Index: config/aarch64/aarch64.h
===================================================================
--- config/aarch64/aarch64.h	(revision 239944)
+++ config/aarch64/aarch64.h	(working copy)
@@ -806,6 +806,10 @@ typedef struct
    correctly.  */
 #define TRAMPOLINE_SECTION text_section
 
+/* Use custom descriptors instead of trampolines when possible, but
+   TARGET_PTRMEMFUNC_VBIT_LOCATION is defined so use bit #1.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 2
+
 /* To start with.  */
 #define BRANCH_COST(SPEED_P, PREDICTABLE_P) \
   (aarch64_branch_cost (SPEED_P, PREDICTABLE_P))
Index: config/alpha/alpha.h
===================================================================
--- config/alpha/alpha.h	(revision 239944)
+++ config/alpha/alpha.h	(working copy)
@@ -996,3 +996,6 @@ extern long alpha_auto_offset;
 #define NO_IMPLICIT_EXTERN_C
 
 #define TARGET_SUPPORTS_WIDE_INT 1
+
+/* Use custom descriptors instead of trampolines when possible if not VMS.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS (TARGET_ABI_OPEN_VMS ? 0 : 1)
Index: config/arm/arm.c
===================================================================
--- config/arm/arm.c	(revision 239944)
+++ config/arm/arm.c	(working copy)
@@ -6818,6 +6818,29 @@ arm_function_ok_for_sibcall (tree decl, tree exp)
       && DECL_WEAK (decl))
     return false;
 
+  /* We cannot do a tailcall for an indirect call by descriptor if all the
+     argument registers are used because the only register left to load the
+     address is IP and it will already contain the static chain.  */
+  if (!decl && CALL_EXPR_BY_DESCRIPTOR (exp) && !flag_trampolines)
+    {
+      tree fntype = TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (exp)));
+      CUMULATIVE_ARGS cum;
+      cumulative_args_t cum_v;
+
+      arm_init_cumulative_args (&cum, fntype, NULL_RTX, NULL_TREE);
+      cum_v = pack_cumulative_args (&cum);
+
+      for (tree t = TYPE_ARG_TYPES (fntype); t; t = TREE_CHAIN (t))
+	{
+	  tree type = TREE_VALUE (t);
+	  if (!VOID_TYPE_P (type))
+	    arm_function_arg_advance (cum_v, TYPE_MODE (type), type, true);
+	}
+
+      if (!arm_function_arg (cum_v, SImode, integer_type_node, true))
+	return false;
+    }
+
   /* Everything else is ok.  */
   return true;
 }
@@ -30187,7 +30210,9 @@ arm_relayout_function (tree fndecl)
     callee_tree = target_option_default_node;
 
   struct cl_target_option *opts = TREE_TARGET_OPTION (callee_tree);
-  SET_DECL_ALIGN (fndecl, FUNCTION_BOUNDARY_P (opts->x_target_flags));
+  SET_DECL_ALIGN (fndecl,
+		  FUNCTION_ALIGNMENT
+		  (FUNCTION_BOUNDARY_P (opts->x_target_flags)));
 }
 
 /* Inner function to process the attribute((target(...))), take an argument and
Index: config/arm/arm.h
===================================================================
--- config/arm/arm.h	(revision 239944)
+++ config/arm/arm.h	(working copy)
@@ -1645,6 +1645,10 @@ typedef struct
 
 /* Alignment required for a trampoline in bits.  */
 #define TRAMPOLINE_ALIGNMENT  32
+
+/* Use custom descriptors instead of trampolines when possible, but
+   TARGET_PTRMEMFUNC_VBIT_LOCATION is defined so use bit #1.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 2
 
 /* Addressing modes, and classification of registers for them.  */
 #define HAVE_POST_INCREMENT   1
Index: config/i386/i386.h
===================================================================
--- config/i386/i386.h	(revision 239944)
+++ config/i386/i386.h	(working copy)
@@ -2670,6 +2670,9 @@ extern void debug_dispatch_window (int);
 
 #define TARGET_SUPPORTS_WIDE_INT 1
 
+/* Use custom descriptors instead of trampolines when possible.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 1
+
 /*
 Local variables:
 version-control: t
Index: config/ia64/ia64.h
===================================================================
--- config/ia64/ia64.h	(revision 239944)
+++ config/ia64/ia64.h	(working copy)
@@ -1714,4 +1714,7 @@ struct GTY(()) machine_function
 /* Switch on code for querying unit reservations.  */
 #define CPU_UNITS_QUERY 1
 
+/* IA-64 already uses descriptors for its standard calling sequence.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 0
+
 /* End of ia64.h */
Index: config/mips/mips.h
===================================================================
--- config/mips/mips.h	(revision 239944)
+++ config/mips/mips.h	(working copy)
@@ -3413,3 +3413,7 @@ struct GTY(())  machine_function {
 #define ENABLE_LD_ST_PAIRS \
   (TARGET_LOAD_STORE_PAIRS && (TUNE_P5600 || TUNE_I6400) \
    && !TARGET_MICROMIPS && !TARGET_FIX_24K)
+
+/* Use custom descriptors instead of trampolines when possible, but
+   TARGET_PTRMEMFUNC_VBIT_LOCATION is defined so use bit #1.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 2
Index: config/pa/pa.h
===================================================================
--- config/pa/pa.h	(revision 239944)
+++ config/pa/pa.h	(working copy)
@@ -1313,3 +1313,6 @@ do {									     \
    seven and four instructions, respectively.  */  
 #define MAX_PCREL17F_OFFSET \
   (flag_pic ? (TARGET_HPUX ? 198164 : 221312) : 240000)
+
+/* HP-PA already uses descriptors for its standard calling sequence.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 0
Index: config/rs6000/rs6000.h
===================================================================
--- config/rs6000/rs6000.h	(revision 239944)
+++ config/rs6000/rs6000.h	(working copy)
@@ -2914,3 +2914,6 @@ extern GTY(()) tree rs6000_builtin_types[RS6000_BT
 extern GTY(()) tree rs6000_builtin_decls[RS6000_BUILTIN_COUNT];
 
 #define TARGET_SUPPORTS_WIDE_INT 1
+
+/* Use custom descriptors instead of trampolines when possible if not AIX.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS (DEFAULT_ABI == ABI_AIX ? 0 : 1)
Index: config/sparc/sparc.h
===================================================================
--- config/sparc/sparc.h	(revision 239944)
+++ config/sparc/sparc.h	(working copy)
@@ -1817,3 +1817,6 @@ extern int sparc_indent_opcode;
 #define SPARC_LOW_FE_EXCEPT_VALUES 0
 
 #define TARGET_SUPPORTS_WIDE_INT 1
+
+/* Use custom descriptors instead of trampolines when possible.  */
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 1