Bug 493599

Created attachment 174042 [details]
The main program, headers and the output files

STEPS TO REPRODUCE
1. Compile main.c from the attachment. I used `clang main.c -o main -lm`. (The actual point here is the usage of CALLGRIND_START_INSTRUMENTATION and CALLGRIND_STOP_INSTRUMENTATION)
2. run `valgrind with valgrind --tool=callgrind --separate-threads=yes --dump-after='find_primes' ./main`
3. Inspect the summary lines in the callgrind output files. One or some of them show very high values close to the maximum ulong value.

(`--dump-before=find_primes` or `--dump-every-bb=100000` cause similar overflow(s) in the summary line of one or more files. Running callgrind with --cache-sim=yes causes the overflow in the cache metrics, too)

The output file `callgrind.out.3476195-02`

```
# callgrind format
version: 1
creator: callgrind-3.23.0
pid: 3476195
cmd:  ./main
part: 2
thread: 2


desc: I1 cache: 
desc: D1 cache: 
desc: LL cache: 

desc: Timerange: Basic block 683044 - 2542554
desc: Trigger: Program termination

positions: line
events: Ir
summary: 18446744073707324667


totals: 0
```

shows the overflow of the Instruction counts in the summary line. The summary of the file `callgrind.out.3476195.1-02` shows `2226949` Instructions.

```
# callgrind format
version: 1
creator: callgrind-3.23.0
pid: 3476195
cmd:  ./main
part: 1
thread: 2


desc: I1 cache:
desc: D1 cache:
desc: LL cache:

desc: Timerange: Basic block 0 - 683044
desc: Trigger: --dump-after=find_primes

positions: line
events: Ir
summary: 2226949
...
```

I don't think it is a coincidence that `18446744073707324667 (Ir from callgrind.out.3476195-02) + 2226949 (Ir from callgrind.out.3476195.1-02) = 0`.

EXPECTED BEHAVIOUR:

I guess the instruction counts in the summary of the `ccallgrind.out.3476195-02` file should actually be 0.

ADDITIONAL INFORMATION

The original bug was observed in a rust program (iai-callgrind) using valgrind/callgrind , and the `main.c` of the attachment is the quick and dirty C implementation of the failing rust test. I hope the main.c suffices to track down the bug.