gcc/testsuite/gcc.dg/tree-ssa/pr22236.c

   1 /* { dg-do run } */
   2 /* { dg-options "-O1 -fno-tree-vrp -fwrapv" } */
   3
   4 /* PR tree-optimization/22236
   5
   6     Avoid conversion of (signed char) {(uchar)1, +, (uchar)1}_x when
   7     it is not possible to prove that the scev does not wrap.
   8
   9     In this PR, a sequence 1, 2, ..., 255 has to be converted to
  10     signed char, but this would wrap: 1, 2, ..., 127, -128, ...  The
  11     result should not be a linear scev {(schar)1, +, (schar)1}_x.
  12     The conversion should be kept: (schar) {(uchar)1, +, (uchar)1}_x.
  13  */
  14
  15 void abort(void);
  16
  17 static inline void
  18 foo (signed char a)
  19 {
  20   int b = a - 0x7F;
  21   if (b > 1)
  22     abort();
  23 }
  24
  25 int main()
  26 {
  27   unsigned char b;
  28   for(b = 0; b < 0xFF; b++)
  29     foo (b);
  30
  31   return 0;
  32 }
  33