[wasm] Initial signal handler

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/assembler-inl.h"
 #include "src/base/adapters.h"
 #include "src/base/atomic-utils.h"
 #include "src/code-stubs.h"
 #include "src/compiler/wasm-compiler.h"
 #include "src/debug/interface-types.h"
 #include "src/objects.h"
 #include "src/property-descriptor.h"
 #include "src/simulator.h"
 #include "src/snapshot/snapshot.h"
+#include "src/trap-handler/trap-handler.h"
 #include "src/v8.h"
 
 #include "src/wasm/function-body-decoder.h"
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-js.h"
 #include "src/wasm/wasm-limits.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-objects.h"
 #include "src/wasm/wasm-result.h"
 
@@ skipping 566 matching lines @@
   WasmInstanceObject* owner = reinterpret_cast<WasmInstanceObject*>(*p);
   Isolate* isolate = reinterpret_cast<Isolate*>(data.GetIsolate());
   // If a link to shared memory instances exists, update the list of memory
   // instances before the instance is destroyed.
   if (owner->has_instance_wrapper()) MemoryInstanceFinalizer(isolate, owner);
   WasmCompiledModule* compiled_module = owner->compiled_module();
   TRACE("Finalizing %d {\n", compiled_module->instance_id());
   DCHECK(compiled_module->has_weak_wasm_module());
   WeakCell* weak_wasm_module = compiled_module->ptr_to_weak_wasm_module();
 
+  if (trap_handler::EnableTrapHandler()) {
+    Handle<FixedArray> code_table = compiled_module->code_table();
+    for (int i = 0; i < code_table->length(); ++i) {
+      Handle<Code> code = code_table->GetValueChecked<Code>(isolate, i);
+      int index = code->trap_handler_index()->value();
+      if (index >= 0) {
+        trap_handler::ReleaseHandlerData(index);
+      }
+    }
+  }
+
   // weak_wasm_module may have been cleared, meaning the module object
   // was GC-ed. In that case, there won't be any new instances created,
   // and we don't need to maintain the links between instances.
   if (!weak_wasm_module->cleared()) {
     JSObject* wasm_module = JSObject::cast(weak_wasm_module->value());
     WasmCompiledModule* current_template =
         WasmCompiledModule::cast(wasm_module->GetInternalField(0));
 
     TRACE("chain before {\n");
     TRACE_CHAIN(current_template);
@@ skipping 712 matching lines @@
           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.
+        if (unpacked.size() > 0) {
+          Handle<Code> code = code_table->GetValueChecked<Code>(isolate_, i);
+          byte* base = code->entry();
+          int size = code->CodeSize();
+          trap_handler::CodeObjectData* handler_data =

[titzer, 2017/01/09 09:26:56]

Is it possible to hide this data structure altogether by making a single API
function that creates and registers the data?

[Eric Holk, 2017/01/10 23:10:48]

Yes. Originally I was thinking keeping them separate would let us share the same
data between different instances, but I don't think this plays nicely with JS
objects and the GC.

Done.

+              CreateHandlerData(reinterpret_cast<void*>(base), size,
+                                unpacked.size(), &unpacked[0]);
+          const int index = RegisterHandlerData(handler_data);
+          // TODO(eholk): if index is negative, fail.
+          DCHECK(index >= 0);
+          code->set_trap_handler_index(Smi::FromInt(index));
+        }
       }
     }
 
     //--------------------------------------------------------------------------
     // 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_);
@@ skipping 951 matching lines @@
   CHECK(!compiled_module->has_weak_owning_instance());
 }
 
 void testing::ValidateOrphanedInstance(Isolate* isolate,
                                        Handle<WasmInstanceObject> instance) {
   DisallowHeapAllocation no_gc;
   WasmCompiledModule* compiled_module = instance->compiled_module();
   CHECK(compiled_module->has_weak_wasm_module());
   CHECK(compiled_module->ptr_to_weak_wasm_module()->cleared());
 }