Uses a conditional move for usage counter increment instead of a branch

runtime/vm/assembler_ia32_test.cc

 // Copyright (c) 2012, 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"
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/os.h"
@@ skipping 3001 matching lines @@
 
 ASSEMBLER_TEST_RUN(ConditionalMovesSign, test) {
   typedef int (*ConditionalMovesSignCode)(int i);
   int res = reinterpret_cast<ConditionalMovesSignCode>(test->entry())(785);
   EXPECT_EQ(1, res);
   res = reinterpret_cast<ConditionalMovesSignCode>(test->entry())(-12);
   EXPECT_EQ(-1, res);
 }
 
 
+// Return 1 if overflow, 0 if no overflow.
+ASSEMBLER_TEST_GENERATE(ConditionalMovesNoOverflow, assembler) {
+  __ movl(EDX, Address(ESP, 1 * kWordSize));
+  __ addl(EDX, Address(ESP, 2 * kWordSize));
+  __ movl(EAX, Immediate(1));
+  __ movl(ECX, Immediate(0));
+  __ cmovno(EAX, ECX);
+  __ ret();
+}
+
+
+ASSEMBLER_TEST_RUN(ConditionalMovesNoOverflow, test) {
+  typedef int (*ConditionalMovesNoOverflowCode)(int i, int j);
+  int res = reinterpret_cast<ConditionalMovesNoOverflowCode>(
+      test->entry())(0x7fffffff, 2);
+  EXPECT_EQ(1, res);
+  res = reinterpret_cast<ConditionalMovesNoOverflowCode>(test->entry())(1, 1);
+  EXPECT_EQ(0, res);
+}
+
+
 // Return 1 if equal, 0 if not equal.
 ASSEMBLER_TEST_GENERATE(ConditionalMovesEqual, assembler) {
   __ xorl(EAX, EAX);
   __ movl(ECX, Immediate(1));
   __ movl(EDX, Address(ESP, 1 * kWordSize));
   __ cmpl(EDX, Immediate(785));
   __ cmove(EAX, ECX);
   __ ret();
 }
 
@@ skipping 208 matching lines @@
                      FieldAddress(ECX, GrowableObjectArray::data_offset()),
                      EAX);
   __ popl(EAX);
   __ popl(CTX);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32