https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88914
Bug ID: 88914
Summary: [GCOV] Wrong frequencies when unreachable statements
within the body of the for loop in gcov
Product: gcc
Version: 7.3.0
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/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
7.3.0-27ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-7
--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 7.3.0 (Ubuntu 7.3.0-27ubuntu1~18.04)
$ cat small.c
int bar(a) { return a*a + 1; }
int main()
{
for (int i = 0; i < 10; i++) {
if (bar(i)) {
continue;
}
if (i == 0) {
abort();
} else {
exit(0);
}
}
}
$ gcc small.c -w --coverage; ./a.out; gcov small.c; cat small.c.gcov
File 'small.c'
Lines executed:62.50% of 8
Creating 'small.c.gcov'
-: 0:Source:small.c
-: 0:Graph:small.gcno
-: 0:Data:small.gcda
-: 0:Runs:1
-: 0:Programs:1
10: 1:int bar(a) { return a*a + 1; }
-: 2:
1: 3:int main()
-: 4:{
22: 5: for (int i = 0; i < 10; i++) {
10: 6: if (bar(i)) {
10: 7: continue;
-: 8: }
-: 9:
#####: 10: if (i == 0) {
#####: 11: abort();
-: 12: } else {
#####: 13: exit(0);
-: 14: }
-: 15: }
-: 16:}
We can found that Line #5 is wrongly marked as executed much more times.
When Line #10 to Line #14 are removed. The result is correct.
