https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93726
Bug ID: 93726 Summary: [GCOV] unexecuted functions lead to incorrect code coverage when it calls a function with a variable argument 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, y; 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 foo(int i, ...) { va_list ap; va_start(ap, i); f1(ap); va_end(ap); } void bar(int i, ...) { va_list ap; va_start(ap, i); switch (i) { case 0: y = va_arg(ap, double); break; default: break; } f1(ap); va_end(ap); } void main(void) { foo(3, 16.0); } $ gcc -O0 --coverage small.c; ./a.out; gcov small.c; cat small.c.gcov File 'small.c' Lines executed:42.11% of 19 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, y; -: 4: -: 5:inline void __attribute__((always_inline)) f1(va_list ap) -: 6:{ #####: 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 foo(int i, ...) -: 13:{ -: 14: va_list ap; 1: 15: va_start(ap, i); -: 16: f1(ap); 1: 17: va_end(ap); 1: 18:} -: 19: #####: 20:void bar(int i, ...) -: 21:{ -: 22: va_list ap; #####: 23: va_start(ap, i); #####: 24: switch (i) -: 25: { #####: 26: case 0: #####: 27: y = va_arg(ap, double); #####: 28: break; #####: 29: default: #####: 30: break; -: 31: } -: 32: f1(ap); #####: 33: va_end(ap); #####: 34:} -: 35: 1: 36:void main(void) { foo(3, 16.0); } ################################################################################ ### We can find that: Line #7 is not executed. ### when the definition of function "bar" is removed from the source code, the coverage will be different. ################################################################################