https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85338
Bug ID: 85338 Summary: [GCOV] Type conversion leads to incorrect coverage in printf Product: gcc Version: 8.0 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 8-20170923-1ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs --enable-languages=c,c++,go,brig,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 --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 --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 8.0.0 20170923 (experimental) [trunk revision 253118] (Ubuntu 8-20170923-1ubuntu2) $ cat small.c #include <stdio.h> void Test(long long Val, int Amt) { printf(" lshr: 0x%llx \t\t shl: 0x%llx\n", Val >> Amt, Val << Amt); printf(" lshr: 0x%llx\t\tshl: 0x%llx\n", Val >> Amt, Val << Amt); printf(" lshr: 0x%llx \t\t shl: 0x%llx\n", (unsigned long long)Val >> Amt, Val << Amt); } int main() { Test(10, 4); return 0; } $ gcc --coverage small.c; ./a.out; gcov-8 small.c; cat small.c.gcov lshr: 0x0 shl: 0xa0 lshr: 0x0 shl: 0xa0 lshr: 0x0 shl: 0xa0 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 -: 0:Programs:1 -: 1:#include <stdio.h> -: 2: 1: 3:void Test(long long Val, int Amt) -: 4:{ 1: 5: printf(" lshr: 0x%llx \t\t shl: 0x%llx\n", Val >> Amt, Val << Amt); 1: 6: printf(" lshr: 0x%llx\t\tshl: 0x%llx\n", -: 7: Val >> Amt, Val << Amt); 2: 8: printf(" lshr: 0x%llx \t\t shl: 0x%llx\n", 1: 9: (unsigned long long)Val >> Amt, Val << Amt); 1: 10:} -: 11: 1: 12:int main() -: 13:{ 1: 14: Test(10, 4); -: 15: 1: 16: return 0; -: 17:} Line #8 is wrongly marked as executed twice. As can be seen from Line #5 and Line #6, I think this incorrect coverage is caused by type conversions.