[Bug gcov-profile/93693] New: [GCOV] incorrect coverage when compiled with option '-fsanitize=undefined' for function defined inside other function

[yangyibiao at hust dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93693

            Bug ID: 93693
           Summary: [GCOV] incorrect coverage when compiled with option
                    '-fsanitize=undefined' for function defined inside
                    other function
           Product: gcc
           Version: 9.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yangyibiao at hust dot edu.cn
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

$ gdb -v
GNU gdb (GDB) 9.0.50.20191210-git
Copyright (C) 2019 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.

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib
--libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++,d --enable-shared
--enable-threads=posix --with-system-zlib --with-isl --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch
--disable-libssp --enable-gnu-unique-object --enable-linker-build-id
--enable-lto --enable-plugin --enable-install-libiberty
--with-linker-hash-style=gnu --enable-gnu-indirect-function --enable-multilib
--disable-werror --enable-checking=release --enable-default-pie
--enable-default-ssp --enable-cet=auto gdc_include_dir=/usr/include/dlang/gdc
Thread model: posix
gcc version 9.2.0 (GCC)


$ cat small.c
int N1 = 0;

int foo(char a[2][++N1])
{
  N1 += 4; return sizeof(a[0]);
}

int bar(int N2)
{
  int foo1(char a[2][++N2])
  {
    N2 += 4; return sizeof(a[0]);
  }

  foo1(0);
}

int main()
{
  foo(0); bar(0);
}

$ gcc -O0 --coverage -fsanitize=undefined small.c; ./a.out; gcov small.c; cat
small.c.gcov
File 'small.c'
Lines executed:100.00% of 9
Creating 'small.c.gcov'

-:    0:Source:small.c
-:    0:Graph:small.gcno
-:    0:Data:small.gcda
-:    0:Runs:1
-:    1:int N1 = 0;
-:    2:
1:    3:int foo(char a[2][++N1])
-:    4:{
1:    5:  N1 += 4; return sizeof(a[0]);
-:    6:}
-:    7:
1:    8:int bar(int N2)
-:    9:{
2:   10:  int foo1(char a[2][++N2])
-:   11:  {
1:   12:    N2 += 4; return sizeof(a[0]);
-:   13:  }
-:   14:
1:   15:  foo1(0);
1:   16:}
-:   17:
1:   18:int main()
-:   19:{
1:   20:  foo(0); bar(0);
-:   21:}

################################################################################
### We can find that: Line #3 is executed 1 times. foo is executed one time. 
### When function foo is defined inside other function, the coverage is
incorrect with compilation option "-fsanitize=undefined". (Line #10 is executed
2 times.) 
### While removing compilation option "-fsanitize=undefined", the coverage will
be correct. 
################################################################################