[wasm] Remove support for trampolines from WasmCodeManager.

R=clemensh@chromium.org

Change-Id: Ic16e1da4ca50070ceff7f9a441250db2d20a868f
Reviewed-on: https://chromium-review.googlesource.com/1104471
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53871}

src/wasm/wasm-code-manager.cc

@@ -49,8 +49,6 @@ constexpr bool kModuleCanAllocateMoreMemory = false;
 constexpr bool kModuleCanAllocateMoreMemory = true;
 #endif
 
-constexpr bool kNeedsTrampoline = !kModuleCanAllocateMoreMemory;
-
 }  // namespace
 
 void DisjointAllocationPool::Merge(AddressRange range) {
@@ -269,8 +267,6 @@ const char* GetWasmCodeKindAsString(WasmCode::Kind kind) {
       return "runtime-stub";
     case WasmCode::kInterpreterEntry:
       return "interpreter entry";
-    case WasmCode::kTrampoline:
-      return "trampoline";
     case WasmCode::kJumpTable:
       return "jump table";
   }
@@ -592,37 +588,6 @@ WasmCode* NativeModule::AddCode(
   return ret;
 }
 
-Address NativeModule::CreateTrampolineTo(Handle<Code> code) {
-  Address dest = code->raw_instruction_start();
-  Address ret = dest;
-  if (kNeedsTrampoline) {
-    JumpTableAssembler jtasm;
-    jtasm.EmitJumpTrampoline(dest);
-    CodeDesc code_desc;
-    jtasm.GetCode(nullptr, &code_desc);
-    Vector<const byte> instructions(code_desc.buffer,
-                                    static_cast<size_t>(code_desc.instr_size));
-    WasmCode* wasm_code = AddOwnedCode(instructions,         // instructions
-                                       nullptr,              // reloc_info
-                                       0,                    // reloc_size
-                                       nullptr,              // source_pos
-                                       0,                    // source_pos_size
-                                       Nothing<uint32_t>(),  // index
-                                       WasmCode::kTrampoline,  // kind
-                                       0,   // constant_pool_offset
-                                       0,   // stack_slots
-                                       0,   // safepoint_table_offset
-                                       0,   // handler_table_offset
-                                       {},  // protected_instructions
-                                       WasmCode::kOther,         // tier
-                                       WasmCode::kFlushICache);  // flush_icache
-    ret = wasm_code->instruction_start();
-  }
-  DCHECK_EQ(0, trampolines_.count(dest));
-  trampolines_.emplace(std::make_pair(dest, ret));
-  return ret;
-}
-
 WasmCode* NativeModule::CreateEmptyJumpTable(uint32_t num_wasm_functions) {
   // Only call this if we really need a jump table.
   DCHECK_LT(0, num_wasm_functions);
@@ -655,22 +620,6 @@ void NativeModule::PatchJumpTable(uint32_t func_index, Address target,
   JumpTableAssembler::PatchJumpTableSlot(jump_table_slot, target, flush_icache);
 }
 
-Address NativeModule::GetLocalAddressFor(Handle<Code> code) {
-  DCHECK(Heap::IsImmovable(*code));
-
-  // Limit calls of {Code} objects on the GC heap to builtins (i.e. disallow
-  // calls to {CodeStub} or dynamic code). The serializer depends on this.
-  DCHECK(code->is_builtin());
-
-  Address index = code->raw_instruction_start();
-  auto trampoline_iter = trampolines_.find(index);
-  if (trampoline_iter == trampolines_.end()) {
-    return CreateTrampolineTo(code);
-  } else {
-    return trampoline_iter->second;
-  }
-}
-
 Address NativeModule::AllocateForCode(size_t size) {
   // This happens under a lock assumed by the caller.
   size = RoundUp(size, kCodeAlignment);

src/wasm/wasm-code-manager.h

@@ -96,7 +96,6 @@ class V8_EXPORT_PRIVATE WasmCode final {
     kLazyStub,
     kRuntimeStub,
     kInterpreterEntry,
-    kTrampoline,
     kJumpTable
   };
 
@@ -128,8 +127,7 @@ class V8_EXPORT_PRIVATE WasmCode final {
   }
 
   uint32_t index() const { return index_.ToChecked(); }
-  // Anonymous functions are functions that don't carry an index, like
-  // trampolines.
+  // Anonymous functions are functions that don't carry an index.
   bool IsAnonymous() const { return index_.IsNothing(); }
   Kind kind() const { return kind_; }
   NativeModule* native_module() const { return native_module_; }
@@ -362,8 +360,6 @@ class V8_EXPORT_PRIVATE NativeModule final {
                          size_t handler_table_offset,
                          std::unique_ptr<ProtectedInstructions>, WasmCode::Tier,
                          WasmCode::FlushICache);
-  Address GetLocalAddressFor(Handle<Code>);
-  Address CreateTrampolineTo(Handle<Code>);
 
   WasmCode* CreateEmptyJumpTable(uint32_t num_wasm_functions);
 
@@ -387,11 +383,6 @@ class V8_EXPORT_PRIVATE NativeModule final {
 
   WasmCode* runtime_stub_table_[WasmCode::kRuntimeStubCount] = {nullptr};
 
-  // Maps from instruction start of an immovable code object to instruction
-  // start of the trampoline.
-  // TODO(mstarzinger): By now trampolines are unused. Remove.
-  std::unordered_map<Address, Address> trampolines_;
-
   // Jump table used to easily redirect wasm function calls.
   WasmCode* jump_table_ = nullptr;
 

src/wasm/wasm-serialization.cc

@@ -218,12 +218,9 @@ class V8_EXPORT_PRIVATE NativeModuleSerializer {
 
  private:
   size_t MeasureCode(const WasmCode*) const;
-
   void WriteHeader(Writer* writer);
   void WriteCode(const WasmCode*, Writer* writer);
 
-  uint32_t EncodeBuiltin(Address);
-
   Isolate* const isolate_;
   const NativeModule* const native_module_;
   bool write_called_;
@@ -231,9 +228,7 @@ class V8_EXPORT_PRIVATE NativeModuleSerializer {
   // wasm code targets reverse lookup
   std::map<Address, uint32_t> wasm_targets_lookup_;
   std::map<Address, uint32_t> wasm_stub_targets_lookup_;
-  // immovable builtins and runtime entries lookup
   std::map<Address, uint32_t> reference_table_lookup_;
-  std::map<Address, uint32_t> builtin_lookup_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeModuleSerializer);
 };
@@ -256,15 +251,6 @@ NativeModuleSerializer::NativeModuleSerializer(Isolate* isolate,
     Address addr = table->address(i);
     reference_table_lookup_.insert(std::make_pair(addr, i));
   }
-  for (auto pair : native_module_->trampolines_) {
-    v8::internal::Code* code = Code::GetCodeFromTargetAddress(pair.first);
-    int builtin_index = code->builtin_index();
-    DCHECK_GE(builtin_index, 0);
-    // Note that ARM64 can only encode 26 bits in branch immediate instructions.
-    DCHECK_LT(builtin_index, 1 << 26);
-    uint32_t tag = static_cast<uint32_t>(builtin_index);
-    builtin_lookup_.insert(std::make_pair(pair.second, tag));
-  }
 }
 
 size_t NativeModuleSerializer::MeasureCode(const WasmCode* code) const {
@@ -331,8 +317,7 @@ void NativeModuleSerializer::WriteCode(const WasmCode* code, Writer* writer) {
 #endif
   memcpy(code_start, code->instructions().start(), code_size);
   // Relocate the code.
-  int mask = RelocInfo::ModeMask(RelocInfo::CODE_TARGET) |
-             RelocInfo::ModeMask(RelocInfo::WASM_CALL) |
+  int mask = RelocInfo::ModeMask(RelocInfo::WASM_CALL) |
              RelocInfo::ModeMask(RelocInfo::WASM_STUB_CALL) |
              RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE);
   RelocIterator orig_iter(code->instructions(), code->reloc_info(),
@@ -344,11 +329,6 @@ void NativeModuleSerializer::WriteCode(const WasmCode* code, Writer* writer) {
        !iter.done(); iter.next(), orig_iter.next()) {
     RelocInfo::Mode mode = orig_iter.rinfo()->rmode();
     switch (mode) {
-      case RelocInfo::CODE_TARGET: {
-        Address orig_target = orig_iter.rinfo()->target_address();
-        uint32_t tag = EncodeBuiltin(orig_target);
-        SetWasmCalleeTag(iter.rinfo(), tag);
-      } break;
       case RelocInfo::WASM_CALL: {
         Address orig_target = orig_iter.rinfo()->wasm_call_address();
         uint32_t tag = wasm_targets_lookup_[orig_target];
@@ -378,11 +358,6 @@ void NativeModuleSerializer::WriteCode(const WasmCode* code, Writer* writer) {
   }
 }
 
-uint32_t NativeModuleSerializer::EncodeBuiltin(Address address) {
-  DCHECK_EQ(1, builtin_lookup_.count(address));
-  return builtin_lookup_.find(address)->second;
-}
-
 bool NativeModuleSerializer::Write(Writer* writer) {
   DCHECK(!write_called_);
   write_called_ = true;
@@ -425,7 +400,6 @@ class V8_EXPORT_PRIVATE NativeModuleDeserializer {
  private:
   bool ReadHeader(Reader* reader);
   bool ReadCode(uint32_t fn_index, Reader* reader);
-  Address GetBuiltinTrampolineFromTag(uint32_t);
 
   Isolate* const isolate_;
   NativeModule* const native_module_;
@@ -504,8 +478,7 @@ bool NativeModuleDeserializer::ReadCode(uint32_t fn_index, Reader* reader) {
                                  WasmCode::kFlushICache);
 
   // Relocate the code.
-  int mask = RelocInfo::ModeMask(RelocInfo::CODE_TARGET) |
-             RelocInfo::ModeMask(RelocInfo::WASM_STUB_CALL) |
+  int mask = RelocInfo::ModeMask(RelocInfo::WASM_STUB_CALL) |
              RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) |
              RelocInfo::ModeMask(RelocInfo::WASM_CODE_TABLE_ENTRY);
   for (RelocIterator iter(ret->instructions(), ret->reloc_info(),
@@ -513,13 +486,6 @@ bool NativeModuleDeserializer::ReadCode(uint32_t fn_index, Reader* reader) {
        !iter.done(); iter.next()) {
     RelocInfo::Mode mode = iter.rinfo()->rmode();
     switch (mode) {
-      case RelocInfo::CODE_TARGET: {
-        uint32_t tag = GetWasmCalleeTag(iter.rinfo());
-        Address target = GetBuiltinTrampolineFromTag(tag);
-        iter.rinfo()->set_target_address(target, SKIP_WRITE_BARRIER,
-                                         SKIP_ICACHE_FLUSH);
-        break;
-      }
       case RelocInfo::WASM_STUB_CALL: {
         uint32_t tag = GetWasmCalleeTag(iter.rinfo());
         DCHECK_LT(tag, WasmCode::kRuntimeStubCount);
@@ -564,12 +530,6 @@ bool NativeModuleDeserializer::ReadCode(uint32_t fn_index, Reader* reader) {
   return true;
 }
 
-Address NativeModuleDeserializer::GetBuiltinTrampolineFromTag(uint32_t tag) {
-  int builtin_id = static_cast<int>(tag);
-  v8::internal::Code* builtin = isolate_->builtins()->builtin(builtin_id);
-  return native_module_->GetLocalAddressFor(handle(builtin, isolate_));
-}
-
 MaybeHandle<WasmModuleObject> DeserializeNativeModule(
     Isolate* isolate, Vector<const byte> data, Vector<const byte> wire_bytes) {
   if (!IsWasmCodegenAllowed(isolate, isolate->native_context())) {