[cleanup] Move many builtin String related functions out of CSA

Moves the following functions only used in string builtins out of
CodeStubAssembler:

StringAdd
AllocateConsString
StringFromSingleUTF16EncodedCodePoint
BranchIfCanDerefIndirectString
DerefIndirectString
MaybeDerefIndirectString
MaybeDerefIndirectStrings

Bug: v8:9396
Change-Id: Ib89966b9c170ca23dd7535a0f550c69966a6e21c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1817608
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63932}

src/builtins/builtins-string-gen.h

@@ -33,6 +33,8 @@ class StringBuiltinsAssembler : public CodeStubAssembler {
                                     SloppyTNode<IntPtrT> index,
                                     UnicodeEncoding encoding);
 
+  TNode<String> StringFromSingleUTF16EncodedCodePoint(TNode<Int32T> codepoint);
+
  protected:
   void StringEqual_Loop(Node* lhs, Node* lhs_instance_type,
                         MachineType lhs_type, Node* rhs,
@@ -82,6 +84,38 @@ class StringBuiltinsAssembler : public CodeStubAssembler {
     return SmiLessThan(value, SmiConstant(0));
   }
 
+  TNode<String> AllocateConsString(TNode<Uint32T> length, TNode<String> left,
+                                   TNode<String> right);
+
+  TNode<String> StringAdd(Node* context, TNode<String> left,
+                          TNode<String> right);
+
+  // Check if |string| is an indirect (thin or flat cons) string type that can
+  // be dereferenced by DerefIndirectString.
+  void BranchIfCanDerefIndirectString(TNode<String> string,
+                                      TNode<Int32T> instance_type,
+                                      Label* can_deref, Label* cannot_deref);
+  // Allocate an appropriate one- or two-byte ConsString with the first and
+  // second parts specified by |left| and |right|.
+  // Unpack an indirect (thin or flat cons) string type.
+  void DerefIndirectString(TVariable<String>* var_string,
+                           TNode<Int32T> instance_type);
+  // Check if |var_string| has an indirect (thin or flat cons) string type, and
+  // unpack it if so.
+  void MaybeDerefIndirectString(TVariable<String>* var_string,
+                                TNode<Int32T> instance_type, Label* did_deref,
+                                Label* cannot_deref);
+  // Check if |var_left| or |var_right| has an indirect (thin or flat cons)
+  // string type, and unpack it/them if so. Fall through if nothing was done.
+  void MaybeDerefIndirectStrings(TVariable<String>* var_left,
+                                 TNode<Int32T> left_instance_type,
+                                 TVariable<String>* var_right,
+                                 TNode<Int32T> right_instance_type,
+                                 Label* did_something);
+  TNode<String> DerefIndirectString(TNode<String> string,
+                                    TNode<Int32T> instance_type,
+                                    Label* cannot_deref);
+
   // Implements boilerplate logic for {match, split, replace, search} of the
   // form:
   //

src/builtins/string.tq

@@ -21,7 +21,8 @@ namespace string {
 
   extern macro StringBuiltinsAssembler::LoadSurrogatePairAt(
       String, intptr, intptr, constexpr UnicodeEncoding): int32;
-  extern macro StringFromSingleUTF16EncodedCodePoint(int32): String;
+  extern macro StringBuiltinsAssembler::StringFromSingleUTF16EncodedCodePoint(
+      int32): String;
 
   // This function assumes StringPrimitiveWithNoCustomIteration is true.
   transitioning builtin StringToList(implicit context: Context)(string: String):

src/codegen/code-stub-assembler.h

@@ -1739,11 +1739,6 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
                                             TNode<String> parent,
                                             TNode<Smi> offset);
 
-  // Allocate an appropriate one- or two-byte ConsString with the first and
-  // second parts specified by |left| and |right|.
-  TNode<String> AllocateConsString(TNode<Uint32T> length, TNode<String> left,
-                                   TNode<String> right);
-
   TNode<NameDictionary> AllocateNameDictionary(int at_least_space_for);
   TNode<NameDictionary> AllocateNameDictionary(
       TNode<IntPtrT> at_least_space_for, AllocationFlags = kNone);
@@ -2617,36 +2612,6 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
   TNode<String> SubString(TNode<String> string, TNode<IntPtrT> from,
                           TNode<IntPtrT> to);
 
-  // Return a new string object produced by concatenating |first| with |second|.
-  TNode<String> StringAdd(Node* context, TNode<String> first,
-                          TNode<String> second);
-
-  // Check if |string| is an indirect (thin or flat cons) string type that can
-  // be dereferenced by DerefIndirectString.
-  void BranchIfCanDerefIndirectString(TNode<String> string,
-                                      TNode<Int32T> instance_type,
-                                      Label* can_deref, Label* cannot_deref);
-  // Unpack an indirect (thin or flat cons) string type.
-  void DerefIndirectString(TVariable<String>* var_string,
-                           TNode<Int32T> instance_type);
-  // Check if |var_string| has an indirect (thin or flat cons) string type,
-  // and unpack it if so.
-  void MaybeDerefIndirectString(TVariable<String>* var_string,
-                                TNode<Int32T> instance_type, Label* did_deref,
-                                Label* cannot_deref);
-  // Check if |var_left| or |var_right| has an indirect (thin or flat cons)
-  // string type, and unpack it/them if so. Fall through if nothing was done.
-  void MaybeDerefIndirectStrings(TVariable<String>* var_left,
-                                 TNode<Int32T> left_instance_type,
-                                 TVariable<String>* var_right,
-                                 TNode<Int32T> right_instance_type,
-                                 Label* did_something);
-  TNode<String> DerefIndirectString(TNode<String> string,
-                                    TNode<Int32T> instance_type,
-                                    Label* cannot_deref);
-
-  TNode<String> StringFromSingleUTF16EncodedCodePoint(TNode<Int32T> codepoint);
-
   // Type conversion helpers.
   enum class BigIntHandling { kConvertToNumber, kThrow };
   // Convert a String to a Number.