[Bug tree-optimization/20256] Perfect nest transformation not conservative enough

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2005-06-28 23:17 -------
Andrew's code in comment #4 is invalid (don't call no-arg functions with 
arguments!), but here's a version that also passes through the c++ 
frontend and crashes the optimizers: 
 
---------------------- 
int foo() { 
  int x[2][2], y[2]; 
  int s; 
  for (int n=0; n<2; n++) 
    { 
      s = 0; 
      for (int i=0; i<2; i++) 
        s += x[n][i]*y[i]; 
      s += 1; 
    } 
  return s; 
} 
-------------------- 
 
g/x> /home/bangerth/bin/gcc-4.1-pre/bin/gcc -c x.cc -O2 -ftree-loop-linear 
x.cc: In function ‘int foo()’: 
x.cc:1: error: Definition in block 9 does not dominate use in block 3 
for SSA_NAME: s_11 in statement: 
s_7 = PHI <s_11(3)>; 
PHI argument 
s_11 
for PHI node 
s_7 = PHI <s_11(3)>; 
x.cc:1: internal compiler error: verify_ssa failed. 
Please submit a full bug report, 
with preprocessed source if appropriate. 
See <URL:http://gcc.gnu.org/bugs.html> for instructions. 
 
W. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20256