[Bug breakpoints/25293] New: gdb failed to break on an executed address

yangyibiao at hust dot edu.cn sourceware-bugzilla@sourceware.org
Thu Dec 19 09:04:00 GMT 2019


https://sourceware.org/bugzilla/show_bug.cgi?id=25293

            Bug ID: 25293
           Summary: gdb failed to break on an executed address
           Product: gdb
           Version: 8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: breakpoints
          Assignee: unassigned at sourceware dot org
          Reporter: yangyibiao at hust dot edu.cn
  Target Milestone: ---

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
8.3.0-6ubuntu1~18.04.1' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-8
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie
--with-system-zlib --with-target-system-zlib --enable-objc-gc=auto
--enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 8.3.0 (Ubuntu 8.3.0-6ubuntu1~18.04.1)

$ gdb -v
GNU gdb (Ubuntu 8.2-0ubuntu1~18.04) 8.2
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.



############################ test program ############################

$ cat small.c
/* { dg-do run } */
/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */

int __attribute__((noinline,noclone))
h(int a)
{
  return 2 * (a * (__INT_MAX__/2 + 1));
}
int __attribute__((noinline,noclone))
i(int a)
{
  return (2 * a) * (__INT_MAX__/2 + 1);
}
int __attribute__((noinline,noclone))
j(int a, int b)
{
  return (b * a) * (__INT_MAX__/2 + 1);
}
int __attribute__((noinline,noclone))
k(int a, int b)
{
  return (2 * a) * b;
}
int main()
{
  volatile int tem = h(-1);
  tem = i(-1);
  tem = j(-1, 2);
  tem = k(-1, __INT_MAX__/2 + 1);
  return 0;
}



############################ gcc compilation ############################

$ gcc -w -g -O0 small.c -o small.obj



############################ gdb commands ############################

$ cat cmds1
break *i+0x0
run
kill
q



$ cat cmds2
break *j+0x0
run
kill
q



############################ execute commands ############################


$ gdb -batch -x cmds1 ./small.obj
Breakpoint 1 at 0x5e6: file small.c, line 11.

[7]+  Stopped                 gdb -batch -x cmds ./small.obj


$ gdb -batch -x cmds2 ./small.obj
Breakpoint 1 at 0x5f7: file small.c, line 16.

Breakpoint 1, j (a=-1, b=0) at small.c:16
16      {
Kill the program being debugged? (y or n) [answered Y; input not from terminal]
[Inferior 1 (process 15108) killed]




############################ problem ############################

gdb failed to break at address "*i+0x0" while it breaks at address "*j+0x0"

function "i" and "j" are both executed functions called by "main" function in
the test program.

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