llvm-cov: wrong coverage for the "for-expression"


Bugzilla Link	45846
Version	trunk
OS	Linux
Reporter	LLVM Bugzilla Contributor
CC	@dwblaikie

Extended Description

$ clang --version clang version 11.0.0 (/home/yibiao/.cache/yay/llvm-git/llvm-project 871beba234a83a2a02da9dedbd59b91a1bfbd7af) Target: x86_64-pc-linux-gnu Thread model: posix InstalledDir: /usr/bin

$ clang -O0 -w -fcoverage-mapping -fprofile-instr-generate=small.profraw small.c; ./a.out; llvm-profdata merge small.profraw -o small.profdata; llvm-cov show a.out -instr-profile=small.profdata small.c > small.c.lcov; cat small.c.lcov 1| 1|void ok() { exit(0); } 2| | 3| 1|void foo() { 4| 1| int i; 5| 2| for (i=1; 1>0; ++i) 6| 1| ok(); 7| 1|} 8| | 9| 1|int main() { 10| 1| foo(); 11| 1|}

Line 5 is wrongly marked as executed twice. However, when called ok, the program is exit. Thus, the for expression should be executed only once. When setting breakpoint for Line 5 in LLDB, it only hit one time as follow: $ clang -w -g small.c; lldb a.out (lldb) target create "a.out" Current executable set to '/home/yibiao/Decov/a.out' (x86_64). (lldb) b 5 Breakpoint 1: where = a.out`foo + 8 at small.c:5:9, address = 0x0000000000401148 (lldb) r Process 447035 launched: '/home/yibiao/Decov/a.out' (x86_64) Process 447035 stopped

thread #1, name = 'a.out', stop reason = breakpoint 1.1 frame #0: 0x0000000000401148 a.out`foo at small.c:5:9 2
3 void foo() { 4 int i; -> 5 for (i=1; 1>0; ++i) 6 ok(); 7 } 8
(lldb) c Process 447035 resuming Process 447035 exited with status = 0 (0x00000000)

When we replace Line 6 with "exit(0); // ok();", the coverage is correct as follow:

1|      0|void ok() { exit(0); }
2|       |
3|      1|void foo() {
4|      1|  int i;
5|      1|  for (i=1; 1>0; ++i)
6|      1|    exit(0); // ok();
7|      1|}
8|       |
9|      1|int main() {

10| 1| foo(); 11| 1|}

$ cat small.c void ok() { exit(0); }

void foo() { int i; for (i=1; 1>0; ++i) ok(); }

int main() { foo(); }

llvm / llvm-project

llvm-cov: wrong coverage for the "for-expression" #45191

Extended Description