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LibJS: Lazily collect stack trace information

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The previous implementation was calling `backtrace()` for every
function call, which is quite slow.

Instead, this implementation provides VM::stack_trace() which unwinds
the native stack, maps it through NativeExecutable::get_source_range
and combines it with source ranges from interpreted call frames.
This commit is contained in:
Simon Wanner 2023-11-01 00:39:28 +01:00 • committed by Andreas Kling
parent 77dc7c4d36
commit 68f4d21de2
11 changed files with 96 additions and 46 deletions
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39
Userland/Libraries/LibJS/JIT/NativeExecutable.cpp
View file

@ -12,15 +12,6 @@
#include <LibX86/Disassembler.h>
#include <sys/mman.h>
#if __has_include(<execinfo.h>)
# include <execinfo.h>
# define EXECINFO_BACKTRACE
#endif
#if defined(AK_OS_ANDROID) && (__ANDROID_API__ < 33)
# undef EXECINFO_BACKTRACE
#endif
namespace JS::JIT {
NativeExecutable::NativeExecutable(void* code, size_t size, Vector<BytecodeMapping> mapping)
@ -159,32 +150,20 @@ BytecodeMapping const& NativeExecutable::find_mapping_entry(size_t native_offset
return m_mapping[nearby_index];
}
Optional<Bytecode::InstructionStreamIterator const&> NativeExecutable::instruction_stream_iterator([[maybe_unused]] Bytecode::Executable const& executable) const
Optional<UnrealizedSourceRange> NativeExecutable::get_source_range(Bytecode::Executable const& executable, FlatPtr address) const
{
#ifdef EXECINFO_BACKTRACE
void* buffer[10];
auto count = backtrace(buffer, 10);
auto start = bit_cast<FlatPtr>(m_code);
auto end = start + m_size;
for (auto i = 0; i < count; i++) {
auto address = bit_cast<FlatPtr>(buffer[i]);
if (address < start || address >= end)
continue;
// return address points after the call
// let's subtract 1 to make sure we don't hit the next bytecode
// (in practice that's not necessary, because our native_call() sequence continues)
auto offset = address - start - 1;
auto& entry = find_mapping_entry(offset);
if (entry.block_index < executable.basic_blocks.size()) {
auto const& block = *executable.basic_blocks[entry.block_index];
if (entry.bytecode_offset < block.size()) {
// This is rather clunky, but Interpreter::instruction_stream_iterator() gives out references, so we need to keep it alive.
m_instruction_stream_iterator = make<Bytecode::InstructionStreamIterator>(block.instruction_stream(), &executable, entry.bytecode_offset);
return *m_instruction_stream_iterator;
}
if (address < start || address >= end)
return {};
auto const& entry = find_mapping_entry(address - start - 1);
if (entry.block_index < executable.basic_blocks.size()) {
auto const& block = *executable.basic_blocks[entry.block_index];
if (entry.bytecode_offset < block.size()) {
auto iterator = Bytecode::InstructionStreamIterator { block.instruction_stream(), &executable, entry.bytecode_offset };
return iterator.source_range();
}
}
#endif
return {};
}