ARM64: Optimize RegList::IsValid() to speed up simulation in (opt)debug mode.

src/arm64/assembler-arm64.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 555 matching lines @@
     ASSERT((size_in_bits % kBitsPerByte) == 0);
     return size_in_bits / kBitsPerByte;
   }
 
  private:
   RegList list_;
   unsigned size_;
   CPURegister::RegisterType type_;
 
   bool IsValid() const {
-    if ((type_ == CPURegister::kRegister) ||
-        (type_ == CPURegister::kFPRegister)) {
-      bool is_valid = true;
-      // Try to create a CPURegister for each element in the list.
-      for (int i = 0; i < kRegListSizeInBits; i++) {
-        if (((list_ >> i) & 1) != 0) {
-          is_valid &= CPURegister::Create(i, size_, type_).IsValid();
-        }
-      }
-      return is_valid;
-    } else if (type_ == CPURegister::kNoRegister) {
-      // The kNoRegister type is valid only for empty lists.
-      // We can't use IsEmpty here because that asserts IsValid().
-      return list_ == 0;
-    } else {
-      return false;
+    const RegList kValidRegisters = 0x8000000ffffffff;
+    const RegList kValidFPRegisters = 0x0000000ffffffff;
+    switch (type_) {
+      case CPURegister::kRegister:
+        return (list_ & kValidRegisters) == list_;
+      case CPURegister::kFPRegister:
+        return (list_ & kValidFPRegisters) == list_;
+      case CPURegister::kNoRegister:
+        return list_ == 0;
+      default:
+        UNREACHABLE();
+        return false;
     }
   }
 };
 
 
 // AAPCS64 callee-saved registers.
 #define kCalleeSaved CPURegList::GetCalleeSaved()
 #define kCalleeSavedFP CPURegList::GetCalleeSavedFP()
 
 
@@ skipping 1611 matching lines @@
 class EnsureSpace BASE_EMBEDDED {
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBuffer();
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM64_ASSEMBLER_ARM64_H_