[wasm] Print debug side table together with code

For debugging (either with --print-wasm-code, or inspecting the current
code object in a debugger) it's helpful to also see the debug side
table, if available.

This CL adds print support for that, and uses it when printing wasm
code, and after generating a new debug side table.

R=thibaudm@chromium.org

Bug: v8:10359
Change-Id: I700b6eacb80f015212115e91b94c513e88c04288
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2202902
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67848}

src/wasm/wasm-code-manager.cc

@@ -327,6 +327,12 @@ void WasmCode::Print(const char* name) const {
   StdoutStream os;
   os << "--- WebAssembly code ---\n";
   Disassemble(name, os);
+  if (native_module_->HasDebugInfo()) {
+    if (auto* debug_side_table =
+            native_module_->GetDebugInfo()->GetDebugSideTableIfExists(this)) {
+      debug_side_table->Print(os);
+    }
+  }
   os << "--- End code ---\n";
 }
 
@@ -923,7 +929,7 @@ WasmCode* NativeModule::AddCodeForTesting(Handle<Code> code) {
                    WasmCode::kFunction,     // kind
                    ExecutionTier::kNone,    // tier
                    kNoDebugging}};          // for_debugging
-  new_code->MaybePrint(nullptr);
+  new_code->MaybePrint();
   new_code->Validate();
 
   return PublishCode(std::move(new_code));
@@ -1881,6 +1887,11 @@ size_t NativeModule::GetNumberOfCodeSpacesForTesting() const {
   return code_allocator_.GetNumCodeSpaces();
 }
 
+bool NativeModule::HasDebugInfo() const {
+  base::MutexGuard guard(&allocation_mutex_);
+  return debug_info_ != nullptr;
+}
+
 DebugInfo* NativeModule::GetDebugInfo() {
   base::MutexGuard guard(&allocation_mutex_);
   if (!debug_info_) debug_info_ = std::make_unique<DebugInfo>(this);

src/wasm/wasm-code-manager.h

@@ -623,6 +623,9 @@ class V8_EXPORT_PRIVATE NativeModule final {
   // Retrieve the number of separately reserved code spaces for this module.
   size_t GetNumberOfCodeSpacesForTesting() const;
 
+  // Check whether there is DebugInfo for this NativeModule.
+  bool HasDebugInfo() const;
+
   // Get or create the debug info for this NativeModule.
   DebugInfo* GetDebugInfo();
 

src/wasm/wasm-debug.cc

@@ -4,6 +4,7 @@
 
 #include "src/wasm/wasm-debug.h"
 
+#include <iomanip>
 #include <unordered_map>
 
 #include "src/base/optional.h"
@@ -15,7 +16,6 @@
 #include "src/execution/frames-inl.h"
 #include "src/execution/isolate.h"
 #include "src/heap/factory.h"
-#include "src/utils/identity-map.h"
 #include "src/wasm/baseline/liftoff-compiler.h"
 #include "src/wasm/baseline/liftoff-register.h"
 #include "src/wasm/module-decoder.h"
@@ -304,6 +304,32 @@ Address FindNewPC(WasmCode* wasm_code, int byte_offset,
 
 }  // namespace
 
+void DebugSideTable::Print(std::ostream& os) const {
+  os << "Debug side table (" << num_locals_ << " locals, " << entries_.size()
+     << " entries):\n";
+  for (auto& entry : entries_) entry.Print(os);
+  os << "\n";
+}
+
+void DebugSideTable::Entry::Print(std::ostream& os) const {
+  os << std::setw(6) << std::hex << pc_offset_ << std::dec << " [";
+  for (auto& value : values_) {
+    os << " " << value.type.type_name() << ":";
+    switch (value.kind) {
+      case kConstant:
+        os << "const#" << value.i32_const;
+        break;
+      case kRegister:
+        os << "reg#" << value.reg_code;
+        break;
+      case kStack:
+        os << "stack#" << value.stack_offset;
+        break;
+    }
+  }
+  os << " ]\n";
+}
+
 Handle<JSObject> GetModuleScopeObject(Handle<WasmInstanceObject> instance) {
   Isolate* isolate = instance->GetIsolate();
 
@@ -619,6 +645,12 @@ class DebugInfoImpl {
     }
   }
 
+  DebugSideTable* GetDebugSideTableIfExists(const WasmCode* code) const {
+    base::MutexGuard guard(&mutex_);
+    auto it = debug_side_tables_.find(code);
+    return it == debug_side_tables_.end() ? nullptr : it->second.get();
+  }
+
  private:
   struct FrameInspectionScope {
     FrameInspectionScope(DebugInfoImpl* debug_info, Isolate* isolate,
@@ -672,6 +704,9 @@ class DebugInfoImpl {
       base::MutexGuard guard(&mutex_);
       debug_side_tables_[code] = std::move(debug_side_table);
     }
+
+    // Print the code together with the debug table, if requested.
+    code->MaybePrint();
     return ret;
   }
 
@@ -794,7 +829,7 @@ class DebugInfoImpl {
   mutable base::Mutex mutex_;
 
   // DebugSideTable per code object, lazily initialized.
-  std::unordered_map<WasmCode*, std::unique_ptr<DebugSideTable>>
+  std::unordered_map<const WasmCode*, std::unique_ptr<DebugSideTable>>
       debug_side_tables_;
 
   // Names of locals, lazily decoded from the wire bytes.
@@ -874,6 +909,11 @@ void DebugInfo::RemoveDebugSideTables(Vector<WasmCode* const> code) {
   impl_->RemoveDebugSideTables(code);
 }
 
+DebugSideTable* DebugInfo::GetDebugSideTableIfExists(
+    const WasmCode* code) const {
+  return impl_->GetDebugSideTableIfExists(code);
+}
+
 }  // namespace wasm
 
 Handle<WasmDebugInfo> WasmDebugInfo::New(Handle<WasmInstanceObject> instance) {

src/wasm/wasm-debug.h

@@ -91,6 +91,8 @@ class DebugSideTable {
       return values_[index].reg_code;
     }
 
+    void Print(std::ostream&) const;
+
    private:
     int pc_offset_;
     std::vector<Value> values_;
@@ -120,6 +122,8 @@ class DebugSideTable {
 
   int num_locals() const { return num_locals_; }
 
+  void Print(std::ostream&) const;
+
  private:
   struct EntryPositionLess {
     bool operator()(const Entry& a, const Entry& b) const {
@@ -172,6 +176,10 @@ class V8_EXPORT_PRIVATE DebugInfo {
 
   void RemoveDebugSideTables(Vector<WasmCode* const>);
 
+  // Return the debug side table for the given code object, but only if it has
+  // already been created. This will never trigger generation of the table.
+  DebugSideTable* GetDebugSideTableIfExists(const WasmCode*) const;
+
  private:
   std::unique_ptr<DebugInfoImpl> impl_;
 };