aarch64: Improve swp generation

Allow zero as an input; fix constraints; avoid unnecessary split.

	* config/aarch64/aarch64.c (aarch64_emit_atomic_swap): Remove.
	(aarch64_gen_atomic_ldop): Don't call it.
	* config/aarch64/atomics.md (atomic_exchange<ALLI>):
	Use aarch64_reg_or_zero.
	(aarch64_atomic_exchange<ALLI>): Likewise.
	(aarch64_atomic_exchange<ALLI>_lse): Remove split; remove & from
	operand 0; use aarch64_reg_or_zero for input; merge ...
	(@aarch64_atomic_swp<ALLI>): ... this and remove.

From-SVN: r265659

gcc/ChangeLog

 2018-10-31  Richard Henderson  <richard.henderson@linaro.org>
 
+	* config/aarch64/aarch64.c (aarch64_emit_atomic_swap): Remove.
+	(aarch64_gen_atomic_ldop): Don't call it.
+	* config/aarch64/atomics.md (atomic_exchange<ALLI>):
+	Use aarch64_reg_or_zero.
+	(aarch64_atomic_exchange<ALLI>): Likewise.
+	(aarch64_atomic_exchange<ALLI>_lse): Remove split; remove & from
+	operand 0; use aarch64_reg_or_zero for input; merge ...
+	(@aarch64_atomic_swp<ALLI>): ... this and remove.
+
 	* config/aarch64/aarch64.c (aarch64_gen_compare_reg_maybe_ze): New.
 	(aarch64_split_compare_and_swap): Use it.
 	(aarch64_expand_compare_and_swap): Likewise.  Remove convert_modes;

gcc/config/aarch64/aarch64.c

@@ -14840,15 +14840,6 @@ aarch64_emit_bic (machine_mode mode, rtx dst, rtx s1, rtx s2, int shift)
   emit_insn (gen (dst, s2, shift_rtx, s1));
 }
 
-/* Emit an atomic swap.  */
-
-static void
-aarch64_emit_atomic_swap (machine_mode mode, rtx dst, rtx value,
-			  rtx mem, rtx model)
-{
-  emit_insn (gen_aarch64_atomic_swp (mode, dst, mem, value, model));
-}
-
 /* Emit an atomic load+operate.  CODE is the operation.  OUT_DATA is the
    location to store the data read from memory.  OUT_RESULT is the location to
    store the result of the operation.  MEM is the memory location to read and
@@ -14889,10 +14880,6 @@ aarch64_gen_atomic_ldop (enum rtx_code code, rtx out_data, rtx out_result,
      a SET then emit a swap instruction and finish.  */
   switch (code)
     {
-    case SET:
-      aarch64_emit_atomic_swap (mode, out_data, src, mem, model_rtx);
-      return;
-
     case MINUS:
       /* Negate the value and treat it as a PLUS.  */
       {

gcc/config/aarch64/atomics.md

@@ -136,7 +136,7 @@
 (define_expand "atomic_exchange<mode>"
  [(match_operand:ALLI 0 "register_operand" "")
   (match_operand:ALLI 1 "aarch64_sync_memory_operand" "")
-  (match_operand:ALLI 2 "register_operand" "")
+  (match_operand:ALLI 2 "aarch64_reg_or_zero" "")
   (match_operand:SI 3 "const_int_operand" "")]
   ""
   {
@@ -159,7 +159,7 @@
     (match_operand:ALLI 1 "aarch64_sync_memory_operand" "+Q"))	;; memory
    (set (match_dup 1)
     (unspec_volatile:ALLI
-      [(match_operand:ALLI 2 "register_operand" "r")	;; input
+      [(match_operand:ALLI 2 "aarch64_reg_or_zero" "rZ")	;; input
        (match_operand:SI 3 "const_int_operand" "")]		;; model
       UNSPECV_ATOMIC_EXCHG))
    (clobber (reg:CC CC_REGNUM))
@@ -175,22 +175,25 @@
   }
 )
 
-(define_insn_and_split "aarch64_atomic_exchange<mode>_lse"
-  [(set (match_operand:ALLI 0 "register_operand" "=&r")
+(define_insn "aarch64_atomic_exchange<mode>_lse"
+  [(set (match_operand:ALLI 0 "register_operand" "=r")
     (match_operand:ALLI 1 "aarch64_sync_memory_operand" "+Q"))
    (set (match_dup 1)
     (unspec_volatile:ALLI
-      [(match_operand:ALLI 2 "register_operand" "r")
+      [(match_operand:ALLI 2 "aarch64_reg_or_zero" "rZ")
        (match_operand:SI 3 "const_int_operand" "")]
       UNSPECV_ATOMIC_EXCHG))]
   "TARGET_LSE"
-  "#"
-  "&& reload_completed"
-  [(const_int 0)]
   {
-    aarch64_gen_atomic_ldop (SET, operands[0], NULL, operands[1],
-			     operands[2], operands[3]);
-    DONE;
+    enum memmodel model = memmodel_from_int (INTVAL (operands[3]));
+    if (is_mm_relaxed (model))
+      return "swp<atomic_sfx>\t%<w>2, %<w>0, %1";
+    else if (is_mm_acquire (model) || is_mm_consume (model))
+      return "swpa<atomic_sfx>\t%<w>2, %<w>0, %1";
+    else if (is_mm_release (model))
+      return "swpl<atomic_sfx>\t%<w>2, %<w>0, %1";
+    else
+      return "swpal<atomic_sfx>\t%<w>2, %<w>0, %1";
   }
 )
 
@@ -585,28 +588,6 @@
 
 ;; ARMv8.1-A LSE instructions.
 
-;; Atomic swap with memory.
-(define_insn "@aarch64_atomic_swp<mode>"
- [(set (match_operand:ALLI 0 "register_operand" "+&r")
-   (match_operand:ALLI 1 "aarch64_sync_memory_operand" "+Q"))
-  (set (match_dup 1)
-   (unspec_volatile:ALLI
-    [(match_operand:ALLI 2 "register_operand" "r")
-     (match_operand:SI 3 "const_int_operand" "")]
-    UNSPECV_ATOMIC_SWP))]
-  "TARGET_LSE && reload_completed"
-  {
-    enum memmodel model = memmodel_from_int (INTVAL (operands[3]));
-    if (is_mm_relaxed (model))
-      return "swp<atomic_sfx>\t%<w>2, %<w>0, %1";
-    else if (is_mm_acquire (model) || is_mm_consume (model))
-      return "swpa<atomic_sfx>\t%<w>2, %<w>0, %1";
-    else if (is_mm_release (model))
-      return "swpl<atomic_sfx>\t%<w>2, %<w>0, %1";
-    else
-      return "swpal<atomic_sfx>\t%<w>2, %<w>0, %1";
-  })
-
 ;; Atomic load-op: Load data, operate, store result, keep data.
 
 (define_insn "@aarch64_atomic_load<atomic_ldop><mode>"