https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90057
Bug ID: 90057
Summary: [GCOV] Wrong coverage for "if()" statement while it is
embedded with an empty "for(;0;)" loop statement
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: gcov-profile
Assignee: unassigned at gcc dot gnu.org
Reporter: yangyibiao at nju dot edu.cn
CC: marxin at gcc dot gnu.org
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
8.2.0-1ubuntu2~18.04' --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 --with-sysroot=/ --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 8.2.0 (Ubuntu 8.2.0-1ubuntu2~18.04)
$ cat small.c
int main()
{
int b = 0, d = 0, f = 0, p = -1;
if (f > p && p)
for (; 0;)
;
else if (d)
b = 0 >= b;
return 0;
}
$ gcc -w -O0 --coverage small.c; ./a.out; gcov-8 small.c; cat small.c.gcov
File 'small.c'
Lines executed:71.43% of 7
Creating 'small.c.gcov'
-: 0:Source:small.c
-: 0:Graph:small.gcno
-: 0:Data:small.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:
1: 2:int main()
-: 3:{
1: 4: int b = 0, d = 0, f = 0, p = -1;
-: 5:
2: 6: if (f > p && p)
1: 7: for (; 0;)
-: 8: ;
#####: 9: else if (d)
#####: 10: b = 0 >= b;
-: 11:
1: 12: return 0;
-: 13:}
Line #6 is wrongly marked as executed twice.
While Line 7 is removed. The result is correct as:
$ gcc -w -O0 --coverage small.c; ./a.out; gcov-8 small.c; cat small.c.gcov
File 'small.c'
Lines executed:66.67% of 6
Creating 'small.c.gcov'
-: 0:Source:small.c
-: 0:Graph:small.gcno
-: 0:Data:small.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:
1: 2:int main()
-: 3:{
1: 4: int b = 0, d = 0, f = 0, p = -1;
-: 5:
1: 6: if (f > p && p)
-: 7: // for (; 0;)
-: 8: ;
#####: 9: else if (d)
#####: 10: b = 0 >= b;
-: 11:
1: 12: return 0;
-: 13:}
While Line #9 and Line #10 are both removed, the result is also correct as:
$ gcc -w -O0 --coverage small.c; ./a.out; gcov-8 small.c; cat small.c.gcov
File 'small.c'
Lines executed:100.00% of 5
Creating 'small.c.gcov'
-: 0:Source:small.c
-: 0:Graph:small.gcno
-: 0:Data:small.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:
1: 2:int main()
-: 3:{
1: 4: int b = 0, d = 0, f = 0, p = -1;
-: 5:
1: 6: if (f > p && p)
1: 7: for (; 0;)
-: 8: ;
-: 9: // else if (d)
-: 10: // b = 0 >= b;
-: 11:
1: 12: return 0;
-: 13:}
