diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp index 91f3a6ce383b1..b4422a7d58077 100644 --- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp +++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp @@ -86,6 +86,7 @@ #include "lldb/Host/Host.h" #include "lldb/Utility/StringExtractorGDBRemote.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/ADT/ScopeExit.h" #include "llvm/ADT/StringMap.h" #include "llvm/ADT/StringSwitch.h" @@ -2762,6 +2763,108 @@ size_t ProcessGDBRemote::DoReadMemory(addr_t addr, void *buf, size_t size, return 0; } +llvm::SmallVector> +ProcessGDBRemote::ReadMemoryRanges( + llvm::ArrayRef> ranges, + llvm::MutableArrayRef buffer) { + if (!m_gdb_comm.GetMultiMemReadSupported()) + return Process::ReadMemoryRanges(ranges, buffer); + + llvm::Expected response = + SendMultiMemReadPacket(ranges); + if (!response) { + LLDB_LOG_ERROR(GetLog(GDBRLog::Process), response.takeError(), + "MultiMemRead error response: {0}"); + return Process::ReadMemoryRanges(ranges, buffer); + } + + llvm::StringRef response_str = response->GetStringRef(); + const unsigned expected_num_ranges = ranges.size(); + llvm::Expected>> + parsed_response = + ParseMultiMemReadPacket(response_str, buffer, expected_num_ranges); + if (!parsed_response) { + LLDB_LOG_ERROR(GetLog(GDBRLog::Process), parsed_response.takeError(), + "MultiMemRead error parsing response: {0}"); + return Process::ReadMemoryRanges(ranges, buffer); + } + return std::move(*parsed_response); +} + +llvm::Expected +ProcessGDBRemote::SendMultiMemReadPacket( + llvm::ArrayRef> ranges) { + std::string packet_str; + llvm::raw_string_ostream stream(packet_str); + stream << "MultiMemRead:ranges:"; + + auto range_to_stream = [&](auto range) { + // the "-" marker omits the '0x' prefix. + stream << llvm::formatv("{0:x-},{1:x-}", range.base, range.size); + }; + llvm::interleave(ranges, stream, range_to_stream, ","); + stream << ";"; + + StringExtractorGDBRemote response; + GDBRemoteCommunication::PacketResult packet_result = + m_gdb_comm.SendPacketAndWaitForResponse(packet_str.data(), response, + GetInterruptTimeout()); + if (packet_result != GDBRemoteCommunication::PacketResult::Success) + return llvm::createStringError( + llvm::formatv("MultiMemRead failed to send packet: '{0}'", packet_str)); + + if (response.IsErrorResponse()) + return llvm::createStringError( + llvm::formatv("MultiMemRead failed: '{0}'", response.GetStringRef())); + + if (!response.IsNormalResponse()) + return llvm::createStringError(llvm::formatv( + "MultiMemRead unexpected response: '{0}'", response.GetStringRef())); + + return response; +} + +llvm::Expected>> +ProcessGDBRemote::ParseMultiMemReadPacket(llvm::StringRef response_str, + llvm::MutableArrayRef buffer, + unsigned expected_num_ranges) { + // The sizes and the data are separated by a `;`. + auto [sizes_str, memory_data] = response_str.split(';'); + if (sizes_str.size() == response_str.size()) + return llvm::createStringError(llvm::formatv( + "MultiMemRead response missing field separator ';' in: '{0}'", + response_str)); + + llvm::SmallVector> read_results; + + // Sizes are separated by a `,`. + for (llvm::StringRef size_str : llvm::split(sizes_str, ',')) { + uint64_t read_size; + if (size_str.getAsInteger(16, read_size)) + return llvm::createStringError(llvm::formatv( + "MultiMemRead response has invalid size string: {0}", size_str)); + + if (memory_data.size() < read_size) + return llvm::createStringError( + llvm::formatv("MultiMemRead response did not have enough data, " + "requested sizes: {0}", + sizes_str)); + + llvm::StringRef region_to_read = memory_data.take_front(read_size); + memory_data = memory_data.drop_front(read_size); + + assert(buffer.size() >= read_size); + llvm::MutableArrayRef region_to_write = + buffer.take_front(read_size); + buffer = buffer.drop_front(read_size); + + memcpy(region_to_write.data(), region_to_read.data(), read_size); + read_results.push_back(region_to_write); + } + + return read_results; +} + bool ProcessGDBRemote::SupportsMemoryTagging() { return m_gdb_comm.GetMemoryTaggingSupported(); } diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h index 7c3dfb179a4b3..eb33b52b57441 100644 --- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h +++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h @@ -137,6 +137,22 @@ class ProcessGDBRemote : public Process, size_t DoReadMemory(lldb::addr_t addr, void *buf, size_t size, Status &error) override; + /// Override of ReadMemoryRanges that uses MultiMemRead to optimize this + /// operation. + llvm::SmallVector> + ReadMemoryRanges(llvm::ArrayRef> ranges, + llvm::MutableArrayRef buf) override; + +private: + llvm::Expected + SendMultiMemReadPacket(llvm::ArrayRef> ranges); + + llvm::Expected>> + ParseMultiMemReadPacket(llvm::StringRef response_str, + llvm::MutableArrayRef buffer, + unsigned expected_num_ranges); + +public: Status WriteObjectFile(std::vector entries) override; diff --git a/lldb/test/API/lang/objc/foundation/TestObjCMethodsNSError.py b/lldb/test/API/lang/objc/foundation/TestObjCMethodsNSError.py index a14035db5e057..a9fbe54e074ff 100644 --- a/lldb/test/API/lang/objc/foundation/TestObjCMethodsNSError.py +++ b/lldb/test/API/lang/objc/foundation/TestObjCMethodsNSError.py @@ -45,3 +45,30 @@ def test_NSError_p(self): ], ) self.runCmd("process continue") + + @skipIfOutOfTreeDebugserver + def test_runtime_types_efficient_memreads(self): + # Test that we use an efficient reading of memory when reading + # Objective-C method descriptions. + logfile = os.path.join(self.getBuildDir(), "log.txt") + self.runCmd(f"log enable -f {logfile} gdb-remote packets process") + self.addTearDownHook(lambda: self.runCmd("log disable gdb-remote packets")) + + self.build() + self.target, process, thread, bkpt = lldbutil.run_to_source_breakpoint( + self, "// Break here for NSString tests", lldb.SBFileSpec("main.m", False) + ) + + self.runCmd(f"proc plugin packet send StartTesting", check=False) + self.expect('expression str = [NSString stringWithCString: "new"]') + self.runCmd(f"proc plugin packet send EndTesting", check=False) + + self.assertTrue(os.path.exists(logfile)) + log_text = open(logfile).read() + log_text = log_text.split("StartTesting", 1)[-1].split("EndTesting", 1)[0] + + # This test is only checking that the packet it used at all (and that + # no errors are produced). It doesn't check that the packet is being + # used to solve a problem in an optimal way. + self.assertIn("MultiMemRead:", log_text) + self.assertNotIn("MultiMemRead error", log_text)