Revert "[wasm] Further reduce the size of WasmCode"

This reverts commit 79398ab0.

Reason for revert: Makes UBSan unhappy: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20UBSan/10186

Original change's description:
> [wasm] Further reduce the size of WasmCode
> 
> Also, save dynamic allocations (plus their memory overhead).
> This is realized by storing the relocation information, source position
> table, and protected instruction information together in one "metadata"
> byte array.
> For each of the three components, we just store their size, such that
> the accessors can return the respecitive {Vector} views as before.
> 
> This makes each WasmCode object 24 bytes smaller on 64-bit
> architectures. It also saves a few more bytes per code object because
> less padding is needed for the individual allocations, and each dynamic
> allocation comes with some constant memory overhead.
> 
> Since the protected instructions will just be stored in a byte array
> now, some APIs are refactored to just return that byte array directly
> (instead of an array of {ProtectedInstructionData}). This also
> simplifies serialization and deserialization, and will allow for
> switching to a more compact representation in the future.
> 
> Drive-by: Add some more checks to {Vector::cast} to protect against
>   undefined behaviour.
> 
> R=​ahaas@chromium.org
> 
> Bug: v8:10254
> Change-Id: I81ca847023841110e3e52cc402fcb0349325d7af
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2078545
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#66596}

TBR=jkummerow@chromium.org,ahaas@chromium.org,clemensb@chromium.org,tebbi@chromium.org

Change-Id: Id80aa82cfce8942879031032b322ee66855b5600
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10254
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2089933Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66597}

src/compiler/backend/code-generator.cc

@@ -432,9 +432,10 @@ OwnedVector<byte> CodeGenerator::GetSourcePositionTable() {
   return source_position_table_builder_.ToSourcePositionTableVector();
 }
 
-OwnedVector<byte> CodeGenerator::GetProtectedInstructionsData() {
-  return OwnedVector<byte>::Of(
-      Vector<byte>::cast(VectorOf(protected_instructions_)));
+OwnedVector<trap_handler::ProtectedInstructionData>
+CodeGenerator::GetProtectedInstructions() {
+  return OwnedVector<trap_handler::ProtectedInstructionData>::Of(
+      protected_instructions_);
 }
 
 MaybeHandle<Code> CodeGenerator::FinalizeCode() {

src/compiler/backend/code-generator.h

@@ -125,7 +125,8 @@ class V8_EXPORT_PRIVATE CodeGenerator final : public GapResolver::Assembler {
   MaybeHandle<Code> FinalizeCode();
 
   OwnedVector<byte> GetSourcePositionTable();
-  OwnedVector<byte> GetProtectedInstructionsData();
+  OwnedVector<trap_handler::ProtectedInstructionData>
+  GetProtectedInstructions();
 
   InstructionSequence* instructions() const { return instructions_; }
   FrameAccessState* frame_access_state() const { return frame_access_state_; }

src/compiler/pipeline.cc

@@ -2765,8 +2765,7 @@ wasm::WasmCompilationResult Pipeline::GenerateCodeForWasmNativeStub(
       static_cast<int>(code_generator->GetHandlerTableOffset()));
   result.instr_buffer = instruction_buffer->ReleaseBuffer();
   result.source_positions = code_generator->GetSourcePositionTable();
-  result.protected_instructions_data =
-      code_generator->GetProtectedInstructionsData();
+  result.protected_instructions = code_generator->GetProtectedInstructions();
   result.frame_slot_count = code_generator->frame()->GetTotalFrameSlotCount();
   result.tagged_parameter_slots = call_descriptor->GetTaggedParameterSlots();
   result.result_tier = wasm::ExecutionTier::kTurbofan;
@@ -2973,8 +2972,7 @@ void Pipeline::GenerateCodeForWasmFunction(
   result->frame_slot_count = code_generator->frame()->GetTotalFrameSlotCount();
   result->tagged_parameter_slots = call_descriptor->GetTaggedParameterSlots();
   result->source_positions = code_generator->GetSourcePositionTable();
-  result->protected_instructions_data =
-      code_generator->GetProtectedInstructionsData();
+  result->protected_instructions = code_generator->GetProtectedInstructions();
   result->result_tier = wasm::ExecutionTier::kTurbofan;
 
   if (data.info()->trace_turbo_json_enabled()) {

src/compiler/wasm-compiler.cc

@@ -6666,9 +6666,8 @@ wasm::WasmCode* CompileWasmCapiCallWrapper(wasm::WasmEngine* wasm_engine,
       WasmStubAssemblerOptions(), source_positions);
   std::unique_ptr<wasm::WasmCode> wasm_code = native_module->AddCode(
       wasm::kAnonymousFuncIndex, result.code_desc, result.frame_slot_count,
-      result.tagged_parameter_slots,
-      result.protected_instructions_data.as_vector(),
-      result.source_positions.as_vector(), wasm::WasmCode::kWasmToCapiWrapper,
+      result.tagged_parameter_slots, std::move(result.protected_instructions),
+      std::move(result.source_positions), wasm::WasmCode::kWasmToCapiWrapper,
       wasm::ExecutionTier::kNone);
   return native_module->PublishCode(std::move(wasm_code));
 }

src/utils/vector.h

@@ -9,7 +9,6 @@
 #include <cstring>
 #include <iterator>
 #include <memory>
-#include <type_traits>
 
 #include "src/common/checks.h"
 #include "src/common/globals.h"
@@ -117,14 +116,6 @@ class Vector {
 
   template <typename S>
   static constexpr Vector<T> cast(Vector<S> input) {
-    // Casting is potentially dangerous, so be really restrictive here. This
-    // might be lifted once we have use cases for that.
-    STATIC_ASSERT(std::is_pod<S>::value);
-    STATIC_ASSERT(std::is_pod<T>::value);
-#if V8_HAS_CXX14_CONSTEXPR
-    DCHECK_EQ(0, (input.length() * sizeof(S)) % sizeof(T));
-    DCHECK_EQ(0, reinterpret_cast<uintptr_t>(input.begin()) % alignof(T));
-#endif
     return Vector<T>(reinterpret_cast<T*>(input.begin()),
                      input.length() * sizeof(S) / sizeof(T));
   }

src/wasm/baseline/liftoff-compiler.cc

@@ -321,9 +321,10 @@ class LiftoffCompiler {
     return source_position_table_builder_.ToSourcePositionTableVector();
   }
 
-  OwnedVector<uint8_t> GetProtectedInstructionsData() const {
-    return OwnedVector<uint8_t>::Of(
-        Vector<const uint8_t>::cast(VectorOf(protected_instructions_)));
+  OwnedVector<trap_handler::ProtectedInstructionData> GetProtectedInstructions()
+      const {
+    return OwnedVector<trap_handler::ProtectedInstructionData>::Of(
+        protected_instructions_);
   }
 
   uint32_t GetTotalFrameSlotCount() const {
@@ -2795,7 +2796,7 @@ WasmCompilationResult ExecuteLiftoffCompilation(
   compiler->GetCode(&result.code_desc);
   result.instr_buffer = instruction_buffer->ReleaseBuffer();
   result.source_positions = compiler->GetSourcePositionTable();
-  result.protected_instructions_data = compiler->GetProtectedInstructionsData();
+  result.protected_instructions = compiler->GetProtectedInstructions();
   result.frame_slot_count = compiler->GetTotalFrameSlotCount();
   result.tagged_parameter_slots = call_descriptor->GetTaggedParameterSlots();
   result.func_index = func_index;

src/wasm/function-compiler.h

@@ -67,7 +67,7 @@ struct WasmCompilationResult {
   uint32_t frame_slot_count = 0;
   uint32_t tagged_parameter_slots = 0;
   OwnedVector<byte> source_positions;
-  OwnedVector<byte> protected_instructions_data;
+  OwnedVector<trap_handler::ProtectedInstructionData> protected_instructions;
   int func_index = kAnonymousFuncIndex;
   ExecutionTier requested_tier;
   ExecutionTier result_tier;

src/wasm/module-compiler.cc

@@ -2972,9 +2972,8 @@ WasmCode* CompileImportWrapper(
       wasm_engine, &env, kind, sig, source_positions);
   std::unique_ptr<WasmCode> wasm_code = native_module->AddCode(
       result.func_index, result.code_desc, result.frame_slot_count,
-      result.tagged_parameter_slots,
-      result.protected_instructions_data.as_vector(),
-      result.source_positions.as_vector(), GetCodeKind(result),
+      result.tagged_parameter_slots, std::move(result.protected_instructions),
+      std::move(result.source_positions), GetCodeKind(result),
       ExecutionTier::kNone);
   WasmCode* published_code = native_module->PublishCode(std::move(wasm_code));
   (*cache_scope)[key] = published_code;

src/wasm/wasm-code-manager.h

@@ -127,12 +127,9 @@ class V8_EXPORT_PRIVATE WasmCode final {
   Address instruction_start() const {
     return reinterpret_cast<Address>(instructions_.begin());
   }
-  Vector<const byte> reloc_info() const {
-    return {protected_instructions_data().end(),
-            static_cast<size_t>(reloc_info_size_)};
-  }
+  Vector<const byte> reloc_info() const { return reloc_info_.as_vector(); }
   Vector<const byte> source_positions() const {
-    return {reloc_info().end(), static_cast<size_t>(source_positions_size_)};
+    return source_position_table_.as_vector();
   }
 
   // TODO(clemensb): Make this return int.
@@ -163,15 +160,9 @@ class V8_EXPORT_PRIVATE WasmCode final {
            pc < reinterpret_cast<Address>(instructions_.end());
   }
 
-  Vector<const uint8_t> protected_instructions_data() const {
-    return {meta_data_.get(),
-            static_cast<size_t>(protected_instructions_size_)};
-  }
-
-  Vector<const trap_handler::ProtectedInstructionData> protected_instructions()
+  Vector<trap_handler::ProtectedInstructionData> protected_instructions()
       const {
-    return Vector<const trap_handler::ProtectedInstructionData>::cast(
-        protected_instructions_data());
+    return protected_instructions_.as_vector();
   }
 
   void Validate() const;
@@ -227,17 +218,15 @@ class V8_EXPORT_PRIVATE WasmCode final {
            int safepoint_table_offset, int handler_table_offset,
            int constant_pool_offset, int code_comments_offset,
            int unpadded_binary_size,
-           Vector<const byte> protected_instructions_data,
-           Vector<const byte> reloc_info,
-           Vector<const byte> source_position_table, Kind kind,
+           OwnedVector<trap_handler::ProtectedInstructionData>
+               protected_instructions,
+           OwnedVector<const byte> reloc_info,
+           OwnedVector<const byte> source_position_table, Kind kind,
            ExecutionTier tier)
       : instructions_(instructions),
+        reloc_info_(std::move(reloc_info)),
+        source_position_table_(std::move(source_position_table)),
         native_module_(native_module),
-        meta_data_(ConcatenateBytes(
-            {protected_instructions_data, reloc_info, source_position_table})),
-        reloc_info_size_(reloc_info.length()),
-        source_positions_size_(source_position_table.length()),
-        protected_instructions_size_(protected_instructions_data.length()),
         index_(index),
         kind_(kind),
         constant_pool_offset_(constant_pool_offset),
@@ -247,6 +236,7 @@ class V8_EXPORT_PRIVATE WasmCode final {
         handler_table_offset_(handler_table_offset),
         code_comments_offset_(code_comments_offset),
         unpadded_binary_size_(unpadded_binary_size),
+        protected_instructions_(std::move(protected_instructions)),
         tier_(tier) {
     DCHECK_LE(safepoint_table_offset, unpadded_binary_size);
     DCHECK_LE(handler_table_offset, unpadded_binary_size);
@@ -254,9 +244,6 @@ class V8_EXPORT_PRIVATE WasmCode final {
     DCHECK_LE(constant_pool_offset, unpadded_binary_size);
   }
 
-  std::unique_ptr<const byte[]> ConcatenateBytes(
-      std::initializer_list<Vector<const byte>>);
-
   // Code objects that have been registered with the global trap handler within
   // this process, will have a {trap_handler_index} associated with them.
   int trap_handler_index() const {
@@ -278,16 +265,9 @@ class V8_EXPORT_PRIVATE WasmCode final {
   V8_NOINLINE bool DecRefOnPotentiallyDeadCode();
 
   Vector<byte> instructions_;
+  OwnedVector<const byte> reloc_info_;
+  OwnedVector<const byte> source_position_table_;
   NativeModule* native_module_ = nullptr;
-  // {meta_data_} contains several byte vectors concatenated into one:
-  //  - protected instructions data of size {protected_instructions_size_}
-  //  - relocation info of size {reloc_info_size_}
-  //  - source positions of size {source_positions_size_}
-  // Note that the protected instructions come first to ensure alignment.
-  std::unique_ptr<const byte[]> meta_data_;
-  const int reloc_info_size_;
-  const int source_positions_size_;
-  const int protected_instructions_size_;
   int index_;
   Kind kind_;
   int constant_pool_offset_ = 0;
@@ -302,6 +282,7 @@ class V8_EXPORT_PRIVATE WasmCode final {
   int code_comments_offset_ = 0;
   int unpadded_binary_size_ = 0;
   int trap_handler_index_ = -1;
+  OwnedVector<trap_handler::ProtectedInstructionData> protected_instructions_;
   ExecutionTier tier_;
 
   // WasmCode is ref counted. Counters are held by:
@@ -323,7 +304,7 @@ class V8_EXPORT_PRIVATE WasmCode final {
 // often for rather small functions.
 // Increase the limit if needed, but first check if the size increase is
 // justified.
-STATIC_ASSERT(sizeof(WasmCode) <= 96);
+STATIC_ASSERT(sizeof(WasmCode) <= 120);
 
 WasmCode::Kind GetCodeKind(const WasmCompilationResult& result);
 
@@ -430,11 +411,13 @@ class V8_EXPORT_PRIVATE NativeModule final {
   // {AddCode} is thread safe w.r.t. other calls to {AddCode} or methods adding
   // code below, i.e. it can be called concurrently from background threads.
   // The returned code still needs to be published via {PublishCode}.
-  std::unique_ptr<WasmCode> AddCode(int index, const CodeDesc& desc,
-                                    int stack_slots, int tagged_parameter_slots,
-                                    Vector<const byte> protected_instructions,
-                                    Vector<const byte> source_position_table,
-                                    WasmCode::Kind kind, ExecutionTier tier);
+  std::unique_ptr<WasmCode> AddCode(
+      int index, const CodeDesc& desc, int stack_slots,
+      int tagged_parameter_slots,
+      OwnedVector<trap_handler::ProtectedInstructionData>
+          protected_instructions,
+      OwnedVector<const byte> source_position_table, WasmCode::Kind kind,
+      ExecutionTier tier);
 
   // {PublishCode} makes the code available to the system by entering it into
   // the code table and patching the jump table. It returns a raw pointer to the
@@ -448,9 +431,11 @@ class V8_EXPORT_PRIVATE NativeModule final {
       int tagged_parameter_slots, int safepoint_table_offset,
       int handler_table_offset, int constant_pool_offset,
       int code_comments_offset, int unpadded_binary_size,
-      Vector<const byte> protected_instructions_data,
-      Vector<const byte> reloc_info, Vector<const byte> source_position_table,
-      WasmCode::Kind kind, ExecutionTier tier);
+      OwnedVector<trap_handler::ProtectedInstructionData>
+          protected_instructions,
+      OwnedVector<const byte> reloc_info,
+      OwnedVector<const byte> source_position_table, WasmCode::Kind kind,
+      ExecutionTier tier);
 
   // Adds anonymous code for testing purposes.
   WasmCode* AddCodeForTesting(Handle<Code> code);
@@ -616,8 +601,9 @@ class V8_EXPORT_PRIVATE NativeModule final {
   std::unique_ptr<WasmCode> AddCodeWithCodeSpace(
       int index, const CodeDesc& desc, int stack_slots,
       int tagged_parameter_slots,
-      Vector<const byte> protected_instructions_data,
-      Vector<const byte> source_position_table, WasmCode::Kind kind,
+      OwnedVector<trap_handler::ProtectedInstructionData>
+          protected_instructions,
+      OwnedVector<const byte> source_position_table, WasmCode::Kind kind,
       ExecutionTier tier, Vector<uint8_t> code_space,
       const JumpTablesRef& jump_tables_ref);
 

src/wasm/wasm-debug.cc

@@ -900,9 +900,8 @@ void WasmDebugInfo::RedirectToInterpreter(Handle<WasmDebugInfo> debug_info,
         module->functions[func_index].sig);
     std::unique_ptr<wasm::WasmCode> wasm_code = native_module->AddCode(
         func_index, result.code_desc, result.frame_slot_count,
-        result.tagged_parameter_slots,
-        result.protected_instructions_data.as_vector(),
-        result.source_positions.as_vector(), wasm::WasmCode::kInterpreterEntry,
+        result.tagged_parameter_slots, std::move(result.protected_instructions),
+        std::move(result.source_positions), wasm::WasmCode::kInterpreterEntry,
         wasm::ExecutionTier::kInterpreter);
     native_module->PublishCode(std::move(wasm_code));
     DCHECK(native_module->IsRedirectedToInterpreter(func_index));

src/wasm/wasm-objects.cc

@@ -1460,9 +1460,8 @@ void WasmInstanceObject::ImportWasmJSFunctionIntoTable(
         isolate->wasm_engine(), &env, kind, sig, false);
     std::unique_ptr<wasm::WasmCode> wasm_code = native_module->AddCode(
         result.func_index, result.code_desc, result.frame_slot_count,
-        result.tagged_parameter_slots,
-        result.protected_instructions_data.as_vector(),
-        result.source_positions.as_vector(), GetCodeKind(result),
+        result.tagged_parameter_slots, std::move(result.protected_instructions),
+        std::move(result.source_positions), GetCodeKind(result),
         wasm::ExecutionTier::kNone);
     wasm::WasmCode* published_code =
         native_module->PublishCode(std::move(wasm_code));

src/wasm/wasm-serialization.cc

@@ -99,17 +99,16 @@ class Reader {
     return value;
   }
 
-  template <typename T>
-  Vector<const T> ReadVector(size_t size) {
-    DCHECK_GE(current_size(), size);
-    Vector<const byte> bytes{pos_, size * sizeof(T)};
-    pos_ += size * sizeof(T);
+  void ReadVector(Vector<byte> v) {
+    if (v.size() > 0) {
+      DCHECK_GE(current_size(), v.size());
+      memcpy(v.begin(), current_location(), v.size());
+      pos_ += v.size();
+    }
     if (FLAG_trace_wasm_serialization) {
-      StdoutStream{} << "read vector of " << size << " elements of size "
-                     << sizeof(T) << " (total size " << size * sizeof(T) << ")"
+      StdoutStream{} << "read vector of " << v.size() << " elements"
                      << std::endl;
     }
-    return Vector<const T>::cast(bytes);
   }
 
   void Skip(size_t size) { pos_ += size; }
@@ -305,7 +304,8 @@ size_t NativeModuleSerializer::MeasureCode(const WasmCode* code) const {
          code->kind() == WasmCode::kInterpreterEntry);
   return kCodeHeaderSize + code->instructions().size() +
          code->reloc_info().size() + code->source_positions().size() +
-         code->protected_instructions_data().size();
+         code->protected_instructions().size() *
+             sizeof(trap_handler::ProtectedInstructionData);
 }
 
 size_t NativeModuleSerializer::Measure() const {
@@ -343,7 +343,7 @@ void NativeModuleSerializer::WriteCode(const WasmCode* code, Writer* writer) {
   writer->Write(code->instructions().length());
   writer->Write(code->reloc_info().length());
   writer->Write(code->source_positions().length());
-  writer->Write(code->protected_instructions_data().length());
+  writer->Write(code->protected_instructions().length());
   writer->Write(code->kind());
   writer->Write(code->tier());
 
@@ -355,7 +355,7 @@ void NativeModuleSerializer::WriteCode(const WasmCode* code, Writer* writer) {
   // Write the reloc info, source positions, and protected code.
   writer->WriteVector(code->reloc_info());
   writer->WriteVector(code->source_positions());
-  writer->WriteVector(code->protected_instructions_data());
+  writer->WriteVector(Vector<byte>::cast(code->protected_instructions()));
 #if V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_ARM || \
     V8_TARGET_ARCH_PPC || V8_TARGET_ARCH_PPC64 || V8_TARGET_ARCH_S390X
   // On platforms that don't support misaligned word stores, copy to an aligned
@@ -516,17 +516,25 @@ bool NativeModuleDeserializer::ReadCode(int fn_index, Reader* reader) {
   WasmCode::Kind kind = reader->Read<WasmCode::Kind>();
   ExecutionTier tier = reader->Read<ExecutionTier>();
 
-  auto code_buffer = reader->ReadVector<byte>(code_size);
-  auto reloc_info = reader->ReadVector<byte>(reloc_size);
-  auto source_pos = reader->ReadVector<byte>(source_position_size);
+  Vector<const byte> code_buffer{reader->current_location(),
+                                 static_cast<size_t>(code_size)};
+  reader->Skip(code_size);
+
+  OwnedVector<byte> reloc_info = OwnedVector<byte>::New(reloc_size);
+  reader->ReadVector(reloc_info.as_vector());
+  OwnedVector<byte> source_pos = OwnedVector<byte>::New(source_position_size);
+  reader->ReadVector(source_pos.as_vector());
   auto protected_instructions =
-      reader->ReadVector<byte>(protected_instructions_size);
+      OwnedVector<trap_handler::ProtectedInstructionData>::New(
+          protected_instructions_size);
+  reader->ReadVector(Vector<byte>::cast(protected_instructions.as_vector()));
 
   WasmCode* code = native_module_->AddDeserializedCode(
       fn_index, code_buffer, stack_slot_count, tagged_parameter_slots,
       safepoint_table_offset, handler_table_offset, constant_pool_offset,
-      code_comment_offset, unpadded_binary_size, protected_instructions,
-      std::move(reloc_info), std::move(source_pos), kind, tier);
+      code_comment_offset, unpadded_binary_size,
+      std::move(protected_instructions), std::move(reloc_info),
+      std::move(source_pos), kind, tier);
 
   // Relocate the code.
   int mask = RelocInfo::ModeMask(RelocInfo::WASM_CALL) |

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

@@ -3753,9 +3753,9 @@ TEST(Liftoff_tier_up) {
     memcpy(buffer.get(), sub_code->instructions().begin(), sub_size);
     desc.buffer = buffer.get();
     desc.instr_size = static_cast<int>(sub_size);
-    std::unique_ptr<WasmCode> new_code =
-        native_module->AddCode(add.function_index(), desc, 0, 0, {}, {},
-                               WasmCode::kFunction, ExecutionTier::kTurbofan);
+    std::unique_ptr<WasmCode> new_code = native_module->AddCode(
+        add.function_index(), desc, 0, 0, {}, OwnedVector<byte>(),
+        WasmCode::kFunction, ExecutionTier::kTurbofan);
     native_module->PublishCode(std::move(new_code));
 
     // Second run should now execute {sub}.

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

@@ -144,9 +144,8 @@ uint32_t TestingModuleBuilder::AddFunction(const FunctionSig* sig,
         sig);
     std::unique_ptr<wasm::WasmCode> code = native_module_->AddCode(
         index, result.code_desc, result.frame_slot_count,
-        result.tagged_parameter_slots,
-        result.protected_instructions_data.as_vector(),
-        result.source_positions.as_vector(), wasm::WasmCode::kInterpreterEntry,
+        result.tagged_parameter_slots, std::move(result.protected_instructions),
+        std::move(result.source_positions), wasm::WasmCode::kInterpreterEntry,
         wasm::ExecutionTier::kInterpreter);
     native_module_->PublishCode(std::move(code));
   }