[string] Move String.p.toLowerCase to CSA

src/builtins/builtins-intl-gen.cc

Index: src/builtins/builtins-intl-gen.cc
diff --git a/src/builtins/builtins-intl-gen.cc b/src/builtins/builtins-intl-gen.cc
new file mode 100644
index 0000000000000000000000000000000000000000..89da1c39328e0245b5c24109dd38c9ee5b8fb818
--- /dev/null
+++ b/src/builtins/builtins-intl-gen.cc
@@ -0,0 +1,110 @@
+// 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);
+
+  GotoIfNot(IsOneByteStringInstanceType(to_direct.instance_type()), &runtime);

[Camillo Bruni, 2017/05/05 10:10:03]

I'd prefer to check for IsOneByteSequential here, that's the only case you
handle anyway (unles I misread ToDirectStringAssembler and we return the
instance_type of the outer string).

[jgruber, 2017/05/05 10:21:58]

If we reach this point the string is guaranteed to be sequential or external,
and we handle both cases in the following code. We can't check for IsOneByteSeq
because it could be external.

[Camillo Bruni, 2017/05/05 11:44:26]

right, I thought I missed a case. But it would definitely never be a cons
string.

+
+  // 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 = 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