https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65357
Bug ID: 65357
Summary: aggressive loop optimization not correct
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: weiming at ms1 dot url.com.tw
source:
#include <stdio.h>
#include <stdlib.h>
void addlist(int n, int *list)
{
int i;
for (i=0; i<n; i++)
{
*list++=*list+10;
*list++=*list+11;
}
}
int tlist[10]={ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
void main(void)
{
int i;
addlist(5, tlist);
for (i=0; i<10; i++)
{
fprintf(stdout, "%d: %d\n", i, tlist[i]);
}
}
makefile:
tt.exe: tt.c
gcc -O3 -o $@ $<
result of gcc 4.7.3:
0: 10
1: 12
2: 12
3: 14
4: 14
5: 16
6: 16
7: 18
8: 18
9: 20
result of gcc 4.8.4 and 4.9.2:
0: 11
1: 13
2: 13
3: 15
4: 15
5: 17
6: 17
7: 19
8: 19
9: 11
which is correct?
