[turbofan] Lower StringCharCodeAt to a dedicated builtin.

src/compiler/effect-control-linearizer.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/effect-control-linearizer.h"
 
 #include "src/code-factory.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/compiler-source-position-table.h"
 #include "src/compiler/js-graph.h"
@@ skipping 2229 matching lines @@
                     jsgraph()->HeapConstant(callable.code()));
   node->InsertInput(graph()->zone(), 3, jsgraph()->NoContextConstant());
   node->InsertInput(graph()->zone(), 4, effect);
   NodeProperties::ChangeOp(node, common()->Call(desc));
   return ValueEffectControl(node, node, control);
 }
 
 EffectControlLinearizer::ValueEffectControl
 EffectControlLinearizer::LowerStringCharCodeAt(Node* node, Node* effect,
                                                Node* control) {
-  Node* subject = node->InputAt(0);
-  Node* index = node->InputAt(1);
-
-  // We may need to loop several times for ConsString/SlicedString {subject}s.
-  Node* loop =
-      graph()->NewNode(common()->Loop(4), control, control, control, control);
-  Node* lsubject =
-      graph()->NewNode(common()->Phi(MachineRepresentation::kTagged, 4),
-                       subject, subject, subject, subject, loop);
-  Node* lindex =
-      graph()->NewNode(common()->Phi(MachineRepresentation::kWord32, 4), index,
-                       index, index, index, loop);
-  Node* leffect = graph()->NewNode(common()->EffectPhi(4), effect, effect,
-                                   effect, effect, loop);
-
-  control = loop;
-  effect = leffect;
-
-  // Determine the instance type of {lsubject}.
-  Node* lsubject_map = effect =
-      graph()->NewNode(simplified()->LoadField(AccessBuilder::ForMap()),
-                       lsubject, effect, control);
-  Node* lsubject_instance_type = effect = graph()->NewNode(
-      simplified()->LoadField(AccessBuilder::ForMapInstanceType()),
-      lsubject_map, effect, control);
-
-  // Check if {lsubject} is a SeqString.
-  Node* check0 = graph()->NewNode(
-      machine()->Word32Equal(),
-      graph()->NewNode(machine()->Word32And(), lsubject_instance_type,
-                       jsgraph()->Int32Constant(kStringRepresentationMask)),
-      jsgraph()->Int32Constant(kSeqStringTag));
-  Node* branch0 = graph()->NewNode(common()->Branch(), check0, control);
-
-  Node* if_true0 = graph()->NewNode(common()->IfTrue(), branch0);
-  Node* etrue0 = effect;
-  Node* vtrue0;
-  {
-    // Check if the {lsubject} is a TwoByteSeqString or a OneByteSeqString.
-    Node* check1 = graph()->NewNode(
-        machine()->Word32Equal(),
-        graph()->NewNode(machine()->Word32And(), lsubject_instance_type,
-                         jsgraph()->Int32Constant(kStringEncodingMask)),
-        jsgraph()->Int32Constant(kTwoByteStringTag));
-    Node* branch1 = graph()->NewNode(common()->Branch(), check1, if_true0);
-
-    Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
-    Node* etrue1 = etrue0;
-    Node* vtrue1 = etrue1 =
-        graph()->NewNode(simplified()->LoadElement(
-                             AccessBuilder::ForSeqTwoByteStringCharacter()),
-                         lsubject, lindex, etrue1, if_true1);
-
-    Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
-    Node* efalse1 = etrue0;
-    Node* vfalse1 = efalse1 =
-        graph()->NewNode(simplified()->LoadElement(
-                             AccessBuilder::ForSeqOneByteStringCharacter()),
-                         lsubject, lindex, efalse1, if_false1);
-
-    if_true0 = graph()->NewNode(common()->Merge(2), if_true1, if_false1);
-    etrue0 =
-        graph()->NewNode(common()->EffectPhi(2), etrue1, efalse1, if_true0);
-    vtrue0 = graph()->NewNode(common()->Phi(MachineRepresentation::kWord32, 2),
-                              vtrue1, vfalse1, if_true0);
-  }
-
-  Node* if_false0 = graph()->NewNode(common()->IfFalse(), branch0);
-  Node* efalse0 = effect;
-  Node* vfalse0;
-  {
-    // Check if the {lsubject} is a ConsString.
-    Node* check1 = graph()->NewNode(
-        machine()->Word32Equal(),
-        graph()->NewNode(machine()->Word32And(), lsubject_instance_type,
-                         jsgraph()->Int32Constant(kStringRepresentationMask)),
-        jsgraph()->Int32Constant(kConsStringTag));
-    Node* branch1 = graph()->NewNode(common()->Branch(), check1, if_false0);
-
-    Node* if_true1 = graph()->NewNode(common()->IfTrue(), branch1);
-    Node* etrue1 = efalse0;
-    {
-      // Load the right hand side of the {lsubject} ConsString.
-      Node* lsubject_second = etrue1 = graph()->NewNode(
-          simplified()->LoadField(AccessBuilder::ForConsStringSecond()),
-          lsubject, etrue1, if_true1);
-
-      // Check whether the right hand side is the empty string (i.e. if
-      // this is really a flat string in a cons string). If that is not
-      // the case we flatten the string first.
-      Node* check2 = graph()->NewNode(machine()->WordEqual(), lsubject_second,
-                                      jsgraph()->EmptyStringConstant());
-      Node* branch2 = graph()->NewNode(common()->Branch(BranchHint::kTrue),
-                                       check2, if_true1);
-
-      Node* if_true2 = graph()->NewNode(common()->IfTrue(), branch2);
-      Node* etrue2 = etrue1;
-      Node* vtrue2 = etrue2 = graph()->NewNode(
-          simplified()->LoadField(AccessBuilder::ForConsStringFirst()),
-          lsubject, etrue2, if_true2);
-
-      Node* if_false2 = graph()->NewNode(common()->IfFalse(), branch2);
-      Node* efalse2 = etrue1;
-      Node* vfalse2;
-      {
-        // Flatten the {lsubject} ConsString first.
-        Operator::Properties properties =
-            Operator::kNoDeopt | Operator::kNoThrow;
-        Runtime::FunctionId id = Runtime::kFlattenString;
-        CallDescriptor const* desc = Linkage::GetRuntimeCallDescriptor(
-            graph()->zone(), id, 1, properties, CallDescriptor::kNoFlags);
-        vfalse2 = efalse2 = graph()->NewNode(
-            common()->Call(desc), jsgraph()->CEntryStubConstant(1), lsubject,
-            jsgraph()->ExternalConstant(ExternalReference(id, isolate())),
-            jsgraph()->Int32Constant(1), jsgraph()->NoContextConstant(),
-            efalse2, if_false2);
-      }
-
-      // Retry the {loop} with the new subject.
-      loop->ReplaceInput(1, if_true2);
-      lindex->ReplaceInput(1, lindex);
-      leffect->ReplaceInput(1, etrue2);
-      lsubject->ReplaceInput(1, vtrue2);
-      loop->ReplaceInput(2, if_false2);
-      lindex->ReplaceInput(2, lindex);
-      leffect->ReplaceInput(2, efalse2);
-      lsubject->ReplaceInput(2, vfalse2);
-    }
-
-    Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);
-    Node* efalse1 = efalse0;
-    Node* vfalse1;
-    {
-      // Check if the {lsubject} is an ExternalString.
-      Node* check2 = graph()->NewNode(
-          machine()->Word32Equal(),
-          graph()->NewNode(machine()->Word32And(), lsubject_instance_type,
-                           jsgraph()->Int32Constant(kStringRepresentationMask)),
-          jsgraph()->Int32Constant(kExternalStringTag));
-      Node* branch2 = graph()->NewNode(common()->Branch(BranchHint::kTrue),
-                                       check2, if_false1);
-
-      Node* if_true2 = graph()->NewNode(common()->IfTrue(), branch2);
-      Node* etrue2 = efalse1;
-      Node* vtrue2;
-      {
-        // Check if the {lsubject} is a short external string.
-        Node* check3 = graph()->NewNode(
-            machine()->Word32Equal(),
-            graph()->NewNode(
-                machine()->Word32And(), lsubject_instance_type,
-                jsgraph()->Int32Constant(kShortExternalStringMask)),
-            jsgraph()->Int32Constant(0));
-        Node* branch3 = graph()->NewNode(common()->Branch(BranchHint::kTrue),
-                                         check3, if_true2);
-
-        Node* if_true3 = graph()->NewNode(common()->IfTrue(), branch3);
-        Node* etrue3 = etrue2;
-        Node* vtrue3;
-        {
-          // Load the actual resource data from the {lsubject}.
-          Node* lsubject_resource_data = etrue3 = graph()->NewNode(
-              simplified()->LoadField(
-                  AccessBuilder::ForExternalStringResourceData()),
-              lsubject, etrue3, if_true3);
-
-          // Check if the {lsubject} is a TwoByteExternalString or a
-          // OneByteExternalString.
-          Node* check4 = graph()->NewNode(
-              machine()->Word32Equal(),
-              graph()->NewNode(machine()->Word32And(), lsubject_instance_type,
-                               jsgraph()->Int32Constant(kStringEncodingMask)),
-              jsgraph()->Int32Constant(kTwoByteStringTag));
-          Node* branch4 =
-              graph()->NewNode(common()->Branch(), check4, if_true3);
-
-          Node* if_true4 = graph()->NewNode(common()->IfTrue(), branch4);
-          Node* etrue4 = etrue3;
-          Node* vtrue4 = etrue4 = graph()->NewNode(
-              simplified()->LoadElement(
-                  AccessBuilder::ForExternalTwoByteStringCharacter()),
-              lsubject_resource_data, lindex, etrue4, if_true4);
-
-          Node* if_false4 = graph()->NewNode(common()->IfFalse(), branch4);
-          Node* efalse4 = etrue3;
-          Node* vfalse4 = efalse4 = graph()->NewNode(
-              simplified()->LoadElement(
-                  AccessBuilder::ForExternalOneByteStringCharacter()),
-              lsubject_resource_data, lindex, efalse4, if_false4);
-
-          if_true3 = graph()->NewNode(common()->Merge(2), if_true4, if_false4);
-          etrue3 = graph()->NewNode(common()->EffectPhi(2), etrue4, efalse4,
-                                    if_true3);
-          vtrue3 =
-              graph()->NewNode(common()->Phi(MachineRepresentation::kWord32, 2),
-                               vtrue4, vfalse4, if_true3);
-        }
-
-        Node* if_false3 = graph()->NewNode(common()->IfFalse(), branch3);
-        Node* efalse3 = etrue2;
-        Node* vfalse3;
-        {
-          // The {lsubject} might be compressed, call the runtime.
-          Operator::Properties properties =
-              Operator::kNoDeopt | Operator::kNoThrow;
-          Runtime::FunctionId id = Runtime::kExternalStringGetChar;
-          CallDescriptor const* desc = Linkage::GetRuntimeCallDescriptor(
-              graph()->zone(), id, 2, properties, CallDescriptor::kNoFlags);
-          vfalse3 = efalse3 = graph()->NewNode(
-              common()->Call(desc), jsgraph()->CEntryStubConstant(1), lsubject,
-              ChangeInt32ToSmi(lindex),
-              jsgraph()->ExternalConstant(ExternalReference(id, isolate())),
-              jsgraph()->Int32Constant(2), jsgraph()->NoContextConstant(),
-              efalse3, if_false3);
-          vfalse3 = ChangeSmiToInt32(vfalse3);
-        }
-
-        if_true2 = graph()->NewNode(common()->Merge(2), if_true3, if_false3);
-        etrue2 =
-            graph()->NewNode(common()->EffectPhi(2), etrue3, efalse3, if_true2);
-        vtrue2 =
-            graph()->NewNode(common()->Phi(MachineRepresentation::kWord32, 2),
-                             vtrue3, vfalse3, if_true2);
-      }
-
-      Node* if_false2 = graph()->NewNode(common()->IfFalse(), branch2);
-      Node* efalse2 = efalse1;
-      {
-        // The {lsubject} is a SlicedString, continue with its parent.
-        Node* lsubject_parent = efalse2 = graph()->NewNode(
-            simplified()->LoadField(AccessBuilder::ForSlicedStringParent()),
-            lsubject, efalse2, if_false2);
-        Node* lsubject_offset = efalse2 = graph()->NewNode(
-            simplified()->LoadField(AccessBuilder::ForSlicedStringOffset()),
-            lsubject, efalse2, if_false2);
-        Node* lsubject_index = graph()->NewNode(
-            machine()->Int32Add(), lindex, ChangeSmiToInt32(lsubject_offset));
-
-        // Retry the {loop} with the parent subject.
-        loop->ReplaceInput(3, if_false2);
-        leffect->ReplaceInput(3, efalse2);
-        lindex->ReplaceInput(3, lsubject_index);
-        lsubject->ReplaceInput(3, lsubject_parent);
-      }
-
-      if_false1 = if_true2;
-      efalse1 = etrue2;
-      vfalse1 = vtrue2;
-    }
-
-    if_false0 = if_false1;
-    efalse0 = efalse1;
-    vfalse0 = vfalse1;
-  }
-
-  control = graph()->NewNode(common()->Merge(2), if_true0, if_false0);
-  effect = graph()->NewNode(common()->EffectPhi(2), etrue0, efalse0, control);
-  Node* value =
-      graph()->NewNode(common()->Phi(MachineRepresentation::kWord32, 2), vtrue0,
-                       vfalse0, control);
-
-  return ValueEffectControl(value, effect, control);
+  Callable const callable = CodeFactory::StringCharCodeAt(isolate());
+  Operator::Properties properties = Operator::kNoThrow | Operator::kNoWrite;
+  CallDescriptor::Flags flags = CallDescriptor::kNoFlags;
+  CallDescriptor* desc = Linkage::GetStubCallDescriptor(
+      isolate(), graph()->zone(), callable.descriptor(), 0, flags, properties,
+      MachineType::TaggedSigned());
+  node->InsertInput(graph()->zone(), 0,
+                    jsgraph()->HeapConstant(callable.code()));
+  node->InsertInput(graph()->zone(), 3, jsgraph()->NoContextConstant());
+  node->InsertInput(graph()->zone(), 4, effect);
+  NodeProperties::ChangeOp(node, common()->Call(desc));
+  return ValueEffectControl(node, node, control);
 }
 
 EffectControlLinearizer::ValueEffectControl
 EffectControlLinearizer::LowerStringFromCharCode(Node* node, Node* effect,
                                                  Node* control) {
   Node* value = node->InputAt(0);
 
   // Compute the character code.
   Node* code =
       graph()->NewNode(machine()->Word32And(), value,
@@ skipping 1313 matching lines @@
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
         Operator::kEliminatable);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8