Recognize and optimize a.runtimeType == b.runtimeType pattern.

runtime/vm/assembler_arm64.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // NOLINT
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 664 matching lines @@
     adds(dest, rn, op);
   } else {
     // TODO(zra): Try subtracting top 12 bits, then bottom 12 bits.
     ASSERT(rn != TMP2);
     LoadImmediate(TMP2, imm);
     subs(dest, rn, Operand(TMP2));
   }
 }
 
 
+void Assembler::SubImmediate(Register dest, Register rn, int64_t imm) {

[regis, 2016/10/08 09:10:37]

Same comment as for arm.

[Vyacheslav Egorov (Google), 2016/10/24 20:23:03]

Done.

+  Operand op;
+  if (Operand::CanHold(imm, kXRegSizeInBits, &op) == Operand::Immediate) {
+    // Handles imm == kMinInt64.
+    sub(dest, rn, op);
+  } else if (Operand::CanHold(-imm, kXRegSizeInBits, &op) ==
+             Operand::Immediate) {
+    ASSERT(imm != kMinInt64);  // Would cause erroneous overflow detection.
+    add(dest, rn, op);
+  } else {
+    // TODO(zra): Try subtracting top 12 bits, then bottom 12 bits.
+    ASSERT(rn != TMP2);
+    LoadImmediate(TMP2, imm);
+    sub(dest, rn, Operand(TMP2));
+  }
+}
+
+
 void Assembler::AndImmediate(Register rd, Register rn, int64_t imm) {
   Operand imm_op;
   if (Operand::IsImmLogical(imm, kXRegSizeInBits, &imm_op)) {
     andi(rd, rn, Immediate(imm));
   } else {
     LoadImmediate(TMP, imm);
     and_(rd, rn, Operand(TMP));
   }
 }
 
@@ skipping 775 matching lines @@
     add(base, array, Operand(index, LSL, shift));
   }
   const OperandSize size = Address::OperandSizeFor(cid);
   ASSERT(Address::CanHoldOffset(offset, Address::Offset, size));
   return Address(base, offset, Address::Offset, size);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64