Lazily generate disassembly for WASM functions

Instead of computing the disassmebly and offset tables eagerly on
registering a WASM function with a debugger agent, only generate
it when the source or offset tables are actually required. This is
implemented using a lazy, memoizing supplier that is shared
between the debugger agent and wasm translator.

Bug: chromium:794941
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I1a2f7dd71ab65c80f91ddee4f7babbdf33d2e74b
Reviewed-on: https://chromium-review.googlesource.com/918641
Commit-Queue: Stephan Herhut <herhut@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51762}

src/api.cc

@@ -69,6 +69,7 @@
 #include "src/snapshot/natives.h"
 #include "src/snapshot/snapshot.h"
 #include "src/startup-data-util.h"
+#include "src/string-hasher.h"
 #include "src/tracing/trace-event.h"
 #include "src/trap-handler/trap-handler.h"
 #include "src/unicode-cache-inl.h"
@@ -9467,6 +9468,25 @@ std::pair<int, int> debug::WasmScript::GetFunctionRange(
                         static_cast<int>(func.code.end_offset()));
 }
 
+uint32_t debug::WasmScript::GetFunctionHash(int function_index) {
+  i::DisallowHeapAllocation no_gc;
+  i::Handle<i::Script> script = Utils::OpenHandle(this);
+  DCHECK_EQ(i::Script::TYPE_WASM, script->type());
+  i::WasmCompiledModule* compiled_module =
+      i::WasmCompiledModule::cast(script->wasm_compiled_module());
+  i::wasm::WasmModule* module = compiled_module->shared()->module();
+  DCHECK_LE(0, function_index);
+  DCHECK_GT(module->functions.size(), function_index);
+  i::wasm::WasmFunction& func = module->functions[function_index];
+  i::SeqOneByteString* module_bytes = compiled_module->shared()->module_bytes();
+  i::wasm::ModuleWireBytes wire_bytes(
+      module_bytes->GetFlatContent().ToOneByteVector());
+  i::Vector<const i::byte> function_bytes = wire_bytes.GetFunctionBytes(&func);
+  // TODO(herhut): Maybe also take module, name and signature into account.
+  return i::StringHasher::HashSequentialString(function_bytes.start(),
+                                               function_bytes.length(), 0);
+}
+
 debug::WasmDisassembly debug::WasmScript::DisassembleFunction(
     int function_index) const {
   i::DisallowHeapAllocation no_gc;

src/debug/debug-interface.h

@@ -166,6 +166,7 @@ class WasmScript : public Script {
   std::pair<int, int> GetFunctionRange(int function_index) const;
 
   debug::WasmDisassembly DisassembleFunction(int function_index) const;
+  uint32_t GetFunctionHash(int function_index);
 };
 
 void GetLoadedScripts(Isolate* isolate, PersistentValueVector<Script>& scripts);

src/inspector/string-16.cc

@@ -493,22 +493,39 @@ void String16Builder::append(const char* characters, size_t length) {
 }
 
 void String16Builder::appendNumber(int number) {
-  const int kBufferSize = 11;
+  constexpr int kBufferSize = 11;
   char buffer[kBufferSize];
   int chars = v8::base::OS::SNPrintF(buffer, kBufferSize, "%d", number);
-  DCHECK_GT(kBufferSize, chars);
+  DCHECK_LE(0, chars);
   m_buffer.insert(m_buffer.end(), buffer, buffer + chars);
 }
 
 void String16Builder::appendNumber(size_t number) {
-  const int kBufferSize = 20;
+  constexpr int kBufferSize = 20;
   char buffer[kBufferSize];
 #if !defined(_WIN32) && !defined(_WIN64)
   int chars = v8::base::OS::SNPrintF(buffer, kBufferSize, "%zu", number);
 #else
   int chars = v8::base::OS::SNPrintF(buffer, kBufferSize, "%Iu", number);
 #endif
-  DCHECK_GT(kBufferSize, chars);
+  DCHECK_LE(0, chars);
+  m_buffer.insert(m_buffer.end(), buffer, buffer + chars);
+}
+
+void String16Builder::appendUnsignedAsHex(uint64_t number) {
+  constexpr int kBufferSize = 17;
+  char buffer[kBufferSize];
+  int chars =
+      v8::base::OS::SNPrintF(buffer, kBufferSize, "%016" PRIx64, number);
+  DCHECK_LE(0, chars);
+  m_buffer.insert(m_buffer.end(), buffer, buffer + chars);
+}
+
+void String16Builder::appendUnsignedAsHex(uint32_t number) {
+  constexpr int kBufferSize = 9;
+  char buffer[kBufferSize];
+  int chars = v8::base::OS::SNPrintF(buffer, kBufferSize, "%08" PRIx32, number);
+  DCHECK_LE(0, chars);
   m_buffer.insert(m_buffer.end(), buffer, buffer + chars);
 }
 

src/inspector/string-16.h

@@ -112,6 +112,8 @@ class String16Builder {
   void append(const char*, size_t);
   void appendNumber(int);
   void appendNumber(size_t);
+  void appendUnsignedAsHex(uint64_t);
+  void appendUnsignedAsHex(uint32_t);
   String16 toString();
   void reserveCapacity(size_t);
 

src/inspector/v8-debugger-agent-impl.cc

@@ -156,9 +156,8 @@ String16 breakpointHint(const V8DebuggerScript& script, int lineNumber,
   return hint;
 }
 
-void adjustBreakpointLocation(const V8DebuggerScript& script,
-                              const String16& hint, int* lineNumber,
-                              int* columnNumber) {
+void adjustBreakpointLocation(V8DebuggerScript& script, const String16& hint,
+                              int* lineNumber, int* columnNumber) {
   if (*lineNumber < script.startLine() || *lineNumber > script.endLine())
     return;
   if (hint.isEmpty()) return;
@@ -467,7 +466,7 @@ Response V8DebuggerAgentImpl::setSkipAllPauses(bool skip) {
   return Response::OK();
 }
 
-static bool matches(V8InspectorImpl* inspector, const V8DebuggerScript& script,
+static bool matches(V8InspectorImpl* inspector, V8DebuggerScript& script,
                     BreakpointType type, const String16& selector) {
   switch (type) {
     case BreakpointType::kByUrl:
@@ -1357,10 +1356,12 @@ bool V8DebuggerAgentImpl::isPaused() const {
 void V8DebuggerAgentImpl::didParseSource(
     std::unique_ptr<V8DebuggerScript> script, bool success) {
   v8::HandleScope handles(m_isolate);
+  if (!success) {
+    DCHECK(!script->isSourceLoadedLazily());
     String16 scriptSource = script->source();
-  if (!success) script->setSourceURL(findSourceURL(scriptSource, false));
-  if (!success)
+    script->setSourceURL(findSourceURL(scriptSource, false));
     script->setSourceMappingURL(findSourceMapURL(scriptSource, false));
+  }
 
   int contextId = script->executionContextId();
   int contextGroupId = m_inspector->contextGroupId(contextId);
@@ -1402,6 +1403,15 @@ void V8DebuggerAgentImpl::didParseSource(
       stack && !stack->isEmpty() ? stack->buildInspectorObjectImpl(m_debugger)
                                  : nullptr;
   if (success) {
+    // TODO(herhut, dgozman): Report correct length for WASM if needed for
+    // coverage. Or do not send the length at all and change coverage instead.
+    if (scriptRef->isSourceLoadedLazily()) {
+      m_frontend.scriptParsed(
+          scriptId, scriptURL, 0, 0, 0, 0, contextId, scriptRef->hash(),
+          std::move(executionContextAuxDataParam), isLiveEditParam,
+          std::move(sourceMapURLParam), hasSourceURLParam, isModuleParam, 0,
+          std::move(stackTrace));
+    } else {
       m_frontend.scriptParsed(
           scriptId, scriptURL, scriptRef->startLine(), scriptRef->startColumn(),
           scriptRef->endLine(), scriptRef->endColumn(), contextId,
@@ -1409,6 +1419,7 @@ void V8DebuggerAgentImpl::didParseSource(
           isLiveEditParam, std::move(sourceMapURLParam), hasSourceURLParam,
           isModuleParam, static_cast<int>(scriptRef->source().length()),
           std::move(stackTrace));
+    }
   } else {
     m_frontend.scriptFailedToParse(
         scriptId, scriptURL, scriptRef->startLine(), scriptRef->startColumn(),

src/inspector/v8-debugger-script.cc

@@ -16,10 +16,10 @@ namespace {
 const char hexDigits[17] = "0123456789ABCDEF";
 const char kGlobalDebuggerScriptHandleLabel[] = "DevTools debugger";
 
-void appendUnsignedAsHex(uint64_t number, String16Builder* destination) {
+void appendUnsignedAsHex(uint64_t number, String16Builder& destination) {
   for (size_t i = 0; i < 8; ++i) {
     UChar c = hexDigits[number & 0xF];
-    destination->append(c);
+    destination.append(c);
     number >>= 4;
   }
 }
@@ -82,7 +82,8 @@ String16 calculateHash(const String16& str) {
     hashes[i] = (hashes[i] + zi[i] * (prime[i] - 1)) % prime[i];
 
   String16Builder hash;
-  for (size_t i = 0; i < hashesSize; ++i) appendUnsignedAsHex(hashes[i], &hash);
+  // TODO(herhut): Use String16Builder.appendUnsignedAsHex.
+  for (size_t i = 0; i < hashesSize; ++i) appendUnsignedAsHex(hashes[i], hash);
   return hash.toString();
 }
 
@@ -157,6 +158,13 @@ class ActualScript : public V8DebuggerScript {
   bool isLiveEdit() const override { return m_isLiveEdit; }
   bool isModule() const override { return m_isModule; }
 
+  const String16& source() const override { return m_source; }
+  int startLine() const override { return m_startLine; }
+  int startColumn() const override { return m_startColumn; }
+  int endLine() const override { return m_endLine; }
+  int endColumn() const override { return m_endColumn; }
+  bool isSourceLoadedLazily() const override { return false; }
+
   const String16& sourceMappingURL() const override {
     return m_sourceMappingURL;
   }
@@ -241,6 +249,12 @@ class ActualScript : public V8DebuggerScript {
                                    id);
   }
 
+  const String16& hash() override {
+    if (m_hash.isEmpty()) m_hash = calculateHash(source());
+    DCHECK(!m_hash.isEmpty());
+    return m_hash;
+  }
+
  private:
   String16 GetNameOrSourceUrl(v8::Local<v8::debug::Script> script) {
     v8::Local<v8::String> name;
@@ -256,6 +270,12 @@ class ActualScript : public V8DebuggerScript {
   String16 m_sourceMappingURL;
   bool m_isLiveEdit = false;
   bool m_isModule = false;
+  String16 m_source;
+  mutable String16 m_hash;
+  int m_startLine = 0;
+  int m_startColumn = 0;
+  int m_endLine = 0;
+  int m_endColumn = 0;
   v8::Global<v8::debug::Script> m_script;
 };
 
@@ -265,22 +285,12 @@ class WasmVirtualScript : public V8DebuggerScript {
  public:
   WasmVirtualScript(v8::Isolate* isolate, WasmTranslation* wasmTranslation,
                     v8::Local<v8::debug::WasmScript> script, String16 id,
-                    String16 url, String16 source)
+                    String16 url, int functionIndex)
       : V8DebuggerScript(isolate, std::move(id), std::move(url)),
         m_script(isolate, script),
-        m_wasmTranslation(wasmTranslation) {
+        m_wasmTranslation(wasmTranslation),
+        m_functionIndex(functionIndex) {
     m_script.AnnotateStrongRetainer(kGlobalDebuggerScriptHandleLabel);
-    int num_lines = 0;
-    int last_newline = -1;
-    size_t next_newline = source.find('\n', last_newline + 1);
-    while (next_newline != String16::kNotFound) {
-      last_newline = static_cast<int>(next_newline);
-      next_newline = source.find('\n', last_newline + 1);
-      ++num_lines;
-    }
-    m_endLine = num_lines;
-    m_endColumn = static_cast<int>(source.length()) - last_newline - 1;
-    m_source = std::move(source);
     m_executionContextId = script->ContextId().ToChecked();
   }
 
@@ -289,6 +299,22 @@ class WasmVirtualScript : public V8DebuggerScript {
   bool isModule() const override { return false; }
   void setSourceMappingURL(const String16&) override {}
   void setSource(const String16&, bool, bool*) override { UNREACHABLE(); }
+  bool isSourceLoadedLazily() const override { return true; }
+  const String16& source() const override {
+    return m_wasmTranslation->GetSource(m_id, m_functionIndex);
+  }
+  int startLine() const override {
+    return m_wasmTranslation->GetStartLine(m_id, m_functionIndex);
+  }
+  int startColumn() const override {
+    return m_wasmTranslation->GetStartColumn(m_id, m_functionIndex);
+  }
+  int endLine() const override {
+    return m_wasmTranslation->GetEndLine(m_id, m_functionIndex);
+  }
+  int endColumn() const override {
+    return m_wasmTranslation->GetEndColumn(m_id, m_functionIndex);
+  }
 
   bool getPossibleBreakpoints(
       const v8::debug::Location& start, const v8::debug::Location& end,
@@ -347,6 +373,13 @@ class WasmVirtualScript : public V8DebuggerScript {
     return true;
   }
 
+  const String16& hash() override {
+    if (m_hash.isEmpty()) {
+      m_hash = m_wasmTranslation->GetHash(m_id, m_functionIndex);
+    }
+    return m_hash;
+  }
+
  private:
   static const String16& emptyString() {
     static const String16 singleEmptyString;
@@ -359,6 +392,8 @@ class WasmVirtualScript : public V8DebuggerScript {
 
   v8::Global<v8::debug::WasmScript> m_script;
   WasmTranslation* m_wasmTranslation;
+  int m_functionIndex;
+  mutable String16 m_hash;
 };
 
 }  // namespace
@@ -373,10 +408,10 @@ std::unique_ptr<V8DebuggerScript> V8DebuggerScript::Create(
 std::unique_ptr<V8DebuggerScript> V8DebuggerScript::CreateWasm(
     v8::Isolate* isolate, WasmTranslation* wasmTranslation,
     v8::Local<v8::debug::WasmScript> underlyingScript, String16 id,
-    String16 url, String16 source) {
+    String16 url, int functionIndex) {
   return std::unique_ptr<WasmVirtualScript>(
       new WasmVirtualScript(isolate, wasmTranslation, underlyingScript,
-                            std::move(id), std::move(url), std::move(source)));
+                            std::move(id), std::move(url), functionIndex));
 }
 
 V8DebuggerScript::V8DebuggerScript(v8::Isolate* isolate, String16 id,
@@ -389,12 +424,6 @@ const String16& V8DebuggerScript::sourceURL() const {
   return m_sourceURL.isEmpty() ? m_url : m_sourceURL;
 }
 
-const String16& V8DebuggerScript::hash() const {
-  if (m_hash.isEmpty()) m_hash = calculateHash(source());
-  DCHECK(!m_hash.isEmpty());
-  return m_hash;
-}
-
 void V8DebuggerScript::setSourceURL(const String16& sourceURL) {
   m_sourceURL = sourceURL;
 }

src/inspector/v8-debugger-script.h

@@ -50,7 +50,7 @@ class V8DebuggerScript {
   static std::unique_ptr<V8DebuggerScript> CreateWasm(
       v8::Isolate* isolate, WasmTranslation* wasmTranslation,
       v8::Local<v8::debug::WasmScript> underlyingScript, String16 id,
-      String16 url, String16 source);
+      String16 url, int functionIndex);
 
   virtual ~V8DebuggerScript();
 
@@ -59,15 +59,16 @@ class V8DebuggerScript {
   bool hasSourceURL() const { return !m_sourceURL.isEmpty(); }
   const String16& sourceURL() const;
   virtual const String16& sourceMappingURL() const = 0;
-  const String16& source() const { return m_source; }
-  const String16& hash() const;
-  int startLine() const { return m_startLine; }
-  int startColumn() const { return m_startColumn; }
-  int endLine() const { return m_endLine; }
-  int endColumn() const { return m_endColumn; }
+  virtual const String16& source() const = 0;
+  virtual const String16& hash() = 0;
+  virtual int startLine() const = 0;
+  virtual int startColumn() const = 0;
+  virtual int endLine() const = 0;
+  virtual int endColumn() const = 0;
   int executionContextId() const { return m_executionContextId; }
   virtual bool isLiveEdit() const = 0;
   virtual bool isModule() const = 0;
+  virtual bool isSourceLoadedLazily() const = 0;
 
   void setSourceURL(const String16&);
   virtual void setSourceMappingURL(const String16&) = 0;
@@ -95,12 +96,6 @@ class V8DebuggerScript {
   String16 m_id;
   String16 m_url;
   String16 m_sourceURL;
-  String16 m_source;
-  mutable String16 m_hash;
-  int m_startLine = 0;
-  int m_startColumn = 0;
-  int m_endLine = 0;
-  int m_endColumn = 0;
   int m_executionContextId = 0;
 
   v8::Isolate* m_isolate;

src/inspector/wasm-translation.h

@@ -56,6 +56,13 @@ class WasmTranslation {
                                                      int* line_number,
                                                      int* column_number);
 
+  const String16& GetSource(const String16& script_id, int func_index);
+  int GetStartLine(const String16& script_id, int func_index) { return 0; }
+  int GetStartColumn(const String16& script_id, int func_index) { return 0; }
+  int GetEndLine(const String16& script_id, int func_index);
+  int GetEndColumn(const String16& script_id, int func_index);
+  String16 GetHash(const String16& script_id, int func_index);
+
  private:
   class TranslatorImpl;
   friend class TranslatorImpl;