target-insns.def: Add memory_blockage.

	* target-insns.def: Add memory_blockage.
	* optabs.c (expand_memory_blockage): New function.
	(expand_asm_memory_barrier): Rename ...
	(expand_asm_memory_blockage): ... to this.
	(expand_mem_thread_fence): Call expand_memory_blockage
	instead of expand_asm_memory_barrier.
	(expand_mem_singnal_fence): Ditto.
	(expand_atomic_load): Ditto.
	(expand_atomic_store): Ditto.
	* doc/md.texi (Standard Pattern Names For Generation):
	Document memory_blockage instruction pattern.

From-SVN: r253750

gcc/ChangeLog

+2017-10-14  Uros Bizjak  <ubizjak@gmail.com>
+
+	* target-insns.def: Add memory_blockage.
+	* optabs.c (expand_memory_blockage): New function.
+	(expand_asm_memory_barrier): Rename ...
+	(expand_asm_memory_blockage): ... to this.
+	(expand_mem_thread_fence): Call expand_memory_blockage
+	instead of expand_asm_memory_barrier.
+	(expand_mem_singnal_fence): Ditto.
+	(expand_atomic_load): Ditto.
+	(expand_atomic_store): Ditto.
+	* doc/md.texi (Standard Pattern Names For Generation):
+	Document memory_blockage instruction pattern.
+
 2017-10-13  Sebastian Perta  <sebastian.perta@renesas.com>
 
 	* config/rl78/rl78.c (rl78_emit_libcall): New function.
@@ -27,8 +41,7 @@
 
 2017-10-13  Jan Hubicka  <hubicka@ucw.cz>
 
-	* cfghooks.c (verify_flow_info): Check that edge probabilities are
-	set.
+	* cfghooks.c (verify_flow_info): Check that edge probabilities are set.
 
 2017-10-13  Nathan Sidwell  <nathan@acm.org>
 
@@ -63,8 +76,7 @@
 	graphite_expression_type_precision): Avoid global constructor
 	by moving ...
 	(translate_isl_ast_to_gimple::translate_isl_ast_to_gimple): Here.
-	(translate_isl_ast_to_gimple::graphite_expr_type): Add type
-	member.
+	(translate_isl_ast_to_gimple::graphite_expr_type): Add type member.
 	(translate_isl_ast_to_gimple::translate_isl_ast_node_for): Use it.
 	(translate_isl_ast_to_gimple::build_iv_mapping): Likewise.
 	(translate_isl_ast_to_gimple::graphite_create_new_guard): Likewise.

gcc/doc/md.texi

@@ -6734,6 +6734,15 @@ scheduler and other passes from moving instructions and using register
 equivalences across the boundary defined by the blockage insn.
 This needs to be an UNSPEC_VOLATILE pattern or a volatile ASM.
 
+@cindex @code{memory_blockage} instruction pattern
+@item @samp{memory_blockage}
+This pattern, if defined, represents a compiler memory barrier, and will be
+placed at points across which RTL passes may not propagate memory accesses.
+This instruction needs to read and write volatile BLKmode memory.  It does
+not need to generate any machine instruction.  If this pattern is not defined,
+the compiler falls back to emitting an instruction corresponding
+to @code{asm volatile ("" ::: "memory")}.
+
 @cindex @code{memory_barrier} instruction pattern
 @item @samp{memory_barrier}
 If the target memory model is not fully synchronous, then this pattern

gcc/optabs.c

@@ -6273,10 +6273,10 @@ expand_atomic_compare_and_swap (rtx *ptarget_bool, rtx *ptarget_oval,
   return true;
 }
 
-/* Generate asm volatile("" : : : "memory") as the memory barrier.  */
+/* Generate asm volatile("" : : : "memory") as the memory blockage.  */
 
 static void
-expand_asm_memory_barrier (void)
+expand_asm_memory_blockage (void)
 {
   rtx asm_op, clob;
 
@@ -6292,6 +6292,17 @@ expand_asm_memory_barrier (void)
   emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, asm_op, clob)));
 }
 
+/* Do not propagate memory accesses across this point.  */
+
+static void
+expand_memory_blockage (void)
+{
+  if (targetm.have_memory_blockage)
+    emit_insn (gen_memory_blockage ());
+  else
+    expand_asm_memory_blockage ();
+}
+
 /* This routine will either emit the mem_thread_fence pattern or issue a 
    sync_synchronize to generate a fence for memory model MEMMODEL.  */
 
@@ -6303,14 +6314,14 @@ expand_mem_thread_fence (enum memmodel model)
   if (targetm.have_mem_thread_fence ())
     {
       emit_insn (targetm.gen_mem_thread_fence (GEN_INT (model)));
-      expand_asm_memory_barrier ();
+      expand_memory_blockage ();
     }
   else if (targetm.have_memory_barrier ())
     emit_insn (targetm.gen_memory_barrier ());
   else if (synchronize_libfunc != NULL_RTX)
     emit_library_call (synchronize_libfunc, LCT_NORMAL, VOIDmode);
   else
-    expand_asm_memory_barrier ();
+    expand_memory_blockage ();
 }
 
 /* Emit a signal fence with given memory model.  */
@@ -6321,7 +6332,7 @@ expand_mem_signal_fence (enum memmodel model)
   /* No machine barrier is required to implement a signal fence, but
      a compiler memory barrier must be issued, except for relaxed MM.  */
   if (!is_mm_relaxed (model))
-    expand_asm_memory_barrier ();
+    expand_memory_blockage ();
 }
 
 /* This function expands the atomic load operation:
@@ -6343,7 +6354,7 @@ expand_atomic_load (rtx target, rtx mem, enum memmodel model)
       struct expand_operand ops[3];
       rtx_insn *last = get_last_insn ();
       if (is_mm_seq_cst (model))
-	expand_asm_memory_barrier ();
+	expand_memory_blockage ();
 
       create_output_operand (&ops[0], target, mode);
       create_fixed_operand (&ops[1], mem);
@@ -6351,7 +6362,7 @@ expand_atomic_load (rtx target, rtx mem, enum memmodel model)
       if (maybe_expand_insn (icode, 3, ops))
 	{
 	  if (!is_mm_relaxed (model))
-	    expand_asm_memory_barrier ();
+	    expand_memory_blockage ();
 	  return ops[0].value;
 	}
       delete_insns_since (last);
@@ -6401,14 +6412,14 @@ expand_atomic_store (rtx mem, rtx val, enum memmodel model, bool use_release)
     {
       rtx_insn *last = get_last_insn ();
       if (!is_mm_relaxed (model))
-	expand_asm_memory_barrier ();
+	expand_memory_blockage ();
       create_fixed_operand (&ops[0], mem);
       create_input_operand (&ops[1], val, mode);
       create_integer_operand (&ops[2], model);
       if (maybe_expand_insn (icode, 3, ops))
 	{
 	  if (is_mm_seq_cst (model))
-	    expand_asm_memory_barrier ();
+	    expand_memory_blockage ();
 	  return const0_rtx;
 	}
       delete_insns_since (last);

gcc/target-insns.def

@@ -60,6 +60,7 @@ DEF_TARGET_INSN (jump, (rtx x0))
 DEF_TARGET_INSN (load_multiple, (rtx x0, rtx x1, rtx x2))
 DEF_TARGET_INSN (mem_thread_fence, (rtx x0))
 DEF_TARGET_INSN (memory_barrier, (void))
+DEF_TARGET_INSN (memory_blockage, (void))
 DEF_TARGET_INSN (movstr, (rtx x0, rtx x1, rtx x2))
 DEF_TARGET_INSN (nonlocal_goto, (rtx x0, rtx x1, rtx x2, rtx x3))
 DEF_TARGET_INSN (nonlocal_goto_receiver, (void))