8a27ef676e
This patch adds a frame recognizer for Clang's `__builtin_verbose_trap`, which behaves like a `__builtin_trap`, but emits a failure-reason string into debug-info in order for debuggers to display it to a user. The frame recognizer triggers when we encounter a frame with a function name that begins with `__clang_trap_msg`, which is the magic prefix Clang emits into debug-info for verbose traps. Once such frame is encountered we display the frame function name as the `Stop Reason` and display that frame to the user. Example output: ``` (lldb) run warning: a.out was compiled with optimization - stepping may behave oddly; variables may not be available. Process 35942 launched: 'a.out' (arm64) Process 35942 stopped * thread #1, queue = 'com.apple.main-thread', stop reason = Misc.: Function is not implemented frame #1: 0x0000000100003fa4 a.out`main [inlined] Dummy::func(this=<unavailable>) at verbose_trap.cpp:3:5 [opt] 1 struct Dummy { 2 void func() { -> 3 __builtin_verbose_trap("Misc.", "Function is not implemented"); 4 } 5 }; 6 7 int main() { (lldb) bt * thread #1, queue = 'com.apple.main-thread', stop reason = Misc.: Function is not implemented frame #0: 0x0000000100003fa4 a.out`main [inlined] __clang_trap_msg$Misc.$Function is not implemented$ at verbose_trap.cpp:0 [opt] * frame #1: 0x0000000100003fa4 a.out`main [inlined] Dummy::func(this=<unavailable>) at verbose_trap.cpp:3:5 [opt] frame #2: 0x0000000100003fa4 a.out`main at verbose_trap.cpp:8:13 [opt] frame #3: 0x0000000189d518b4 dyld`start + 1988 ```
123 lines
3.5 KiB
C++
123 lines
3.5 KiB
C++
#include "lldb/Target/VerboseTrapFrameRecognizer.h"
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#include "lldb/Core/Module.h"
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#include "lldb/Symbol/Function.h"
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#include "lldb/Symbol/SymbolContext.h"
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#include "lldb/Target/Process.h"
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#include "lldb/Target/StackFrameRecognizer.h"
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#include "lldb/Target/Target.h"
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#include "lldb/Utility/LLDBLog.h"
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#include "lldb/Utility/Log.h"
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#include "clang/CodeGen/ModuleBuilder.h"
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using namespace llvm;
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using namespace lldb;
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using namespace lldb_private;
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VerboseTrapRecognizedStackFrame::VerboseTrapRecognizedStackFrame(
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StackFrameSP most_relevant_frame_sp, std::string stop_desc)
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: m_most_relevant_frame(most_relevant_frame_sp) {
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m_stop_desc = std::move(stop_desc);
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}
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lldb::RecognizedStackFrameSP
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VerboseTrapFrameRecognizer::RecognizeFrame(lldb::StackFrameSP frame_sp) {
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if (frame_sp->GetFrameIndex())
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return {};
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ThreadSP thread_sp = frame_sp->GetThread();
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ProcessSP process_sp = thread_sp->GetProcess();
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StackFrameSP most_relevant_frame_sp = thread_sp->GetStackFrameAtIndex(1);
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if (!most_relevant_frame_sp) {
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Log *log = GetLog(LLDBLog::Unwind);
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LLDB_LOG(
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log,
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"Failed to find most relevant frame: Hit unwinding bound (1 frame)!");
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return {};
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}
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SymbolContext sc = frame_sp->GetSymbolContext(eSymbolContextEverything);
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if (!sc.block)
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return {};
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// The runtime error is set as the function name in the inlined function info
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// of frame #0 by the compiler
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const InlineFunctionInfo *inline_info = nullptr;
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Block *inline_block = sc.block->GetContainingInlinedBlock();
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if (!inline_block)
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return {};
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inline_info = sc.block->GetInlinedFunctionInfo();
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if (!inline_info)
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return {};
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auto func_name = inline_info->GetName().GetStringRef();
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if (func_name.empty())
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return {};
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static auto trap_regex =
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llvm::Regex(llvm::formatv("^{0}\\$(.*)\\$(.*)$", ClangTrapPrefix).str());
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SmallVector<llvm::StringRef, 3> matches;
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std::string regex_err_msg;
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if (!trap_regex.match(func_name, &matches, ®ex_err_msg)) {
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LLDB_LOGF(GetLog(LLDBLog::Unwind),
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"Failed to parse match trap regex for '%s': %s", func_name.data(),
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regex_err_msg.c_str());
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return {};
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}
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// For `__clang_trap_msg$category$message$` we expect 3 matches:
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// 1. entire string
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// 2. category
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// 3. message
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if (matches.size() != 3) {
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LLDB_LOGF(GetLog(LLDBLog::Unwind),
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"Unexpected function name format. Expected '<trap prefix>$<trap "
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"category>$<trap message>'$ but got: '%s'.",
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func_name.data());
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return {};
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}
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auto category = matches[1];
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auto message = matches[2];
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std::string stop_reason =
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category.empty() ? "<empty category>" : category.str();
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if (!message.empty()) {
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stop_reason += ": ";
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stop_reason += message.str();
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}
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return std::make_shared<VerboseTrapRecognizedStackFrame>(
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most_relevant_frame_sp, std::move(stop_reason));
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}
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lldb::StackFrameSP VerboseTrapRecognizedStackFrame::GetMostRelevantFrame() {
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return m_most_relevant_frame;
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}
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namespace lldb_private {
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void RegisterVerboseTrapFrameRecognizer(Process &process) {
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RegularExpressionSP module_regex_sp = nullptr;
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auto symbol_regex_sp = std::make_shared<RegularExpression>(
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llvm::formatv("^{0}", ClangTrapPrefix).str());
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StackFrameRecognizerSP srf_recognizer_sp =
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std::make_shared<VerboseTrapFrameRecognizer>();
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process.GetTarget().GetFrameRecognizerManager().AddRecognizer(
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srf_recognizer_sp, module_regex_sp, symbol_regex_sp, false);
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}
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} // namespace lldb_private
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