[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/asmjs/asm-wasm-builder.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 624 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::ShouldEnableTrapHandler()) {

[titzer, 2017/02/20 09:50:08]

Heads up that this code is going to move (see
https://codereview.chromium.org/2696143006/)

[Eric Holk, 2017/02/23 02:16:57]

Acknowledged. (Interestingly, I didn't get any significant merge conflicts
here...)

+    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);
+        code->set_trap_handler_index(Smi::FromInt(-1));
+      }
+    }
+  }
+
   // 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 729 matching lines @@
 
     // Patch new call sites and the context.
     PatchDirectCallsAndContext(code_table, compiled_module_, module_,
                                num_imported_functions);
 
     FlushICache(isolate_, code_table);
 
     //--------------------------------------------------------------------------
     // Unpack and notify signal handler of protected instructions.
     //--------------------------------------------------------------------------
-    if (FLAG_wasm_trap_handler) {
+    if (trap_handler::ShouldEnableTrapHandler()) {
       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;
         }
 
         const intptr_t base = reinterpret_cast<intptr_t>(code->entry());
 
         Zone zone(isolate_->allocator(), "Wasm Module");
         ZoneVector<trap_handler::ProtectedInstructionData> unpacked(&zone);
         const int mode_mask =
             RelocInfo::ModeMask(RelocInfo::WASM_PROTECTED_INSTRUCTION_LANDING);
         for (RelocIterator it(*code, mode_mask); !it.done(); it.next()) {
           trap_handler::ProtectedInstructionData data;
           data.instr_offset = it.rinfo()->data();
           data.landing_offset =
               reinterpret_cast<intptr_t>(it.rinfo()->pc()) - base;
           unpacked.emplace_back(data);
         }
-        // TODO(eholk): Register the protected instruction information once the
-        // trap handler is in place.
+        if (unpacked.size() > 0) {
+          int size = code->CodeSize();
+          const int index =
+              RegisterHandlerData(reinterpret_cast<void*>(base), size,
+                                  unpacked.size(), &unpacked[0]);
+          // 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 1375 matching lines @@
   Handle<FixedArray> storage = factory->NewFixedArray(num_custom_sections);
   JSArray::SetContent(array_object, storage);
   array_object->set_length(Smi::FromInt(num_custom_sections));
 
   for (int i = 0; i < num_custom_sections; i++) {
     storage->set(i, *matching_sections[i]);
   }
 
   return array_object;
 }