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

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 41d4c5458d2bcb0c622e51ae931d9c5ddd8c92bc..f48a7239e0f8085de3a5b39bddc204e11d2395a0 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -172,12 +172,10 @@ class Arm64OperandConverter FINAL : public InstructionOperandConverter {
   } while (0)
 
 
-#define ASSEMBLE_TEST_AND_BRANCH(asm_instr, width)           \
-  do {                                                       \
-    bool fallthrough = IsNextInAssemblyOrder(i.InputRpo(3)); \
-    __ asm_instr(i.InputRegister##width(0), i.InputInt6(1),  \
-                 GetLabel(i.InputRpo(2)));                   \
-    if (!fallthrough) __ B(GetLabel(i.InputRpo(3)));         \
+#define ASSEMBLE_BRANCH_TO(target)                    \
+  do {                                                \
+    bool fallthrough = IsNextInAssemblyOrder(target); \
+    if (!fallthrough) __ B(GetLabel(target));         \
   } while (0)
 
 
@@ -430,16 +428,28 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
               i.InputInt8(2));
       break;
     case kArm64Tbz:
-      ASSEMBLE_TEST_AND_BRANCH(Tbz, 64);
+      __ Tbz(i.InputRegister64(0), i.InputInt6(1), GetLabel(i.InputRpo(2)));
+      ASSEMBLE_BRANCH_TO(i.InputRpo(3));
       break;
     case kArm64Tbz32:
-      ASSEMBLE_TEST_AND_BRANCH(Tbz, 32);
+      __ Tbz(i.InputRegister32(0), i.InputInt5(1), GetLabel(i.InputRpo(2)));
+      ASSEMBLE_BRANCH_TO(i.InputRpo(3));
       break;
     case kArm64Tbnz:
-      ASSEMBLE_TEST_AND_BRANCH(Tbnz, 64);
+      __ Tbnz(i.InputRegister64(0), i.InputInt6(1), GetLabel(i.InputRpo(2)));
+      ASSEMBLE_BRANCH_TO(i.InputRpo(3));
       break;
     case kArm64Tbnz32:
-      ASSEMBLE_TEST_AND_BRANCH(Tbnz, 32);
+      __ Tbnz(i.InputRegister32(0), i.InputInt5(1), GetLabel(i.InputRpo(2)));
+      ASSEMBLE_BRANCH_TO(i.InputRpo(3));
+      break;
+    case kArm64Cbz32:
+      __ Cbz(i.InputRegister32(0), GetLabel(i.InputRpo(1)));
+      ASSEMBLE_BRANCH_TO(i.InputRpo(2));
+      break;
+    case kArm64Cbnz32:
+      __ Cbnz(i.InputRegister32(0), GetLabel(i.InputRpo(1)));
+      ASSEMBLE_BRANCH_TO(i.InputRpo(2));
       break;
     case kArm64Claim: {
       int words = MiscField::decode(instr->opcode());