gcc/testsuite/g++.dg/tree-ssa/pr20963.C

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2" } */
   3
   4 /* This was causing PRE to insert the value of the ADDR variable, to
   5    remove the invariant cast but in doing so, it was creating a
   6    non-invariant expression out of the invariant one, causing a later
   7    failure in PRE.  */
   8 struct sMCB {
   9   unsigned char type;
  10 };
  11
  12 extern void foo (void);
  13 unsigned char mem_readb(char *pt) __attribute__((nothrow));
  14
  15 void DOS_FreeProcessMemory(unsigned short pspseg) {
  16         while (1) {
  17                 if (pspseg)
  18                         foo ();
  19                 char *addr = (char*)(&((sMCB*)0)->type);
  20                 if (mem_readb(addr)==0x5a) break;
  21         }
  22 };
  23