[Mesa-stable] [PATCH] ac/nir: Add workaround for GFX9 buffer views.

Bas Nieuwenhuizen bas at basnieuwenhuizen.nl
Wed Apr 11 23:55:22 UTC 2018


On Thu, Apr 12, 2018 at 1:22 AM, Mark Janes <mark.a.janes at intel.com> wrote:
> I apologize about my lack of communication on this one.  I noticed right
> away that Bas's commit wouldn't apply cleanly, and let him know about
> it.  It was the first time my robo-cherry-picker identified a problem
> with a commit.
>
> Bas sent his backport to the list, but I'm noticing now that the
> backport didn't cc mesa-stable, so you would not have seen it.

Yeah, that was my fault too, I usually use the Fixes tag, but that
doesn't help of course when the backport does not get committed.

My bigger concern was that the upstream patch had a Fixes tag pointing
to a pre-17.3 commit and was committed 2 weeks ago, and I got the
impression that if the backport had not been CC'd to mesa-stable, it
would be silently ignored with pretty much no recourse to fix with the
release pre-announcement being after the cooking from the release
manager.

i.e. it all ended well this time (thanks Mark!), but I'm worried about
patches being silently ignored going forward.

>
> -Mark
>
> "Juan A. Suarez Romero" <jasuarez at igalia.com> writes:
>
>> On Wed, 2018-04-11 at 18:26 +0200, Bas Nieuwenhuizen wrote:
>>> On Wed, Apr 11, 2018 at 6:23 PM, Juan A. Suarez Romero
>>> <jasuarez at igalia.com> wrote:
>>> > On Wed, 2018-04-11 at 16:48 +0200, Bas Nieuwenhuizen wrote:
>>> > > On Wed, Apr 11, 2018 at 4:25 PM, Juan A. Suarez Romero
>>> > > <jasuarez at igalia.com> wrote:
>>> > > > Hi, Bas.
>>> > > >
>>> > > > Unfortunately, I can't apply this patch neither in next 17.3 release stable, nor
>>> > > > in 18.0, as this patch does not apply cleanly, and it requires other different
>>> > > > commits that didn't land in the stable branches.
>>> > >
>>> > > This backport (https://patchwork.freedesktop.org/patch/214949/)
>>> > > applies cleanly on 17.3 for me.
>>> > >
>>> >
>>> > Thanks for the patch!
>>> >
>>> > I managed to backport this also to 18.0, so I'll include it.
>>> >
>>> > > >
>>> > > >
>>> > > > For 17.3 I think it is probably not worth to try to provide a specific version
>>> > > > for the stable, as I'm already cooking the pre-release, and this is the latest
>>> > > > release for 17.3 series.
>>> > >
>>> > > Can we please get this in 17.3? This has been submitted upstream
>>> > > laready for 2 weeks and this backport has been available for a week
>>> > > and fixes one of the major games from Feral on Vega:
>>> > >
>>> >
>>> > Sure. I included this patch for next 17.3. release.
>>> >
>>> > Just said it was not worth because I thought it would take more time to get a
>>> > backport.
>>> >
>>> >
>>> > > commit 4503ff760c794c3bb15b978a47c530037d56498e (dow3)
>>> > > Author: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
>>> > > Date:   Wed Mar 28 23:54:40 2018 +0200
>>> > >
>>> > > Why did I not get a message that that commit could not be applied?
>>> > >
>>> >
>>> > I got the email for nominating this patch for stable today, so I couldn't reply
>>> > before.
>>>
>>> That was the backport. I'd expect the Fixes tag to be nominating the
>>> upstream patch?
>>>
>>
>> Correct. The fixes also nominates, but I couldn't check them before. So
>> apologies for inconveniences.
>>
>>       J.A.
>>
>>> >
>>> > > >
>>> > > >
>>> > > > Maybe it is worth to provide a version for 18.0 branch, though. Probably it
>>> > > > wouldn't enter in this release, but surely in the next one which should happen
>>> > > > in 1 or 2 weeks.
>>> > > >
>>> > > >
>>> > > > For more information, for 18.0 this patch seems to require 1251f08ef ("ac: add
>>> > > > ac_build_buffer_load_common() helper"), bac9fa9f17f ("ac: add glc parameter to
>>> > > > ac_build_buffer_load_format"), and probably others.
>>> > > >
>>> > > >
>>> > > >         J.A.
>>> > > >
>>> > > >
>>> > > > On Wed, 2018-04-11 at 11:26 +0200, Bas Nieuwenhuizen wrote:
>>> > > > > On Wed, Apr 4, 2018 at 10:19 PM, Bas Nieuwenhuizen
>>> > > > > <bas at basnieuwenhuizen.nl> wrote:
>>> > > > > > On GFX9 whether the buffer size is interpreted as elements or bytes
>>> > > > > > depends on whether IDXEN is enabled in the instruction. If the index
>>> > > > > > is a constant zero, LLVM optimizes IDXEN to 0.
>>> > > > > >
>>> > > > > > Now the size in elements is interpreted in bytes which of course
>>> > > > > > results in out of bounds accesses.
>>> > > > > >
>>> > > > > > The correct fix is most likely to disable the LLVM optimization,
>>> > > > > > but we need something to work with LLVM <= 6.0.
>>> > > > > >
>>> > > > > > radeonsi does the max between stride and element count on the CPU
>>> > > > > > but that results in the size intrinsics returning the wrong size
>>> > > > > > for the buffer. This would cause CTS errors for radv.
>>> > > > > >
>>> > > > > > v2: Also include the store changes.
>>> > > > > >
>>> > > > > > Fixes: e38685cc62e 'Revert "radv: disable support for VEGA for now."'
>>> > > > > > (backported from 4503ff760c794c3bb15b978a47c530037d56498e for 17.3)
>>> > > > > > ---
>>> > > > > >  src/amd/common/ac_llvm_build.c  | 20 ++++++++++++++++++++
>>> > > > > >  src/amd/common/ac_llvm_build.h  |  8 ++++++++
>>> > > > > >  src/amd/common/ac_nir_to_llvm.c | 36 ++++++++++++++++++++++++++++++------
>>> > > > > >  src/amd/common/ac_shader_abi.h  |  4 ++++
>>> > > > > >  4 files changed, 62 insertions(+), 6 deletions(-)
>>> > > > > >
>>> > > > > > diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
>>> > > > > > index e5cd23e025..f193f71c3e 100644
>>> > > > > > --- a/src/amd/common/ac_llvm_build.c
>>> > > > > > +++ b/src/amd/common/ac_llvm_build.c
>>> > > > > > @@ -960,6 +960,26 @@ LLVMValueRef ac_build_buffer_load_format(struct ac_llvm_context *ctx,
>>> > > > > >                                           AC_FUNC_ATTR_READONLY);
>>> > > > > >  }
>>> > > > > >
>>> > > > > > +LLVMValueRef ac_build_buffer_load_format_gfx9_safe(struct ac_llvm_context *ctx,
>>> > > > > > +                                                  LLVMValueRef rsrc,
>>> > > > > > +                                                  LLVMValueRef vindex,
>>> > > > > > +                                                  LLVMValueRef voffset,
>>> > > > > > +                                                  bool can_speculate)
>>> > > > > > +{
>>> > > > > > +       LLVMValueRef elem_count = LLVMBuildExtractElement(ctx->builder, rsrc, LLVMConstInt(ctx->i32, 2, 0), "");
>>> > > > > > +       LLVMValueRef stride = LLVMBuildExtractElement(ctx->builder, rsrc, LLVMConstInt(ctx->i32, 1, 0), "");
>>> > > > > > +       stride = LLVMBuildLShr(ctx->builder, stride, LLVMConstInt(ctx->i32, 16, 0), "");
>>> > > > > > +
>>> > > > > > +       LLVMValueRef new_elem_count = LLVMBuildSelect(ctx->builder,
>>> > > > > > +                                                     LLVMBuildICmp(ctx->builder, LLVMIntUGT, elem_count, stride, ""),
>>> > > > > > +                                                     elem_count, stride, "");
>>> > > > > > +
>>> > > > > > +       LLVMValueRef new_rsrc = LLVMBuildInsertElement(ctx->builder, rsrc, new_elem_count,
>>> > > > > > +                                                      LLVMConstInt(ctx->i32, 2, 0), "");
>>> > > > > > +
>>> > > > > > +       return ac_build_buffer_load_format(ctx, new_rsrc, vindex, voffset, can_speculate);
>>> > > > > > +}
>>> > > > > > +
>>> > > > > >  /**
>>> > > > > >   * Set range metadata on an instruction.  This can only be used on load and
>>> > > > > >   * call instructions.  If you know an instruction can only produce the values
>>> > > > > > diff --git a/src/amd/common/ac_llvm_build.h b/src/amd/common/ac_llvm_build.h
>>> > > > > > index aa2a2899ab..d4264f2879 100644
>>> > > > > > --- a/src/amd/common/ac_llvm_build.h
>>> > > > > > +++ b/src/amd/common/ac_llvm_build.h
>>> > > > > > @@ -188,6 +188,14 @@ LLVMValueRef ac_build_buffer_load_format(struct ac_llvm_context *ctx,
>>> > > > > >                                          LLVMValueRef voffset,
>>> > > > > >                                          bool can_speculate);
>>> > > > > >
>>> > > > > > +/* load_format that handles the stride & element count better if idxen is
>>> > > > > > + * disabled by LLVM. */
>>> > > > > > +LLVMValueRef ac_build_buffer_load_format_gfx9_safe(struct ac_llvm_context *ctx,
>>> > > > > > +                                                  LLVMValueRef rsrc,
>>> > > > > > +                                                  LLVMValueRef vindex,
>>> > > > > > +                                                  LLVMValueRef voffset,
>>> > > > > > +                                                  bool can_speculate);
>>> > > > > > +
>>> > > > > >  LLVMValueRef
>>> > > > > >  ac_get_thread_id(struct ac_llvm_context *ctx);
>>> > > > > >
>>> > > > > > diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
>>> > > > > > index b696cb8a45..8ee80b1a67 100644
>>> > > > > > --- a/src/amd/common/ac_nir_to_llvm.c
>>> > > > > > +++ b/src/amd/common/ac_nir_to_llvm.c
>>> > > > > > @@ -2257,11 +2257,19 @@ static LLVMValueRef build_tex_intrinsic(struct ac_nir_context *ctx,
>>> > > > > >                                         struct ac_image_args *args)
>>> > > > > >  {
>>> > > > > >         if (instr->sampler_dim == GLSL_SAMPLER_DIM_BUF) {
>>> > > > > > -               return ac_build_buffer_load_format(&ctx->ac,
>>> > > > > > -                                                  args->resource,
>>> > > > > > -                                                  args->addr,
>>> > > > > > -                                                  LLVMConstInt(ctx->ac.i32, 0, false),
>>> > > > > > -                                                  true);
>>> > > > > > +               if (ctx->abi->gfx9_stride_size_workaround) {
>>> > > > > > +                       return ac_build_buffer_load_format_gfx9_safe(&ctx->ac,
>>> > > > > > +                                                                    args->resource,
>>> > > > > > +                                                                    args->addr,
>>> > > > > > +                                                                    ctx->ac.i32_0,
>>> > > > > > +                                                                    true);
>>> > > > > > +               } else {
>>> > > > > > +                       return ac_build_buffer_load_format(&ctx->ac,
>>> > > > > > +                                                          args->resource,
>>> > > > > > +                                                          args->addr,
>>> > > > > > +                                                          ctx->ac.i32_0,
>>> > > > > > +                                                          true);
>>> > > > > > +               }
>>> > > > > >         }
>>> > > > > >
>>> > > > > >         args->opcode = ac_image_sample;
>>> > > > > > @@ -3613,8 +3621,23 @@ static void visit_image_store(struct ac_nir_context *ctx,
>>> > > > > >                 glc = i1true;
>>> > > > > >
>>> > > > > >         if (glsl_get_sampler_dim(type) == GLSL_SAMPLER_DIM_BUF) {
>>> > > > > > +               LLVMValueRef rsrc = get_sampler_desc(ctx, instr->variables[0], AC_DESC_BUFFER, true, true);
>>> > > > > > +
>>> > > > > > +               if (ctx->abi->gfx9_stride_size_workaround) {
>>> > > > > > +                       LLVMValueRef elem_count = LLVMBuildExtractElement(ctx->ac.builder, rsrc, LLVMConstInt(ctx->ac.i32, 2, 0), "");
>>> > > > > > +                       LLVMValueRef stride = LLVMBuildExtractElement(ctx->ac.builder, rsrc, LLVMConstInt(ctx->ac.i32, 1, 0), "");
>>> > > > > > +                       stride = LLVMBuildLShr(ctx->ac.builder, stride, LLVMConstInt(ctx->ac.i32, 16, 0), "");
>>> > > > > > +
>>> > > > > > +                       LLVMValueRef new_elem_count = LLVMBuildSelect(ctx->ac.builder,
>>> > > > > > +                                                                     LLVMBuildICmp(ctx->ac.builder, LLVMIntUGT, elem_count, stride, ""),
>>> > > > > > +                                                                     elem_count, stride, "");
>>> > > > > > +
>>> > > > > > +                       rsrc = LLVMBuildInsertElement(ctx->ac.builder, rsrc, new_elem_count,
>>> > > > > > +                                                     LLVMConstInt(ctx->ac.i32, 2, 0), "");
>>> > > > > > +               }
>>> > > > > > +
>>> > > > > >                 params[0] = ac_to_float(&ctx->ac, get_src(ctx, instr->src[2])); /* data */
>>> > > > > > -               params[1] = get_sampler_desc(ctx, instr->variables[0], AC_DESC_BUFFER, true, true);
>>> > > > > > +               params[1] = rsrc;
>>> > > > > >                 params[2] = LLVMBuildExtractElement(ctx->ac.builder, get_src(ctx, instr->src[0]),
>>> > > > > >                                                     ctx->ac.i32_0, ""); /* vindex */
>>> > > > > >                 params[3] = ctx->ac.i32_0; /* voffset */
>>> > > > > > @@ -6645,6 +6668,7 @@ LLVMModuleRef ac_translate_nir_to_llvm(LLVMTargetMachineRef tm,
>>> > > > > >         ctx.abi.load_ssbo = radv_load_ssbo;
>>> > > > > >         ctx.abi.load_sampler_desc = radv_get_sampler_desc;
>>> > > > > >         ctx.abi.clamp_shadow_reference = false;
>>> > > > > > +       ctx.abi.gfx9_stride_size_workaround = ctx.ac.chip_class == GFX9;
>>> > > > > >
>>> > > > > >         if (shader_count >= 2)
>>> > > > > >                 ac_init_exec_full_mask(&ctx.ac);
>>> > > > > > diff --git a/src/amd/common/ac_shader_abi.h b/src/amd/common/ac_shader_abi.h
>>> > > > > > index 14517d5570..b04dc076de 100644
>>> > > > > > --- a/src/amd/common/ac_shader_abi.h
>>> > > > > > +++ b/src/amd/common/ac_shader_abi.h
>>> > > > > > @@ -92,6 +92,10 @@ struct ac_shader_abi {
>>> > > > > >         /* Whether to clamp the shadow reference value to [0,1]on VI. Radeonsi currently
>>> > > > > >          * uses it due to promoting D16 to D32, but radv needs it off. */
>>> > > > > >         bool clamp_shadow_reference;
>>> > > > > > +
>>> > > > > > +       /* Whether to workaround GFX9 ignoring the stride for the buffer size if IDXEN=0
>>> > > > > > +        * and LLVM optimizes an indexed load with constant index to IDXEN=0. */
>>> > > > > > +       bool gfx9_stride_size_workaround;
>>> > > > > >  };
>>> > > > > >
>>> > > > > >  #endif /* AC_SHADER_ABI_H */
>>> > > > > > --
>>> > > > > > 2.16.2
>>> > > > > >
>>> > > > >
>>> > > > > _______________________________________________
>>> > > > > mesa-stable mailing list
>>> > > > > mesa-stable at lists.freedesktop.org
>>> > > > > https://lists.freedesktop.org/mailman/listinfo/mesa-stable
>>> > >
>>> > > _______________________________________________
>>> > > mesa-stable mailing list
>>> > > mesa-stable at lists.freedesktop.org
>>> > > https://lists.freedesktop.org/mailman/listinfo/mesa-stable
>>>
>>>
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