[Interpreter] Avoid accessing on-heap literal in VisitLiteral.

Move VisitLiteral to decide what type of literal is being emitted by
checking the raw ASTValue type, instead of the internalized on-heap
value. This is required for concurrent bytecode generation.

As part of this change, the NUMBER AstValue constructor is modified to
try to convert numbers without a dot to SMIs where possible. This is to
maintain the behavior in NewNumber where such numbers are internalized as
SMIs, and ensures that we still emit LdaSmi bytecodes for these values
in the generated bytecode.

BUG=v8:5203

Review-Url: https://codereview.chromium.org/2152853002
Cr-Commit-Position: refs/heads/master@{#37931}

src/ast/ast-value-factory.h

@@ -146,10 +146,8 @@ class AstValue : public ZoneObject {
   bool ContainsDot() const { return type_ == NUMBER_WITH_DOT; }
 
   const AstRawString* AsString() const {
-    if (type_ == STRING)
+    CHECK_EQ(STRING, type_);
     return string_;
-    UNREACHABLE();
-    return 0;
   }
 
   double AsNumber() const {
@@ -161,6 +159,11 @@ class AstValue : public ZoneObject {
     return 0;
   }
 
+  Smi* AsSmi() const {
+    CHECK_EQ(SMI, type_);
+    return Smi::FromInt(smi_);
+  }
+
   bool EqualsString(const AstRawString* string) const {
     return type_ == STRING && string_ == string;
   }
@@ -169,7 +172,12 @@ class AstValue : public ZoneObject {
 
   bool BooleanValue() const;
 
+  bool IsSmi() const { return type_ == SMI; }
+  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);
 
@@ -204,11 +212,18 @@ class AstValue : public ZoneObject {
   explicit AstValue(double n, bool with_dot) {
     if (with_dot) {
       type_ = NUMBER_WITH_DOT;
+      number_ = n;
+    } else {
+      int int_value;
+      if (DoubleToSmiInteger(n, &int_value)) {
+        type_ = SMI;
+        smi_ = int_value;
       } else {
         type_ = NUMBER;
-    }
         number_ = n;
       }
+    }
+  }
 
   AstValue(Type t, int i) : type_(t) {
     DCHECK(type_ == SMI);

src/conversions-inl.h

@@ -97,6 +97,13 @@ int32_t DoubleToInt32(double x) {
   }
 }
 
+bool DoubleToSmiInteger(double value, int* smi_int_value) {
+  if (IsMinusZero(value)) return false;
+  int i = FastD2IChecked(value);
+  if (value != i || !Smi::IsValid(i)) return false;
+  *smi_int_value = i;
+  return true;
+}
 
 bool IsSmiDouble(double value) {
   return !IsMinusZero(value) && value >= Smi::kMinValue &&

src/conversions.h

@@ -147,27 +147,26 @@ char* DoubleToExponentialCString(double value, int f);
 char* DoubleToPrecisionCString(double value, int f);
 char* DoubleToRadixCString(double value, int radix);
 
-
 static inline bool IsMinusZero(double value) {
   return bit_cast<int64_t>(value) == bit_cast<int64_t>(-0.0);
 }
 
+// Returns true if value can be converted to a SMI, and returns the resulting
+// integer value of the SMI in |smi_int_value|.
+inline bool DoubleToSmiInteger(double value, int* smi_int_value);
 
 inline bool IsSmiDouble(double value);
 
-
 // Integer32 is an integer that can be represented as a signed 32-bit
 // integer. It has to be in the range [-2^31, 2^31 - 1].
 // We also have to check for negative 0 as it is not an Integer32.
 inline bool IsInt32Double(double value);
 
-
 // UInteger32 is an integer that can be represented as an unsigned 32-bit
 // integer. It has to be in the range [0, 2^32 - 1].
 // We also have to check for negative 0 as it is not a UInteger32.
 inline bool IsUint32Double(double value);
 
-
 // Convert from Number object to C integer.
 inline int32_t NumberToInt32(Object* number);
 inline uint32_t NumberToUint32(Object* number);

src/factory.cc

@@ -1094,13 +1094,9 @@ Handle<FixedDoubleArray> Factory::CopyFixedDoubleArray(
 
 Handle<Object> Factory::NewNumber(double value,
                                   PretenureFlag pretenure) {
-  // We need to distinguish the minus zero value and this cannot be
-  // done after conversion to int. Doing this by comparing bit
-  // patterns is faster than using fpclassify() et al.
-  if (IsMinusZero(value)) return NewHeapNumber(-0.0, IMMUTABLE, pretenure);
-
-  int int_value = FastD2IChecked(value);
-  if (value == int_value && Smi::IsValid(int_value)) {
+  // Materialize as a SMI if possible
+  int32_t int_value;
+  if (DoubleToSmiInteger(value, &int_value)) {
     return handle(Smi::FromInt(int_value), isolate());
   }
 

src/interpreter/bytecode-generator.cc

@@ -549,7 +549,7 @@ BytecodeGenerator::BytecodeGenerator(CompilationInfo* info)
       register_allocator_(nullptr),
       generator_resume_points_(info->literal()->yield_count(), info->zone()),
       generator_state_() {
-  InitializeAstVisitor(isolate());
+  InitializeAstVisitor(isolate()->stack_guard()->real_climit());
 }
 
 Handle<BytecodeArray> BytecodeGenerator::MakeBytecode() {
@@ -1484,21 +1484,21 @@ void BytecodeGenerator::VisitConditional(Conditional* expr) {
 
 void BytecodeGenerator::VisitLiteral(Literal* expr) {
   if (!execution_result()->IsEffect()) {
-    Handle<Object> value = expr->value();
-    if (value->IsSmi()) {
-      builder()->LoadLiteral(Smi::cast(*value));
-    } else if (value->IsUndefined(isolate())) {
+    const AstValue* raw_value = expr->raw_value();
+    if (raw_value->IsSmi()) {
+      builder()->LoadLiteral(raw_value->AsSmi());
+    } else if (raw_value->IsUndefined()) {
       builder()->LoadUndefined();
-    } else if (value->IsTrue(isolate())) {
+    } else if (raw_value->IsTrue()) {
       builder()->LoadTrue();
-    } else if (value->IsFalse(isolate())) {
+    } else if (raw_value->IsFalse()) {
       builder()->LoadFalse();
-    } else if (value->IsNull(isolate())) {
+    } else if (raw_value->IsNull()) {
       builder()->LoadNull();
-    } else if (value->IsTheHole(isolate())) {
+    } else if (raw_value->IsTheHole()) {
       builder()->LoadTheHole();
     } else {
-      builder()->LoadLiteral(value);
+      builder()->LoadLiteral(raw_value->value());
     }
     execution_result()->SetResultInAccumulator();
   }
@@ -2861,6 +2861,8 @@ void BytecodeGenerator::VisitCompareOperation(CompareOperation* expr) {
 }
 
 void BytecodeGenerator::VisitArithmeticExpression(BinaryOperation* expr) {
+  // TODO(rmcilroy): Special case "x * 1.0" and "x * -1" which are generated for
+  // +x and -x by the parser.
   Register lhs = VisitForRegisterValue(expr->left());
   VisitForAccumulatorValue(expr->right());
   builder()->BinaryOperation(expr->op(), lhs);

test/cctest/interpreter/bytecode_expectations/PrimitiveReturnStatements.golden

@@ -176,3 +176,21 @@ constant pool: [
 handlers: [
 ]
 
+---
+snippet: "
+  return 2.0;
+"
+frame size: 0
+parameter count: 1
+bytecode array length: 4
+bytecodes: [
+  /*   30 E> */ B(StackCheck),
+  /*   34 S> */ B(LdaConstant), U8(0),
+  /*   46 S> */ B(Return),
+]
+constant pool: [
+  2,
+]
+handlers: [
+]
+

test/cctest/interpreter/bytecode_expectations/UnaryOperators.golden

@@ -150,11 +150,12 @@ bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   42 S> */ B(LdaSmi), U8(13),
                 B(Star), R(0),
-  /*   46 S> */ B(LdaSmi), U8(1),
+  /*   46 S> */ B(LdaConstant), U8(0),
                 B(Mul), R(0),
   /*   57 S> */ B(Return),
 ]
 constant pool: [
+  1,
 ]
 handlers: [
 ]

test/cctest/interpreter/test-bytecode-generator.cc

@@ -177,6 +177,8 @@ TEST(PrimitiveReturnStatements) {
       "return +127;\n",
 
       "return -128;\n",
+
+      "return 2.0;\n",
   };
 
   CHECK(CompareTexts(BuildActual(printer, snippets),