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

runtime/vm/assembler_arm.cc

 // Copyright (c) 2013, 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_ARM)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 2999 matching lines @@
       mvn(IP, o, cond);
       adds(rd, rn, Operand(IP), cond);
     } else {
       LoadDecodableImmediate(IP, value, cond);
       subs(rd, rn, Operand(IP), cond);
     }
   }
 }
 
 
+void Assembler::SubImmediate(Register rd, Register rn, int32_t value,
+                             Condition cond) {

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

Why do you need this new flavor? Since you are not setting the flags, calling
AddImmediate(rd, rn, -value, cond) should be equivalent.

[Vyacheslav Egorov (Google), 2016/10/24 20:23:02]

Done.

+  Operand o;
+  if (Operand::CanHold(value, &o)) {
+    // Handles value == kMinInt32.
+    sub(rd, rn, o, cond);
+  } else if (Operand::CanHold(-value, &o)) {
+    ASSERT(value != kMinInt32);  // Would cause erroneous overflow detection.
+    add(rd, rn, o, cond);
+  } else {
+    ASSERT(rn != IP);
+    if (Operand::CanHold(~value, &o)) {
+      mvn(IP, o, cond);
+      sub(rd, rn, Operand(IP), cond);
+    } else if (Operand::CanHold(~(-value), &o)) {
+      ASSERT(value != kMinInt32);  // Would cause erroneous overflow detection.
+      mvn(IP, o, cond);
+      add(rd, rn, Operand(IP), cond);
+    } else {
+      LoadDecodableImmediate(IP, value, cond);
+      sub(rd, rn, Operand(IP), cond);
+    }
+  }
+}
+
+
 void Assembler::AndImmediate(Register rd, Register rs, int32_t imm,
                              Condition cond) {
   Operand o;
   if (Operand::CanHold(imm, &o)) {
     and_(rd, rs, Operand(o), cond);
   } else {
     LoadImmediate(TMP, imm, cond);
     and_(rd, rs, Operand(TMP), cond);
   }
 }
@@ skipping 518 matching lines @@
 
 
 const char* Assembler::FpuRegisterName(FpuRegister reg) {
   ASSERT((0 <= reg) && (reg < kNumberOfFpuRegisters));
   return fpu_reg_names[reg];
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM