[ARM] Deprecate -mneon-for-64bits

Deprecate -mneon-for-64bits since it no longer has any effect after
the DImode codegen improvements.

    gcc/
	* gcc/doc/invoke.texi (mneon-for-64bits): Deprecate option.
	* gcc/config/arm/arm.opt (mneon-for-64bits): Deprecate option.
	* gcc/config/arm/arm.h (TARGET_PREFER_NEON_64BITS): Remove.
	(prefer_neon_for_64bits): Remove.
	* gcc/config/arm/arm.c (prefer_neon_for_64bits): Remove.
	(tune_params): Remove PREF_NEON_64_FALSE uses.
	(arm_option_override): Remove prefer_neon selection code.
	(arm_print_tune_info): Remove prefer_neon_for_64bits.
	* gcc/config/arm/arm-protos.h (tune_params): Remove
	prefer_neon_for_64bits.
	(prefer_neon_for_64bits): Remove.

From-SVN: r274858

gcc/ChangeLog

+2019-08-23  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* gcc/doc/invoke.texi (mneon-for-64bits): Deprecate option.
+	* gcc/config/arm/arm.opt (mneon-for-64bits): Deprecate option.
+	* gcc/config/arm/arm.h (TARGET_PREFER_NEON_64BITS): Remove.
+	(prefer_neon_for_64bits): Remove.
+	* gcc/config/arm/arm.c (prefer_neon_for_64bits): Remove.
+	(tune_params): Remove PREF_NEON_64_FALSE uses.
+	(arm_option_override): Remove prefer_neon selection code.
+	(arm_print_tune_info): Remove prefer_neon_for_64bits.
+	* gcc/config/arm/arm-protos.h (tune_params): Remove
+	prefer_neon_for_64bits.
+	(prefer_neon_for_64bits): Remove.
+
 2019-08-23  Iain Sandoe  <iain@sandoe.co.uk>
 
 	PR pch/61250

gcc/config/arm/arm-protos.h

@@ -327,7 +327,6 @@ struct tune_params
   /* Prefer 32-bit encoding instead of flag-setting 16-bit encoding.  */
   enum {DISPARAGE_FLAGS_NEITHER, DISPARAGE_FLAGS_PARTIAL, DISPARAGE_FLAGS_ALL}
     disparage_flag_setting_t16_encodings: 2;
-  enum {PREF_NEON_64_FALSE, PREF_NEON_64_TRUE} prefer_neon_for_64bits: 1;
   /* Prefer to inline string operations like memset by using Neon.  */
   enum {PREF_NEON_STRINGOPS_FALSE, PREF_NEON_STRINGOPS_TRUE}
     string_ops_prefer_neon: 1;
@@ -472,10 +471,6 @@ extern int arm_arch_thumb_hwdiv;
 /* Nonzero if chip disallows volatile memory access in IT block.  */
 extern int arm_arch_no_volatile_ce;
 
-/* Nonzero if we should use Neon to handle 64-bits operations rather
-   than core registers.  */
-extern int prefer_neon_for_64bits;
-
 /* Structure defining the current overall architectural target and tuning.  */
 struct arm_build_target
 {

gcc/config/arm/arm.h

@@ -313,9 +313,6 @@ emission of floating point pcs attributes.  */
 /* Nonzero if disallow volatile memory access in IT block.  */
 #define TARGET_NO_VOLATILE_CE		(arm_arch_no_volatile_ce)
 
-/* Should NEON be used for 64-bits bitops.  */
-#define TARGET_PREFER_NEON_64BITS (prefer_neon_for_64bits)
-
 /* Should constant I be slplit for OP.  */
 #define DONT_EARLY_SPLIT_CONSTANT(i, op) \
 				((optimize >= 2) \
@@ -509,10 +506,6 @@ extern int arm_arch_thumb_hwdiv;
 /* Nonzero if chip disallows volatile memory access in IT block.  */
 extern int arm_arch_no_volatile_ce;
 
-/* Nonzero if we should use Neon to handle 64-bits operations rather
-   than core registers.  */
-extern int prefer_neon_for_64bits;
-
 /* Nonzero if we shouldn't use literal pools.  */
 #ifndef USED_FOR_TARGET
 extern bool arm_disable_literal_pool;

gcc/config/arm/arm.opt

@@ -276,8 +276,8 @@ Target Report Var(unaligned_access) Init(2) Save
 Enable unaligned word and halfword accesses to packed data.
 
 mneon-for-64bits
-Target Report RejectNegative Var(use_neon_for_64bits) Init(0)
-Use Neon to perform 64-bits operations rather than core registers.
+Target Deprecated
+This option is deprecated and has no effect.
 
 mslow-flash-data
 Target Report Var(target_slow_flash_data) Init(0)

gcc/doc/invoke.texi

@@ -18005,9 +18005,7 @@ defined.
 
 @item -mneon-for-64bits
 @opindex mneon-for-64bits
-Enables using Neon to handle scalar 64-bits operations. This is
-disabled by default since the cost of moving data from core registers
-to Neon is high.
+This option is deprecated and has no effect.
 
 @item -mslow-flash-data
 @opindex mslow-flash-data