[Mesa-dev] [PATCH 2/2] nir: add pass to lower atomic counters to SSBO

Jose Fonseca jfonseca at vmware.com
Fri May 5 15:27:58 UTC 2017


On 05/05/17 12:07, Rob Clark wrote:
> On Fri, May 5, 2017 at 4:22 AM, Andres Gomez <agomez at igalia.com> wrote:
>> Rob, I believe this is causing a linking failure in the Windows scons
>> build:
>> https://ci.appveyor.com/project/AndresGomez/mesa/build/321
>>
>>    Creating library build\windows-x86-debug\gallium\targets\osmesa\osmesa.lib and object build\windows-x86-debug\gallium\targets\osmesa\osmesa.exp
>> nir.lib(nir_lower_atomics_to_ssbo.obj) : error LNK2019: unresolved external symbol _snprintf referenced in function _nir_lower_atomics_to_ssbo
>>
>
> hmm, bleh.. is snprintf() not a thing on windows?

I no longer recall the details, but MSVC provides `_foo` instead of 
`foo` for lot's of "unsafe" string manipulation functions.  It provides 
"foo_s" safe alternatives.

Maybe for our puposes plain old snprintf is good enough.  But when one 
is doing manipulation of unsafe string data it requires a lot of typing 
to get old C string functions to do safe things (like ensureing strings 
are zero terminated always ,etc).  So one is really better not using 
snprintf for those things.

 > Looks like nir_print.c does:
>
> #if defined(_WIN32) && !defined(snprintf)
> #define snprintf _snprintf
> #endif
>
> I guess we could just move that into nir.h?
>
> BR,

Sounds good to me.  At some point, it might be better to put this 
definition in a mesa/include/*.h header, but centralizing in nir sounds 
simple enough for now.

Jose

> -R
>
>> Br.
>>
>> On Mon, 2017-04-24 at 11:28 -0400, Rob Clark wrote:
>>> This is equivalent to what mesa/st does in glsl_to_tgsi.  For most hw
>>> there isn't a particularly good reason to treat these differently.
>>>
>>> Signed-off-by: Rob Clark <robdclark at gmail.com>
>>> ---
>>> v2: do the interface_type thing properly
>>>
>>>  src/compiler/Makefile.sources                |   1 +
>>>  src/compiler/nir/nir.h                       |   1 +
>>>  src/compiler/nir/nir_lower_atomics_to_ssbo.c | 222 +++++++++++++++++++++++++++
>>>  3 files changed, 224 insertions(+)
>>>  create mode 100644 src/compiler/nir/nir_lower_atomics_to_ssbo.c
>>>
>>> diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
>>> index 2455d4e..b2a3a42 100644
>>> --- a/src/compiler/Makefile.sources
>>> +++ b/src/compiler/Makefile.sources
>>> @@ -208,6 +208,7 @@ NIR_FILES = \
>>>       nir/nir_lower_64bit_packing.c \
>>>       nir/nir_lower_alu_to_scalar.c \
>>>       nir/nir_lower_atomics.c \
>>> +     nir/nir_lower_atomics_to_ssbo.c \
>>>       nir/nir_lower_bitmap.c \
>>>       nir/nir_lower_clamp_color_outputs.c \
>>>       nir/nir_lower_clip.c \
>>> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
>>> index ce5b434..be35930 100644
>>> --- a/src/compiler/nir/nir.h
>>> +++ b/src/compiler/nir/nir.h
>>> @@ -2546,6 +2546,7 @@ void nir_lower_bitmap(nir_shader *shader, const nir_lower_bitmap_options *option
>>>
>>>  bool nir_lower_atomics(nir_shader *shader,
>>>                         const struct gl_shader_program *shader_program);
>>> +bool nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset);
>>>  bool nir_lower_to_source_mods(nir_shader *shader);
>>>
>>>  bool nir_lower_gs_intrinsics(nir_shader *shader);
>>> diff --git a/src/compiler/nir/nir_lower_atomics_to_ssbo.c b/src/compiler/nir/nir_lower_atomics_to_ssbo.c
>>> new file mode 100644
>>> index 0000000..2c04485
>>> --- /dev/null
>>> +++ b/src/compiler/nir/nir_lower_atomics_to_ssbo.c
>>> @@ -0,0 +1,222 @@
>>> +/*
>>> + * Copyright © 2017 Red Hat
>>> + *
>>> + * Permission is hereby granted, free of charge, to any person obtaining a
>>> + * copy of this software and associated documentation files (the "Software"),
>>> + * to deal in the Software without restriction, including without limitation
>>> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
>>> + * and/or sell copies of the Software, and to permit persons to whom the
>>> + * Software is furnished to do so, subject to the following conditions:
>>> + *
>>> + * The above copyright notice and this permission notice (including the next
>>> + * paragraph) shall be included in all copies or substantial portions of the
>>> + * Software.
>>> + *
>>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
>>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
>>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
>>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
>>> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
>>> + * IN THE SOFTWARE.
>>> + *
>>> + * Authors:
>>> + *    Rob Clark <robclark at freedesktop.org>
>>> + */
>>> +
>>> +#include "nir.h"
>>> +#include "nir_builder.h"
>>> +
>>> +/*
>>> + * Remap atomic counters to SSBOs.  Atomic counters get remapped to
>>> + * SSBO binding points [0..ssbo_offset) and the original SSBOs are
>>> + * remapped to [ssbo_offset..n) (mostly to align with what mesa/st
>>> + * does.
>>> + */
>>> +
>>> +static bool
>>> +lower_instr(nir_intrinsic_instr *instr, unsigned ssbo_offset, nir_builder *b)
>>> +{
>>> +   nir_intrinsic_op op;
>>> +   switch (instr->intrinsic) {
>>> +   case nir_intrinsic_ssbo_atomic_add:
>>> +   case nir_intrinsic_ssbo_atomic_imin:
>>> +   case nir_intrinsic_ssbo_atomic_umin:
>>> +   case nir_intrinsic_ssbo_atomic_imax:
>>> +   case nir_intrinsic_ssbo_atomic_umax:
>>> +   case nir_intrinsic_ssbo_atomic_and:
>>> +   case nir_intrinsic_ssbo_atomic_or:
>>> +   case nir_intrinsic_ssbo_atomic_xor:
>>> +   case nir_intrinsic_ssbo_atomic_exchange:
>>> +   case nir_intrinsic_ssbo_atomic_comp_swap:
>>> +   case nir_intrinsic_store_ssbo:
>>> +   case nir_intrinsic_load_ssbo:
>>> +      /* keep same opcode, remap buffer_index */
>>> +      op = instr->intrinsic;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_inc:
>>> +   case nir_intrinsic_atomic_counter_add:
>>> +   case nir_intrinsic_atomic_counter_dec:
>>> +      /* inc and dec get remapped to add: */
>>> +      op = nir_intrinsic_ssbo_atomic_add;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_read:
>>> +      op = nir_intrinsic_load_ssbo;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_min:
>>> +      op = nir_intrinsic_ssbo_atomic_umin;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_max:
>>> +      op = nir_intrinsic_ssbo_atomic_umax;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_and:
>>> +      op = nir_intrinsic_ssbo_atomic_and;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_or:
>>> +      op = nir_intrinsic_ssbo_atomic_or;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_xor:
>>> +      op = nir_intrinsic_ssbo_atomic_xor;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_exchange:
>>> +      op = nir_intrinsic_ssbo_atomic_exchange;
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_comp_swap:
>>> +      op = nir_intrinsic_ssbo_atomic_comp_swap;
>>> +      break;
>>> +   default:
>>> +      return false;
>>> +   }
>>> +
>>> +   b->cursor = nir_before_instr(&instr->instr);
>>> +
>>> +   /* easy case, just remap SSBO buffer index: */
>>> +   if (op == instr->intrinsic) {
>>> +      unsigned srcn = (op == nir_intrinsic_store_ssbo) ? 1 : 0;
>>> +      nir_ssa_def *old_idx = nir_ssa_for_src(b, instr->src[srcn], 1);
>>> +      nir_ssa_def *new_idx = nir_iadd(b, old_idx, nir_imm_int(b, ssbo_offset));
>>> +      nir_instr_rewrite_src(&instr->instr,
>>> +                            &instr->src[srcn],
>>> +                            nir_src_for_ssa(new_idx));
>>> +
>>> +      return true;
>>> +   }
>>> +
>>> +   nir_ssa_def *buffer = nir_imm_int(b, nir_intrinsic_base(instr));
>>> +   nir_ssa_def *temp = NULL;
>>> +   nir_intrinsic_instr *new_instr =
>>> +         nir_intrinsic_instr_create(ralloc_parent(instr), op);
>>> +
>>> +   /* a couple instructions need special handling since they don't map
>>> +    * 1:1 with ssbo atomics
>>> +    */
>>> +   switch (instr->intrinsic) {
>>> +   case nir_intrinsic_atomic_counter_inc:
>>> +      /* remapped to ssbo_atomic_add: { buffer_idx, offset, +1 } */
>>> +      temp = nir_imm_int(b, +1);
>>> +      new_instr->src[0] = nir_src_for_ssa(buffer);
>>> +      new_instr->src[1] = instr->src[0];
>>> +      new_instr->src[2] = nir_src_for_ssa(temp);
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_dec:
>>> +      /* remapped to ssbo_atomic_add: { buffer_idx, offset, -1 } */
>>> +      /* NOTE semantic difference so we adjust the return value below */
>>> +      temp = nir_imm_int(b, -1);
>>> +      new_instr->src[0] = nir_src_for_ssa(buffer);
>>> +      new_instr->src[1] = instr->src[0];
>>> +      new_instr->src[2] = nir_src_for_ssa(temp);
>>> +      break;
>>> +   case nir_intrinsic_atomic_counter_read:
>>> +      /* remapped to load_ssbo: { buffer_idx, offset } */
>>> +      new_instr->src[0] = nir_src_for_ssa(buffer);
>>> +      new_instr->src[1] = instr->src[0];
>>> +      break;
>>> +   default:
>>> +      /* remapped to ssbo_atomic_x: { buffer_idx, offset, data, (compare)? } */
>>> +      new_instr->src[0] = nir_src_for_ssa(buffer);
>>> +      new_instr->src[1] = instr->src[0];
>>> +      new_instr->src[2] = instr->src[1];
>>> +      if (op == nir_intrinsic_ssbo_atomic_comp_swap)
>>> +         new_instr->src[3] = instr->src[2];
>>> +      break;
>>> +   }
>>> +
>>> +   nir_ssa_dest_init(&new_instr->instr, &new_instr->dest,
>>> +                     instr->dest.ssa.num_components,
>>> +                     instr->dest.ssa.bit_size, NULL);
>>> +   nir_instr_insert_before(&instr->instr, &new_instr->instr);
>>> +   nir_instr_remove(&instr->instr);
>>> +
>>> +   if (instr->intrinsic == nir_intrinsic_atomic_counter_dec) {
>>> +      b->cursor = nir_after_instr(&new_instr->instr);
>>> +      nir_ssa_def *result = nir_iadd(b, &new_instr->dest.ssa, temp);
>>> +      nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(result));
>>> +   } else {
>>> +      nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&new_instr->dest.ssa));
>>> +   }
>>> +
>>> +   return true;
>>> +}
>>> +
>>> +bool
>>> +nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset)
>>> +{
>>> +   bool progress = false;
>>> +
>>> +   nir_foreach_function(function, shader) {
>>> +      if (function->impl) {
>>> +         nir_builder builder;
>>> +         nir_builder_init(&builder, function->impl);
>>> +         nir_foreach_block(block, function->impl) {
>>> +            nir_foreach_instr_safe(instr, block) {
>>> +               if (instr->type == nir_instr_type_intrinsic)
>>> +                  progress |= lower_instr(nir_instr_as_intrinsic(instr),
>>> +                                          ssbo_offset, &builder);
>>> +            }
>>> +         }
>>> +
>>> +         nir_metadata_preserve(function->impl, nir_metadata_block_index |
>>> +                                               nir_metadata_dominance);
>>> +      }
>>> +   }
>>> +
>>> +   if (progress) {
>>> +      /* replace atomic_uint uniforms with ssbo's: */
>>> +      unsigned replaced = 0;
>>> +      nir_foreach_variable_safe(var, &shader->uniforms) {
>>> +         if (glsl_get_base_type(var->type) == GLSL_TYPE_ATOMIC_UINT) {
>>> +            exec_node_remove(&var->node);
>>> +
>>> +            if (replaced & (1 << var->data.binding))
>>> +               continue;
>>> +
>>> +            nir_variable *ssbo;
>>> +            char name[16];
>>> +
>>> +            /* A length of 0 is used to denote unsized arrays */
>>> +            const struct glsl_type *type = glsl_array_type(glsl_uint_type(), 0);
>>> +
>>> +            snprintf(name, sizeof(name), "counter%d", var->data.binding);
>>> +
>>> +            ssbo = nir_variable_create(shader, nir_var_shader_storage,
>>> +                                       type, name);
>>> +            ssbo->data.binding = var->data.binding;
>>> +
>>> +            struct glsl_struct_field field = {
>>> +                  .type = type,
>>> +                  .name = "counters",
>>> +                  .location = -1,
>>> +            };
>>> +
>>> +            ssbo->interface_type =
>>> +                  glsl_interface_type(&field, 1, GLSL_INTERFACE_PACKING_STD430,
>>> +                                      false, "counters");
>>> +
>>> +            replaced |= (1 << var->data.binding);
>>> +         }
>>> +      }
>>> +   }
>>> +
>>> +   return progress;
>>> +}
>>> +
>> --
>> Br,
>>
>> Andres



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