[Bug tree-optimization/57719] [4.8/4.9 Regression] wrong code at -O3 on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57719

--- Comment #2 from Zhendong Su <su at cs dot ucdavis.edu> ---
Hi Jakub, below are three additional (possibly related) testcases that may help
you folks diagnose the issue; they (including the original testcase) all
manifest differently: 

---------------------

test #2: wrong code from both gcc trunk and 4.8 at -O3 in 32-bit mode only: 


int printf (const char *, ...);

int c, e[2], f, g, *l; 
long long h;

int foo ()
{
  int s[1];
  int i = 0;
  for (; i < 1; i++)
    s[0] = 0;
  h = 0;
  for (; h; h = 1) { 
    int *dp[1] = {&s[0]};
    *dp[0] = 0;
  }
  g = 0;
  return 0;
}

void bar ()
{
  for (; c < 2; c++) { 
    int *ip = &f;
    *ip = 0;
    *ip = 0 < foo (); 
    l = &e[c];
    *ip = 1;
    *l = 0;
  }
}

int main ()
{
  bar ();
  printf ("%d\n", f);
  return 0;
}

---------------------

test #3: wrong code from gcc trunk (but not gcc 4.8) at -O3 in 32-bit mode
only: 


int printf (const char *, ...);

int f1;
int a, b, c; 
volatile int d;
int e[2], f, g; 
long long h;
int j, k, *l; 

short fn1 (unsigned short ui1)
{
  return ui1 - a;
}

int fn4 (int p)
{
  int s[1];
  int *tp = &f;
  int *cp = &g;
  int i = 0;
  for (; i < 1; i++)
    s[0] = 0;
  h = 0;
  for (; h; h = 1) { 
    int *dp[1] = {&s[0]};
    *dp[0] = 0;
  }
  *cp = p % (1 ^ *tp);
  return 0;
}

void
fn5 ()
{
  unsigned short t = 0;
  for (; c < 2; c++) { 
    int *ip = &f1;
    b = 0;
    j = 0;
    d ^ (*ip = 0); 
    t = fn1 (k);
    *ip = e[0] < fn4 (t);
    l = &e[c];
    *ip = 1;
    *l = 0;
  }
}

int
main ()
{
  fn5 ();
  printf ("%d\n", f1);
  return 0;
}

---------------------

test #4: wrong code from gcc trunk (but not gcc 4.8) at -O3 in both 32-bit and
64-bit modes: 


int printf (const char *, ...);

int a;
int b;
int c;
volatile int d;
int e; 
int f[2];
int g;
int h;
int j;
int *k = &f[0];
int l;

short
fn1 (unsigned short p)
{
  return p * a;
}

int
fn2 (int p)
{
  int m[1];
  int i = 0;
  for (; i < 1; i++)
    m[0] = 0;
  g = 0; 
  for (; g; g = 1) {
    int *n[1] = {&m[0]};
  }
  l = p % (1 ^ *k);
  return 0;
}

int
main ()
{
  unsigned short o = 0;
  int *p;
  for (; c < 2; c++) {
    int *q = &e;
    b = 0;
    h = 0;
    d ^ (*q = 0);
    o = fn1 (j);
    *q = f[0] < fn2 (o);
    p = &f[c];
    *q = 1;
    fn2 (0);
    *p = 0;
  }
  printf ("%d\n", e);
  return 0;
}