https://llvm.org/bugs/show_bug.cgi?id=23613
Bug ID: 23613
Summary: Erroneous Dissassembly obtained when breakpoint is
inserted
Product: lldb
Version: unspecified
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: All Bugs
Assignee: lldb-dev@cs.uiuc.edu
Reporter: ravithejaw...@gmail.com
Classification: Unclassified
Created attachment 14356
--> https://llvm.org/bugs/attachment.cgi?id=14356&action=edit
C++ source file
When a breakpoint is inserted at an instruction, the subsequent instructions
are erroneously decoded by LLDB. Possible reason could be that while decoding
instructions (when a breakpoint is also inserted), LLDB should substitute the
complete original instruction before decoding. Instead the dissassembly is
decoded correctly till the breakpoint instruction but since the breakpoint
instruction is basically modifying 1 byte of an already existing instruction,
LLDB interprets the rest of the bytes as new instructions.
Disassembly by GDB
0x0000000000400922 <+0>: push %rbp
0x0000000000400923 <+1>: mov %rsp,%rbp
0x0000000000400926 <+4>: sub $0x30,%rsp
0x000000000040092a <+8>: mov %rdi,-0x18(%rbp)
0x000000000040092e <+12>: mov %esi,-0x1c(%rbp)
0x0000000000400931 <+15>: mov %edx,-0x20(%rbp)
0x0000000000400934 <+18>: mov %ecx,-0x24(%rbp)
=> 0x0000000000400937 <+21>: mov -0x1c(%rbp),%eax
0x000000000040093a <+24>: cmp -0x20(%rbp),%eax
0x000000000040093d <+27>: jle 0x40094b <binary_search(int*, int, int,
int)+41>
0x000000000040093f <+29>: movl $0xffffffff,-0x8(%rbp)
0x0000000000400946 <+36>: jmpq 0x4009d9 <binary_search(int*, int, int,
int)+183>
Corresponding Disassembly by LLDB
0x400922 <+0>: pushq %rbp
0x400923 <+1>: movq %rsp, %rbp
0x400926 <+4>: subq $0x30, %rsp
0x40092a <+8>: movq %rdi, -0x18(%rbp)
0x40092e <+12>: movl %esi, -0x1c(%rbp)
0x400931 <+15>: movl %edx, -0x20(%rbp)
0x400934 <+18>: movl %ecx, -0x24(%rbp)
-> 0x400937 <+21>: int3
0x400938 <+22>: inb $0x3b, %al
0x40093b <+25>: loopne 0x4009bc ; <+154> at test.cpp:34
0x40093e <+28>: orb $-0x39, %al
0x400940 <+30>: clc
As it can be seen in the disassembly by LLDB, after breakpoint at <+21> the
instructions are not correctly decoded.
Steps to reproduce
1) Compile attached source with g++ (with -g option)
2) Start debugging with LLDB
3) Insert breakpoint at binary_search (b binary_search)
4) Execute command "disassemble"
--
You are receiving this mail because:
You are the assignee for the bug.
_______________________________________________
lldb-dev mailing list
lldb-dev@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
