[Bug gcov-profile/93725] New: [GCOV] inline attribute leads to incorrect code coverage for calling variable argument function

[yangyibiao at hust dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93725

            Bug ID: 93725
           Summary: [GCOV] inline attribute leads to incorrect code
                    coverage for calling variable argument 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: ---

$ gcov -v
gcov (GCC) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or 
FITNESS FOR A PARTICULAR PURPOSE.


$ 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
#include <stdarg.h>

long x;

inline void __attribute__((always_inline)) f1(va_list ap)
{
  x = va_arg(ap, double);
  x += va_arg(ap, long);
  x += va_arg(ap, double);
}

void f(int i, ...)
{
  va_list ap;
  va_start(ap, i);
  f1(ap);
  va_end(ap);
}

int main(void) { f(3, 16.0); return 0; }

$ gcc -O0 --coverage 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:#include <stdarg.h>
-:    2:
-:    3:long x;
-:    4:
-:    5:inline void __attribute__((always_inline)) f1(va_list ap)
-:    6:{
2:    7:  x = va_arg(ap, double);
1:    8:  x += va_arg(ap, long);
1:    9:  x += va_arg(ap, double);
1:   10:}
-:   11:
1:   12:void f(int i, ...)
-:   13:{
-:   14:  va_list ap;
1:   15:  va_start(ap, i);
-:   16:  f1(ap);
1:   17:  va_end(ap);
1:   18:}
-:   19:
1:   20:int main(void) { f(3, 16.0); return 0; }


################################################################################
### We can find that: Line #7 is calling an function with variable argument
which is wrongly marked as executed 2 times
### When the "__attribute__ ((always_inline))" is removed for function "f1",
the code coverage is correct
################################################################################