gcc/testsuite/gcc.dg/combine-clobber.c

   1 /* { dg-do compile { target i?86-*-* x86_64-*-* } } */
   2 /* { dg-options "-O2 -fdump-rtl-combine-all" } */
   3
   4 /* This testcase checks if combine tries to combine sequences where the last
   5    insn has a clobber of a reg, and a previous insn sets that reg.
   6
   7    In this case, we have three insns
   8
   9    (set flags (compare a b))
  10    (set tmp (eq flags 0))
  11    (parallel [(set dst (neg tmp))
  12               (clobber flags)])
  13
  14    Previously, combine would not try the three-insn combination because of
  15    the set and clobber of flags.  Now it does.  Test that.  */
  16
  17
  18 int f(int a, int b) { return -(a == b); }
  19
  20 /* This regexp works for reg parameters as well as mem parameters.  */
  21 /* { dg-final { scan-rtl-dump {neg:SI[^:]*eq:SI[^:]*:SI} "combine" } } */