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![void
$__lldb_expr(void *$__lldb_arg)
{
some_variable;
}
Expression Evaluation
ClangExpressionDeclMap::FindExternalVisibleDecls[2] for
'some_variable' in a 'TranslationUnit'
CEDM::FEVD[2] Searching the root namespace
CEDM::FEVD[2] Found variable some_variable,
returned static int &some_variable (original int)](https://image.slidesharecdn.com/eurobsdcon2014lldb-150111074814-conversion-gate02/85/The-LLDB-Debugger-in-FreeBSD-by-Ed-Maste-37-320.jpg)
Uploaded byeurobsdcon
The LLDB Debugger in FreeBSD by Ed Maste
The document discusses the LLDB debugger in FreeBSD, covering its history, design, and status regarding various functionalities like userland and kernel core file debugging. It outlines the differences in syntax between LLDB and GDB, along with statuses of target support and remote debugging capabilities. Additionally, the roadmap for future development of LLDB within FreeBSD is presented, detailing updates and integration plans.
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The LLDB Debugger in FreeBSD by Ed Maste
- 1. The LLDB Debugger inFreeBSD Ed Maste EuroBSDCon 2014
- 2. Why a NewDebugger?
- 3. Why a NewDebugger? Upstream FreeBSD
- 4. Why a NewDebugger?
- 5. Why a NewDebugger?
- 6. Why a NewDebugger? . . .
- 7. Why a NewDebugger?
- 8. A New Debugger •GDB • BSDdbg • ngdb (written in D) • pathdb
- 9. A New Debugger •GDB • BSDdbg • ngdb (written in D) • pathdb • LLDB
- 10.
- 11.
- 12.
- 13.
- 14.
- 15.
- 19.
- 20. Syntax GDB! % gdb a.out (gdb)break main Breakpoint 1 at 0x100000f33: file main.c, line 4 (gdb) run LLDB! % lldb a.out (lldb) breakpoint set --name main Breakpoint created: 1: name = 'main', locations = 1 (lldb) process launch
- 21. Syntax GDB! (gdb) run (gdb) r (gdb)step (gdb) s (gdb) info break (gdb) info args & (gdb) info args LLDB! (lldb) process launch (lldb) run (lldb) r (lldb) thread step-in (lldb) step (lldb) s (lldb) breakpoint list (lldb) br l (lldb) frame variable (lldb) fr v
- 22.
- 23. FreeBSD LLDB Status Testsuite •311 tests run • Failures have PRs in LLVM's bugzilla
- 24. FreeBSD LLDB Status Targets •amd64 • i386 (code in tree) • MIPS (userland core files) • ARM (in LLDB core, not FreeBSD/Linux) • AArch64 • PowerPC / PowerPC64 • Sparc64 • ia64
- 25. FreeBSD LLDB Status Userlandcore file debugging • Works on 9.2+ and HEAD • Testing always welcome Userland live debugging (ptrace) • Process launch • Process attach by pid • Process attach by name • Breakpoints • Watchpoints • Threads
- 26. FreeBSD LLDB Status Kernelcore file debugging • GSoC proof of concept • Consider switch to ELF dumps ! Kernel live debugging • GSoC proof of concept • /dev/mem • gdb remote (serial) • remote debugging over Ethernet (TBD) !
- 27. FreeBSD LLDB Status RemoteDebugging - GDB Protocol • Testing required ! Debugserver • lldb-gdbserver (llgs) in progress on Linux ! Cross debugging • Cross-arch and Cross-OS • Minor issues • Needs testing
- 28. FreeBSD LLDB Roadmap •Source in contrib/llvm/tools/lldb • FreeBSD build infrastructure in the tree • Optional build, in /etc/src.conf WITH_LLDB=YES ! • Clang 3.5 import • LLDB update • Enable by default
- 29. FreeBSD LLDB Roadmap Python •not in base system • currently a compile-time option • move to a run-time option with a special bridge port
- 31. Front Ends • Built-intext user interface • Codelite • XCode • GDB/MI-compatible interface • Eclipse • Many others
- 34. Expression Evaluation (lldb) exprsome_variable
- 35.
- 36. Expression Evaluation #undef NULL #defineNULL (__null) typedef signed __INT8_TYPE__ int8_t; typedef unsigned __INT8_TYPE__ uint8_t; … void $__lldb_expr(void *$__lldb_arg) { some_variable; }
- 37. void $__lldb_expr(void *$__lldb_arg) { some_variable; } Expression Evaluation ClangExpressionDeclMap::FindExternalVisibleDecls[2]for 'some_variable' in a 'TranslationUnit' CEDM::FEVD[2] Searching the root namespace CEDM::FEVD[2] Found variable some_variable, returned static int &some_variable (original int)
- 38. void $__lldb_expr(void *$__lldb_arg) { some_variable; } Expression Evaluation Laststatement is an lvalue with type: int T *$__lldb_expr_result_ptr = …
- 39. void $__lldb_expr(void *$__lldb_arg) { some_variable; } Expression Evaluation Laststatement is an lvalue with type: int *(arg + 0) = *(arg + 8)
- 40. Expression Evaluation ; FunctionAttrs: nounwind define void @"_Z12$__lldb_exprPv"(i8* %"$__lldb_arg") #0 { %1 = alloca i8*, align 8, !clang.decl.ptr !8 store i8* %"$__lldb_arg", i8** $1, align 8 %2 = load i8* @"_ZGVZ12$__lldb_exprPvE23$__lldb_expr_result_ptr", align 1 %3 = icmp eq i8 %2, 0 br i1 %3, label %4, label %6 ; <label>:4 ; preds = %0 %5 = load i32** @_ZL13some_variable, align 8 store i32* %5, i32** @"_ZZ12$__lldb_exprPvE23$__lldb_expr_result_ptr", align 8 store i8 1, i8* @"_ZGVZ12$__lldb_exprPvE23$__lldb_expr_result_ptr" br label %6 ; <label>:6 ; press = %4, %0 ret void }
- 41. Expression Evaluation ; FunctionAttrs: nounwind define void @"_Z12$__lldb_exprPv"(i8* %"$__lldb_arg") #0 { %1 = getelementptr i8* %"$__lldb_arg", i32 8 %2 = bitcast i8* %1 to i32** %3 = getelementptr i8* %"$__lldb_arg", i32 0 %4 = bitcast i8* %3 to i32** %5 = alloca i8*, align 8, !clang.decl.ptr !8 store i8* %"$__lldb_arg", i8** %5, align 8 %6 = icmp eq i8 0, 0 br i1 %6, label %7, label %9 ! ; <label>:7 ; preds = %0 %8 = load i32** %2, align 8 store i32* %8, i32** %4, align 8 br label %9 ! ; <label>:9 ; preds = %7, %0 ret void }