[ast] Remove heap accesses from AST numbering

src/ast/ast-value-factory.h

 // Copyright 2014 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 141 matching lines @@
 
 
 // AstValue is either a string, a number, a string array, a boolean, or a
 // special value (null, undefined, the hole).
 class AstValue : public ZoneObject {
  public:
   bool IsString() const {
     return type_ == STRING;
   }
 
-  bool IsNumber() const {
-    return type_ == NUMBER || type_ == NUMBER_WITH_DOT || type_ == SMI ||
-           type_ == SMI_WITH_DOT;
-  }
+  bool IsNumber() const { return IsSmi() || IsHeapNumber(); }
 
   bool ContainsDot() const {
     return type_ == NUMBER_WITH_DOT || type_ == SMI_WITH_DOT;
   }
 
   const AstRawString* AsString() const {
     CHECK_EQ(STRING, type_);
     return string_;
   }
 
   double AsNumber() const {
-    if (type_ == NUMBER || type_ == NUMBER_WITH_DOT)
-      return number_;
-    if (type_ == SMI || type_ == SMI_WITH_DOT)
-      return smi_;
+    if (IsHeapNumber()) return number_;
+    if (IsSmi()) return smi_;
     UNREACHABLE();
     return 0;
   }
 
   Smi* AsSmi() const {
-    CHECK(type_ == SMI || type_ == SMI_WITH_DOT);
+    CHECK(IsSmi());
     return Smi::FromInt(smi_);
   }
 
+  bool ToUint32(uint32_t* value) const {
+    if (IsSmi()) {
+      int num = smi_;
+      if (num < 0) return false;
+      *value = static_cast<uint32_t>(num);
+      return true;
+    }
+    if (IsHeapNumber()) {
+      double num = number_;
+      if (num < 0) return false;
+      uint32_t uint_value = FastD2UI(num);
+      if (FastUI2D(uint_value) == num) {
+        *value = uint_value;
+        return true;
+      }

[rmcilroy, 2017/01/13 09:53:57]

You need to be careful to check for minus 0.0 as well. How about making a
variant of IsUint32Double in conversions.h which takes an argument to return the
uint32 value, and just use that here?

[Leszek Swirski, 2017/01/13 10:58:10]

Done, and amended the code in objects-inl.h that I stole to call teh same
function.

+    }
+    return false;
+  }
+
   bool EqualsString(const AstRawString* string) const {
     return type_ == STRING && string_ == string;
   }
 
   bool IsPropertyName() const;
 
   bool BooleanValue() const;
 
   bool IsSmi() const { return type_ == SMI || type_ == SMI_WITH_DOT; }
+  bool IsHeapNumber() const {
+    return type_ == NUMBER || type_ == NUMBER_WITH_DOT;
+  }
   bool IsFalse() const { return type_ == BOOLEAN && !bool_; }
   bool IsTrue() const { return type_ == BOOLEAN && bool_; }
   bool IsUndefined() const { return type_ == UNDEFINED; }
   bool IsTheHole() const { return type_ == THE_HOLE; }
   bool IsNull() const { return type_ == NULL_TYPE; }
 
   void Internalize(Isolate* isolate);
 
   // Can be called after Internalize has been called.
   V8_INLINE Handle<Object> value() const {
@@ skipping 237 matching lines @@
   OTHER_CONSTANTS(F)
 #undef F
 };
 }  // namespace internal
 }  // namespace v8
 
 #undef STRING_CONSTANTS
 #undef OTHER_CONSTANTS
 
 #endif  // V8_AST_AST_VALUE_FACTORY_H_