Revert of [crankshaft] Re-add fast-case for string add left/right. (patchset...

Revert of [crankshaft] Re-add fast-case for string add left/right. (patchset #1 id:1 of https://codereview.chromium.org/1339053002/ )

Reason for revert:
[Sheriff] Fails mozilla with deadcode:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20deadcode/builds/5357

Original issue's description:
> [crankshaft] Re-add fast-case for string add left/right.
>
> Now the StringAddStub can optionally convert it's parameters to strings
> (following the rules for the addition operator). This could be further
> optimized once we have a ToPrimitiveStub, but it should be sufficient
> for the moment.
>
> Also removed the unused Strength parameter to the HStringAdd operator,
> because string addition does not depend on language mode.
>
> CQ_INCLUDE_TRYBOTS=tryserver.v8:v8_win_nosnap_shared_rel,v8_linux_nosnap_dbg
> R=mstarzinger@chromium.org
> BUG=v8:4307
> LOG=n
>
> Committed: https://crrev.com/d261849e53fbf8c36efae42d478271f87acff70f
> Cr-Commit-Position: refs/heads/master@{#30726}

TBR=mstarzinger@chromium.org,jarin@chromium.org,bmeurer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4307

Review URL: https://codereview.chromium.org/1347473003

Cr-Commit-Position: refs/heads/master@{#30727}

src/code-stubs-hydrogen.cc

@@ -113,8 +113,6 @@ class CodeStubGraphBuilderBase : public HGraphBuilder {
                                         HValue* shared_info,
                                         HValue* native_context);
 
-  HValue* CheckString(HValue* input, bool convert);
-
  private:
   HValue* BuildArraySingleArgumentConstructor(JSArrayBuilder* builder);
   HValue* BuildArrayNArgumentsConstructor(JSArrayBuilder* builder,
@@ -1458,66 +1456,6 @@ Handle<Code> BinaryOpWithAllocationSiteStub::GenerateCode() {
 }
 
 
-HValue* CodeStubGraphBuilderBase::CheckString(HValue* input, bool convert) {
-  if (!convert) return BuildCheckString(input);
-  IfBuilder if_inputissmi(this);
-  HValue* inputissmi = if_inputissmi.If<HIsSmiAndBranch>(input);
-  if_inputissmi.Then();
-  {
-    // Convert the input smi to a string.
-    Push(BuildNumberToString(input, Type::SignedSmall()));
-  }
-  if_inputissmi.Else();
-  {
-    HValue* input_map =
-        Add<HLoadNamedField>(input, inputissmi, HObjectAccess::ForMap());
-    HValue* input_instance_type = Add<HLoadNamedField>(
-        input_map, inputissmi, HObjectAccess::ForMapInstanceType());
-    IfBuilder if_inputisstring(this);
-    if_inputisstring.If<HCompareNumericAndBranch>(
-        input_instance_type, Add<HConstant>(FIRST_NONSTRING_TYPE), Token::LT);
-    if_inputisstring.Then();
-    {
-      // The input is already a string.
-      Push(input);
-    }
-    if_inputisstring.Else();
-    {
-      // Convert to primitive first (if necessary), see
-      // ES6 section 12.7.3 The Addition operator.
-      IfBuilder if_inputisprimitive(this);
-      STATIC_ASSERT(FIRST_PRIMITIVE_TYPE == FIRST_TYPE);
-      if_inputisprimitive.If<HCompareNumericAndBranch>(
-          input_instance_type, Add<HConstant>(LAST_PRIMITIVE_TYPE), Token::LTE);
-      if_inputisprimitive.Then();
-      {
-        // The input is already a primitive.
-        Push(input);
-      }
-      if_inputisprimitive.Else();
-      {
-        // TODO(bmeurer): Add support for fast ToPrimitive conversion using
-        // a dedicated ToPrimitiveStub.
-        Add<HPushArguments>(input);
-        Push(Add<HCallRuntime>(Runtime::FunctionForId(Runtime::kToPrimitive),
-                               1));
-      }
-      if_inputisprimitive.End();
-      // Convert the primitive to a string value.
-      ToStringDescriptor descriptor(isolate());
-      ToStringStub stub(isolate());
-      HValue* values[] = {context(), Pop()};
-      Push(AddUncasted<HCallWithDescriptor>(
-          Add<HConstant>(stub.GetCode()), 0, descriptor,
-          Vector<HValue*>(values, arraysize(values))));
-    }
-    if_inputisstring.End();
-  }
-  if_inputissmi.End();
-  return Pop();
-}
-
-
 template <>
 HValue* CodeStubGraphBuilder<StringAddStub>::BuildCodeInitializedStub() {
   StringAddStub* stub = casted_stub();
@@ -1529,12 +1467,10 @@ HValue* CodeStubGraphBuilder<StringAddStub>::BuildCodeInitializedStub() {
 
   // Make sure that both arguments are strings if not known in advance.
   if ((flags & STRING_ADD_CHECK_LEFT) == STRING_ADD_CHECK_LEFT) {
-    left =
-        CheckString(left, (flags & STRING_ADD_CONVERT) == STRING_ADD_CONVERT);
+    left = BuildCheckString(left);
   }
   if ((flags & STRING_ADD_CHECK_RIGHT) == STRING_ADD_CHECK_RIGHT) {
-    right =
-        CheckString(right, (flags & STRING_ADD_CONVERT) == STRING_ADD_CONVERT);
+    right = BuildCheckString(right);
   }
 
   return BuildStringAdd(left, right, HAllocationMode(pretenure_flag));

src/code-stubs.cc

@@ -324,12 +324,6 @@ std::ostream& operator<<(std::ostream& os, const StringAddFlags& flags) {
       return os << "CheckRight";
     case STRING_ADD_CHECK_BOTH:
       return os << "CheckBoth";
-    case STRING_ADD_CONVERT_LEFT:
-      return os << "ConvertLeft";
-    case STRING_ADD_CONVERT_RIGHT:
-      return os << "ConvertRight";
-    case STRING_ADD_CONVERT:
-      break;
   }
   UNREACHABLE();
   return os;

src/code-stubs.h

@@ -676,11 +676,7 @@ enum StringAddFlags {
   // Check right parameter.
   STRING_ADD_CHECK_RIGHT = 1 << 1,
   // Check both parameters.
-  STRING_ADD_CHECK_BOTH = STRING_ADD_CHECK_LEFT | STRING_ADD_CHECK_RIGHT,
-  // Convert parameters when check fails (instead of throwing an exception).
-  STRING_ADD_CONVERT = 1 << 2,
-  STRING_ADD_CONVERT_LEFT = STRING_ADD_CHECK_LEFT | STRING_ADD_CONVERT,
-  STRING_ADD_CONVERT_RIGHT = STRING_ADD_CHECK_RIGHT | STRING_ADD_CONVERT
+  STRING_ADD_CHECK_BOTH = STRING_ADD_CHECK_LEFT | STRING_ADD_CHECK_RIGHT
 };
 
 
@@ -705,8 +701,8 @@ class StringAddTFStub : public TurboFanCodeStub {
   }
 
  private:
-  class StringAddFlagsBits : public BitField<StringAddFlags, 0, 3> {};
-  class PretenureFlagBits : public BitField<PretenureFlag, 3, 1> {};
+  class StringAddFlagsBits : public BitField<StringAddFlags, 0, 2> {};
+  class PretenureFlagBits : public BitField<PretenureFlag, 2, 1> {};
 
   void PrintBaseName(std::ostream& os) const override;  // NOLINT
 
@@ -1651,8 +1647,8 @@ class StringAddStub final : public HydrogenCodeStub {
   static const int kRight = 1;
 
  private:
-  class StringAddFlagsBits : public BitField<StringAddFlags, 0, 3> {};
-  class PretenureFlagBits : public BitField<PretenureFlag, 3, 1> {};
+  class StringAddFlagsBits: public BitField<StringAddFlags, 0, 2> {};
+  class PretenureFlagBits: public BitField<PretenureFlag, 2, 1> {};
 
   void PrintBaseName(std::ostream& os) const override;  // NOLINT
 

src/hydrogen-instructions.cc

@@ -3997,7 +3997,7 @@ DEFINE_NEW_H_SIMPLE_ARITHMETIC_INSTR(HSub, -)
 
 
 HInstruction* HStringAdd::New(Isolate* isolate, Zone* zone, HValue* context,
-                              HValue* left, HValue* right,
+                              HValue* left, HValue* right, Strength strength,
                               PretenureFlag pretenure_flag,
                               StringAddFlags flags,
                               Handle<AllocationSite> allocation_site) {
@@ -4015,8 +4015,8 @@ HInstruction* HStringAdd::New(Isolate* isolate, Zone* zone, HValue* context,
       }
     }
   }
-  return new (zone)
-      HStringAdd(context, left, right, pretenure_flag, flags, allocation_site);
+  return new (zone) HStringAdd(context, left, right, strength, pretenure_flag,
+                               flags, allocation_site);
 }
 
 

src/hydrogen-instructions.h

@@ -7355,7 +7355,8 @@ class HStringAdd final : public HBinaryOperation {
  public:
   static HInstruction* New(
       Isolate* isolate, Zone* zone, HValue* context, HValue* left,
-      HValue* right, PretenureFlag pretenure_flag = NOT_TENURED,
+      HValue* right, Strength strength = Strength::WEAK,
+      PretenureFlag pretenure_flag = NOT_TENURED,
       StringAddFlags flags = STRING_ADD_CHECK_BOTH,
       Handle<AllocationSite> allocation_site = Handle<AllocationSite>::null());
 
@@ -7377,10 +7378,10 @@ class HStringAdd final : public HBinaryOperation {
   }
 
  private:
-  HStringAdd(HValue* context, HValue* left, HValue* right,
+  HStringAdd(HValue* context, HValue* left, HValue* right, Strength strength,
              PretenureFlag pretenure_flag, StringAddFlags flags,
              Handle<AllocationSite> allocation_site)
-      : HBinaryOperation(context, left, right, Strength::WEAK, HType::String()),
+      : HBinaryOperation(context, left, right, strength, HType::String()),
         flags_(flags),
         pretenure_flag_(pretenure_flag) {
     set_representation(Representation::Tagged());

src/hydrogen.cc

@@ -10995,9 +10995,11 @@ HValue* HGraphBuilder::BuildBinaryOperation(
         left = BuildNumberToString(left, left_type);
       } else if (!left_type->Is(Type::String())) {
         DCHECK(right_type->Is(Type::String()));
-        return AddUncasted<HStringAdd>(
-            left, right, allocation_mode.GetPretenureMode(),
-            STRING_ADD_CONVERT_LEFT, allocation_mode.feedback_site());
+        // TODO(bmeurer): We might want to optimize this, because we already
+        // know that the right hand side is a string.
+        Add<HPushArguments>(left, right);
+        return AddUncasted<HCallRuntime>(Runtime::FunctionForId(Runtime::kAdd),
+                                         2);
       }
 
       // Convert right argument as necessary.
@@ -11006,9 +11008,11 @@ HValue* HGraphBuilder::BuildBinaryOperation(
         right = BuildNumberToString(right, right_type);
       } else if (!right_type->Is(Type::String())) {
         DCHECK(left_type->Is(Type::String()));
-        return AddUncasted<HStringAdd>(
-            left, right, allocation_mode.GetPretenureMode(),
-            STRING_ADD_CONVERT_RIGHT, allocation_mode.feedback_site());
+        // TODO(bmeurer): We might want to optimize this, because we already
+        // know that the left hand side is a string.
+        Add<HPushArguments>(left, right);
+        return AddUncasted<HCallRuntime>(Runtime::FunctionForId(Runtime::kAdd),
+                                         2);
       }
     }
 
@@ -11025,7 +11029,7 @@ HValue* HGraphBuilder::BuildBinaryOperation(
     if (!right_string.is_null() && right_string->length() == 0) return left;
     if (!left_string.is_null() && !right_string.is_null()) {
       return AddUncasted<HStringAdd>(
-          left, right, allocation_mode.GetPretenureMode(),
+          left, right, strength, allocation_mode.GetPretenureMode(),
           STRING_ADD_CHECK_NONE, allocation_mode.feedback_site());
     }
 
@@ -11054,8 +11058,8 @@ HValue* HGraphBuilder::BuildBinaryOperation(
 
     // Fallback to using the string add stub.
     return AddUncasted<HStringAdd>(
-        left, right, allocation_mode.GetPretenureMode(), STRING_ADD_CHECK_NONE,
-        allocation_mode.feedback_site());
+        left, right, strength, allocation_mode.GetPretenureMode(),
+        STRING_ADD_CHECK_NONE, allocation_mode.feedback_site());
   }
 
   if (graph()->info()->IsStub()) {
@@ -12468,7 +12472,8 @@ void HOptimizedGraphBuilder::GenerateStringAdd(CallRuntime* call) {
   CHECK_ALIVE(VisitForValue(call->arguments()->at(1)));
   HValue* right = Pop();
   HValue* left = Pop();
-  HInstruction* result = NewUncasted<HStringAdd>(left, right);
+  HInstruction* result =
+      NewUncasted<HStringAdd>(left, right, strength(function_language_mode()));
   return ast_context()->ReturnInstruction(result, call->id());
 }