[wasm] Avoid specializing code on instance finalization.

Now that {WasmCode} objects are no longer specific to an instance, it is
no longer needed to patch code when the last instance is finalized. The
code specialization in {WasmCompiledModule::Reset} is no longer needed.

R=clemensh@chromium.org

Change-Id: I430e7f7258d309916de1188d47677c7feb8123b0
Reviewed-on: https://chromium-review.googlesource.com/1057488Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53155}

src/wasm/wasm-code-specialization.cc

@@ -136,14 +136,10 @@ bool CodeSpecialization::ApplyToWasmCode(wasm::WasmCode* code,
   bool reloc_direct_calls = relocate_direct_calls_module_ != nullptr;
 
   int reloc_mode = 0;
-  auto add_mode = [&reloc_mode](bool cond, RelocInfo::Mode mode) {
-    if (cond) reloc_mode |= RelocInfo::ModeMask(mode);
-  };
-  add_mode(reloc_direct_calls, RelocInfo::WASM_CALL);
-
-  // Always patch the code table entry address which is used in Liftoff
-  // prologue to jump to optimized code if existent.
-  reloc_mode |= RelocInfo::ModeMask(RelocInfo::WASM_CODE_TABLE_ENTRY);
+  if (reloc_direct_calls) {
+    reloc_mode |= RelocInfo::ModeMask(RelocInfo::WASM_CALL);
+  }
+  if (!reloc_mode) return false;
 
   base::Optional<PatchDirectCallsHelper> patch_direct_calls_helper;
   bool changed = false;
@@ -177,14 +173,6 @@ bool CodeSpecialization::ApplyToWasmCode(wasm::WasmCode* code,
                                           icache_flush_mode);
         changed = true;
       } break;
-      case RelocInfo::WASM_CODE_TABLE_ENTRY: {
-        DCHECK(FLAG_wasm_tier_up);
-        DCHECK(code->is_liftoff());
-        WasmCode* const* code_table_entry =
-            native_module->code_table().data() + code->index();
-        it.rinfo()->set_wasm_code_table_entry(
-            reinterpret_cast<Address>(code_table_entry), icache_flush_mode);
-      } break;
 
       default:
         UNREACHABLE();

src/wasm/wasm-objects.cc

@@ -15,7 +15,6 @@
 #include "src/wasm/module-compiler.h"
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-code-manager.h"
-#include "src/wasm/wasm-code-specialization.h"
 #include "src/wasm/wasm-engine.h"
 #include "src/wasm/wasm-limits.h"
 #include "src/wasm/wasm-memory.h"
@@ -1407,25 +1406,6 @@ void WasmCompiledModule::Reset(Isolate* isolate,
   if (native_module->use_trap_handler()) {
     native_module->ReleaseProtectedInstructions();
   }
-
-  // Patch code to update memory references, global references, and function
-  // table references.
-  wasm::CodeSpecialization code_specialization;
-
-  for (uint32_t i = native_module->num_imported_functions(),
-                end = native_module->function_count();
-       i < end; ++i) {
-    wasm::WasmCode* code = native_module->code(i);
-    // Skip lazy compile stubs.
-    if (code == nullptr || code->kind() != wasm::WasmCode::kFunction) continue;
-    bool changed = code_specialization.ApplyToWasmCode(code, SKIP_ICACHE_FLUSH);
-    // TODO(wasm): Check if this is faster than passing FLUSH_ICACHE_IF_NEEDED
-    // above.
-    if (changed) {
-      Assembler::FlushICache(code->instructions().start(),
-                             code->instructions().size());
-    }
-  }
 }
 
 MaybeHandle<String> WasmSharedModuleData::ExtractUtf8StringFromModuleBytes(
@@ -1486,13 +1466,6 @@ void WasmCompiledModule::RemoveFromChain() {
   }
 }
 
-void WasmCompiledModule::ReinitializeAfterDeserialization(
-    Isolate* isolate, Handle<WasmCompiledModule> compiled_module) {
-  // Reset, but don't delete any global handles, because their owning instance
-  // may still be active.
-  WasmCompiledModule::Reset(isolate, *compiled_module);
-}
-
 MaybeHandle<String> WasmSharedModuleData::GetModuleNameOrNull(
     Isolate* isolate, Handle<WasmSharedModuleData> shared) {
   WasmModule* module = shared->module();

src/wasm/wasm-objects.h

@@ -598,9 +598,6 @@ class WasmCompiledModule : public Struct {
 
   void PrintInstancesChain();
 
-  static void ReinitializeAfterDeserialization(Isolate*,
-                                               Handle<WasmCompiledModule>);
-
   void LogWasmCodes(Isolate* isolate);
 
  private:

src/wasm/wasm-serialization.cc

@@ -557,7 +557,8 @@ bool NativeModuleDeserializer::ReadCode(uint32_t fn_index, Reader* reader) {
   int mask = RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
              RelocInfo::ModeMask(RelocInfo::CODE_TARGET) |
              RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY) |
-             RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE);
+             RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) |
+             RelocInfo::ModeMask(RelocInfo::WASM_CODE_TABLE_ENTRY);
   for (RelocIterator iter(ret->instructions(), ret->reloc_info(),
                           ret->constant_pool(), mask);
        !iter.done(); iter.next()) {
@@ -591,6 +592,15 @@ bool NativeModuleDeserializer::ReadCode(uint32_t fn_index, Reader* reader) {
         iter.rinfo()->set_target_external_reference(address, SKIP_ICACHE_FLUSH);
         break;
       }
+      case RelocInfo::WASM_CODE_TABLE_ENTRY: {
+        DCHECK(FLAG_wasm_tier_up);
+        DCHECK(ret->is_liftoff());
+        WasmCode* const* code_table_entry =
+            native_module_->code_table().data() + ret->index();
+        iter.rinfo()->set_wasm_code_table_entry(
+            reinterpret_cast<Address>(code_table_entry), SKIP_ICACHE_FLUSH);
+        break;
+      }
       default:
         UNREACHABLE();
     }
@@ -671,8 +681,11 @@ MaybeHandle<WasmModuleObject> DeserializeNativeModule(
   // into the allocator.
   CodeSpaceMemoryModificationScope modification_scope(isolate->heap());
   CompileJsToWasmWrappers(isolate, module_object, isolate->counters());
-  WasmCompiledModule::ReinitializeAfterDeserialization(isolate,
-                                                       compiled_module);
+
+  // There are no instances for this module yet, which means we need to reset
+  // the module into a state as if the last instance was collected.
+  WasmCompiledModule::Reset(isolate, *compiled_module);
+
   return module_object;
 }