src/broadcom/compiler/v3d_nir_lower_image_load_store.c - third_party/mesa - Git at Google

 /*
  * Copyright © 2018 Intel Corporation
  * Copyright © 2018 Broadcom
  *
  * 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.
  */

 #include "v3d_compiler.h"
 #include "compiler/nir/nir_builder.h"
 #include "compiler/nir/nir_format_convert.h"

 /** @file v3d_nir_lower_image_load_store.c
  *
  * Performs any necessary lowering of GL_ARB_shader_image_load_store
  * operations.
  *
  * On V3D 4.x, we just need to do format conversion for stores such that the
  * GPU can effectively memcpy the arguments (in increments of 32-bit words)
  * into the texel.  Loads are the same as texturing, where we may need to
  * unpack from 16-bit ints or floats.
  *
  * On V3D 3.x, to implement image load store we would need to do manual tiling
  * calculations and load/store using the TMU general memory access path.
  */

 bool
 v3d_gl_format_is_return_32(GLenum format)
 {
         switch (format) {
         case GL_R8:
         case GL_R8_SNORM:
         case GL_R8UI:
         case GL_R8I:
         case GL_RG8:
         case GL_RG8_SNORM:
         case GL_RG8UI:
         case GL_RG8I:
         case GL_RGBA8:
         case GL_RGBA8_SNORM:
         case GL_RGBA8UI:
         case GL_RGBA8I:
         case GL_R11F_G11F_B10F:
         case GL_RGB10_A2:
         case GL_RGB10_A2UI:
         case GL_R16F:
         case GL_R16UI:
         case GL_R16I:
         case GL_RG16F:
         case GL_RG16UI:
         case GL_RG16I:
         case GL_RGBA16F:
         case GL_RGBA16UI:
         case GL_RGBA16I:
                 return false;
         case GL_R16:
         case GL_R16_SNORM:
         case GL_RG16:
         case GL_RG16_SNORM:
         case GL_RGBA16:
         case GL_RGBA16_SNORM:
         case GL_R32F:
         case GL_R32UI:
         case GL_R32I:
         case GL_RG32F:
         case GL_RG32UI:
         case GL_RG32I:
         case GL_RGBA32F:
         case GL_RGBA32UI:
         case GL_RGBA32I:
                 return true;
         default:
                 unreachable("Invalid image format");
         }
 }

 /* Packs a 32-bit vector of colors in the range [0, (1 << bits[i]) - 1] to a
  * 32-bit SSA value, with as many channels as necessary to store all the bits
  */
 static nir_ssa_def *
 pack_bits(nir_builder *b, nir_ssa_def *color, const unsigned *bits,
           int num_components, bool mask)
 {
         nir_ssa_def *results[4];
         int offset = 0;
         for (int i = 0; i < num_components; i++) {
                 nir_ssa_def *chan = nir_channel(b, color, i);

                 /* Channels being stored shouldn't cross a 32-bit boundary. */
                 assert((offset & ~31) == ((offset + bits[i] - 1) & ~31));

                 if (mask) {
                         chan = nir_iand(b, chan,
                                         nir_imm_int(b, (1 << bits[i]) - 1));
                 }

                 if (offset % 32 == 0) {
                         results[offset / 32] = chan;
                 } else {
                         results[offset / 32] =
                                 nir_ior(b, results[offset / 32],
                                         nir_ishl(b, chan,
                                                  nir_imm_int(b, offset % 32)));
                 }
                 offset += bits[i];
         }

         return nir_vec(b, results, DIV_ROUND_UP(offset, 32));
 }

 static nir_ssa_def *
 pack_unorm(nir_builder *b, nir_ssa_def *color, const unsigned *bits,
            int num_components)
 {
         color = nir_channels(b, color, (1 << num_components) - 1);
         color = nir_format_float_to_unorm(b, color, bits);
         return pack_bits(b, color, bits, color->num_components, false);
 }

 static nir_ssa_def *
 pack_snorm(nir_builder *b, nir_ssa_def *color, const unsigned *bits,
            int num_components)
 {
         color = nir_channels(b, color, (1 << num_components) - 1);
         color = nir_format_float_to_snorm(b, color, bits);
         return pack_bits(b, color, bits, color->num_components, true);
 }

 static nir_ssa_def *
 pack_uint(nir_builder *b, nir_ssa_def *color, const unsigned *bits,
           int num_components)
 {
         color = nir_channels(b, color, (1 << num_components) - 1);
         color = nir_format_clamp_uint(b, color, bits);
         return pack_bits(b, color, bits, num_components, false);
 }

 static nir_ssa_def *
 pack_sint(nir_builder *b, nir_ssa_def *color, const unsigned *bits,
           int num_components)
 {
         color = nir_channels(b, color, (1 << num_components) - 1);
         color = nir_format_clamp_sint(b, color, bits);
         return pack_bits(b, color, bits, num_components, true);
 }

 static nir_ssa_def *
 pack_half(nir_builder *b, nir_ssa_def *color, const unsigned *bits,
           int num_components)
 {
         color = nir_channels(b, color, (1 << num_components) - 1);
         color = nir_format_float_to_half(b, color);
         return pack_bits(b, color, bits, color->num_components, false);
 }

 static void
 v3d_nir_lower_image_store(nir_builder *b, nir_intrinsic_instr *instr)
 {
         nir_variable *var = nir_intrinsic_get_var(instr, 0);
         GLenum format = var->data.image.format;
         static const unsigned bits_8[4] = {8, 8, 8, 8};
         static const unsigned bits_16[4] = {16, 16, 16, 16};
         static const unsigned bits_1010102[4] = {10, 10, 10, 2};

         b->cursor = nir_before_instr(&instr->instr);

         nir_ssa_def *unformatted = nir_ssa_for_src(b, instr->src[3], 4);
         nir_ssa_def *formatted = NULL;
         switch (format) {
         case GL_RGBA32F:
         case GL_RGBA32UI:
         case GL_RGBA32I:
                 /* For 4-component 32-bit components, there's no packing to be
                  * done.
                  */
                 return;

         case GL_R32F:
         case GL_R32UI:
         case GL_R32I:
                 /* For other 32-bit components, just reduce the size of
                  * the input vector.
                  */
                 formatted = nir_channels(b, unformatted, 1);
                 break;
         case GL_RG32F:
         case GL_RG32UI:
         case GL_RG32I:
                 formatted = nir_channels(b, unformatted, 2);
                 break;

         case GL_R8:
                 formatted = pack_unorm(b, unformatted, bits_8, 1);
                 break;
         case GL_RG8:
                 formatted = pack_unorm(b, unformatted, bits_8, 2);
                 break;
         case GL_RGBA8:
                 formatted = pack_unorm(b, unformatted, bits_8, 4);
                 break;

         case GL_R8_SNORM:
                 formatted = pack_snorm(b, unformatted, bits_8, 1);
                 break;
         case GL_RG8_SNORM:
                 formatted = pack_snorm(b, unformatted, bits_8, 2);
                 break;
         case GL_RGBA8_SNORM:
                 formatted = pack_snorm(b, unformatted, bits_8, 4);
                 break;

         case GL_R16:
                 formatted = pack_unorm(b, unformatted, bits_16, 1);
                 break;
         case GL_RG16:
                 formatted = pack_unorm(b, unformatted, bits_16, 2);
                 break;
         case GL_RGBA16:
                 formatted = pack_unorm(b, unformatted, bits_16, 4);
                 break;

         case GL_R16_SNORM:
                 formatted = pack_snorm(b, unformatted, bits_16, 1);
                 break;
         case GL_RG16_SNORM:
                 formatted = pack_snorm(b, unformatted, bits_16, 2);
                 break;
         case GL_RGBA16_SNORM:
                 formatted = pack_snorm(b, unformatted, bits_16, 4);
                 break;

         case GL_R16F:
                 formatted = pack_half(b, unformatted, bits_16, 1);
                 break;
         case GL_RG16F:
                 formatted = pack_half(b, unformatted, bits_16, 2);
                 break;
         case GL_RGBA16F:
                 formatted = pack_half(b, unformatted, bits_16, 4);
                 break;

         case GL_R8UI:
                 formatted = pack_uint(b, unformatted, bits_8, 1);
                 break;
         case GL_R8I:
                 formatted = pack_sint(b, unformatted, bits_8, 1);
                 break;
         case GL_RG8UI:
                 formatted = pack_uint(b, unformatted, bits_8, 2);
                 break;
         case GL_RG8I:
                 formatted = pack_sint(b, unformatted, bits_8, 2);
                 break;
         case GL_RGBA8UI:
                 formatted = pack_uint(b, unformatted, bits_8, 4);
                 break;
         case GL_RGBA8I:
                 formatted = pack_sint(b, unformatted, bits_8, 4);
                 break;

         case GL_R16UI:
                 formatted = pack_uint(b, unformatted, bits_16, 1);
                 break;
         case GL_R16I:
                 formatted = pack_sint(b, unformatted, bits_16, 1);
                 break;
         case GL_RG16UI:
                 formatted = pack_uint(b, unformatted, bits_16, 2);
                 break;
         case GL_RG16I:
                 formatted = pack_sint(b, unformatted, bits_16, 2);
                 break;
         case GL_RGBA16UI:
                 formatted = pack_uint(b, unformatted, bits_16, 4);
                 break;
         case GL_RGBA16I:
                 formatted = pack_sint(b, unformatted, bits_16, 4);
                 break;

         case GL_R11F_G11F_B10F:
                 formatted = nir_format_pack_11f11f10f(b, unformatted);
                 break;
         case GL_RGB9_E5:
                 formatted = nir_format_pack_r9g9b9e5(b, unformatted);
                 break;

         case GL_RGB10_A2:
                 formatted = pack_unorm(b, unformatted, bits_1010102, 4);
                 break;

         case GL_RGB10_A2UI:
                 formatted = pack_uint(b, unformatted, bits_1010102, 4);
                 break;

         default:
                 unreachable("bad format");
         }

         nir_instr_rewrite_src(&instr->instr, &instr->src[3],
                               nir_src_for_ssa(formatted));
         instr->num_components = formatted->num_components;
 }

 static void
 v3d_nir_lower_image_load(nir_builder *b, nir_intrinsic_instr *instr)
 {
         static const unsigned bits16[] = {16, 16, 16, 16};
         nir_variable *var = nir_intrinsic_get_var(instr, 0);
         const struct glsl_type *sampler_type = glsl_without_array(var->type);
         enum glsl_base_type base_type =
                 glsl_get_sampler_result_type(sampler_type);

         if (v3d_gl_format_is_return_32(var->data.image.format))
                 return;

         b->cursor = nir_after_instr(&instr->instr);

         assert(instr->dest.is_ssa);
         nir_ssa_def *result = &instr->dest.ssa;
         if (base_type == GLSL_TYPE_FLOAT) {
             nir_ssa_def *rg = nir_channel(b, result, 0);
             nir_ssa_def *ba = nir_channel(b, result, 1);
             result = nir_vec4(b,
                               nir_unpack_half_2x16_split_x(b, rg),
                               nir_unpack_half_2x16_split_y(b, rg),
                               nir_unpack_half_2x16_split_x(b, ba),
                               nir_unpack_half_2x16_split_y(b, ba));
         } else if (base_type == GLSL_TYPE_INT) {
                 result = nir_format_unpack_sint(b, result, bits16, 4);
         } else {
                 assert(base_type == GLSL_TYPE_UINT);
                 result = nir_format_unpack_uint(b, result, bits16, 4);
         }

         nir_ssa_def_rewrite_uses_after(&instr->dest.ssa, nir_src_for_ssa(result),
                                        result->parent_instr);
 }

 void
 v3d_nir_lower_image_load_store(nir_shader *s)
 {
         nir_foreach_function(function, s) {
                 if (!function->impl)
                         continue;

                 nir_builder b;
                 nir_builder_init(&b, function->impl);

                 nir_foreach_block(block, function->impl) {
                         nir_foreach_instr_safe(instr, block) {
                                 if (instr->type != nir_instr_type_intrinsic)
                                         continue;

                                 nir_intrinsic_instr *intr =
                                         nir_instr_as_intrinsic(instr);

                                 switch (intr->intrinsic) {
                                 case nir_intrinsic_image_deref_load:
                                         v3d_nir_lower_image_load(&b, intr);
                                         break;
                                 case nir_intrinsic_image_deref_store:
                                         v3d_nir_lower_image_store(&b, intr);
                                         break;
                                 default:
                                         break;
                                 }
                         }
                 }

                 nir_metadata_preserve(function->impl,
                                       nir_metadata_block_index |
                                       nir_metadata_dominance);
         }
 }
	/*
	* Copyright © 2018 Intel Corporation
	* Copyright © 2018 Broadcom
	*
	* 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.
	*/

	#include "v3d_compiler.h"
	#include "compiler/nir/nir_builder.h"
	#include "compiler/nir/nir_format_convert.h"

	/** @file v3d_nir_lower_image_load_store.c
	*
	* Performs any necessary lowering of GL_ARB_shader_image_load_store
	* operations.
	*
	* On V3D 4.x, we just need to do format conversion for stores such that the
	* GPU can effectively memcpy the arguments (in increments of 32-bit words)
	* into the texel. Loads are the same as texturing, where we may need to
	* unpack from 16-bit ints or floats.
	*
	* On V3D 3.x, to implement image load store we would need to do manual tiling
	* calculations and load/store using the TMU general memory access path.
	*/

	bool
	v3d_gl_format_is_return_32(GLenum format)
	{
	switch (format) {
	case GL_R8:
	case GL_R8_SNORM:
	case GL_R8UI:
	case GL_R8I:
	case GL_RG8:
	case GL_RG8_SNORM:
	case GL_RG8UI:
	case GL_RG8I:
	case GL_RGBA8:
	case GL_RGBA8_SNORM:
	case GL_RGBA8UI:
	case GL_RGBA8I:
	case GL_R11F_G11F_B10F:
	case GL_RGB10_A2:
	case GL_RGB10_A2UI:
	case GL_R16F:
	case GL_R16UI:
	case GL_R16I:
	case GL_RG16F:
	case GL_RG16UI:
	case GL_RG16I:
	case GL_RGBA16F:
	case GL_RGBA16UI:
	case GL_RGBA16I:
	return false;
	case GL_R16:
	case GL_R16_SNORM:
	case GL_RG16:
	case GL_RG16_SNORM:
	case GL_RGBA16:
	case GL_RGBA16_SNORM:
	case GL_R32F:
	case GL_R32UI:
	case GL_R32I:
	case GL_RG32F:
	case GL_RG32UI:
	case GL_RG32I:
	case GL_RGBA32F:
	case GL_RGBA32UI:
	case GL_RGBA32I:
	return true;
	default:
	unreachable("Invalid image format");
	}
	}

	/* Packs a 32-bit vector of colors in the range [0, (1 << bits[i]) - 1] to a
	* 32-bit SSA value, with as many channels as necessary to store all the bits
	*/
	static nir_ssa_def *
	pack_bits(nir_builder b, nir_ssa_def color, const unsigned *bits,
	int num_components, bool mask)
	{
	nir_ssa_def *results[4];
	int offset = 0;
	for (int i = 0; i < num_components; i++) {
	nir_ssa_def *chan = nir_channel(b, color, i);

	/* Channels being stored shouldn't cross a 32-bit boundary. */
	assert((offset & ~31) == ((offset + bits[i] - 1) & ~31));

	if (mask) {
	chan = nir_iand(b, chan,
	nir_imm_int(b, (1 << bits[i]) - 1));
	}

	if (offset % 32 == 0) {
	results[offset / 32] = chan;
	} else {
	results[offset / 32] =
	nir_ior(b, results[offset / 32],
	nir_ishl(b, chan,
	nir_imm_int(b, offset % 32)));
	}
	offset += bits[i];
	}

	return nir_vec(b, results, DIV_ROUND_UP(offset, 32));
	}

	static nir_ssa_def *
	pack_unorm(nir_builder b, nir_ssa_def color, const unsigned *bits,
	int num_components)
	{
	color = nir_channels(b, color, (1 << num_components) - 1);
	color = nir_format_float_to_unorm(b, color, bits);
	return pack_bits(b, color, bits, color->num_components, false);
	}

	static nir_ssa_def *
	pack_snorm(nir_builder b, nir_ssa_def color, const unsigned *bits,
	int num_components)
	{
	color = nir_channels(b, color, (1 << num_components) - 1);
	color = nir_format_float_to_snorm(b, color, bits);
	return pack_bits(b, color, bits, color->num_components, true);
	}

	static nir_ssa_def *
	pack_uint(nir_builder b, nir_ssa_def color, const unsigned *bits,
	int num_components)
	{
	color = nir_channels(b, color, (1 << num_components) - 1);
	color = nir_format_clamp_uint(b, color, bits);
	return pack_bits(b, color, bits, num_components, false);
	}

	static nir_ssa_def *
	pack_sint(nir_builder b, nir_ssa_def color, const unsigned *bits,
	int num_components)
	{
	color = nir_channels(b, color, (1 << num_components) - 1);
	color = nir_format_clamp_sint(b, color, bits);
	return pack_bits(b, color, bits, num_components, true);
	}

	static nir_ssa_def *
	pack_half(nir_builder b, nir_ssa_def color, const unsigned *bits,
	int num_components)
	{
	color = nir_channels(b, color, (1 << num_components) - 1);
	color = nir_format_float_to_half(b, color);
	return pack_bits(b, color, bits, color->num_components, false);
	}

	static void
	v3d_nir_lower_image_store(nir_builder b, nir_intrinsic_instr instr)
	{
	nir_variable *var = nir_intrinsic_get_var(instr, 0);
	GLenum format = var->data.image.format;
	static const unsigned bits_8[4] = {8, 8, 8, 8};
	static const unsigned bits_16[4] = {16, 16, 16, 16};
	static const unsigned bits_1010102[4] = {10, 10, 10, 2};

	b->cursor = nir_before_instr(&instr->instr);

	nir_ssa_def *unformatted = nir_ssa_for_src(b, instr->src[3], 4);
	nir_ssa_def *formatted = NULL;
	switch (format) {
	case GL_RGBA32F:
	case GL_RGBA32UI:
	case GL_RGBA32I:
	/* For 4-component 32-bit components, there's no packing to be
	* done.
	*/
	return;

	case GL_R32F:
	case GL_R32UI:
	case GL_R32I:
	/* For other 32-bit components, just reduce the size of
	* the input vector.
	*/
	formatted = nir_channels(b, unformatted, 1);
	break;
	case GL_RG32F:
	case GL_RG32UI:
	case GL_RG32I:
	formatted = nir_channels(b, unformatted, 2);
	break;

	case GL_R8:
	formatted = pack_unorm(b, unformatted, bits_8, 1);
	break;
	case GL_RG8:
	formatted = pack_unorm(b, unformatted, bits_8, 2);
	break;
	case GL_RGBA8:
	formatted = pack_unorm(b, unformatted, bits_8, 4);
	break;

	case GL_R8_SNORM:
	formatted = pack_snorm(b, unformatted, bits_8, 1);
	break;
	case GL_RG8_SNORM:
	formatted = pack_snorm(b, unformatted, bits_8, 2);
	break;
	case GL_RGBA8_SNORM:
	formatted = pack_snorm(b, unformatted, bits_8, 4);
	break;

	case GL_R16:
	formatted = pack_unorm(b, unformatted, bits_16, 1);
	break;
	case GL_RG16:
	formatted = pack_unorm(b, unformatted, bits_16, 2);
	break;
	case GL_RGBA16:
	formatted = pack_unorm(b, unformatted, bits_16, 4);
	break;

	case GL_R16_SNORM:
	formatted = pack_snorm(b, unformatted, bits_16, 1);
	break;
	case GL_RG16_SNORM:
	formatted = pack_snorm(b, unformatted, bits_16, 2);
	break;
	case GL_RGBA16_SNORM:
	formatted = pack_snorm(b, unformatted, bits_16, 4);
	break;

	case GL_R16F:
	formatted = pack_half(b, unformatted, bits_16, 1);
	break;
	case GL_RG16F:
	formatted = pack_half(b, unformatted, bits_16, 2);
	break;
	case GL_RGBA16F:
	formatted = pack_half(b, unformatted, bits_16, 4);
	break;

	case GL_R8UI:
	formatted = pack_uint(b, unformatted, bits_8, 1);
	break;
	case GL_R8I:
	formatted = pack_sint(b, unformatted, bits_8, 1);
	break;
	case GL_RG8UI:
	formatted = pack_uint(b, unformatted, bits_8, 2);
	break;
	case GL_RG8I:
	formatted = pack_sint(b, unformatted, bits_8, 2);
	break;
	case GL_RGBA8UI:
	formatted = pack_uint(b, unformatted, bits_8, 4);
	break;
	case GL_RGBA8I:
	formatted = pack_sint(b, unformatted, bits_8, 4);
	break;

	case GL_R16UI:
	formatted = pack_uint(b, unformatted, bits_16, 1);
	break;
	case GL_R16I:
	formatted = pack_sint(b, unformatted, bits_16, 1);
	break;
	case GL_RG16UI:
	formatted = pack_uint(b, unformatted, bits_16, 2);
	break;
	case GL_RG16I:
	formatted = pack_sint(b, unformatted, bits_16, 2);
	break;
	case GL_RGBA16UI:
	formatted = pack_uint(b, unformatted, bits_16, 4);
	break;
	case GL_RGBA16I:
	formatted = pack_sint(b, unformatted, bits_16, 4);
	break;

	case GL_R11F_G11F_B10F:
	formatted = nir_format_pack_11f11f10f(b, unformatted);
	break;
	case GL_RGB9_E5:
	formatted = nir_format_pack_r9g9b9e5(b, unformatted);
	break;

	case GL_RGB10_A2:
	formatted = pack_unorm(b, unformatted, bits_1010102, 4);
	break;

	case GL_RGB10_A2UI:
	formatted = pack_uint(b, unformatted, bits_1010102, 4);
	break;

	default:
	unreachable("bad format");
	}

	nir_instr_rewrite_src(&instr->instr, &instr->src[3],
	nir_src_for_ssa(formatted));
	instr->num_components = formatted->num_components;
	}

	static void
	v3d_nir_lower_image_load(nir_builder b, nir_intrinsic_instr instr)
	{
	static const unsigned bits16[] = {16, 16, 16, 16};
	nir_variable *var = nir_intrinsic_get_var(instr, 0);
	const struct glsl_type *sampler_type = glsl_without_array(var->type);
	enum glsl_base_type base_type =
	glsl_get_sampler_result_type(sampler_type);

	if (v3d_gl_format_is_return_32(var->data.image.format))
	return;

	b->cursor = nir_after_instr(&instr->instr);

	assert(instr->dest.is_ssa);
	nir_ssa_def *result = &instr->dest.ssa;
	if (base_type == GLSL_TYPE_FLOAT) {
	nir_ssa_def *rg = nir_channel(b, result, 0);
	nir_ssa_def *ba = nir_channel(b, result, 1);
	result = nir_vec4(b,
	nir_unpack_half_2x16_split_x(b, rg),
	nir_unpack_half_2x16_split_y(b, rg),
	nir_unpack_half_2x16_split_x(b, ba),
	nir_unpack_half_2x16_split_y(b, ba));
	} else if (base_type == GLSL_TYPE_INT) {
	result = nir_format_unpack_sint(b, result, bits16, 4);
	} else {
	assert(base_type == GLSL_TYPE_UINT);
	result = nir_format_unpack_uint(b, result, bits16, 4);
	}

	nir_ssa_def_rewrite_uses_after(&instr->dest.ssa, nir_src_for_ssa(result),
	result->parent_instr);
	}

	void
	v3d_nir_lower_image_load_store(nir_shader *s)
	{
	nir_foreach_function(function, s) {
	if (!function->impl)
	continue;

	nir_builder b;
	nir_builder_init(&b, function->impl);

	nir_foreach_block(block, function->impl) {
	nir_foreach_instr_safe(instr, block) {
	if (instr->type != nir_instr_type_intrinsic)
	continue;

	nir_intrinsic_instr *intr =
	nir_instr_as_intrinsic(instr);

	switch (intr->intrinsic) {
	case nir_intrinsic_image_deref_load:
	v3d_nir_lower_image_load(&b, intr);
	break;
	case nir_intrinsic_image_deref_store:
	v3d_nir_lower_image_store(&b, intr);
	break;
	default:
	break;
	}
	}
	}

	nir_metadata_preserve(function->impl,
	nir_metadata_block_index \|
	nir_metadata_dominance);
	}
	}