From b3e103466085312f5431253af8a1cb6f41629dc5 Mon Sep 17 00:00:00 2001
From: Joyee Cheung <joyeec9h3@gmail.com>
Date: Sat, 11 Feb 2023 17:49:32 +0100
Subject: [PATCH] buffer: use v8 fast API calls for `Buffer.byteLength`
 implementation

Use v8 fast API calls for Buffer.byteLength with sequential one-byte
strings.

PR-URL: https://github.com/nodejs/node/pull/46616
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 src/node_buffer.cc            | 28 +++++++++++++++++++++++++---
 src/node_external_reference.h |  3 +++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index 4bc7336e8d6033..fae5b8431926ee 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -32,6 +32,7 @@
 #include "string_bytes.h"
 #include "string_search.h"
 #include "util-inl.h"
+#include "v8-fast-api-calls.h"
 #include "v8.h"
 
 #include <cstring>
@@ -786,7 +787,7 @@ void StringWrite(const FunctionCallbackInfo<Value>& args) {
   args.GetReturnValue().Set(written);
 }
 
-void ByteLengthUtf8(const FunctionCallbackInfo<Value> &args) {
+void SlowByteLengthUtf8(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   CHECK(args[0]->IsString());
 
@@ -794,6 +795,21 @@ void ByteLengthUtf8(const FunctionCallbackInfo<Value> &args) {
   args.GetReturnValue().Set(args[0].As<String>()->Utf8Length(env->isolate()));
 }
 
+uint32_t FastByteLengthUtf8(Local<Value> receiver,
+                            const v8::FastOneByteString& source) {
+  uint32_t result = 0;
+  uint32_t length = source.length;
+  const uint8_t* data = reinterpret_cast<const uint8_t*>(source.data);
+  for (uint32_t i = 0; i < length; ++i) {
+    result += (data[i] >> 7);
+  }
+  result += length;
+  return result;
+}
+
+static v8::CFunction fast_byte_length_utf8(
+    v8::CFunction::Make(FastByteLengthUtf8));
+
 // Normalize val to be an integer in the range of [1, -1] since
 // implementations of memcmp() can vary by platform.
 static int normalizeCompareVal(int val, size_t a_length, size_t b_length) {
@@ -1368,7 +1384,11 @@ void Initialize(Local<Object> target,
   SetMethodNoSideEffect(context, target, "createFromString", CreateFromString);
   SetMethodNoSideEffect(context, target, "decodeUTF8", DecodeUTF8);
 
-  SetMethodNoSideEffect(context, target, "byteLengthUtf8", ByteLengthUtf8);
+  SetFastMethodNoSideEffect(context,
+                            target,
+                            "byteLengthUtf8",
+                            SlowByteLengthUtf8,
+                            &fast_byte_length_utf8);
   SetMethod(context, target, "copy", Copy);
   SetMethodNoSideEffect(context, target, "compare", Compare);
   SetMethodNoSideEffect(context, target, "compareOffset", CompareOffset);
@@ -1429,7 +1449,9 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(CreateFromString);
   registry->Register(DecodeUTF8);
 
-  registry->Register(ByteLengthUtf8);
+  registry->Register(SlowByteLengthUtf8);
+  registry->Register(fast_byte_length_utf8.GetTypeInfo());
+  registry->Register(FastByteLengthUtf8);
   registry->Register(Copy);
   registry->Register(Compare);
   registry->Register(CompareOffset);
diff --git a/src/node_external_reference.h b/src/node_external_reference.h
index 38ba3b21a74a69..063dd4cb794422 100644
--- a/src/node_external_reference.h
+++ b/src/node_external_reference.h
@@ -10,6 +10,8 @@
 
 namespace node {
 
+using CFunctionCallbackWithOneByteString =
+    uint32_t (*)(v8::Local<v8::Value>, const v8::FastOneByteString&);
 using CFunctionCallback = void (*)(v8::Local<v8::Value> receiver);
 
 // This class manages the external references from the V8 heap
@@ -20,6 +22,7 @@ class ExternalReferenceRegistry {
 
 #define ALLOWED_EXTERNAL_REFERENCE_TYPES(V)                                    \
   V(CFunctionCallback)                                                         \
+  V(CFunctionCallbackWithOneByteString)                                        \
   V(const v8::CFunctionInfo*)                                                  \
   V(v8::FunctionCallback)                                                      \
   V(v8::AccessorGetterCallback)                                                \