[arm64] Optimize fcmp when lhs operand is #0.0

src/compiler/x64/code-generator-x64.cc

Index: src/compiler/x64/code-generator-x64.cc
diff --git a/src/compiler/x64/code-generator-x64.cc b/src/compiler/x64/code-generator-x64.cc
index 06befa83f4c53144037a45d8f77728d1055e4594..4c991718f8b641996361ef2cfafed6e70adb589b 100644
--- a/src/compiler/x64/code-generator-x64.cc
+++ b/src/compiler/x64/code-generator-x64.cc
@@ -1383,6 +1383,9 @@ void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
     case kNotOverflow:
       __ j(no_overflow, tlabel);
       break;
+    default:
+      UNREACHABLE();
+      break;
   }
   if (!branch->fallthru) __ jmp(flabel, flabel_distance);
 }
@@ -1452,6 +1455,9 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
     case kNotOverflow:
       cc = no_overflow;
       break;
+    default:
+      UNREACHABLE();
+      break;
   }
   __ bind(&check);
   __ setcc(cc, reg);