[Mesa-dev] [PATCH] nv50/ir: Add mul and mod constant optimizations

[Karol Herbst]

On Tue, Jul 23, 2019 at 4:50 PM Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>
> You handle 1/n but not 1%n? TBH, the 1/n code isn't 100% obvious to
> me... 1/n = |n|-1 > 0 ? .... i forget how SLCT works, but I can't
> think of a way to finish that expression in terms of |n|-1 and n. And
> what about n == 0. I'd just as soon drop that case.
>

is 1/0 actually defined in glsl? I thought that the result is
undefined and we can basically do whatever, no? At least intel seems
to return INT_MAX for 1/0

> On Tue, Jul 23, 2019 at 10:20 AM Mark Menzynski <mmenzyns at redhat.com> wrote:
> >
> > Optimizations for 0/n, 1/n and 0%n.
> > No changes in shader db tests, because it is never used here, but it
> > should become handy.
> >
> > Signed-off-by: Mark Menzynski <mmenzyns at redhat.com>
> > ---
> >  .../nouveau/codegen/nv50_ir_peephole.cpp      | 30 +++++++++++++++++--
> >  1 file changed, 28 insertions(+), 2 deletions(-)
> >
> > diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> > index 0b3220903b9..12069e19808 100644
> > --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> > +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> > @@ -1177,10 +1177,28 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue &imm0, int s)
> >        break;
> >
> >     case OP_DIV:
> > -      if (s != 1 || (i->dType != TYPE_S32 && i->dType != TYPE_U32))
> > +      if (i->dType != TYPE_S32 && i->dType != TYPE_U32)
> >           break;
> > +
> >        bld.setPosition(i, false);
> > -      if (imm0.reg.data.u32 == 0) {
> > +      if (s == 0) {
> > +         if (imm0.reg.data.u32 == 0) {
> > +            i->op = OP_MOV;
> > +            i->setSrc(1, NULL);
> > +         }
> > +         else if (imm0.reg.data.u32 == 1) {
> > +            Value *tA, *tB;
> > +            Instruction *slct;
> > +
> > +            tA = bld.mkOp1v(OP_ABS, TYPE_U32, bld.getSSA(), i->getSrc(1));
> > +            tB = bld.mkOp2v(OP_ADD, TYPE_S32, bld.getSSA(), tA, bld.loadImm(NULL, -1));
> > +            slct = bld.mkCmp(OP_SLCT, CC_GT, i->dType, bld.getSSA(), TYPE_U32, bld.loadImm(NULL, 0), i->getSrc(1), tB);
> > +            i->def(0).replace(slct->getDef(0), false);
> > +         }
> > +         break;
> > +      }
> > +
> > +      if (s != 1 || imm0.reg.data.u32 == 0) {
> >           break;
> >        } else
> >        if (imm0.reg.data.u32 == 1) {
> > @@ -1259,6 +1277,14 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue &imm0, int s)
> >        break;
> >
> >     case OP_MOD:
> > +      if (s == 0) {
> > +         if (imm0.reg.data.u32 == 0) {
> > +            i->op = OP_MOV;
> > +            i->setSrc(1, NULL);
> > +         }
> > +         break;
> > +      }
> > +
> >        if (s == 1 && imm0.isPow2()) {
> >           bld.setPosition(i, false);
> >           if (i->sType == TYPE_U32) {
> > --
> > 2.21.0
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-dev