txf supplies an lod, but tg4's is implicitly always 0.
On Thu, May 30, 2019 at 2:26 PM Bas Nieuwenhuizen
<b...@basnieuwenhuizen.nl> wrote:
>
> On Thu, May 30, 2019 at 6:50 PM Rhys Perry <pendingchao...@gmail.com> wrote:
> >
> > Otherwise LLVM can sink them and their texture coordinate calculations
> > into divergent branches.
> >
> > Cc: <mesa-sta...@lists.freedesktop.org>
> > Signed-off-by: Rhys Perry <pendingchao...@gmail.com>
> > ---
> > src/amd/common/ac_nir_to_llvm.c | 29 +++++++++++++++++++++++++++++
> > 1 file changed, 29 insertions(+)
> >
> > diff --git a/src/amd/common/ac_nir_to_llvm.c
> > b/src/amd/common/ac_nir_to_llvm.c
> > index 265e3b636c4..d2dc617de36 100644
> > --- a/src/amd/common/ac_nir_to_llvm.c
> > +++ b/src/amd/common/ac_nir_to_llvm.c
> > @@ -1316,6 +1316,30 @@ static nir_deref_instr *get_tex_texture_deref(const
> > nir_tex_instr *instr)
> > return texture_deref_instr;
> > }
> >
> > +static bool has_implicit_derivatives(const nir_tex_instr *instr)
> > +{
> > + switch (instr->op) {
> > + case nir_texop_txs:
> > + case nir_texop_query_levels:
> > + case nir_texop_texture_samples:
> > + case nir_texop_samples_identical:
> > + return false;
> > + default:
> > + break;
> > + }
> > + for (unsigned i = 0; i < instr->num_srcs; i++) {
> > + switch (instr->src[i].src_type) {
> > + case nir_tex_src_lod:
> > + case nir_tex_src_ddx:
> > + case nir_tex_src_ddy:
> > + return false;
> > + default:
> > + break;
> > + }
> > + }
> > + return true;
> > +}
>
> txf, tg4 and friends do not provide any of lod/ddx/ddy do they?
>
> > +
> > static LLVMValueRef build_tex_intrinsic(struct ac_nir_context *ctx,
> > const nir_tex_instr *instr,
> > struct ac_image_args *args)
> > @@ -1394,6 +1418,11 @@ static LLVMValueRef build_tex_intrinsic(struct
> > ac_nir_context *ctx,
> > }
> >
> > args->attributes = AC_FUNC_ATTR_READNONE;
> > + /* Prevent texture instructions with implicit derivatives from being
> > + * sinked into branches. */
> > + if (has_implicit_derivatives(instr))
> > + args->attributes |= AC_FUNC_ATTR_CONVERGENT;
> > +
> > return ac_build_image_opcode(&ctx->ac, args);
> > }
> >
> > --
> > 2.21.0
> >
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