Faster to number conversion

src/hydrogen.cc

 // 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 3104 matching lines @@
           instruction->DeleteAndReplaceWith(instruction->RedefinedOperand());
         } else {
           instruction->ReplaceAllUsesWith(instruction->ActualValue());
         }
       }
     }
   }
 }
 
 
-void HOptimizedGraphBuilder::PushAndAdd(HInstruction* instr) {
+void HGraphBuilder::PushAndAdd(HInstruction* instr) {
   Push(instr);
   AddInstruction(instr);
 }
 
 
 template <class Instruction>
 HInstruction* HOptimizedGraphBuilder::PreProcessCall(Instruction* call) {
   int count = call->argument_count();
   ZoneList<HValue*> arguments(count, zone());
   for (int i = 0; i < count; ++i) {
@@ skipping 4345 matching lines @@
   CHECK_ALIVE(VisitForTypeOf(expr->expression()));
   HValue* value = Pop();
   HValue* context = environment()->LookupContext();
   HInstruction* instr = new(zone()) HTypeof(context, value);
   return ast_context()->ReturnInstruction(instr, expr->id());
 }
 
 
 void HOptimizedGraphBuilder::VisitSub(UnaryOperation* expr) {
   CHECK_ALIVE(VisitForValue(expr->expression()));
-  HValue* value = Pop();
   Handle<Type> operand_type = expr->expression()->bounds().lower;
+  HValue* value = TruncateToNumber(Pop(), &operand_type);
   HInstruction* instr = BuildUnaryMathOp(value, operand_type, Token::SUB);
   return ast_context()->ReturnInstruction(instr, expr->id());
 }
 
 
 void HOptimizedGraphBuilder::VisitBitNot(UnaryOperation* expr) {
   CHECK_ALIVE(VisitForValue(expr->expression()));
-  HValue* value = Pop();
   Handle<Type> operand_type = expr->expression()->bounds().lower;
+  HValue* value = TruncateToNumber(Pop(), &operand_type);
   HInstruction* instr = BuildUnaryMathOp(value, operand_type, Token::BIT_NOT);
   return ast_context()->ReturnInstruction(instr, expr->id());
 }
 
 
 void HOptimizedGraphBuilder::VisitNot(UnaryOperation* expr) {
   if (ast_context()->IsTest()) {
     TestContext* context = TestContext::cast(ast_context());
     VisitForControl(expr->expression(),
                     context->if_false(),
@@ skipping 310 matching lines @@
     HConstant* right_const = HConstant::cast(right);
     if (right_const->HasInteger32Value() &&
        (right_const->Integer32Value() & 0x1f) != 0) {
       return false;
     }
   }
   return true;
 }
 
 
+HValue* HGraphBuilder::TruncateToNumber(HValue* value, Handle<Type>* expected) {
+  if (value->IsConstant()) {
+    HConstant* constant = HConstant::cast(value);
+    HConstant* number = constant->CopyToTruncatedNumber(zone());
+    if (number != NULL) {
+      *expected = handle(Type::Number(), isolate());
+      return AddInstruction(number);
+    }
+    return value;
+  }
+
+  Handle<Type> expected_type = *expected;
+  Representation rep = Representation::FromType(expected_type);
+  if (!rep.IsTagged()) return value;
+
+  // If our type feedback suggests that we can non-observably truncate to number
+  // we introduce the appropriate check here. This avoids 'value' having a
+  // tagged representation later on.
+  if (expected_type->Is(Type::Oddball())) {
+    // TODO(olivf) The BinaryOpStub only records undefined. It might pay off to
+    // also record booleans and convert them to 0/1 here.
+    IfBuilder if_nan(this);
+    if_nan.If<HCompareObjectEqAndBranch>(value,
+        graph()->GetConstantUndefined());
+    if_nan.Then();
+    Push(Add<HConstant>(OS::nan_value(), Representation::Double()));

[Jakob Kummerow, 2013/07/22 07:43:47]

Stack height mismatches at basic block joins are a pattern that we need to
eliminate/avoid. Suggestion:

HValue copied_constant = Add<HConstant>(...);
IfBuilder if_nan(this);
if_nan.If<...>(...);
if_nan.Then();
if_nan.ElseDeopt();
if_nan.End();
return copied_constant;

[oliv, 2013/07/22 13:56:43]

Done.

+    if_nan.ElseDeopt();
+    if_nan.End();
+    return Pop();
+  }
+
+  return value;
+}
+
+
 HInstruction* HOptimizedGraphBuilder::BuildBinaryOperation(
     BinaryOperation* expr,
     HValue* left,
     HValue* right) {
   HValue* context = environment()->LookupContext();
   Handle<Type> left_type = expr->left()->bounds().lower;
   Handle<Type> right_type = expr->right()->bounds().lower;
   Handle<Type> result_type = expr->bounds().lower;
   Maybe<int> fixed_right_arg = expr->fixed_right_arg();
   Representation left_rep = Representation::FromType(left_type);
   Representation right_rep = Representation::FromType(right_type);
   Representation result_rep = Representation::FromType(result_type);
 
+  if (expr->op() != Token::ADD ||
+      (left->type().IsNoString() && right->type().IsNoString())) {
+    // For addition we can only truncate the arguments to number if we can
+    // prove that we will not end up in string concatenation mode.
+    left = TruncateToNumber(left, &left_type);
+    right = TruncateToNumber(right, &right_type);
+  }
+
   if (left_type->Is(Type::None())) {
     AddSoftDeoptimize();
     // TODO(rossberg): we should be able to get rid of non-continuous defaults.
     left_type = handle(Type::Any(), isolate());
   }
   if (right_type->Is(Type::None())) {
     AddSoftDeoptimize();
     right_type = handle(Type::Any(), isolate());
   }
   HInstruction* instr = NULL;
@@ skipping 2075 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal