public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug tree-optimization/114684] New: `-(int)(unsigned:1)signed:1` could just be `(int)signed:1`
@ 2024-04-10 20:49 pinskia at gcc dot gnu.org
  2024-04-10 20:57 ` [Bug tree-optimization/114684] " pinskia at gcc dot gnu.org
  2024-04-11  6:41 ` rguenth at gcc dot gnu.org
  0 siblings, 2 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-04-10 20:49 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114684

            Bug ID: 114684
           Summary: `-(int)(unsigned:1)signed:1` could just be
                    `(int)signed:1`
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
struct t{
  signed s1 : 1;
  unsigned u1 : 1;
} b = {-1};

int f()
{
  struct t tt = b;
  return tt.s1;
}
int f1()
{
  struct t tt = b;
  tt.u1 = tt.s1;
  int ttt = tt.u1;
  return -ttt;
}
```

These 2 functions should produce the same code. (For aarch64 it almost does,
there is an extra sign extend in f). I noticed this while fixing PR 114666. It
is also related to PR 101955. Note this only works for 1bit signed values.

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2024-04-11  6:41 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-04-10 20:49 [Bug tree-optimization/114684] New: `-(int)(unsigned:1)signed:1` could just be `(int)signed:1` pinskia at gcc dot gnu.org
2024-04-10 20:57 ` [Bug tree-optimization/114684] " pinskia at gcc dot gnu.org
2024-04-11  6:41 ` rguenth at gcc dot gnu.org

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).