[lldb-dev] [Bug 48468] New: An address belongs to different source code lines when debugging at source-level and instruction-level

[via lldb-dev]

https://bugs.llvm.org/show_bug.cgi?id=48468

            Bug ID: 48468
           Summary: An address belongs to different source code lines when
                    debugging at source-level and instruction-level
           Product: lldb
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: All Bugs
          Assignee: lldb-dev at lists.llvm.org
          Reporter: yangyibiao at nju.edu.cn
                CC: jdevlieghere at apple.com, llvm-bugs at lists.llvm.org

Created attachment 24260
  --> https://bugs.llvm.org/attachment.cgi?id=24260&action=edit
binary

$ clang -v
Ubuntu clang version
12.0.0-++20201202063839+f0193623297-1~exp1~20201202174527.2077
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/10
Candidate multilib: .;@m64
Selected multilib: .;@m64

$ lldb -v
lldb version 12.0.0

$ cat small.c
int a[2];

int foo(int n)
{
  switch(n) {
    case 0:
      for(n = 7, a[0]++; 0;) {
    case 2:
        a[1] = a[0] + 1;
      }
  }
  return n;
}

void main()
{
  foo(0);
  foo(2);
}


$ clang -O2 -g small.c

$ lldb a.out
(lldb) b main
Breakpoint 1: where = a.out`main [inlined] foo at small.c:17, address =
0x00000000004004d0
(lldb) r
    frame #0: 0x00000000004004d0 a.out`main [inlined] foo(n=7) at small.c:7:22
-> 7          for(n = 7, a[0]++; 0;) {
(lldb) s
    frame #0: 0x00000000004004df a.out`main at small.c:18
-> 18     foo(2);
(lldb) s
    frame #0: 0x00000000004004df a.out`main [inlined] foo(n=2) at small.c:9:21
-> 9            a[1] = a[0] + 1;
(lldb)



###############################################
when step line by line, 0x00000000004004df belongs to Line 18 and Line 9.
However, when step instruction by instruction, 0x00000000004004df only belongs
to Line 18 as follow.
###############################################



$ lldb a.out
(lldb) b main
Breakpoint 1: where = a.out`main [inlined] foo at small.c:17, address =
0x00000000004004d0
(lldb) r
    frame #0: 0x00000000004004d0 a.out`main [inlined] foo(n=7) at small.c:7:22
-> 7          for(n = 7, a[0]++; 0;) {
(lldb) si
    frame #0: 0x00000000004004d6 a.out`main [inlined] foo(n=7) at small.c:7:22
-> 7          for(n = 7, a[0]++; 0;) {
(lldb) si
    frame #0: 0x00000000004004d9 a.out`main [inlined] foo(n=7) at small.c:7:22
-> 7          for(n = 7, a[0]++; 0;) {
(lldb) si
    frame #0: 0x00000000004004df a.out`main at small.c:18
-> 18     foo(2);
(lldb) si
    frame #0: 0x00000000004004e2 a.out`main [inlined] foo(n=2) at small.c:9:14
-> 9            a[1] = a[0] + 1;
(lldb)

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