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// Copyright (c) 2017, 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.
#include "vm/dwarf.h"
#include "vm/code_comments.h"
#include "vm/code_descriptors.h"
#include "vm/elf.h"
#include "vm/image_snapshot.h"
#include "vm/object_store.h"
#include "vm/version.h"
namespace dart {
#if defined(DART_PRECOMPILER)
DEFINE_FLAG(bool,
resolve_dwarf_paths,
false,
"Resolve script URIs to absolute or relative file paths in DWARF");
DEFINE_FLAG(charp,
write_code_comments_as_synthetic_source_to,
nullptr,
"Print comments associated with instructions into the given file");
class DwarfPosition {
public:
DwarfPosition(int32_t line, int32_t column) : line_(line), column_(column) {
// Should only have no line information if also no column information.
ASSERT(line_ > kNoLine || column_ <= kNoColumn);
}
// CodeSourceMaps start the line and column registers at -1, not at 0, and
// the arguments passed to ChangePosition are retrieved from CodeSourceMaps.
explicit DwarfPosition(int32_t line) : DwarfPosition(line, -1) {}
constexpr DwarfPosition() : line_(-1), column_(-1) {}
// The DWARF standard uses 0 to denote missing line or column
// information.
static constexpr int32_t kNoLine = 0;
static constexpr int32_t kNoColumn = 0;
int32_t line() const { return line_ > kNoLine ? line_ : kNoLine; }
int32_t column() const { return column_ > kNoColumn ? column_ : kNoColumn; }
// Adjusts the contents given the arguments to a ChangePosition instruction
// from CodeSourceMaps.
void ChangePosition(int32_t line_delta, int32_t new_column) {
line_ = Utils::AddWithWrapAround(line_, line_delta);
column_ = new_column;
}
private:
int32_t line_;
int32_t column_;
};
static constexpr auto kNoDwarfPositionInfo = DwarfPosition();
class InliningNode : public ZoneAllocated {
public:
InliningNode(const Function& function,
const DwarfPosition& position,
int32_t start_pc_offset)
: function(function),
position(position),
start_pc_offset(start_pc_offset),
end_pc_offset(-1),
children_head(nullptr),
children_tail(nullptr),
children_next(nullptr) {
ASSERT(!function.IsNull());
DEBUG_ASSERT(function.IsNotTemporaryScopedHandle());
}
void AppendChild(InliningNode* child) {
if (children_tail == nullptr) {
children_head = children_tail = child;
} else {
children_tail->children_next = child;
children_tail = child;
}
}
const Function& function;
DwarfPosition position;
int32_t start_pc_offset;
int32_t end_pc_offset;
InliningNode* children_head;
InliningNode* children_tail;
InliningNode* children_next;
};
Dwarf::Dwarf(Zone* zone, const Trie<const char>* deobfuscation_trie)
: zone_(zone),
deobfuscation_trie_(deobfuscation_trie),
codes_(zone, 1024),
code_to_label_(zone),
functions_(zone, 1024),
function_to_index_(zone),
scripts_(zone, 1024),
script_to_index_(zone) {}
void Dwarf::AddCode(const Code& orig_code, intptr_t label) {
ASSERT(!orig_code.IsNull());
ASSERT(label > 0);
if (auto const old_pair = code_to_label_.Lookup(&orig_code)) {
// Dwarf objects can be shared, so we may get the same information for a
// given code object in different calls. In DEBUG mode, make sure the
// information is the same before returning.
ASSERT_EQUAL(label, old_pair->value);
return;
}
// Generate an appropriately zoned ZoneHandle for storing.
const auto& code = Code::ZoneHandle(zone_, orig_code.ptr());
codes_.Add(&code);
// Currently assumes the name has the same lifetime as the Zone of the
// Dwarf object (which is currently true). Otherwise, need to copy.
code_to_label_.Insert({&code, label});
if (code.IsFunctionCode() && !code.IsUnknownDartCode()) {
const Function& function = Function::Handle(zone_, code.function());
AddFunction(function);
}
const Array& inline_functions =
Array::Handle(zone_, code.inlined_id_to_function());
if (!inline_functions.IsNull()) {
Function& function = Function::Handle(zone_);
for (intptr_t i = 0; i < inline_functions.Length(); i++) {
function ^= inline_functions.At(i);
AddFunction(function);
}
}
}
intptr_t Dwarf::AddFunction(const Function& function) {
RELEASE_ASSERT(!function.IsNull());
FunctionIndexPair* pair = function_to_index_.Lookup(&function);
if (pair != nullptr) {
return pair->index_;
}
intptr_t index = functions_.length();
const Function& zone_func = Function::ZoneHandle(zone_, function.ptr());
function_to_index_.Insert(FunctionIndexPair(&zone_func, index));
functions_.Add(&zone_func);
const Script& script = Script::Handle(zone_, function.script());
AddScript(script);
return index;
}
intptr_t Dwarf::AddScript(const Script& script) {
RELEASE_ASSERT(!script.IsNull());
ScriptIndexPair* pair = script_to_index_.Lookup(&script);
if (pair != nullptr) {
return pair->index_;
}
// DWARF file numbers start from 1.
intptr_t index = scripts_.length() + 1;
const Script& zone_script = Script::ZoneHandle(zone_, script.ptr());
script_to_index_.Insert(ScriptIndexPair(&zone_script, index));
scripts_.Add(&zone_script);
return index;
}
intptr_t Dwarf::LookupFunction(const Function& function) {
RELEASE_ASSERT(!function.IsNull());
FunctionIndexPair* pair = function_to_index_.Lookup(&function);
if (pair == nullptr) {
FATAL("Function detected too late during DWARF generation: %s",
function.ToCString());
}
return pair->index_;
}
intptr_t Dwarf::LookupScript(const Script& script) {
RELEASE_ASSERT(!script.IsNull());
ScriptIndexPair* pair = script_to_index_.Lookup(&script);
if (pair == nullptr) {
FATAL("Script detected too late during DWARF generation: %s",
script.ToCString());
}
return pair->index_;
}
void Dwarf::WriteAbbreviations(DwarfWriteStream* stream) {
// Dwarf data mostly takes the form of a tree, whose nodes are called
// DIEs. Each DIE begins with an abbreviation code, and the abbreviation
// describes the attributes of that DIE and their representation.
stream->uleb128(kCompilationUnit); // Abbrev code.
stream->uleb128(DW_TAG_compile_unit); // Type.
stream->u1(DW_CHILDREN_yes);
stream->uleb128(DW_AT_name); // Start of attributes.
stream->uleb128(DW_FORM_string);
stream->uleb128(DW_AT_producer);
stream->uleb128(DW_FORM_string);
stream->uleb128(DW_AT_comp_dir);
stream->uleb128(DW_FORM_string);
stream->uleb128(DW_AT_low_pc);
stream->uleb128(DW_FORM_addr);
stream->uleb128(DW_AT_high_pc);
stream->uleb128(DW_FORM_addr);
stream->uleb128(DW_AT_stmt_list);
stream->uleb128(DW_FORM_sec_offset);
stream->uleb128(0);
stream->uleb128(0); // End of attributes.
stream->uleb128(kAbstractFunction); // Abbrev code.
stream->uleb128(DW_TAG_subprogram); // Type.
stream->u1(DW_CHILDREN_yes);
stream->uleb128(DW_AT_name); // Start of attributes.
stream->uleb128(DW_FORM_string);
stream->uleb128(DW_AT_decl_file);
stream->uleb128(DW_FORM_udata);
stream->uleb128(DW_AT_decl_line);
stream->uleb128(DW_FORM_udata);
stream->uleb128(DW_AT_decl_column);
stream->uleb128(DW_FORM_udata);
stream->uleb128(DW_AT_inline);
stream->uleb128(DW_FORM_udata);
stream->uleb128(0);
stream->uleb128(0); // End of attributes.
stream->uleb128(kConcreteFunction); // Abbrev code.
stream->uleb128(DW_TAG_subprogram); // Type.
stream->u1(DW_CHILDREN_yes);
stream->uleb128(DW_AT_abstract_origin); // Start of attributes.
stream->uleb128(DW_FORM_ref4);
stream->uleb128(DW_AT_low_pc);
stream->uleb128(DW_FORM_addr);
stream->uleb128(DW_AT_high_pc);
stream->uleb128(DW_FORM_addr);
stream->uleb128(DW_AT_artificial);
stream->uleb128(DW_FORM_flag);
stream->uleb128(0);
stream->uleb128(0); // End of attributes.
stream->uleb128(kInlinedFunction); // Abbrev code.
stream->uleb128(DW_TAG_inlined_subroutine); // Type.
stream->u1(DW_CHILDREN_yes);
stream->uleb128(DW_AT_abstract_origin); // Start of attributes.
stream->uleb128(DW_FORM_ref4);
stream->uleb128(DW_AT_low_pc);
stream->uleb128(DW_FORM_addr);
stream->uleb128(DW_AT_high_pc);
stream->uleb128(DW_FORM_addr);
stream->uleb128(DW_AT_call_file);
stream->uleb128(DW_FORM_udata);
stream->uleb128(DW_AT_call_line);
stream->uleb128(DW_FORM_udata);
stream->uleb128(DW_AT_call_column);
stream->uleb128(DW_FORM_udata);
stream->uleb128(DW_AT_artificial);
stream->uleb128(DW_FORM_flag);
stream->uleb128(0);
stream->uleb128(0); // End of attributes.
stream->uleb128(0); // End of abbreviations.
}
void Dwarf::WriteDebugInfo(DwarfWriteStream* stream) {
// 7.5.1.1 Compilation Unit Header
// Unit length.
stream->WritePrefixedLength("cu", [&]() {
stream->u2(2); // DWARF version 2
stream->u4(0); // debug_abbrev_offset
stream->u1(compiler::target::kWordSize); // address_size
// Compilation Unit DIE. We describe the entire Dart program as a single
// compilation unit. Note we write attributes in the same order we declared
// them in our abbreviation above in WriteAbbreviations.
stream->uleb128(kCompilationUnit);
const Library& root_library = Library::Handle(
zone_, IsolateGroup::Current()->object_store()->root_library());
const String& root_uri = String::Handle(zone_, root_library.url());
stream->string(root_uri.ToCString()); // DW_AT_name
const char* producer = zone_->PrintToString("Dart %s\n", Version::String());
stream->string(producer); // DW_AT_producer
stream->string(""); // DW_AT_comp_dir
// DW_AT_low_pc
// The lowest instruction address in this object file that is part of our
// compilation unit. Dwarf consumers use this to quickly decide which
// compilation unit DIE to consult for a given pc.
auto const isolate_instructions_label = ImageWriter::SectionLabel(
ImageWriter::ProgramSection::Text, /*vm=*/false);
stream->OffsetFromSymbol(isolate_instructions_label, 0);
// DW_AT_high_pc
// The highest instruction address in this object file that is part of our
// compilation unit. Dwarf consumers use this to quickly decide which
// compilation unit DIE to consult for a given pc.
if (codes_.is_empty()) {
// No code objects in this program, so set high_pc to same as low_pc.
stream->OffsetFromSymbol(isolate_instructions_label, 0);
} else {
const Code& last_code = *codes_.Last();
auto const last_code_label = code_to_label_.LookupValue(&last_code);
ASSERT(last_code_label > 0);
stream->OffsetFromSymbol(last_code_label, last_code.Size());
}
// DW_AT_stmt_list (offset into .debug_line)
// Indicates which line number program is associated with this compilation
// unit. We only emit a single line number program.
stream->u4(0);
WriteAbstractFunctions(stream);
WriteConcreteFunctions(stream);
stream->uleb128(0); // End of children.
stream->uleb128(0); // End of entries.
});
}
void Dwarf::WriteAbstractFunctions(DwarfWriteStream* stream) {
Script& script = Script::Handle(zone_);
String& name = String::Handle(zone_);
stream->InitializeAbstractOrigins(functions_.length());
// By the point we're creating DWARF information, scripts have already lost
// their token stream and we can't look up their line number or column
// information, hence the lack of DW_AT_decl_line and DW_AT_decl_column.
for (intptr_t i = 0; i < functions_.length(); i++) {
const Function& function = *(functions_[i]);
name = function.QualifiedUserVisibleName();
script = function.script();
const intptr_t file = LookupScript(script);
intptr_t line = 0;
intptr_t column = 0;
script.GetTokenLocation(function.token_pos(), &line, &column);
auto const name_cstr =
ImageWriter::Deobfuscate(zone_, deobfuscation_trie_, name.ToCString());
stream->RegisterAbstractOrigin(i);
stream->uleb128(kAbstractFunction);
stream->string(name_cstr); // DW_AT_name
stream->uleb128(file); // DW_AT_decl_file
stream->uleb128(line); // DW_AT_decl_line
stream->uleb128(column); // DW_AT_decl_column
stream->uleb128(DW_INL_inlined); // DW_AT_inline
stream->uleb128(0); // End of children.
}
}
void Dwarf::WriteConcreteFunctions(DwarfWriteStream* stream) {
Function& function = Function::Handle(zone_);
Script& script = Script::Handle(zone_);
for (intptr_t i = 0; i < codes_.length(); i++) {
const Code& code = *(codes_[i]);
RELEASE_ASSERT(!code.IsNull());
if (!code.IsFunctionCode() || code.IsUnknownDartCode()) {
continue;
}
function = code.function();
intptr_t function_index = LookupFunction(function);
script = function.script();
intptr_t label = code_to_label_.LookupValue(&code);
ASSERT(label > 0);
stream->uleb128(kConcreteFunction);
// DW_AT_abstract_origin
// References a node written above in WriteAbstractFunctions.
stream->AbstractOrigin(function_index);
// DW_AT_low_pc
stream->OffsetFromSymbol(label, 0);
// DW_AT_high_pc
stream->OffsetFromSymbol(label, code.Size());
// DW_AT_artificial
stream->u1(function.is_visible() ? 0 : 1);
InliningNode* node = ExpandInliningTree(code);
if (node != nullptr) {
for (InliningNode* child = node->children_head; child != nullptr;
child = child->children_next) {
WriteInliningNode(stream, child, label, script);
}
}
stream->uleb128(0); // End of children.
}
}
// Our state machine encodes position metadata such that we don't know the
// end pc for an inlined function until it is popped, but DWARF DIEs encode
// it where the function is pushed. We expand the state transitions into
// an in-memory tree to do the conversion.
InliningNode* Dwarf::ExpandInliningTree(const Code& code) {
const CodeSourceMap& map =
CodeSourceMap::Handle(zone_, code.code_source_map());
if (map.IsNull()) {
return nullptr;
}
const Array& functions = Array::Handle(zone_, code.inlined_id_to_function());
const Function& root_function = Function::ZoneHandle(zone_, code.function());
if (root_function.IsNull()) {
FATAL("Wherefore art thou functionless code, %s?\n", code.ToCString());
}
GrowableArray<InliningNode*> node_stack(zone_, 4);
GrowableArray<DwarfPosition> token_positions(zone_, 4);
NoSafepointScope no_safepoint;
ReadStream stream(map.Data(), map.Length());
int32_t current_pc_offset = 0;
token_positions.Add(kNoDwarfPositionInfo);
InliningNode* root_node =
new (zone_) InliningNode(root_function, token_positions.Last(), 0);
root_node->end_pc_offset = code.Size();
node_stack.Add(root_node);
while (stream.PendingBytes() > 0) {
int32_t arg1;
int32_t arg2 = -1;
const uint8_t opcode = CodeSourceMapOps::Read(&stream, &arg1, &arg2);
switch (opcode) {
case CodeSourceMapOps::kChangePosition: {
DwarfPosition& pos = token_positions[token_positions.length() - 1];
pos.ChangePosition(arg1, arg2);
break;
}
case CodeSourceMapOps::kAdvancePC: {
current_pc_offset += arg1;
if (arg1 == 0) {
// This happens at the start of the function where we emit a special
// kAdvancePC 0 instruction to record information about the function
// itself. We need to advance current_pc_offset a bit to prevent
// starting inlining interval directy at the start of the function
// itself.
current_pc_offset += 1;
}
break;
}
case CodeSourceMapOps::kPushFunction: {
const Function& child_func =
Function::ZoneHandle(zone_, Function::RawCast(functions.At(arg1)));
InliningNode* child_node = new (zone_)
InliningNode(child_func, token_positions.Last(), current_pc_offset);
node_stack.Last()->AppendChild(child_node);
node_stack.Add(child_node);
token_positions.Add(kNoDwarfPositionInfo);
break;
}
case CodeSourceMapOps::kPopFunction: {
// We never pop the root function.
ASSERT(node_stack.length() > 1);
ASSERT(token_positions.length() > 1);
node_stack.Last()->end_pc_offset = current_pc_offset;
node_stack.RemoveLast();
token_positions.RemoveLast();
break;
}
case CodeSourceMapOps::kNullCheck: {
break;
}
default:
UNREACHABLE();
}
}
while (node_stack.length() > 1) {
node_stack.Last()->end_pc_offset = current_pc_offset;
node_stack.RemoveLast();
token_positions.RemoveLast();
}
ASSERT(node_stack[0] == root_node);
return root_node;
}
void Dwarf::WriteInliningNode(DwarfWriteStream* stream,
InliningNode* node,
intptr_t root_label,
const Script& parent_script) {
ASSERT(root_label > 0);
intptr_t file = LookupScript(parent_script);
intptr_t function_index = LookupFunction(node->function);
const Script& script = Script::Handle(zone_, node->function.script());
stream->uleb128(kInlinedFunction);
// DW_AT_abstract_origin
// References a node written above in WriteAbstractFunctions.
stream->AbstractOrigin(function_index);
// DW_AT_low_pc
stream->OffsetFromSymbol(root_label, node->start_pc_offset);
// DW_AT_high_pc
stream->OffsetFromSymbol(root_label, node->end_pc_offset);
// DW_AT_call_file
stream->uleb128(file);
// DW_AT_call_line
stream->uleb128(node->position.line());
// DW_AT_call_column
stream->uleb128(node->position.column());
// DW_AT_artificial
stream->u1(node->function.is_visible() ? 0 : 1);
for (InliningNode* child = node->children_head; child != nullptr;
child = child->children_next) {
WriteInliningNode(stream, child, root_label, script);
}
stream->uleb128(0); // End of children.
}
// Helper class for tracking state of DWARF registers and emitting
// line number program commands to set these registers to the right
// state.
class LineNumberProgramWriter {
public:
explicit LineNumberProgramWriter(DwarfWriteStream* stream)
: stream_(stream) {}
void EmitRow(intptr_t file,
intptr_t line,
intptr_t column,
intptr_t label,
intptr_t pc_offset) {
if (AddRow(file, line, column, label, pc_offset)) {
// Address register must be updated from 0 before emitting an LNP row
// (dartbug.com/41756).
stream_->u1(Dwarf::DW_LNS_copy);
}
}
// Associates the given file, line, and column information for the instruction
// at the pc_offset into the instructions payload of the Code object with the
// symbol asm_name. Returns whether any changes were made to the stream.
DART_WARN_UNUSED_RESULT bool AddRow(intptr_t file,
intptr_t line,
intptr_t column,
intptr_t label,
intptr_t pc_offset) {
ASSERT_EQUAL(end_sequence_, false);
bool source_info_changed = false;
// Note that files are 1-indexed.
ASSERT(file >= 1);
if (file != file_) {
stream_->u1(Dwarf::DW_LNS_set_file);
stream_->uleb128(file);
file_ = file;
source_info_changed = true;
}
ASSERT(line >= DwarfPosition::kNoLine);
if (line != line_) {
stream_->u1(Dwarf::DW_LNS_advance_line);
stream_->sleb128(line - line_);
line_ = line;
source_info_changed = true;
}
ASSERT(column >= DwarfPosition::kNoColumn);
if (column != column_) {
stream_->u1(Dwarf::DW_LNS_set_column);
stream_->uleb128(column);
column_ = column;
source_info_changed = true;
}
// If the file, line, and column information match that for the previous
// AddRow call, no change is made to the stream. This is because all
// addresses between two line number program rows inherit the source
// information from the first.
if (source_info_changed) {
SetCurrentPosition(label, pc_offset);
}
return source_info_changed;
}
void MarkEnd() {
ASSERT_EQUAL(end_sequence_, false);
// End of contiguous machine code.
stream_->u1(0); // This is an extended opcode
stream_->u1(1); // that is 1 byte long
stream_->u1(Dwarf::DW_LNE_end_sequence);
end_sequence_ = true;
}
void MarkEnd(intptr_t label, intptr_t pc_offset) {
ASSERT_EQUAL(end_sequence_, false);
SetCurrentPosition(label, pc_offset);
MarkEnd();
}
private:
void SetCurrentPosition(intptr_t label, intptr_t pc_offset) {
// Each LNP row is either in a different function from the previous row
// or is at an increasing PC offset into the same function.
ASSERT(label > 0);
ASSERT(pc_offset >= 0);
ASSERT(label_ != label || pc_offset > pc_offset_);
if (label_ != label) {
// Set the address register to the given offset into the new code payload.
auto const instr_size = 1 + compiler::target::kWordSize;
stream_->u1(0); // This is an extended opcode
stream_->u1(instr_size); // that is 5 or 9 bytes long
stream_->u1(Dwarf::DW_LNE_set_address);
stream_->OffsetFromSymbol(label, pc_offset);
} else {
// Change the address register by the difference in the two offsets.
stream_->u1(Dwarf::DW_LNS_advance_pc);
stream_->uleb128(pc_offset - pc_offset_);
}
label_ = label;
pc_offset_ = pc_offset;
}
DwarfWriteStream* const stream_;
// The initial values for the line number program state machine registers
// according to the DWARF standard.
intptr_t pc_offset_ = 0;
intptr_t file_ = 1;
intptr_t line_ = 1;
intptr_t column_ = 0;
bool end_sequence_ = false;
// Other info not stored in the state machine registers.
intptr_t label_ = 0;
};
void Dwarf::WriteSyntheticLineNumberProgram(LineNumberProgramWriter* writer) {
// We emit it last after all other scripts.
const intptr_t comments_file_index = scripts_.length() + 1;
auto file_open = Dart::file_open_callback();
auto file_write = Dart::file_write_callback();
auto file_close = Dart::file_close_callback();
if ((file_open == nullptr) || (file_write == nullptr) ||
(file_close == nullptr)) {
OS::PrintErr("warning: Could not access file callbacks.");
return;
}
TextBuffer comments_buffer(128 * KB);
const char* filename = FLAG_write_code_comments_as_synthetic_source_to;
void* comments_file = file_open(filename, /*write=*/true);
if (comments_file == nullptr) {
OS::PrintErr("warning: Failed to write code comments source: %s\n",
filename);
return;
}
// Lines in DWARF are 1-indexed.
intptr_t current_line = 1;
for (intptr_t i = 0; i < codes_.length(); i++) {
const Code& code = *(codes_[i]);
auto const label = code_to_label_.LookupValue(&code);
ASSERT(label > 0);
auto& comments = code.comments();
for (intptr_t i = 0, len = comments.Length(); i < len;) {
intptr_t current_pc_offset = comments.PCOffsetAt(i);
while (i < len && current_pc_offset == comments.PCOffsetAt(i)) {
comments_buffer.AddString(comments.CommentAt(i));
comments_buffer.AddChar('\n');
current_line++;
i++;
}
writer->EmitRow(comments_file_index, current_line - 1,
DwarfPosition::kNoColumn, label, current_pc_offset);
}
}
file_write(comments_buffer.buffer(), comments_buffer.length(), comments_file);
file_close(comments_file);
}
void Dwarf::WriteLineNumberProgramFromCodeSourceMaps(
LineNumberProgramWriter* writer) {
Function& root_function = Function::Handle(zone_);
Script& script = Script::Handle(zone_);
CodeSourceMap& map = CodeSourceMap::Handle(zone_);
Array& functions = Array::Handle(zone_);
GrowableArray<const Function*> function_stack(zone_, 8);
GrowableArray<DwarfPosition> token_positions(zone_, 8);
for (intptr_t i = 0; i < codes_.length(); i++) {
const Code& code = *(codes_[i]);
auto const label = code_to_label_.LookupValue(&code);
ASSERT(label > 0);
map = code.code_source_map();
if (map.IsNull()) {
continue;
}
root_function = code.function();
functions = code.inlined_id_to_function();
NoSafepointScope no_safepoint;
ReadStream code_map_stream(map.Data(), map.Length());
function_stack.Clear();
token_positions.Clear();
// CodeSourceMap might start in the following way:
//
// ChangePosition function.token_pos()
// AdvancePC 0
// ChangePosition x
// AdvancePC y
//
// This entry is emitted to ensure correct symbolization of
// function listener frames produced by async unwinding.
// (See EmitFunctionEntrySourcePositionDescriptorIfNeeded).
// Directly interpreting this sequence would cause us to emit
// multiple with the same pc into line number table and different
// position information. To avoid this will make an adjustment for
// the second record we emit: if position x is a synthetic one we will
// simply drop the second record, if position x is real then we will
// emit row with a slightly adjusted PC (by 1 byte). This would not
// affect symbolization (you can't have a call that is 1 byte long)
// but will avoid line number table entries with the same PC.
bool function_entry_position_was_emitted = false;
int32_t current_pc_offset = 0;
function_stack.Add(&root_function);
token_positions.Add(kNoDwarfPositionInfo);
while (code_map_stream.PendingBytes() > 0) {
int32_t arg1;
int32_t arg2 = -1;
const uint8_t opcode =
CodeSourceMapOps::Read(&code_map_stream, &arg1, &arg2);
switch (opcode) {
case CodeSourceMapOps::kChangePosition: {
DwarfPosition& pos = token_positions[token_positions.length() - 1];
pos.ChangePosition(arg1, arg2);
break;
}
case CodeSourceMapOps::kAdvancePC: {
// Emit a row for the previous PC value if the source location
// changed since the last row was emitted.
const Function& function = *(function_stack.Last());
script = function.script();
const intptr_t file = LookupScript(script);
const intptr_t line = token_positions.Last().line();
const intptr_t column = token_positions.Last().column();
intptr_t pc_offset_adjustment = 0;
bool should_emit = true;
// If we are at the function entry and have already emitted a row
// then adjust current_pc_offset to avoid duplicated entries.
// See the comment below which explains why this code is here.
if (current_pc_offset == 0 && function_entry_position_was_emitted) {
pc_offset_adjustment = 1;
// Ignore synthetic positions. Function entry position gives
// more information anyway.
should_emit = !(line == 0 && column == 0);
}
if (should_emit) {
writer->EmitRow(file, line, column, label,
current_pc_offset + pc_offset_adjustment);
}
current_pc_offset += arg1;
if (arg1 == 0) { // Special case of AdvancePC 0.
ASSERT(current_pc_offset == 0);
ASSERT(!function_entry_position_was_emitted);
function_entry_position_was_emitted = true;
}
break;
}
case CodeSourceMapOps::kPushFunction: {
auto child_func =
&Function::Handle(zone_, Function::RawCast(functions.At(arg1)));
function_stack.Add(child_func);
token_positions.Add(kNoDwarfPositionInfo);
break;
}
case CodeSourceMapOps::kPopFunction: {
// We never pop the root function.
ASSERT(function_stack.length() > 1);
ASSERT(token_positions.length() > 1);
function_stack.RemoveLast();
token_positions.RemoveLast();
break;
}
case CodeSourceMapOps::kNullCheck: {
break;
}
default:
UNREACHABLE();
}
}
}
}
static constexpr char kResolvedFileRoot[] = "file:///";
static constexpr intptr_t kResolvedFileRootLen = sizeof(kResolvedFileRoot) - 1;
static constexpr char kResolvedFlutterRoot[] = "org-dartlang-sdk:///flutter/";
static constexpr intptr_t kResolvedFlutterRootLen =
sizeof(kResolvedFlutterRoot) - 1;
static constexpr char kResolvedSdkRoot[] = "org-dartlang-sdk:///";
static constexpr intptr_t kResolvedSdkRootLen = sizeof(kResolvedSdkRoot) - 1;
static constexpr char kResolvedGoogle3Root[] = "google3:///";
static constexpr intptr_t kResolvedGoogle3RootLen =
sizeof(kResolvedGoogle3Root) - 1;
static const char* ConvertResolvedURI(const char* str) {
const intptr_t len = strlen(str);
if (len > kResolvedFileRootLen &&
strncmp(str, kResolvedFileRoot, kResolvedFileRootLen) == 0) {
#if defined(DART_HOST_OS_WINDOWS)
return str + kResolvedFileRootLen; // Strip off the entire prefix.
#else
return str + kResolvedFileRootLen - 1; // Leave a '/' on the front.
#endif
}
// Must do kResolvedFlutterRoot before kResolvedSdkRoot, since the latter is
// a prefix of the former.
if (len > kResolvedFlutterRootLen &&
strncmp(str, kResolvedFlutterRoot, kResolvedFlutterRootLen) == 0) {
return str + kResolvedFlutterRootLen; // Strip off the entire prefix.
}
if (len > kResolvedSdkRootLen &&
strncmp(str, kResolvedSdkRoot, kResolvedSdkRootLen) == 0) {
return str + kResolvedSdkRootLen; // Strip off the entire prefix.
}
if (len > kResolvedGoogle3RootLen &&
strncmp(str, kResolvedGoogle3Root, kResolvedGoogle3RootLen) == 0) {
return str + kResolvedGoogle3RootLen; // Strip off the entire prefix.
}
return nullptr;
}
void Dwarf::WriteLineNumberProgram(DwarfWriteStream* stream) {
// 6.2.4 The Line Number Program Header
// 1. unit_length. This encoding implies 32-bit DWARF.
stream->WritePrefixedLength("line", [&]() {
stream->u2(2); // 2. DWARF version 2
// 3. header_length
stream->WritePrefixedLength("lineheader", [&]() {
stream->u1(1); // 4. minimum_instruction_length
stream->u1(1); // 5. default_is_stmt (true for dsymutil compatibility).
stream->u1(0); // 6. line_base
stream->u1(1); // 7. line_range
stream->u1(13); // 8. opcode_base (12 standard opcodes in Dwarf 2)
// 9. standard_opcode_lengths
stream->u1(0); // DW_LNS_copy, 0 operands
stream->u1(1); // DW_LNS_advance_pc, 1 operands
stream->u1(1); // DW_LNS_advance_list, 1 operands
stream->u1(1); // DW_LNS_set_file, 1 operands
stream->u1(1); // DW_LNS_set_column, 1 operands
stream->u1(0); // DW_LNS_negate_stmt, 0 operands
stream->u1(0); // DW_LNS_set_basic_block, 0 operands
stream->u1(0); // DW_LNS_const_add_pc, 0 operands
stream->u1(1); // DW_LNS_fixed_advance_pc, 1 operands
stream->u1(0); // DW_LNS_set_prolog_end, 0 operands
stream->u1(0); // DW_LNS_set_epilogue_begin, 0 operands
stream->u1(1); // DW_LNS_set_isa, 1 operands
// 10. include_directories (sequence of path names)
// We don't emit any because we use full paths below.
stream->u1(0);
// 11. file_names (sequence of file entries)
String& uri = String::Handle(zone_);
for (intptr_t i = 0; i < scripts_.length(); i++) {
const Script& script = *(scripts_[i]);
const char* uri_cstr = nullptr;
if (FLAG_resolve_dwarf_paths) {
uri = script.resolved_url();
// Strictly enforce this to catch unresolvable cases.
if (uri.IsNull()) {
FATAL("no resolved URI for Script %s available",
script.ToCString());
}
// resolved_url is never obfuscated, so just convert the prefix.
auto const orig_cstr = uri.ToCString();
auto const converted_cstr = ConvertResolvedURI(orig_cstr);
// Strictly enforce this to catch inconvertible cases.
if (converted_cstr == nullptr) {
FATAL("cannot convert resolved URI %s", orig_cstr);
}
uri_cstr = converted_cstr;
} else {
uri = script.url();
ASSERT(!uri.IsNull());
uri_cstr = ImageWriter::Deobfuscate(zone_, deobfuscation_trie_,
uri.ToCString());
}
RELEASE_ASSERT(strlen(uri_cstr) != 0);
stream->string(uri_cstr); // NOLINT
stream->uleb128(0); // Include directory index.
stream->uleb128(0); // File modification time.
stream->uleb128(0); // File length.
}
if (FLAG_write_code_comments_as_synthetic_source_to != nullptr) {
stream->string( // NOLINT
FLAG_write_code_comments_as_synthetic_source_to);
stream->uleb128(0); // Include directory index.
stream->uleb128(0); // File modification time.
stream->uleb128(0); // File length.
}
stream->u1(0); // End of file names.
});
// 6.2.5 The Line Number Program
LineNumberProgramWriter lnp_writer(stream);
if (FLAG_write_code_comments_as_synthetic_source_to != nullptr) {
WriteSyntheticLineNumberProgram(&lnp_writer);
} else {
WriteLineNumberProgramFromCodeSourceMaps(&lnp_writer);
}
// Advance pc to end of the compilation unit if not already there.
if (codes_.length() != 0) {
const intptr_t last_code_index = codes_.length() - 1;
const Code& last_code = *(codes_[last_code_index]);
const intptr_t last_pc_offset = last_code.Size();
auto const last_label = code_to_label_.LookupValue(&last_code);
ASSERT(last_label > 0);
lnp_writer.MarkEnd(last_label, last_pc_offset);
} else {
lnp_writer.MarkEnd();
}
});
}
#endif // DART_PRECOMPILER
} // namespace dart