[turbofan] Avoid some redundant checks of unordered comparison on arm/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 636184a086b1a53a11ee3330c36f8c9c32936cf5..8cd03784e54e7cc11bea019186d7b8f1cb53ed74 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -787,8 +787,8 @@ void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
         __ B(eq, tlabel);
         break;
       case kUnorderedNotEqual:
-        __ B(vs, tlabel);
-      // Fall through.
+        // Unordered or not equal can be tested with "ne" condtion.
+        // See ARMv8 manual C1.2.3 - Condition Code.
       case kNotEqual:
         __ B(ne, tlabel);
         break;
@@ -811,8 +811,8 @@ void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
         __ B(lo, tlabel);
         break;
       case kUnorderedGreaterThanOrEqual:
-        __ B(vs, tlabel);
-      // Fall through.
+        // Unordered, greater than or equal can be tested with "hs" condtion.
+        // See ARMv8 manual C1.2.3 - Condition Code.
       case kUnsignedGreaterThanOrEqual:
         __ B(hs, tlabel);
         break;
@@ -823,8 +823,8 @@ void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
         __ B(ls, tlabel);
         break;
       case kUnorderedGreaterThan:
-        __ B(vs, tlabel);
-      // Fall through.
+        // Unordered or greater than can be tested with "hi" condtion.
+        // See ARMv8 manual C1.2.3 - Condition Code.
       case kUnsignedGreaterThan:
         __ B(hi, tlabel);
         break;