[wasm] OOB traps: build protected instruction list during codegen

src/wasm/wasm-module.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <memory>
 
 #include "src/base/atomic-utils.h"
 #include "src/code-stubs.h"
 
 #include "src/macro-assembler.h"
@@ skipping 1242 matching lines @@
     if (function_table_count > 0) InitializeTables(code_table, instance);
 
     if (num_imported_functions > 0 || !owner.is_null()) {
       // If the code was cloned, or new imports were compiled, patch.
       PatchDirectCalls(old_code_table, code_table, num_imported_functions);
     }
 
     FlushICache(isolate_, code_table);
 
     //--------------------------------------------------------------------------
+    // Unpack and notify signal handler of protected instructions.
+    //--------------------------------------------------------------------------
+    {
+      for (int i = 0; i < code_table->length(); ++i) {
+        Handle<Code> code = code_table->GetValueChecked<Code>(isolate_, i);
+
+        if (code->kind() != Code::WASM_FUNCTION) {
+          continue;
+        }
+
+        FixedArray* protected_instructions = code->protected_instructions();
+
+        Zone zone(isolate_->allocator(), "Wasm Module");
+        ZoneVector<trap_handler::ProtectedInstructionData> unpacked(&zone);
+        for (int i = 0; i < protected_instructions->length();
+             i += Code::kTrapDataSize) {
+          trap_handler::ProtectedInstructionData data;
+          data.instr_offset =
+              protected_instructions
+                  ->GetValueChecked<Smi>(isolate_, i + Code::kTrapCodeOffset)
+                  ->value();
+          data.landing_offset =
+              protected_instructions
+                  ->GetValueChecked<Smi>(isolate_, i + Code::kTrapLandingOffset)
+                  ->value();
+          unpacked.emplace_back(data);
+        }
+        // TODO(eholk): Register the protected instruction information once the
+        // trap handler is in place.
+      }
+    }
+
     // Set up and link the new instance.
     //--------------------------------------------------------------------------
     {
       Handle<Object> global_handle =
           isolate_->global_handles()->Create(*instance);
       Handle<WeakCell> link_to_clone = factory->NewWeakCell(compiled_module_);
       Handle<WeakCell> link_to_owning_instance = factory->NewWeakCell(instance);
       MaybeHandle<WeakCell> link_to_original;
       MaybeHandle<WasmCompiledModule> original;
       if (!owner.is_null()) {
@@ skipping 1078 matching lines @@
 MaybeHandle<String> WasmCompiledModule::GetFunctionName(
     Handle<WasmCompiledModule> compiled_module, uint32_t func_index) {
   DCHECK_LT(func_index, compiled_module->module()->functions.size());
   WasmFunction& function = compiled_module->module()->functions[func_index];
   Isolate* isolate = compiled_module->GetIsolate();
   MaybeHandle<String> string = ExtractStringFromModuleBytes(
       isolate, compiled_module, function.name_offset, function.name_length);
   if (!string.is_null()) return string.ToHandleChecked();
   return {};
 }