[PATCH] Oprimize stack_protect_set_1_<mode> followed by a move to the same register (PR target/92841)

[Jakub Jelinek]

On Tue, Dec 10, 2019 at 11:02:39AM +0100, Andreas Schwab wrote:
> On Dez 10 2019, Jakub Jelinek wrote:
> 
> > --- gcc/testsuite/gcc.target/i386/pr92841.c.jj	2019-12-09 19:38:29.572759215 +0100
> > +++ gcc/testsuite/gcc.target/i386/pr92841.c	2019-12-09 19:40:59.642492417 +0100
> > @@ -0,0 +1,17 @@
> > +/* PR target/92841 */
> > +/* { dg-do compile { target fstack_protector } } */
> > +/* { dg-options "-O2 -fstack-protector-strong -masm=att" } */
> > +/* { dg-final { scan-assembler-not "xor\[lq]\t%(\[re]\[a-z0-9]*), %\\1\[\n\r]*\tmov\[lq]\t\[^\n\r]*, %\\1" } } */
> > +
> > +const struct S { int b; } c[] = {30, 12, 20, 0, 11};
> > +void bar (int *);
> > +
> > +void
> > +foo (void)
> > +{
> > +  int e[4];
> > +  const struct S *a;
> > +  for (a = c; a < c + sizeof (c); a++)
> > +    if (a->b)
> 
> This accesses c beyond bounds.  Does that invalidate the test?

Thanks for noticing, changed into
  for (a = c; a < c + sizeof (c) / sizeof (c[0]); a++)
in my copy, the testcase still FAILs before the patch and PASSes with it.

	Jakub