[string] Move String.p.toLowerCase to CSA

src/builtins/builtins-intl-gen.cc

+// Copyright 2017 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.
+
+#ifndef V8_INTL_SUPPORT
+#error Internationalization is expected to be enabled.
+#endif  // V8_INTL_SUPPORT
+
+#include "src/builtins/builtins-utils-gen.h"
+#include "src/code-stub-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+class IntlBuiltinsAssembler : public CodeStubAssembler {
+ public:
+  explicit IntlBuiltinsAssembler(compiler::CodeAssemblerState* state)
+      : CodeStubAssembler(state) {}
+};
+
+TF_BUILTIN(StringPrototypeToLowerCaseIntl, IntlBuiltinsAssembler) {
+  Node* const maybe_string = Parameter(Descriptor::kReceiver);
+  Node* const context = Parameter(Descriptor::kContext);
+
+  Node* const string =
+      ToThisString(context, maybe_string, "String.prototype.toLowerCase");
+
+  Label call_c(this), return_string(this), runtime(this, Label::kDeferred);
+
+  // Early exit on empty strings.
+  Node* const length = SmiUntag(LoadStringLength(string));
+  GotoIf(IntPtrEqual(length, IntPtrConstant(0)), &return_string);
+
+  // Unpack strings if possible, and bail to runtime unless we get a one-byte
+  // flat string.
+  ToDirectStringAssembler to_direct(
+      state(), string, ToDirectStringAssembler::kDontUnpackSlicedStrings);
+  to_direct.TryToDirect(&runtime);
+
+  Node* const instance_type = to_direct.instance_type();
+  CSA_ASSERT(this,
+             Word32BinaryNot(IsIndirectStringInstanceType(instance_type)));
+  GotoIfNot(IsOneByteStringInstanceType(instance_type), &runtime);
+
+  // For short strings, do the conversion in CSA through the lookup table.
+
+  Node* const dst = AllocateSeqOneByteString(context, length);
+
+  const int kMaxShortStringLength = 24;  // Determined empirically.
+  GotoIf(IntPtrGreaterThan(length, IntPtrConstant(kMaxShortStringLength)),
+         &call_c);
+
+  {
+    Node* const dst_ptr = PointerToSeqStringData(dst);
+    VARIABLE(var_cursor, MachineType::PointerRepresentation(),
+             IntPtrConstant(0));
+
+    Node* const start_address = to_direct.PointerToData(&call_c);
+    Node* const end_address = IntPtrAdd(start_address, length);
+
+    Node* const to_lower_table_addr = ExternalConstant(
+        ExternalReference::intl_to_latin1_lower_table(isolate()));
+
+    VariableList push_vars({&var_cursor}, zone());
+    BuildFastLoop(
+        push_vars, start_address, end_address,
+        [=, &var_cursor](Node* current) {
+          Node* c = ChangeInt32ToIntPtr(Load(MachineType::Uint8(), current));
+          Node* lower = Load(MachineType::Uint8(), to_lower_table_addr, c);
+          StoreNoWriteBarrier(MachineRepresentation::kWord8, dst_ptr,
+                              var_cursor.value(), lower);
+          Increment(var_cursor);
+        },
+        kCharSize, INTPTR_PARAMETERS, IndexAdvanceMode::kPost);
+
+    // All lower-case.
+    Return(dst);
+  }
+
+  // Call into C for case conversion. The signature is:
+  // Object* ConvertOneByteToLower(String* src, String* dst, Isolate* isolate);
+  BIND(&call_c);
+  {
+    Node* const src = to_direct.string();
+
+    Node* const function_addr = ExternalConstant(
+        ExternalReference::intl_convert_one_byte_to_lower(isolate()));
+    Node* const isolate_ptr =
+        ExternalConstant(ExternalReference::isolate_address(isolate()));
+
+    MachineType type_ptr = MachineType::Pointer();
+    MachineType type_tagged = MachineType::AnyTagged();
+
+    Node* const result =
+        CallCFunction3(type_tagged, type_tagged, type_tagged, type_ptr,
+                       function_addr, src, dst, isolate_ptr);
+
+    Return(result);
+  }
+
+  BIND(&return_string);
+  Return(string);
+
+  BIND(&runtime);
+  {
+    Node* const result =
+        CallRuntime(Runtime::kStringToLowerCaseIntl, context, string);
+    Return(result);
+  }
+}
+
+}  // namespace internal
+}  // namespace v8