[base] Remove OwnedVector::start

For some reason, {OwnedVector} defines both a {start()} and a {begin()}
accessor which return the same value. As {begin()} is the name that the
standard library uses, this CL removes {start()} and switches all uses
to {begin()}.

R=mslekova@chromium.org

Change-Id: Ib505fe146db396f7589404c5a630e19248624729
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4075865
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84643}

src/base/vector.h

@@ -235,14 +235,12 @@ class OwnedVector {
   // Returns whether or not the vector is empty.
   constexpr bool empty() const { return length_ == 0; }
 
-  // Returns the pointer to the start of the data in the vector.
-  T* start() const {
+  constexpr T* begin() const {
     DCHECK_IMPLIES(length_ > 0, data_ != nullptr);
     return data_.get();
   }
 
-  constexpr T* begin() const { return start(); }
-  constexpr T* end() const { return start() + size(); }
+  constexpr T* end() const { return begin() + length_; }
 
   // Access individual vector elements - checks bounds in debug mode.
   T& operator[](size_t index) const {
@@ -251,7 +249,7 @@ class OwnedVector {
   }
 
   // Returns a {Vector<T>} view of the data in this vector.
-  Vector<T> as_vector() const { return Vector<T>(start(), size()); }
+  Vector<T> as_vector() const { return {begin(), size()}; }
 
   // Releases the backing data from this vector and transfers ownership to the
   // caller. This vector will be empty afterwards.
@@ -287,7 +285,7 @@ class OwnedVector {
     using non_const_t = typename std::remove_const<T>::type;
     auto vec =
         OwnedVector<non_const_t>::NewForOverwrite(std::distance(begin, end));
-    std::copy(begin, end, vec.start());
+    std::copy(begin, end, vec.begin());
     return vec;
   }
 

src/codegen/assembler.cc

@@ -102,11 +102,11 @@ class DefaultAssemblerBuffer : public AssemblerBuffer {
       : buffer_(base::OwnedVector<uint8_t>::NewForOverwrite(
             std::max(AssemblerBase::kMinimalBufferSize, size))) {
 #ifdef DEBUG
-    ZapCode(reinterpret_cast<Address>(buffer_.start()), buffer_.size());
+    ZapCode(reinterpret_cast<Address>(buffer_.begin()), buffer_.size());
 #endif
   }
 
-  byte* start() const override { return buffer_.start(); }
+  byte* start() const override { return buffer_.begin(); }
 
   int size() const override { return static_cast<int>(buffer_.size()); }
 

src/wasm/streaming-decoder.cc

@@ -58,12 +58,12 @@ class V8_EXPORT_PRIVATE AsyncStreamingDecoder : public StreamingDecoder {
           bytes_(base::OwnedVector<uint8_t>::NewForOverwrite(
               1 + length_bytes.length() + payload_length)),
           payload_offset_(1 + length_bytes.length()) {
-      bytes_.start()[0] = id;
-      memcpy(bytes_.start() + 1, &length_bytes.first(), length_bytes.length());
+      bytes_.begin()[0] = id;
+      memcpy(bytes_.begin() + 1, &length_bytes.first(), length_bytes.length());
     }
 
     SectionCode section_code() const {
-      return static_cast<SectionCode>(bytes_.start()[0]);
+      return static_cast<SectionCode>(bytes_.begin()[0]);
     }
 
     base::Vector<const uint8_t> GetCode(WireBytesRef ref) const final {

src/wasm/wasm-code-manager.cc

@@ -1072,7 +1072,7 @@ WasmCode* NativeModule::AddCodeForTesting(Handle<Code> code) {
   base::OwnedVector<byte> source_pos =
       base::OwnedVector<byte>::NewForOverwrite(source_pos_table->length());
   if (source_pos_table->length() > 0) {
-    source_pos_table->copy_out(0, source_pos.start(),
+    source_pos_table->copy_out(0, source_pos.begin(),
                                source_pos_table->length());
   }
   CHECK(!code->is_off_heap_trampoline());

src/wasm/wasm-objects.cc

@@ -2036,7 +2036,7 @@ std::unique_ptr<char[]> WasmExportedFunction::GetDebugName(
   // prefix + parameters + delimiter + returns + zero byte
   size_t len = strlen(kPrefix) + sig->all().size() + 2;
   auto buffer = base::OwnedVector<char>::New(len);
-  memcpy(buffer.start(), kPrefix, strlen(kPrefix));
+  memcpy(buffer.begin(), kPrefix, strlen(kPrefix));
   PrintSignature(buffer.as_vector() + strlen(kPrefix), sig);
   return buffer.ReleaseData();
 }

test/cctest/wasm/wasm-run-utils.cc

@@ -273,13 +273,13 @@ uint32_t TestingModuleBuilder::AddBytes(base::Vector<const byte> bytes) {
   base::OwnedVector<uint8_t> new_bytes =
       base::OwnedVector<uint8_t>::New(new_size);
   if (old_size > 0) {
-    memcpy(new_bytes.start(), old_bytes.begin(), old_size);
+    memcpy(new_bytes.begin(), old_bytes.begin(), old_size);
   } else {
     // Set the unused byte. It is never decoded, but the bytes are used as the
     // key in the native module cache.
     new_bytes[0] = 0;
   }
-  memcpy(new_bytes.start() + bytes_offset, bytes.begin(), bytes.length());
+  memcpy(new_bytes.begin() + bytes_offset, bytes.begin(), bytes.length());
   native_module_->SetWireBytes(std::move(new_bytes));
   return bytes_offset;
 }