->expr3 && gfc_option.coarray == GFC_FCOARRAY_LIB
+      && type != EXEC_SYNC_MEMORY)
+    {
+      gcc_assert (code->expr3->expr_type == EXPR_VARIABLE);
+      gfc_init_se (&argse, NULL);
+      gfc_conv_expr (&argse, code->expr3);
+      gfc_conv_string_parameter (&argse);
+      errmsg = argse.expr;
+      errmsglen = argse.string_length;
+    }
+  else if (gfc_option.coarray == GFC_FCOARRAY_LIB && type != EXEC_SYNC_MEMORY)
+    {
+      errmsg = null_pointer_node;
+      errmsglen = build_int_cst (integer_type_node, 0);
     }
 
   /* Check SYNC IMAGES(imageset) for valid image index.
@@ -649,27 +705,88 @@ gfc_trans_sync (gfc_code *code, gfc_exec_op type __attribute__ ((unused)))
       && code->expr1->rank == 0)
     {
       tree cond;
-      gfc_conv_expr (&se, code->expr1);
-      cond = fold_build2_loc (input_location, NE_EXPR, boolean_type_node,
-			      se.expr, build_int_cst (TREE_TYPE (se.expr), 1));
+      if (gfc_option.coarray != GFC_FCOARRAY_LIB)
+	cond = fold_build2_loc (input_location, NE_EXPR, boolean_type_node,
+				images, build_int_cst (TREE_TYPE (images), 1));
+      else
+	{
+	  tree cond2;
+	  cond = fold_build2_loc (input_location, GE_EXPR, boolean_type_node,
+				  images, gfort_gvar_caf_num_images);
+	  cond2 = fold_build2_loc (input_location, LT_EXPR, boolean_type_node,
+				   images,
+				   build_int_cst (TREE_TYPE (images), 1));
+	  cond = fold_build2_loc (input_location, TRUTH_AND_EXPR,
+				  boolean_type_node, cond, cond2);
+	}
       gfc_trans_runtime_check (true, false, cond, &se.pre,
 			       &code->expr1->where, "Invalid image number "
 			       "%d in SYNC IMAGES",
 			       fold_convert (integer_type_node, se.expr));
     }
 
-  /* If STAT is present, set it to zero.  */
-  if (code->expr2)
+  if (gfc_option.coarray != GFC_FCOARRAY_LIB || type == EXEC_SYNC_MEMORY)
     {
-      gcc_assert (code->expr2->expr_type == EXPR_VARIABLE);
-      gfc_conv_expr (&se, code->expr2);
-      gfc_add_modify (&se.pre, se.expr, build_int_cst (TREE_TYPE (se.expr), 0));
+       if (gfc_option.coarray == GFC_FCOARRAY_LIB)
+	 {
+	   tmp = built_in_decls [BUILT_IN_SYNCHRONIZE];
+	   tmp = build_call_expr_loc (input_location, tmp, 0);
+	   gfc_add_expr_to_block (&se.pre, tmp);
+	 }
+
+      /* Set STAT to zero.  */
+      if (code->expr2)
+	gfc_add_modify (&se.pre, stat, build_int_cst (TREE_TYPE (stat), 0));
+    }
+  else if (type == EXEC_SYNC_ALL)
+    {
+      tmp = build_call_expr_loc (input_location, gfor_fndecl_caf_sync_all,
+				 2, errmsg, errmsglen);
+      if (code->expr2)
+	gfc_add_modify (&se.pre, stat, fold_convert (TREE_TYPE (stat), tmp));
+      else
+	gfc_add_expr_to_block (&se.pre, tmp);
     }
+  else
+    {
+      tree len;
+
+      gcc_assert (type == EXEC_SYNC_IMAGES);
 
-  if ((code->expr1 && (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)) || code->expr2)
-    return gfc_finish_block (&se.pre);
- 
-  return NULL_TREE;
+      if (!code->expr1)
+	len = build_int_cst (integer_type_node, -1);
+      else if (code->expr1->rank == 0)
+	{
+	  len = build_int_cst (integer_type_node, 1);
+	  images = gfc_build_addr_expr (NULL_TREE, images);
+	}
+      else
+	{
+	  gfc_conv_array_parameter (&se, code->expr1,
+				    gfc_walk_expr (code->expr1), true, NULL,
+				    NULL, &len);
+	  images = se.expr;
+
+	  tmp = gfc_typenode_for_spec (&code->expr1->ts);
+	  if (GFC_ARRAY_TYPE_P (tmp) || GFC_DESCRIPTOR_TYPE_P (tmp))
+	    tmp = gfc_get_element_type (tmp);
+
+	  len = fold_build2_loc (input_location, TRUNC_DIV_EXPR,
+				 integer_type_node, len,
+				 fold_convert (gfc_array_index_type,
+					       TYPE_SIZE_UNIT (tmp)));
+	}
+
+      tmp = build_call_expr_loc (input_location, gfor_fndecl_caf_sync_images, 4,
+				 fold_convert (integer_type_node, len), images,
+				 errmsg, errmsglen);
+      if (code->expr2)
+	gfc_add_modify (&se.pre, stat, fold_convert (TREE_TYPE (stat), tmp));
+      else
+	gfc_add_expr_to_block (&se.pre, tmp);
+    }
+
+  return gfc_finish_block (&se.pre);
 }
 
 
@@ -870,9 +987,24 @@ gfc_trans_critical (gfc_code *code)
   tree tmp;
 
   gfc_start_block (&block);
+
+  if (gfc_option.coarray == GFC_FCOARRAY_LIB)
+    {
+      tmp = build_call_expr_loc (input_location, gfor_fndecl_caf_critical, 0);
+      gfc_add_expr_to_block (&block, tmp);
+    }
+
   tmp = gfc_trans_code (code->block->next);
   gfc_add_expr_to_block (&block, tmp);
 
+  if (gfc_option.coarray == GFC_FCOARRAY_LIB)
+    {
+      tmp = build_call_expr_loc (input_location, gfor_fndecl_caf_end_critical,
+				 0);
+      gfc_add_expr_to_block (&block, tmp);
+    }
+
+
   return gfc_finish_block (&block);
 }
 
diff --git a/gcc/fortran/trans.h b/gcc/fortran/trans.h
index 1536f2e..997259f 100644
--- a/gcc/fortran/trans.h
+++ b/gcc/fortran/trans.h
@@ -452,6 +452,9 @@ bool gfc_get_module_backend_decl (gfc_symbol *);
 /* Return the variable decl for a symbol.  */
 tree gfc_get_symbol_decl (gfc_symbol *);
 
+/* Initialize coarray global variables.  */
+void gfc_init_coarray_decl (void);
+
 /* Build a static initializer.  */
 tree gfc_conv_initializer (gfc_expr *, gfc_typespec *, tree, bool, bool, bool);
 
@@ -613,6 +616,22 @@ extern GTY(()) tree gfor_fndecl_in_pack;
 extern GTY(()) tree gfor_fndecl_in_unpack;
 extern GTY(()) tree gfor_fndecl_associated;
 
+
+/* Coarray run-time library function decls.  */
+extern GTY(()) tree gfor_fndecl_caf_init;
+extern GTY(()) tree gfor_fndecl_caf_finalize;
+extern GTY(()) tree gfor_fndecl_caf_critical;
+extern GTY(()) tree gfor_fndecl_caf_end_critical;
+extern GTY(()) tree gfor_fndecl_caf_sync_all;
+extern GTY(()) tree gfor_fndecl_caf_sync_images;
+extern GTY(()) tree gfor_fndecl_caf_error_stop;
+extern GTY(()) tree gfor_fndecl_caf_error_stop_str;
+
+/* Coarray global variables for num_images/this_image.  */
+extern GTY(()) tree gfort_gvar_caf_num_images;
+extern GTY(()) tree gfort_gvar_caf_this_image;
+
+
 /* Math functions.  Many other math functions are handled in
    trans-intrinsic.c.  */
 
