https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123124
Bug ID: 123124
Summary: [Gcov] always_inline attribute leads to incorrect
coverage
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: gcov-profile
Assignee: unassigned at gcc dot gnu.org
Reporter: iamanonymous.cs at gmail dot com
Target Milestone: ---
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/compiler/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/16.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --disable-multilib --disable-bootstrap
--enable-languages=c,c++ --prefix=/compiler/gcc-trunk --enable-coverage
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 16.0.0 20251204 (experimental) (GCC)
$ cat small.c
int a;
__attribute__((always_inline)) int b () {
return 0;
}
int main () {
a - b () ;
}
$ gcc-trunk -w -O0 -fprofile-arcs -ftest-coverage small.c -o small && ./small
&& /compiler/gcc-trunk/bin/gcov small.c && cat small.c.gcov
File 'small.c'
Lines executed:75.00% of 4
Creating 'small.c.gcov'
Lines executed:75.00% of 4
-: 0:Source:small.c
-: 0:Graph:small.gcno
-: 0:Data:small.gcda
-: 0:Runs:1
-: 1:int a;
#####: 2:__attribute__((always_inline)) int b () {
1*: 3: return 0;
-: 4:}
1: 5:int main () {
2: 6: a - b () ;
-: 7:}
Line #6 is wrongly marked as executed twice.
If I use lcov, the result I get is as follows：
$ clang-trunk -w -O0 -fcoverage-mapping
-fprofile-instr-generate=small.c.profraw small.c -o small && ./small &&
/compiler/llvm-trunk/bin/llvm-profdata merge small.c.profraw -o
small.c.profdata && /compiler/llvm-trunk/bin/llvm
-cov show small -instr-profile=small.c.profdata small.c
1| |int a;
2| 1|__attribute__((always_inline)) int b () {
3| 1| return 0;
4| 1|}
5| 1|int main () {
6| 1| a - b () ;
7| 1|}
Line #6 is marked as executed once.
