Add outline-atomics to target attribute.

	* common/config/aarch64/aarch64-common.c (aarch64_handle_option):
	Handle OPT_moutline_atomics.
	* config/aarch64/aarch64.c: Add outline-atomics to
	aarch64_attributes.

	* doc/extend.texi: Document the newly added target attribute.

	* gcc.target/aarch64/target_attr_20.c: New test.
	* gcc.target/aarch64/target_attr_21.c: New test.

(cherry picked from commit 9e02b45ffc60e0078bde3c56a14f00c54b7f8039)

gcc/ChangeLog

+2020-05-21  Martin Liska  <mliska@suse.cz>
+
+	* common/config/aarch64/aarch64-common.c (aarch64_handle_option):
+	Handle OPT_moutline_atomics.
+	* config/aarch64/aarch64.c: Add outline-atomics to
+	aarch64_attributes.
+	* doc/extend.texi: Document the newly added target attribute.
+
 2020-05-21  H.J. Lu  <hongjiu.lu@intel.com>
 
 	Backport from master

gcc/common/config/aarch64/aarch64-common.c

@@ -116,6 +116,10 @@ aarch64_handle_option (struct gcc_options *opts,
       opts->x_flag_omit_leaf_frame_pointer = val;
       return true;
 
+    case OPT_moutline_atomics:
+      opts->x_aarch64_flag_outline_atomics = val;
+      return true;
+
     default:
       return true;
     }

gcc/config/aarch64/aarch64.c

@@ -15258,6 +15258,8 @@ static const struct aarch64_attribute_info aarch64_attributes[] =
      aarch64_handle_attr_branch_protection, OPT_mbranch_protection_ },
   { "sign-return-address", aarch64_attr_enum, false, NULL,
      OPT_msign_return_address_ },
+  { "outline-atomics", aarch64_attr_bool, true, NULL,
+     OPT_moutline_atomics},
   { NULL, aarch64_attr_custom, false, NULL, OPT____ }
 };
 

gcc/doc/extend.texi

@@ -4066,6 +4066,12 @@ Select the function scope on which branch protection will be applied.  The
 behavior and permissible arguments are the same as for the command-line option
 @option{-mbranch-protection=}.  The default value is @code{none}.
 
+@item outline-atomics
+@cindex @code{outline-atomics} function attribute, AArch64
+Enable or disable calls to out-of-line helpers to implement atomic operations.
+This corresponds to the behavior of the command line options
+@option{-moutline-atomics} and @option{-mno-outline-atomics}.
+
 @end table
 
 The above target attributes can be specified as follows:

gcc/testsuite/ChangeLog

+2020-05-21  Martin Liska  <mliska@suse.cz>
+
+	* gcc.target/aarch64/target_attr_20.c: New test.
+	* gcc.target/aarch64/target_attr_21.c: New test.
+
 2020-05-20  Mark Eggleston  <markeggleston@gcc.gnu.org>
 
 	Backported from master

gcc/testsuite/gcc.target/aarch64/target_attr_20.c

+/* { dg-do compile } */
+/* { dg-options "-march=armv8-a+nolse -moutline-atomics" } */
+
+int b, c, d, e, f, h;
+short g;
+int foo (int) __attribute__ ((__const__));
+
+__attribute__ ((target ("no-outline-atomics")))
+void
+bar (void)
+{
+  while (1)
+    {
+      while (1)
+	{
+	  __atomic_load_n (&e, 0);
+	  if (foo (2))
+	    __sync_val_compare_and_swap (&c, 0, f);
+	  b = 1;
+	  if (h == e)
+	    break;
+	}
+      __sync_val_compare_and_swap (&g, -1, f);
+    }
+}
+
+/* { dg-final { scan-assembler-not "bl.*__aarch64_cas2_acq_rel" } } */

gcc/testsuite/gcc.target/aarch64/target_attr_21.c

+/* { dg-do compile } */
+/* { dg-options "-march=armv8-a+nolse -mno-outline-atomics" } */
+
+int b, c, d, e, f, h;
+short g;
+int foo (int) __attribute__ ((__const__));
+
+__attribute__ ((target ("outline-atomics")))
+void
+bar (void)
+{
+  while (1)
+    {
+      while (1)
+	{
+	  __atomic_load_n (&e, 0);
+	  if (foo (2))
+	    __sync_val_compare_and_swap (&c, 0, f);
+	  b = 1;
+	  if (h == e)
+	    break;
+	}
+      __sync_val_compare_and_swap (&g, -1, f);
+    }
+}
+
+/* { dg-final { scan-assembler-times "bl.*__aarch64_cas2_acq_rel" 1 } } */