ssa-chrec-27.c

来自「Mac OS X 10.4.9 for x86 Source Code gcc」· C语言 代码 · 共 42 行

/* APPLE LOCAL file lno */
/* { dg-do compile } */ 
/* { dg-options "-O1 -floop-test -fdump-tree-lptest-details" } */


int bar (void);

int foo ()
{
  int a = -100;
  
  /* This exercises a code with two loop nests.  */
  
  /* loop_1 runs 100 times.  */
  while (a < 0)
    a++;
  
  a -= 77;
  
  /* loop_2 runs 26 times.  */
  while (a < 0)
    a+=3;
}

/* The analyzer sees two loop nests:
   for the first, it determines the evolution:
   a  ->  {-100, +, 1}_1
   
   and for the second, it determines that the first loop ends at 0 and then:
   a  ->  {-77, +, 3}_2
   
   When the constant propagation is postponed, the analyzer detects
   for the second loop the evolution function:
   a  ->  {a_5, +, 3}_2

*/

/* { dg-final { scan-tree-dump-times "set_nb_iterations_in_loop = 100" 1 "lptest"} } */
/* { dg-final { scan-tree-dump-times "set_nb_iterations_in_loop = 26" 1 "lptest"} } */