[Bug target/112112] Improper Arithmetic Type Conversion in s390x-linux-gnu-gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112112 Xi Ruoyao changed: What|Removed |Added CC||xry111 at gcc dot gnu.org Status|WAITING |RESOLVED Resolution|--- |DUPLICATE --- Comment #10 from Xi Ruoyao --- Dup of a QEMU bug. *** This bug has been marked as a duplicate of bug 112986 ***
[Bug target/112112] Improper Arithmetic Type Conversion in s390x-linux-gnu-gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112112 --- Comment #4 from 김대영 <22s302h0659 at sonline20 dot sen.go.kr> --- >From your perspective, do you think this could be a compiler bug? When tested with various compiler options following the GCC bug reporting guidelines, the binary compiles without any warnings, yet exhibits these behaviors
[Bug target/112112] Improper Arithmetic Type Conversion in s390x-linux-gnu-gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112112
Thomas Koenig changed:
What|Removed |Added
CC||tkoenig at gcc dot gnu.org
--- Comment #5 from Thomas Koenig ---
(In reply to 김대영 from comment #4)
> From your perspective, do you think this could be a compiler bug? When
> tested with various compiler options following the GCC bug reporting
> guidelines, the binary compiles without any warnings, yet exhibits these
> behaviors
It definitely sounds wrong, there should be consistent results.
Just to make the effect of the signs clear: Could you maybe run the
program
$ cat a.c
#include
SIGN char v1 = -1;
short v2 = 1;
int main()
{
printf("result for " OPT " \"" STR "\" = %d\n", v1 <= v2);
return 0;
}
with the shell script
$ cat do_all.sh
for s in signed unsigned ""
do
for o in -O0 -O1 -O2 -O3
do
gcc $o -DOPT='"'$o'"' -DSTR='"'$s'"' -DSIGN=$s a.c && ./a.out
done
done
and post the results? For reference, on x86_64 (which has signed
chars) this gets
result for -O0 "signed" = 1
result for -O1 "signed" = 1
result for -O2 "signed" = 1
result for -O3 "signed" = 1
result for -O0 "unsigned" = 0
result for -O1 "unsigned" = 0
result for -O2 "unsigned" = 0
result for -O3 "unsigned" = 0
result for -O0 "" = 1
result for -O1 "" = 1
result for -O2 "" = 1
result for -O3 "" = 1
[Bug target/112112] Improper Arithmetic Type Conversion in s390x-linux-gnu-gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112112 --- Comment #6 from 김대영 <22s302h0659 at sonline20 dot sen.go.kr> --- ``` z3rodae0@z3rodae0:~$ ./sh.sh result for -O0 "signed" = 1 result for -O1 "signed" = 1 result for -O2 "signed" = 1 result for -O3 "signed" = 1 result for -O0 "unsigned" = 0 result for -O1 "unsigned" = 0 result for -O2 "unsigned" = 0 result for -O3 "unsigned" = 0 result for -O0 "" = 1 result for -O1 "" = 1 result for -O2 "" = 1 result for -O3 "" = 1 ``` That's correct. I ran your code and script in my environment, and it produced the same results
[Bug target/112112] Improper Arithmetic Type Conversion in s390x-linux-gnu-gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112112 Thomas Koenig changed: What|Removed |Added Last reconfirmed||2023-11-01 Ever confirmed|0 |1 Status|UNCONFIRMED |WAITING --- Comment #7 from Thomas Koenig --- (In reply to 김대영 from comment #6) > ``` > z3rodae0@z3rodae0:~$ ./sh.sh > result for -O0 "signed" = 1 > result for -O1 "signed" = 1 > result for -O2 "signed" = 1 > result for -O3 "signed" = 1 > result for -O0 "unsigned" = 0 > result for -O1 "unsigned" = 0 > result for -O2 "unsigned" = 0 > result for -O3 "unsigned" = 0 > result for -O0 "" = 1 > result for -O1 "" = 1 > result for -O2 "" = 1 > result for -O3 "" = 1 > ``` > > That's correct. I ran your code and script in my environment, and it > produced the same results That is weird. I don't see a meaningful difference between the version without signed or unsigned and your program, and you get inconsistent results with your original program and consistent results with the other one. Or am I missing something?
[Bug target/112112] Improper Arithmetic Type Conversion in s390x-linux-gnu-gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112112 --- Comment #8 from 김대영 <22s302h0659 at sonline20 dot sen.go.kr> --- I'm sorry, I also didn't fully understand these bugs, my friend.
[Bug target/112112] Improper Arithmetic Type Conversion in s390x-linux-gnu-gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112112
--- Comment #9 from 김대영 <22s302h0659 at sonline20 dot sen.go.kr> ---
```
#include
#define M_1 0xad5d6da /* 1010110101011101011011011010 */
char g_1 = -1;
short g_2 = -1;
char v1 = -1;
short v2 = 1;
int main(){
char l_1 = -1;
short l_2 = -1;
printf("char g_1 = %d\n", g_1);
printf("char l_1 = %d\n", l_1);
printf("(char)M_1 = %d\n\n\n", (char)M_1);
printf("short g_2 = %d\n", g_2);
printf("short l_2 = %d\n", l_2);
printf("(short)M_1 = %d\n\n\n", (short)M_1);
printf("(char)-1 <= (short)1 = %s \n\n", (char)-1 <= (short)1 ? "True"
: "False");
printf("char v1= %d\n", v1);
printf("short v2 = %d\n\n", v2);
printf("v1 <= v2 = %s \n", v1 <= v2 ? "True" : "False");
return 0;
}
```
I have been continuously investigating bugs recently. The above code proves
that it cannot reliably handle 'char' type as signed. Additionally, testing in
the s390x native environment with GCC versions 9, 11.4.0, and 12 consistently
revealed the same bug.
```
root@a92c2f395400:~# gcc -o test test.c -O0
root@a92c2f395400:~# ./test
char g_1 = 255
char l_1 = 255
(char)M_1 = 218
short g_2 = -1
short l_2 = -1
(short)M_1 = -10534
(char)-1 <= (short)1 = False
char v1= 255
short v2 = 1
v1 <= v2 = False
root@a92c2f395400:~# gcc -o test test.c -O2
root@a92c2f395400:~# ./test
char g_1 = 255
char l_1 = 255
(char)M_1 = 218
short g_2 = -1
short l_2 = -1
(short)M_1 = -10534
(char)-1 <= (short)1 = False
char v1= 255
short v2 = 1
v1 <= v2 = True
```
