[turbofan] Use cbz/cbnz when possible on arm64.

test/unittests/compiler/arm64/instruction-selector-arm64-unittest.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "test/unittests/compiler/instruction-selector-unittest.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
@@ skipping 934 matching lines @@
     Stream s = m.Build();
     ASSERT_EQ(1U, s.size());
     EXPECT_EQ(kArm64Tbz, s[0]->arch_opcode());
     EXPECT_EQ(4U, s[0]->InputCount());
     EXPECT_EQ(InstructionOperand::IMMEDIATE, s[0]->InputAt(1)->kind());
     EXPECT_EQ(bit, s.ToInt64(s[0]->InputAt(1)));
   }
 }
 
 
+TEST_F(InstructionSelectorTest, CompareAgainstZeroAndBranch) {
+  {
+    StreamBuilder m(this, kMachInt32, kMachInt32);
+    MLabel a, b;
+    Node* p0 = m.Parameter(0);
+    m.Branch(p0, &a, &b);
+    m.Bind(&a);
+    m.Return(m.Int32Constant(1));
+    m.Bind(&b);
+    m.Return(m.Int32Constant(0));
+    Stream s = m.Build();
+    ASSERT_EQ(1U, s.size());
+    EXPECT_EQ(kArm64Cbnz32, s[0]->arch_opcode());
+    EXPECT_EQ(3U, s[0]->InputCount());
+    EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+  }
+
+  {
+    StreamBuilder m(this, kMachInt32, kMachInt32);
+    MLabel a, b;
+    Node* p0 = m.Parameter(0);
+    m.Branch(m.Word32BinaryNot(p0), &a, &b);
+    m.Bind(&a);
+    m.Return(m.Int32Constant(1));
+    m.Bind(&b);
+    m.Return(m.Int32Constant(0));
+    Stream s = m.Build();
+    ASSERT_EQ(1U, s.size());
+    EXPECT_EQ(kArm64Cbz32, s[0]->arch_opcode());
+    EXPECT_EQ(3U, s[0]->InputCount());
+    EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+  }
+}
+
+
 // -----------------------------------------------------------------------------
 // Add and subtract instructions with overflow.
 
 
 typedef InstructionSelectorTestWithParam<MachInst2>
     InstructionSelectorOvfAddSubTest;
 
 
 TEST_P(InstructionSelectorOvfAddSubTest, OvfParameter) {
   const MachInst2 dpi = GetParam();
@@ skipping 1125 matching lines @@
   ASSERT_EQ(2U, s[1]->InputCount());
   EXPECT_EQ(s.ToVreg(s[0]->Output()), s.ToVreg(s[1]->InputAt(0)));
   EXPECT_EQ(32, s.ToInt64(s[1]->InputAt(1)));
   ASSERT_EQ(1U, s[1]->OutputCount());
   EXPECT_EQ(s.ToVreg(n), s.ToVreg(s[1]->Output()));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8