[Bug c++/17972] [3.4 Regression] const/pure functions result in bad asm

["amodra at bigpond dot net dot au" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From amodra at bigpond dot net dot au  2004-12-06 23:31 -------
I checked again with a current x86 gcc, 3.4.4 20041206, and the problem is still
there.  Note that this only happens with cc1plus.  As to why we get the
"impossible" assembly, what happens is that the inline function cti gets
expanded twice, but the first return label is used for both expansions:

 cti body
 jump ret_label
ret_label
 cti body
 jump ret_label

A simpler testcase is:

struct thread_info
{
  short preempt_count;
} x;

static inline struct thread_info *cti (void) __attribute__ ((const));
static inline struct thread_info *cti (void)
{
  return &x;
}

void fn (void)
{
  ++cti()->preempt_count;
}


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17972