[dyn_modules] Add source positions to bytecode

dart2bytecode can optionally add source position information
(including line starts) to the generated bytecode
(when '--bytecode-options=source-positions' flag is specified).

If bytecode has source positions, they are now shown in stack traces
involving interpreter frames.

TEST=ci

Change-Id: I1ae3326bac21201040be32c712514e71e96f51e2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/433760
Reviewed-by: Slava Egorov <[email protected]>
Commit-Queue: Alexander Markov <[email protected]>

Author: alexmarkov

pkg/dart2bytecode/lib/bytecode_generator.dart

@@ -649,7 +649,13 @@ class BytecodeGenerator extends RecursiveVisitor {
     int endPosition = TreeNode.noOffset;
     if (options.emitSourcePositions && member.fileOffset != TreeNode.noOffset) {
       flags |= FunctionDeclaration.hasSourcePositionsFlag;
-      position = (member as dynamic).startFileOffset;
+      if (member is Constructor) {
+        position = member.startFileOffset;
+      } else if (member is Procedure) {
+        position = member.fileStartOffset;
+      } else {
+        throw 'Unexpected ${member.runtimeType} $member';
+      }
       endPosition = member.fileEndOffset;
     }
     final Annotations annotations = getFunctionAnnotations(member);

pkg/test_runner/lib/src/compiler_configuration.dart

@@ -1615,6 +1615,7 @@ class BytecodeCompilerConfiguration extends CompilerConfiguration {
           arguments.contains('--enable-asserts') ||
           arguments.contains('--enable_asserts'))
         '--enable-asserts',
+      if (!isProductMode) '--bytecode-options=source-positions',
     ];
 
     return CompilationCommand(

runtime/vm/bytecode_reader.cc

@@ -1041,7 +1041,10 @@ ObjectPtr BytecodeReaderHelper::ReadObjectContents(uint32_t header) {
     }
     case kScript: {
       const String& uri = String::CheckedHandle(Z, ReadObject());
-      RELEASE_ASSERT((flags & kFlagHasSourceFile) == 0);
+      if ((flags & kFlagHasSourceFile) != 0) {
+        return ReadSourceFile(uri, bytecode_component_->GetSourceFilesOffset() +
+                                       reader_.ReadUInt());
+      }
       return Script::New(uri, Object::null_string());
     }
     case kType: {
@@ -1466,6 +1469,72 @@ StringPtr BytecodeReaderHelper::ReadString(bool is_canonical) {
   }
 }
 
+TypedDataPtr BytecodeReaderHelper::ReadLineStartsData(
+    intptr_t line_starts_offset) {
+  AlternativeReadingScope alt(&reader_, line_starts_offset);
+
+  const intptr_t num_line_starts = reader_.ReadUInt();
+
+  // Choose representation between Uint16 and Uint32 typed data.
+  intptr_t max_start = 0;
+  {
+    AlternativeReadingScope alt2(&reader_, reader_.offset());
+    for (intptr_t i = 0; i < num_line_starts; ++i) {
+      const intptr_t delta = reader_.ReadUInt();
+      max_start += delta;
+    }
+  }
+
+  const intptr_t cid = (max_start <= kMaxUint16) ? kTypedDataUint16ArrayCid
+                                                 : kTypedDataUint32ArrayCid;
+  const TypedData& line_starts_data =
+      TypedData::Handle(Z, TypedData::New(cid, num_line_starts, Heap::kOld));
+
+  intptr_t current_start = 0;
+  for (intptr_t i = 0; i < num_line_starts; ++i) {
+    const intptr_t delta = reader_.ReadUInt();
+    current_start += delta;
+    if (cid == kTypedDataUint16ArrayCid) {
+      line_starts_data.SetUint16(i << 1, static_cast<uint16_t>(current_start));
+    } else {
+      line_starts_data.SetUint32(i << 2, current_start);
+    }
+  }
+
+  return line_starts_data.ptr();
+}
+
+ScriptPtr BytecodeReaderHelper::ReadSourceFile(const String& uri,
+                                               intptr_t offset) {
+  // SourceFile flags, must be in sync with SourceFile constants in
+  // pkg/dart2bytecode/lib/declarations.dart.
+  const int kHasLineStartsFlag = 1 << 0;
+  const int kHasSourceFlag = 1 << 1;
+
+  AlternativeReadingScope alt(&reader_, offset);
+
+  const intptr_t flags = reader_.ReadUInt();
+  const String& import_uri = String::CheckedHandle(Z, ReadObject());
+
+  TypedData& line_starts = TypedData::Handle(Z);
+  if ((flags & kHasLineStartsFlag) != 0) {
+    const intptr_t line_starts_offset =
+        bytecode_component_->GetLineStartsOffset() + reader_.ReadUInt();
+    line_starts = ReadLineStartsData(line_starts_offset);
+  }
+
+  String& source = String::Handle(Z);
+  if ((flags & kHasSourceFlag) != 0) {
+    source = ReadString(/* is_canonical = */ false);
+  }
+
+  const Script& script =
+      Script::Handle(Z, Script::New(import_uri, uri, source));
+  script.set_line_starts(line_starts);
+
+  return script.ptr();
+}
+
 TypeArgumentsPtr BytecodeReaderHelper::ReadTypeArguments() {
   const intptr_t length = reader_.ReadUInt();
   TypeArguments& type_arguments =

runtime/vm/bytecode_reader.h

@@ -346,6 +346,8 @@ class BytecodeReaderHelper : public ValueObject {
   ObjectPtr ReadConstObject(intptr_t tag);
   ObjectPtr ReadType(intptr_t tag, Nullability nullability);
   StringPtr ReadString(bool is_canonical = true);
+  TypedDataPtr ReadLineStartsData(intptr_t line_starts_offset);
+  ScriptPtr ReadSourceFile(const String& uri, intptr_t offset);
   TypeArgumentsPtr ReadTypeArguments();
   void SetupFieldAccessorFunction(const Class& klass,
                                   const Function& function,

runtime/vm/kernel.cc

@@ -18,87 +18,6 @@
 namespace dart {
 namespace kernel {
 
-KernelLineStartsReader::KernelLineStartsReader(
-    const dart::TypedData& line_starts_data,
-    dart::Zone* zone)
-    : line_starts_data_(line_starts_data) {
-  TypedDataElementType type = line_starts_data_.ElementType();
-  if (type == kUint16ArrayElement) {
-    helper_ = new KernelUint16LineStartsHelper();
-  } else if (type == kUint32ArrayElement) {
-    helper_ = new KernelUint32LineStartsHelper();
-  } else {
-    UNREACHABLE();
-  }
-}
-
-uint32_t KernelLineStartsReader::MaxPosition() const {
-  const intptr_t line_count = line_starts_data_.Length();
-  if (line_count == 0) {
-    return 0;
-  }
-  return helper_->At(line_starts_data_, line_count - 1);
-}
-
-bool KernelLineStartsReader::LocationForPosition(intptr_t position,
-                                                 intptr_t* line,
-                                                 intptr_t* col) const {
-  const intptr_t line_count = line_starts_data_.Length();
-  if (position < 0 || static_cast<uint32_t>(position) > MaxPosition() ||
-      line_count == 0) {
-    return false;
-  }
-
-  intptr_t lo = 0;
-  intptr_t hi = line_count;
-  while (hi > lo + 1) {
-    const intptr_t mid = lo + (hi - lo) / 2;
-    const intptr_t mid_position = helper_->At(line_starts_data_, mid);
-    if (mid_position > position) {
-      hi = mid;
-    } else {
-      lo = mid;
-    }
-  }
-  *line = lo + 1;
-  if (col != nullptr) {
-    *col = position - helper_->At(line_starts_data_, lo) + 1;
-  }
-
-  return true;
-}
-
-bool KernelLineStartsReader::TokenRangeAtLine(
-    intptr_t line_number,
-    TokenPosition* first_token_index,
-    TokenPosition* last_token_index) const {
-  const intptr_t line_count = line_starts_data_.Length();
-  if (line_number <= 0 || line_number > line_count) {
-    return false;
-  }
-  *first_token_index = dart::TokenPosition::Deserialize(
-      helper_->At(line_starts_data_, line_number - 1));
-  if (line_number == line_count) {
-    *last_token_index = *first_token_index;
-  } else {
-    *last_token_index = dart::TokenPosition::Deserialize(
-        helper_->At(line_starts_data_, line_number) - 1);
-  }
-  return true;
-}
-
-uint32_t KernelLineStartsReader::KernelUint16LineStartsHelper::At(
-    const dart::TypedData& data,
-    intptr_t index) const {
-  return data.GetUint16(index << 1);
-}
-
-uint32_t KernelLineStartsReader::KernelUint32LineStartsHelper::At(
-    const dart::TypedData& data,
-    intptr_t index) const {
-  return data.GetUint32(index << 2);
-}
-
 class KernelTokenPositionCollector : public KernelReaderHelper {
  public:
   KernelTokenPositionCollector(

runtime/vm/kernel.h

@@ -127,70 +127,6 @@ class Program {
   DISALLOW_COPY_AND_ASSIGN(Program);
 };
 
-class KernelLineStartsReader {
- public:
-  KernelLineStartsReader(const dart::TypedData& line_starts_data,
-                         dart::Zone* zone);
-
-  ~KernelLineStartsReader() { delete helper_; }
-
-  uint32_t At(intptr_t index) const {
-    return helper_->At(line_starts_data_, index);
-  }
-
-  uint32_t MaxPosition() const;
-
-  // Returns whether the given offset corresponds to a valid source offset
-  // If it does, then *line and *column (if column is not nullptr) are set
-  // to the line and column the token starts at.
-  DART_WARN_UNUSED_RESULT bool LocationForPosition(
-      intptr_t position,
-      intptr_t* line,
-      intptr_t* col = nullptr) const;
-
-  // Returns whether any tokens were found for the given line. When found,
-  // *first_token_index and *last_token_index are set to the first and
-  // last token on the line, respectively.
-  DART_WARN_UNUSED_RESULT bool TokenRangeAtLine(
-      intptr_t line_number,
-      dart::TokenPosition* first_token_index,
-      dart::TokenPosition* last_token_index) const;
-
- private:
-  class KernelLineStartsHelper {
-   public:
-    KernelLineStartsHelper() {}
-    virtual ~KernelLineStartsHelper() {}
-    virtual uint32_t At(const dart::TypedData& data, intptr_t index) const = 0;
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(KernelLineStartsHelper);
-  };
-
-  class KernelUint16LineStartsHelper : public KernelLineStartsHelper {
-   public:
-    KernelUint16LineStartsHelper() {}
-    virtual uint32_t At(const dart::TypedData& data, intptr_t index) const;
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(KernelUint16LineStartsHelper);
-  };
-
-  class KernelUint32LineStartsHelper : public KernelLineStartsHelper {
-   public:
-    KernelUint32LineStartsHelper() {}
-    virtual uint32_t At(const dart::TypedData& data, intptr_t index) const;
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(KernelUint32LineStartsHelper);
-  };
-
-  const dart::TypedData& line_starts_data_;
-  KernelLineStartsHelper* helper_;
-
-  DISALLOW_COPY_AND_ASSIGN(KernelLineStartsReader);
-};
-
 ObjectPtr EvaluateStaticConstFieldInitializer(const Field& field);
 ObjectPtr EvaluateMetadata(const Library& library,
                            intptr_t kernel_offset,

runtime/vm/line_starts_reader.cc

@@ -0,0 +1,74 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#if !defined(DART_PRECOMPILED_RUNTIME) || defined(DART_DYNAMIC_MODULES)
+
+#include "vm/line_starts_reader.h"
+#include "vm/object.h"
+#include "vm/token_position.h"
+
+namespace dart {
+
+LineStartsReader::LineStartsReader(const dart::TypedData& line_starts_data)
+    : line_starts_data_(line_starts_data),
+      element_type_(line_starts_data.ElementType()) {
+  RELEASE_ASSERT((element_type_ == kUint16ArrayElement) ||
+                 (element_type_ == kUint32ArrayElement));
+}
+
+uint32_t LineStartsReader::MaxPosition() const {
+  const intptr_t line_count = line_starts_data_.Length();
+  if (line_count == 0) {
+    return 0;
+  }
+  return At(line_count - 1);
+}
+
+bool LineStartsReader::LocationForPosition(intptr_t position,
+                                           intptr_t* line,
+                                           intptr_t* col) const {
+  const intptr_t line_count = line_starts_data_.Length();
+  if (position < 0 || static_cast<uint32_t>(position) > MaxPosition() ||
+      line_count == 0) {
+    return false;
+  }
+
+  intptr_t lo = 0;
+  intptr_t hi = line_count;
+  while (hi > lo + 1) {
+    const intptr_t mid = lo + (hi - lo) / 2;
+    const intptr_t mid_position = At(mid);
+    if (mid_position > position) {
+      hi = mid;
+    } else {
+      lo = mid;
+    }
+  }
+  *line = lo + 1;
+  if (col != nullptr) {
+    *col = position - At(lo) + 1;
+  }
+
+  return true;
+}
+
+bool LineStartsReader::TokenRangeAtLine(intptr_t line_number,
+                                        TokenPosition* first_token_index,
+                                        TokenPosition* last_token_index) const {
+  const intptr_t line_count = line_starts_data_.Length();
+  if (line_number <= 0 || line_number > line_count) {
+    return false;
+  }
+  *first_token_index = TokenPosition::Deserialize(At(line_number - 1));
+  if (line_number == line_count) {
+    *last_token_index = *first_token_index;
+  } else {
+    *last_token_index = TokenPosition::Deserialize(At(line_number) - 1);
+  }
+  return true;
+}
+
+}  // namespace dart
+
+#endif  // !defined(DART_PRECOMPILED_RUNTIME) || defined(DART_DYNAMIC_MODULES)