https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100499
Bug ID: 100499
Summary: Different results with -fpeel-loops
-ftree-loop-vectorize options
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: dongjianqiang2 at huawei dot com
Target Milestone: ---
cat demo.c
#include<stdio.h>
typedef unsigned short uint16_t;
typedef signed int int32_t;
static uint16_t g_2823 = 0xEC75L;
static uint16_t g_116 = 0xBC07L;
static uint16_t
(safe_mul_func_uint16_t_u_u)(uint16_t ui1, uint16_t ui2 )
{
return ((unsigned int)ui1) * ((unsigned int)ui2);
}
int main (int argc, char* argv[])
{
uint16_t l_2815 = 65535UL;
uint16_t *l_2821 = &g_116;
uint16_t *l_2822 = &g_2823;
printf ("start g_2823 = %d\n", g_2823);
lbl_2826:
l_2815 &= 0x9DEF1EAEL;
if (+(safe_mul_func_uint16_t_u_u(((*l_2821) = l_2815), (--(*l_2822)))))
{
goto lbl_2826;
}
printf ("end g_2823 = %d\n", g_2823);
return 0;
}
Compiling with
gcc demo.c -O1
./a.out
start g_2823 = 60533
end g_2823 = 32768
gcc demo.c -O1 -fpeel-loops -ftree-loop-vectorize
./a.out
start g_2823 = 60533
end g_2823 = 60526
gives different results
