aarch64, Darwin : Match conditions for a PRFUM insn.

This unpessimizes the prefetch cases for Darwin where the assembler
is not able to substitute the prfum instructions automagically.

This improves the fix for Issue #43.

	* config/aarch64/aarch64-protos.h
	* config/aarch64/aarch64.c
	* config/aarch64/aarch64.md
	* config/aarch64/constraints.md
	* config/aarch64/predicates.md

gcc/config/aarch64/aarch64-protos.h

@@ -745,6 +745,7 @@ void aarch64_post_cfi_startproc (void);
 poly_int64 aarch64_initial_elimination_offset (unsigned, unsigned);
 int aarch64_get_condition_code (rtx);
 bool aarch64_address_valid_for_prefetch_p (rtx, bool);
+bool aarch64_address_valid_for_unscaled_prefetch_p (rtx, bool);
 bool aarch64_bitmask_imm (HOST_WIDE_INT val, machine_mode);
 unsigned HOST_WIDE_INT aarch64_and_split_imm1 (HOST_WIDE_INT val_in);
 unsigned HOST_WIDE_INT aarch64_and_split_imm2 (HOST_WIDE_INT val_in);

gcc/config/aarch64/aarch64.cc

@@ -10552,6 +10552,29 @@ aarch64_address_valid_for_prefetch_p (rtx x, bool strict_p)
   return addr.type != ADDRESS_REG_WB;
 }
 
+/* Return true if the address X is valid for a PRFUM instruction.
+   STRICT_P is true if we should do strict checking with
+   aarch64_classify_address.  */
+
+bool
+aarch64_address_valid_for_unscaled_prefetch_p (rtx x, bool strict_p)
+{
+  struct aarch64_address_info addr;
+
+  /* PRFUM accepts the same addresses as DImode, but constrained to a range
+     -256..255.  */
+  bool res = aarch64_classify_address (&addr, x, DImode, strict_p);
+  if (!res)
+    return false;
+
+  if (addr.offset && ((INTVAL (addr.offset) > 255)
+		       || (INTVAL (addr.offset) < -256)))
+     return false;
+
+  /* ... except writeback forms.  */
+  return addr.type != ADDRESS_REG_WB;
+}
+
 bool
 aarch64_symbolic_address_p (rtx x)
 {

gcc/config/aarch64/aarch64.md

@@ -850,6 +850,37 @@
   [(set_attr "type" "load_4")]
 )
 
+(define_insn "prefetch_unscaled"
+  [(prefetch (match_operand:DI 0 "aarch64_unscaled_prefetch_operand" "Du")
+            (match_operand:QI 1 "const_int_operand" "")
+            (match_operand:QI 2 "const_int_operand" ""))]
+  ""
+  {
+    const char * pftype[2][4] =
+    {
+      {"prfum\\tPLDL1STRM, %0",
+       "prfum\\tPLDL3KEEP, %0",
+       "prfum\\tPLDL2KEEP, %0",
+       "prfum\\tPLDL1KEEP, %0"},
+      {"prfum\\tPSTL1STRM, %0",
+       "prfum\\tPSTL3KEEP, %0",
+       "prfum\\tPSTL2KEEP, %0",
+       "prfum\\tPSTL1KEEP, %0"},
+    };
+
+    int locality = INTVAL (operands[2]);
+
+    gcc_assert (IN_RANGE (locality, 0, 3));
+
+    /* PRFUM accepts the same addresses as a 64-bit LDR so wrap
+       the address into a DImode MEM so that aarch64_print_operand knows
+       how to print it.  */
+    operands[0] = gen_rtx_MEM (DImode, operands[0]);
+    return pftype[INTVAL(operands[1])][locality];
+  }
+  [(set_attr "type" "load_4")]
+)
+
 (define_insn "trap"
   [(trap_if (const_int 1) (const_int 8))]
   ""

gcc/config/aarch64/constraints.md

@@ -492,6 +492,11 @@
  An address valid for a prefetch instruction."
  (match_test "aarch64_address_valid_for_prefetch_p (op, true)"))
 
+(define_address_constraint "Du"
+  "@internal
+ An address valid for a prefetch instruction with an unscaled offset."
+ (match_test "aarch64_address_valid_for_unscaled_prefetch_p (op, true)"))
+
 (define_constraint "vgb"
   "@internal
    A constraint that matches an immediate offset valid for SVE LD1B

gcc/config/aarch64/predicates.md

@@ -261,6 +261,9 @@
 (define_predicate "aarch64_prefetch_operand"
   (match_test "aarch64_address_valid_for_prefetch_p (op, false)"))
 
+(define_predicate "aarch64_unscaled_prefetch_operand"
+  (match_test "aarch64_address_valid_for_unscaled_prefetch_p (op, false)"))
+
 (define_predicate "aarch64_valid_symref"
   (match_code "const, symbol_ref, label_ref")
 {