On Tue, 2025-01-21 at 21:52 +0800, Xi Ruoyao wrote:
> > struct Pair { unsigned long a, b; };
> >
> > struct Pair
> > test (struct Pair p, long x, long y)
> > {
> > p.a &= 0xffffffff;
> > p.a <<= 2;
> > p.a += x;
> > p.b &= 0xffffffff;
> > p.b <<= 2;
> > p.b += x;
> > return p;
> > }
> >
> > in GCC 13 the result is:
> >
> > or $r12,$r4,$r0
>
> Hmm, this strange move is caused by "&" in bstrpick_alsl_paired. Is it
> really needed for the fusion?
Never mind, it's needed or a = ((a & 0xffffffff) << 1) + a will blow up.
Stupid I.
> > bstrpick.d $r4,$r12,31,0
> > alsl.d $r4,$r4,$r6,2
> > or $r12,$r5,$r0
> > bstrpick.d $r5,$r12,31,0
> > alsl.d $r5,$r5,$r6,2
> > jr $r1
--
Xi Ruoyao <[email protected]>
School of Aerospace Science and Technology, Xidian University
