[Bug breakpoints/27120] New: Step will skip subsequent statements for some libc functions (bug or feature?)

[Bug breakpoints/27120] New: Step will skip subsequent statements for some libc functions (bug or feature?)

[jiangyy at outlook dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27120

            Bug ID: 27120
           Summary: Step will skip subsequent statements for some libc
                    functions (bug or feature?)
           Product: gdb
           Version: HEAD
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: breakpoints
          Assignee: unassigned at sourceware dot org
          Reporter: jiangyy at outlook dot com
  Target Milestone: ---

int main () {
  int res = 0;
  res = (intptr_t)malloc(sizeof(1000)); // L1
  printf("res = %d\n", res);            // L2
  return res;
}

Compiled with -g, optionally -ffreestanding -fno-builtin.

Break point on L1 and step (command: s)
- program ends (with res printed).
- this is also observed for memmove, memcpy (on -ffreestanding -fno-builtin)

Break point on L2 and step (command: s)
- goes into printf.


Looks like a (somewhat tricky) feature tuned (whitelist) for libc? LLDB behaves
like my expectation: step on L1 will stop at L2. DWARF debug info (lines) looks
correct. 


Affects many versions of gdb/gcc. Reproduced on:

- 11.0.50.20201224-git (GCC 10.2.0)
- Ubuntu 9.2-0ubuntu1~20.04 (GCC 9.3)

Seems duplicate with #25565.

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[Bug breakpoints/27120] Step will skip subsequent statements for some libc functions (bug or feature?)

[yangyibiao at outlook dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27120

Yibiao Yang <yangyibiao at outlook dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |yangyibiao at outlook dot com

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[Bug breakpoints/27120] Step will skip subsequent statements for some libc functions (bug or feature?)

[yangyibiao at outlook dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27120

--- Comment #1 from Yibiao Yang <yangyibiao at outlook dot com> ---
In old version of GDB (GNU gdb (GDB) 9.0.50.20191210-git), it behaves as
correct. (see PR#25565)

Thus, I think this should be a bug rather than a feature.

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[Bug breakpoints/27120] Step will skip subsequent statements for some libc functions (bug or feature?)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27120

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vries at gcc dot gnu.org
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Duplicate.

*** This bug has been marked as a duplicate of bug 27151 ***

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