[AArch64] Make -moutline-atomics on by default

2020-04-30  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

	* config/aarch64/aarch64.h (TARGET_OUTLINE_ATOMICS): Define.
	* config/aarch64/aarch64.opt (moutline-atomics): Change to Int variable.
	* doc/invoke.texi (moutline-atomics): Document as on by default.

gcc/ChangeLog

+2020-04-30  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	* config/aarch64/aarch64.h (TARGET_OUTLINE_ATOMICS): Define.
+	* config/aarch64/aarch64.opt (moutline-atomics): Change to Int variable.
+	* doc/invoke.texi (moutline-atomics): Document as on by default.
+
 2020-04-30  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	PR target/94748

gcc/config/aarch64/aarch64.h

@@ -105,6 +105,11 @@
    port.  */
 #define TARGET_PTRMEMFUNC_VBIT_LOCATION ptrmemfunc_vbit_in_delta
 
+
+/* Emit calls to libgcc helpers for atomic operations for runtime detection
+   of LSE instructions.  */
+#define TARGET_OUTLINE_ATOMICS (aarch64_flag_outline_atomics)
+
 /* Align definitions of arrays, unions and structures so that
    initializations and copies can be made more efficient.  This is not
    ABI-changing, so it only affects places where we can see the

gcc/config/aarch64/aarch64.opt

@@ -256,7 +256,7 @@ TargetVariable
 long aarch64_stack_protector_guard_offset = 0
 
 moutline-atomics
-Target Report Mask(OUTLINE_ATOMICS) Save
+Target Report Var(aarch64_flag_outline_atomics) Init(2) Save
 Generate local calls to out-of-line atomic operations.
 
 -param=aarch64-sve-compare-costs=

gcc/doc/invoke.texi

@@ -16886,6 +16886,7 @@ instruction set.  If using a later revision, e.g. @option{-march=armv8.1-a}
 or @option{-march=armv8-a+lse}, the ARMv8.1-Atomics instructions will be
 used directly.  The same applies when using @option{-mcpu=} when the
 selected cpu supports the @samp{lse} feature.
+This option is on by default.
 
 @item -march=@var{name}
 @opindex march