![Symbolic Breakpoint
✴ 소스 코드의 심벌 이름에 설정
✴ [클래스 +] 메서드 형태 심벌 지정
✴ 모듈 (라이브러리) 지정](https://image.slidesharecdn.com/xcodedebugtips-150402045150-conversion-gate01/85/2013-02-02-Xcode-OSXDEV-7-320.jpg)
![osxdev.org
잘못된 예제 코드
CFNumberRef CFNumberError(int param)
{
unsigned int i = 1;
bool isWork = NO;
CFNumberRef x = CFNumberCreate(0, kCFNumberLongType, &i);
if (param==0)
isWork = YES;
return x;
}
void leakError()
{
NSMutableString *aString = [NSMutableString stringWithCapacity:100];
[aString retain];
//...
NSMutableArray *aArray = [[NSMutableArray alloc] initWithCapacity:10];
//...
[aArray removeAllObjects];
//release
}
void NullDerefence(id object)
{
char* pChar = NULL;
///pChar pointer...
*pChar = '!';
}
int uninitialized(int x)
{
int result;
if (x>0) {
result = 1;
}
else if (x==0) {
result = 0;
}
return result;
}](https://image.slidesharecdn.com/xcodedebugtips-150402045150-conversion-gate01/85/2013-02-02-Xcode-OSXDEV-13-320.jpg)
![osxdev.org
LLDB Command Syntax
Command Syntax
<type> <action> [-options [option-value]] [argument [argument...]]
Uses standard getopt_long() for predicate behavior
(lldb) process launch a.out --stop-at-entry
(lldb) process launch a.out -- --arg0 --arg1
(lldb) process launch a.out -st
Options know which other options they are compatible with
(lldb) process attach --pid 123 --name a.out
Type : breakpoint, commands, frame, image, log, memory, process,
regexp-break, register, settings, source, target, thread](https://image.slidesharecdn.com/xcodedebugtips-150402045150-conversion-gate01/85/2013-02-02-Xcode-OSXDEV-28-320.jpg)
![osxdev.org
Built-in Variables
✴ int64_t arg0, arg1, ... arg9
✴ args[]
✴ cwd
✴ errno
✴ execname
✴ pid
✴ stackdepth
✴ timestamp, vtimestamp
✴ probeprov, probemod
✴ probefunc, probename](https://image.slidesharecdn.com/xcodedebugtips-150402045150-conversion-gate01/85/2013-02-02-Xcode-OSXDEV-59-320.jpg)
![osxdev.org
Arrays
/* calculate the wall-clock time it takes to read()
Run with
sudo dtrace -qs ./readtime.d
*/
syscall::read:entry
{
ts[pid, probefunc] = timestamp;
}
syscall::read:return
/ts[pid, probefunc] != 0/
{
delta = timestamp - ts[pid, probefunc];
printf("read in %s took %d nsecs", execname, delta);
}](https://image.slidesharecdn.com/xcodedebugtips-150402045150-conversion-gate01/85/2013-02-02-Xcode-OSXDEV-62-320.jpg)
![osxdev.org
Aggregates
✴ count()
✴ sum(expression)
✴ avg(expression)
✴ min(expression)
✴ max(expression)
✴ quantize(expression)
@name[key] = aggfunc()](https://image.slidesharecdn.com/xcodedebugtips-150402045150-conversion-gate01/85/2013-02-02-Xcode-OSXDEV-64-320.jpg)
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2013.02.02 지앤선 테크니컬 세미나 - Xcode를 활용한 디버깅 팁(OSXDEV)
- 1. 매력적인 Xcode 디버깅 팁 ARC, Instruments, DTrace twitter.com/@godrmOSXDEV.org 오로라플래닛 김정
- 2. Single Window Built-in Interface Builder LLVM Compiler LLDB Debugger Fix-it & Live issue Assistant Version Editor Navigators & Utilities Multi-window & Multi-tab Visual Connections (IB) Refactor Code Complete New Instruments Scheme Workspace
- 5. Breakpoint Action ✴ Condition (조건) ✴ Ignore (무시할 반복회수) ✴ Action (동작) ✴ AppleScript, Capture OpenGL ES Frame, Debugger Command, Log Message, Shell Command, Sound ✴ Options (선택사항)
- 6. Exception Breakpoint ✴ 프로젝트 전체 범위 ✴ 예외(Exception) 발생할 경우 ✴ C++ / Objective-C 형태 예외처리 ✴ 동작 설정 가능
- 7. Symbolic Breakpoint ✴ 소스 코드의 심벌 이름에 설정 ✴ [클래스 +] 메서드 형태 심벌 지정 ✴ 모듈 (라이브러리) 지정
- 8. LLVM
- 9. osxdev.org Introduction • LLVM - Low-Level Virtual Machine • An Infrastructure for Multi-stage Optimization - by Chris Arthur Lattner @2002 • Design and Implementation of a compiler infrastructure - support a unique multi-stage optimization system - support inter-procedural and profile-driven optimizations • LLVM virtual instruction (IR) - with high-level type information • Sponsored by APPLE
- 10. osxdev.org Compiler Architectures GCC#4.2# 프론트엔드# C" Tree*SSA# 최적화기# 코드 생성기#C++" Objec)ve+C" 실행파일" GCC"4.2" GCC#4.2# 프론트엔드# C" LLVM# 최적화기# LLVM# 코드 생성기# C++" Objec)ve+C" 실행파일" LLVM+GCC"4.2" Clang# 프론트엔드# C" LLVM# 최적화기# LLVM# 코드 생성기# C++" Objec)ve+C" 실행파일" LLVM"
- 11. osxdev.org Effective LLVM Projects Xcode OpenCL OpenGL Optimize (speed) Optimize (size) Dynamic Prog. Clang LLDB LLVM
- 13. osxdev.org 잘못된 예제 코드 CFNumberRef CFNumberError(int param) { unsigned int i = 1; bool isWork = NO; CFNumberRef x = CFNumberCreate(0, kCFNumberLongType, &i); if (param==0) isWork = YES; return x; } void leakError() { NSMutableString *aString = [NSMutableString stringWithCapacity:100]; [aString retain]; //... NSMutableArray *aArray = [[NSMutableArray alloc] initWithCapacity:10]; //... [aArray removeAllObjects]; //release } void NullDerefence(id object) { char* pChar = NULL; ///pChar pointer... *pChar = '!'; } int uninitialized(int x) { int result; if (x>0) { result = 1; } else if (x==0) { result = 0; } return result; }
- 14. 잘못된 사용 (API Misuse)
- 15. 죽은 코드 (Dead store)
- 16. 죽은 코드 (Dead store)
- 17. 잠재된 메모리 누수 (Potential Leak)
- 18. 널 참조 (Null Dereference)
- 19. 논리적 오류 (Logic Error)
- 20. Debugging Tip#3 ARC vs no-ARC
- 21. osxdev.org ARC • Automatic Reference Counting - Automatic memory management of Objective-C objects - Just Compile-time, Not Run-time • Not Garbage-Collector • Migration Tool in Xcode 4.2 - with LLVM 3.0 - build-settings : -fobjc-arc (cf. -fno-objc-arc) • New Rules - remove dealloc, retain/release/autorelease ✴ can still use CFRetain / CFRelease in CF - Can’t use NSAllocateObject / NSDeallocateObject - Can’t use object pointer in C Structures - no casual casting id -> void* - Can’t use NSAutoreleasePool -> @autoreleasepool - Can’t use memory zone (NSZone) - Can’t give a property name with new- Automatic Reference Coun
- 23. osxdev.org Diagnostics • Memory Management - Malloc ✴ Enable Scribble ✴ Enable Guard Edges - Guard Malloc - Objective-C - Zombie Objects • Logging - Memory ✴ Distributed Objects ✴ Garbage Collection Activity ✴ Malloc Stack - Exception - Dyld API Usage - Library Loads • Debugger - Stop on Debugger() and DebugStr()
- 25. osxdev.org LLDB • Next-generation • & High-performance Debugger • a set of reusable components in LLVM • Clang expression parser • LLVM disassembler • C/C++, Objective-C • Efficient Multi-threading, symbol manager • Extension - Python script • Support Remote protocol/debug server
- 26. osxdev.org Introduction GDB LLDB % gdb a.out (gdb) break main Breakpoint 1 at 0x100000f33:file main.c line4 (gdb) run % lldb a.out (lldb) breakpoint set --name main Breakpoint created:1:name=‘main’, locations=1 (lldb) process launch
- 27. osxdev.org Introduction GDB LLDB (gdb) info args argc = 1 argv = (const char **) 0x7fff5fbff550 (gdb) info locals i = 32767 (lldb) frame variable argc = 1 argv = 0x00007fff5fbfff68 i = 0
- 28. osxdev.org LLDB Command Syntax Command Syntax <type> <action> [-options [option-value]] [argument [argument...]] Uses standard getopt_long() for predicate behavior (lldb) process launch a.out --stop-at-entry (lldb) process launch a.out -- --arg0 --arg1 (lldb) process launch a.out -st Options know which other options they are compatible with (lldb) process attach --pid 123 --name a.out Type : breakpoint, commands, frame, image, log, memory, process, regexp-break, register, settings, source, target, thread
- 29. osxdev.org Common Commands GDB LLDB (gdb) ^C (gdb) signal 2 (gdb) info break (gdb) continue (gdb) step (gdb) stepi (gdb) next (gdb) nexti (gdb) finish (gdb) info threads (gdb) backtrace (lldb) process interrupt (lldb) process signal SIGINT (lldb) breakpoint list (lldb) process continue (lldb) thread step-in (lldb) thread step-inst (lldb) thread step-over (lldb) thread step-over-inst (lldb) thread step-out (lldb) thread list (lldb) thread backtrace
- 30. osxdev.org Common Commands GDB LLDB (gdb) ^C (gdb) signal 2 (gdb) in br (gdb) c (gdb) s (gdb) si (gdb) n (gdb) ni (gdb) f (gdb) info threads (gdb) bt (lldb) pro int (lldb) pro s SIGINT (lldb) br l (lldb) c (lldb) s (lldb) si (lldb) n (lldb) ni (lldb) f (lldb) th l (lldb) bt
- 31. osxdev.org Apropos Command (lldb) apropos thread The following commands may relate to 'thread': breakporint command add -- Add a set of commands to a breakpoint, to be executed whenever ... breakpoint modify -- Modify the options on a breakpoint or set of breakpoints... breakpoint set -- Sets a breakpoint or set of breakpoints in the executable. frame -- A set of commands for operating on the current thread's... frame info -- List information about the currently selected frame in the... frame select -- Select a frame by index from within the current thread... log enable -- Enable logging for a single log channel. process continue -- Continue execution of all threads in the current process. register -- A set of commands to access thread registers. thread -- A set of commands for operating on one or more... thread backtrace -- Show the stack for one or more threads. If no threads are... thread continue -- Continue execution of one or more threads in an active... thread list -- Show a summary of all current threads in a process. thread select -- Select a thread as the currently active thread. thread step-in -- Source level single step in specified thread (current... thread step-inst -- Single step one instruction in specified thread (current..
- 32. osxdev.org Expression in LLDB LLDB (lldb) expression x+y->getCount() (int) $0 = 2 (lldb) expression pt (struct point_tag) $1 = { (int) x = 2 (int) y = 3 } (lldb) expression $1.x (int) $2 = 2
- 33. osxdev.org References • Apple Documents - Technical Notes • TN2124 Mac OS X Debugging Magic • https://developer.apple.com/library/ios/#technotes/tn2004/ tn2124.html#//apple_ref/doc/uid/DTS10003391 • TN2239 iOS Debugging Magic • https://developer.apple.com/library/ios/#technotes/tn2239/ _index.html#//apple_ref/doc/uid/DTS40010638
- 34. InstrumentsXray
- 35. 새로워진 Instruments #1 ✴ The Jump Bar ✴ Improved View Access ✴ Collapsible, Track, Full screen ✴ The Call Tree ✴ Backtrace Compression with Filtering ✴ The Source View ✴ Timeline Flags - Navigating the improved UI
- 36. 새로워진 Instruments #2 ✴ Immediate vs. Deferred Mode ✴ Immediate mode - “Classic Instruments mode” ✴ Deferred mode ✴ Processes and displays data at end of recording ✴ Vastly reduces “observer effect” ✴ More samples relate to your app. ✴ Launch Daemons and Agents (Mac OS X only) ✴ over Wi-Fi (iPhone OS 3.1+) ✴ Re-Symbolication - Recording Techniques
- 37. 새로워진 Instruments #3 ✴ Time Profiler ✴ more efficient than CPU Sampler ✴ Deferred mode ✴ Heapshots ✴ Part of Allocation template ✴ VM Tracker ✴ Tracks the virtual memory of a process - Advancement to existing Instruments
- 38. 새로워진 Instruments #4 ✴ Energy Diagnostics ✴ Provides diagnostics regarding energy usage ✴ Records battery power and CPU usage ✴ Automation ✴ Simulate UI interaction with iOS app. ✴ Leverages JavaScript to script iPhone UI components ✴ OpenGL ES Analysis - Significant New Instrumentation
- 39. UI Automation ✴ Automates UIKit based applications ✴ Touch based ✴ iPhone, iPod touch and iPhone Simulator ✴ Integrated in Instruments ✴ Accessibility based ✴ JavaScript automation scripts ✴ UI Automation Reference Collection - What is this?
- 40. 새로워진 Instruments #4 ✴ System Trace ✴ Provides comprehensive information on system behavior ✴ Identifies when threads are scheduled and why ✴ Display thread transition from user space into system code ✴ System calls, VM operations ✴ Highlights View - summary - Really New Instrumentation
- 43. DTrace is... ✴ dynamic tracing facility ✴ developed by Sun Microsystems ✴ for Solaris 10 ✴ designed by Bryan Cantrill, Mike Shapiro, and Adam Leventhal. ✴ introduced with Leopard (Prior to 10.5 ktrace) ✴ http://hub.opensolaris.org/bin/view/Community+Group +dtrace/WebHome ✴ http://en.wikipedia.org/wiki/DTrace
- 46. osxdev.org D Language ✴ A Large subset of C ✴ with a special set of functions to analyzing system behavior. ✴ run in kernel-land. ✴ compiled into a safe form (similar to java bytecode) ✴ validated for safety. ✴ filename extension .d
- 47. DTraceToolkit
- 48. osxdev.org DTraceTookits ✴ iosnoop ✴ hfssnoop ✴ execsnoop ✴ opensnoop ✴ dtruss ✴ soconnect_mac ✴ errinfo ✴ bitesize ✴ iotop ✴ maclife
- 49. Probes
- 50. osxdev.org Probes ✴ Providers - the instruments ✴ Module - a specific program location ✴ Function - a specific function name ✴ Name - an indication of the probe’s semantic meaning syscall :: open : entry syscall :: open* : entry syscall ::: entry syscall :::
- 51. osxdev.org BEGIN - END Providers /* show the BEGIN and END providers run with: sudo dtrace -s begin-end.d */ BEGIN { trace("begin the beguine"); exit(0); } END { trace("that's all, folks..."); }
- 52. osxdev.org syscall Provider /* show all system calls being made, system-wide Run with sudo dtrace -qs syscalls.d */ syscall::: /execname != "dtrace"/ { printf("%s fired in %s", probefunc, execname); }
- 53. osxdev.org profile Provider /* show the profile (timer) provider. Run with sudo dtrace -s lubdub.d */ profile:::tick-5sec { trace("five second timer"); } profile:::tick-1min { trace("one minute timer"); } profile:::tick-800msec { trace("800 millisecond timer"); }
- 54. osxdev.org proc Provider /* Show procoess launches across the system. Run with sudo dtrace -s execs.d */ proc:::exec-success { trace(execname); }
- 55. osxdev.org Actions ✴ the lines of code ✴ assign values to variables, perform computations, aggregate values over time... ✴ no flow control (no if, no loops) ✴ use predicates
- 56. osxdev.org Variables ✴ C standard types : char, int, short, long, long long... ✴ display floating point values from probes ✴ cannot perform floating point math ✴ cannot cast float to integer ✴ global by default ✴ standard C operators all work ✴ do comparison operators (^^ XOR) ✴ use strcmp()
- 57. osxdev.org example 9.6 /* sings a pretty song. run with: sudo dtrace -qs beer.d */ int bottles; /* optional */ BEGIN { bottles = 99; } profile:::tick-1sec { printf("%d bottles of beer on the walln", bottles); printf("%d bottles of beer.n", bottles); printf("take one down, pass it aroundn"); printf("%d bottles of beer on the wallnn", bottles); bottles--; } END { printf("that's all, folks..."); }
- 58. osxdev.org Scoped Variables ✴ Thread-local variable = self-> ✴ Clause-local variable = this->
- 59. osxdev.org Built-in Variables ✴ int64_t arg0, arg1, ... arg9 ✴ args[] ✴ cwd ✴ errno ✴ execname ✴ pid ✴ stackdepth ✴ timestamp, vtimestamp ✴ probeprov, probemod ✴ probefunc, probename
- 60. osxdev.org example 9.7 /* show all system calls being made, system-wide Run with sudo dtrace -qs syscalls.d */ syscall::: /execname != "dtrace"/ { printf("%s fired in %s", probefunc, execname); }
- 61. osxdev.org Functions ✴ printf ✴ trace ✴ printa ✴ ustack ✴ exit ✴ copyin, copyinstr
- 62. osxdev.org Arrays /* calculate the wall-clock time it takes to read() Run with sudo dtrace -qs ./readtime.d */ syscall::read:entry { ts[pid, probefunc] = timestamp; } syscall::read:return /ts[pid, probefunc] != 0/ { delta = timestamp - ts[pid, probefunc]; printf("read in %s took %d nsecs", execname, delta); }
- 63. osxdev.org Predicates ✴ logical expressions ✴ enclosed by slashes /* Watch entry into kevent() */ syscall::kevent:entry /execname == "dirwatcher" || execname == "DirectoryServic"/ { printf("%s called kevent()", execname); }
- 64. osxdev.org Aggregates ✴ count() ✴ sum(expression) ✴ avg(expression) ✴ min(expression) ✴ max(expression) ✴ quantize(expression) @name[key] = aggfunc()
- 65. DTrace Reference Book ptg http://www.dtracebook.com/index.php/Main_Page
- 66.