https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115355
Bug ID: 115355
Summary: PPCLE: Auto-vectorization creates wrong code for
Power9
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: jens.seifert at de dot ibm.com
Target Milestone: ---
Input setToIdentity.C:
#include <stdlib.h>
#include <memory.h>
#include <stdio.h>
void setToIdentityGOOD(unsigned long long *mVec, unsigned int mLen)
{
for (unsigned long long i = 0; i < mLen; i++)
{
mVec[i] = i;
}
}
void setToIdentityBAD(unsigned long long *mVec, unsigned int mLen)
{
for (unsigned int i = 0; i < mLen; i++)
{
mVec[i] = i;
}
}
unsigned long long vec1[100];
unsigned long long vec2[100];
int main(int argc, char *argv[])
{
unsigned int l = argc > 1 ? atoi(argv[1]) : 29;
setToIdentityGOOD(vec1, l);
setToIdentityBAD(vec2, l);
if (memcmp(vec1, vec2, l*sizeof(vec1[0])) != 0)
{
for (unsigned int i = 0; i < l; i++)
{
printf("%llu %llu\n", vec1[i], vec2[i]);
}
}
else
{
printf("match\n");
}
return 0;
}
Fails
gcc -O3 -mcpu=power9 -m64 setToIdentity.C -save-temps -fverbose-asm -o pwr9.exe
-mno-isel
Good:
gcc -O3 -mcpu=power8 -m64 setToIdentity.C -save-temps -fverbose-asm -o pwr8.exe
-mno-isel
"-mno-isel" is only specified to reduce the diff.
Failing output:
pwr9.exe
0 0
1 1
2 0
3 4294967296
4 4
5 5
6 6
7 7
8 8
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
4th element contains wrong data.
