nir/linker: add gl_nir_link_uniform_blocks.c

Adding the ability to link uniform blocks and shader storage blocks
using NIR, intended for ARB_gl_spirv support. Among other things, this
linking needs to take into account that everything should work without
names, as they could be not present, while the GLSL IR uniform block
linking was wrote with the names on its core.

The other major difference compared with the GLSL IR linker is that we
don't deal with layouts. There are no references to std140, std430,
etc. Layouts are expressed through explicit offset, array stride and
matrix stride. That simplifies how the buffer size are computed. But
also means that we couldn't use the existing methods at glsl_types, so
we needed to implement new methods.

It is worth to note that this linking do a iteration over the
glsl_types, similarly to what the linking uniforms do. A possible
future improvement would be refactor both cases to try to share more
code that it sharing right now. On GLSL IR there are a class visitor,
specialized on each case, for that sharing. As adding a class visitor
on C would more complicated, for now we are just iterating on both.

Signed-off-by: Alejandro Piñeiro <[email protected]>
Signed-off-by: Neil Roberts <[email protected]>
Signed-off-by: Antia Puentes <[email protected]>

v2: (from Timothy review)
   * Fix variable name convention
   * Stop to use _function_name convention
   * Don't use // for comments
   * "nir/linker: Keep track of the stages referencing an UBO/SSBO"
     squashed with this patch

v3: (from Caio review)
   * Don't delete the linked shader on failure
   * Use rzalloc_array to avoid some explicit initializations

Reviewed-by: Timothy Arceri <[email protected]>
Reviewed-by: Caio Marcelo de Oliveira Filho <[email protected]>

4 files changed, 648 insertions, 0 deletions

diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index d6b12fcea1b..c94ec24b2e6 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -31,6 +31,7 @@ LIBGLSL_FILES = \
 	glsl/gl_nir_lower_samplers.c \
 	glsl/gl_nir_lower_samplers_as_deref.c \
 	glsl/gl_nir_link_atomics.c \
+	glsl/gl_nir_link_uniform_blocks.c \
 	glsl/gl_nir_link_uniform_initializers.c \
 	glsl/gl_nir_link_uniforms.c \
 	glsl/gl_nir_link_xfb.c \
diff --git a/src/compiler/glsl/gl_nir_link_uniform_blocks.c b/src/compiler/glsl/gl_nir_link_uniform_blocks.c
new file mode 100644
index 00000000000..28faa7e7626
--- /dev/null
+++ b/src/compiler/glsl/gl_nir_link_uniform_blocks.c
@@ -0,0 +1,643 @@
+/*
+ * Copyright © 2019 Intel Corporation
+ *
+ * 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 "nir.h"
+#include "gl_nir_linker.h"
+#include "ir_uniform.h" /* for gl_uniform_storage */
+#include "linker_util.h"
+#include "main/mtypes.h"
+
+/* Summary: This file contains code to do a nir-based linking for uniform
+ * blocks. This includes ubos and ssbos.  Note that it is tailored to
+ * ARB_gl_spirv needs and particularities.
+ *
+ * More details:
+ *
+ * 1. Linking doesn't use names: GLSL linking use names as core concept. But
+ *    on SPIR-V, uniform block name, fields names, and other names are
+ *    considered optional debug infor so could not be present. So the linking
+ *    should work without it, and it is optional to not handle them at
+ *    all. From ARB_gl_spirv spec.
+ *
+ *    "19. How should the program interface query operations behave for program
+ *         objects created from SPIR-V shaders?
+ *
+ *     DISCUSSION: we previously said we didn't need reflection to work for
+ *     SPIR-V shaders (at least for the first version), however we are left
+ *     with specifying how it should "not work". The primary issue is that
+ *     SPIR-V binaries are not required to have names associated with
+ *     variables. They can be associated in debug information, but there is no
+ *     requirement for that to be present, and it should not be relied upon.
+ *
+ *     Options:
+ *
+ *     <skip>
+ *
+ *    C) Allow as much as possible to work "naturally". You can query for the
+ *    number of active resources, and for details about them. Anything that
+ *    doesn't query by name will work as expected. Queries for maximum length
+ *    of names return one. Queries for anything "by name" return INVALID_INDEX
+ *    (or -1). Querying the name property of a resource returns an empty
+ *    string. This may allow many queries to work, but it's not clear how
+ *    useful it would be if you can't actually know which specific variable
+ *    you are retrieving information on. If everything is specified a-priori
+ *    by location/binding/offset/index/component in the shader, this may be
+ *    sufficient.
+ *
+ *    RESOLVED.  Pick (c), but also allow debug names to be returned if an
+ *    implementation wants to."
+ *
+ * This implemention doesn't care for the names, as the main objective is
+ * functional, and not support optional debug features.
+ *
+ * 2. Terminology: this file handles both UBO and SSBO, including both as
+ *    "uniform blocks" analogously to what is done in the GLSL (IR) path.
+ *
+ *    From ARB_gl_spirv spec:
+ *      "Mapping of Storage Classes:
+ *       <skip>
+ *       uniform blockN { ... } ...;  -> Uniform, with Block decoration
+ *       <skip>
+ *       buffer  blockN { ... } ...;  -> Uniform, with BufferBlock decoration"
+ *
+ * 3. Explicit data: The code assumes that all structure members have an
+ *    Offset decoration, all arrays have an ArrayStride and all matrices have
+ *    a MatrixStride, even for nested structures. That way we don’t have to
+ *    worry about the different layout modes. This is explicitly required in
+ *    the SPIR-V spec:
+ *
+ *    "Composite objects in the UniformConstant, Uniform, and PushConstant
+ *     Storage Classes must be explicitly laid out. The following apply to all
+ *     the aggregate and matrix types describing such an object, recursively
+ *     through their nested types:
+ *
+ *    – Each structure-type member must have an Offset Decoration.
+ *    – Each array type must have an ArrayStride Decoration.
+ *    – Each structure-type member that is a matrix or array-of-matrices must
+ *      have be decorated with a MatrixStride Decoration, and one of the
+ *      RowMajor or ColMajor Decorations."
+ *
+ *    Additionally, the structure members are expected to be presented in
+ *    increasing offset order:
+ *
+ *   "a structure has lower-numbered members appearing at smaller offsets than
+ *    higher-numbered members"
+ */
+
+enum block_type {
+   BLOCK_UBO,
+   BLOCK_SSBO
+};
+
+/*
+ * It is worth to note that ARB_gl_spirv spec doesn't require us to do this
+ * validation, but at the same time, it allow us to do it. The following
+ * validation is easy and a nice-to-have.
+*/
+static bool
+link_blocks_are_compatible(const struct gl_uniform_block *a,
+                           const struct gl_uniform_block *b)
+{
+   /*
+    * Names on ARB_gl_spirv are optional, so we are ignoring them. So
+    * meanwhile on the equivalent GLSL method the matching is done using the
+    * name, here we use the binding, that for SPIR-V binaries is explicit, and
+    * mandatory, from OpenGL 4.6 spec, section "7.4.2. SPIR-V Shader Interface
+    * Matching":
+    *    "Uniform and shader storage block variables must also be decorated
+    *     with a Binding"
+    */
+   if (a->Binding != b->Binding)
+      return false;
+
+   /* We are explicitly ignoring the names, so it would be good to check that
+    * this is happening.
+    */
+   assert(a->Name == NULL);
+   assert(b->Name == NULL);
+
+   if (a->NumUniforms != b->NumUniforms)
+      return false;
+
+   if (a->_Packing != b->_Packing)
+      return false;
+
+   if (a->_RowMajor != b->_RowMajor)
+      return false;
+
+   for (unsigned i = 0; i < a->NumUniforms; i++) {
+      if (a->Uniforms[i].Type != b->Uniforms[i].Type)
+         return false;
+
+      if (a->Uniforms[i].RowMajor != b->Uniforms[i].RowMajor)
+         return false;
+
+      if (a->Uniforms[i].Offset != b->Uniforms[i].Offset)
+         return false;
+
+      /* See comment on previous assert */
+      assert(a->Uniforms[i].Name == NULL);
+      assert(b->Uniforms[i].Name == NULL);
+   }
+
+   return true;
+}
+
+/**
+ * Merges a buffer block into an array of buffer blocks that may or may not
+ * already contain a copy of it.
+ *
+ * Returns the index of the block in the array (new if it was needed, or the
+ * index of the copy of it). -1 if there are two incompatible block
+ * definitions with the same binding.
+ *
+ */
+static int
+link_cross_validate_uniform_block(void *mem_ctx,
+                                  struct gl_uniform_block **linked_blocks,
+                                  unsigned int *num_linked_blocks,
+                                  struct gl_uniform_block *new_block)
+{
+   /* We first check if new_block was already linked */
+   for (unsigned int i = 0; i < *num_linked_blocks; i++) {
+      struct gl_uniform_block *old_block = &(*linked_blocks)[i];
+
+      if (old_block->Binding == new_block->Binding)
+         return link_blocks_are_compatible(old_block, new_block) ? i : -1;
+   }
+
+   *linked_blocks = reralloc(mem_ctx, *linked_blocks,
+                             struct gl_uniform_block,
+                             *num_linked_blocks + 1);
+   int linked_block_index = (*num_linked_blocks)++;
+   struct gl_uniform_block *linked_block = &(*linked_blocks)[linked_block_index];
+
+   memcpy(linked_block, new_block, sizeof(*new_block));
+   linked_block->Uniforms = ralloc_array(*linked_blocks,
+                                         struct gl_uniform_buffer_variable,
+                                         linked_block->NumUniforms);
+
+   memcpy(linked_block->Uniforms,
+          new_block->Uniforms,
+          sizeof(*linked_block->Uniforms) * linked_block->NumUniforms);
+
+   return linked_block_index;
+}
+
+
+/**
+ * Accumulates the array of buffer blocks and checks that all definitions of
+ * blocks agree on their contents.
+ */
+static bool
+nir_interstage_cross_validate_uniform_blocks(struct gl_shader_program *prog,
+                                             enum block_type block_type)
+{
+   int *interfaceBlockStageIndex[MESA_SHADER_STAGES];
+   struct gl_uniform_block *blks = NULL;
+   unsigned *num_blks = block_type == BLOCK_SSBO ? &prog->data->NumShaderStorageBlocks :
+      &prog->data->NumUniformBlocks;
+
+   unsigned max_num_buffer_blocks = 0;
+   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
+      if (prog->_LinkedShaders[i]) {
+         if (block_type == BLOCK_SSBO) {
+            max_num_buffer_blocks +=
+               prog->_LinkedShaders[i]->Program->info.num_ssbos;
+         } else {
+            max_num_buffer_blocks +=
+               prog->_LinkedShaders[i]->Program->info.num_ubos;
+         }
+      }
+   }
+
+   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
+      struct gl_linked_shader *sh = prog->_LinkedShaders[i];
+
+      interfaceBlockStageIndex[i] = malloc(max_num_buffer_blocks * sizeof(int));
+      for (unsigned int j = 0; j < max_num_buffer_blocks; j++)
+         interfaceBlockStageIndex[i][j] = -1;
+
+      if (sh == NULL)
+         continue;
+
+      unsigned sh_num_blocks;
+      struct gl_uniform_block **sh_blks;
+      if (block_type == BLOCK_SSBO) {
+         sh_num_blocks = prog->_LinkedShaders[i]->Program->info.num_ssbos;
+         sh_blks = sh->Program->sh.ShaderStorageBlocks;
+      } else {
+         sh_num_blocks = prog->_LinkedShaders[i]->Program->info.num_ubos;
+         sh_blks = sh->Program->sh.UniformBlocks;
+      }
+
+      for (unsigned int j = 0; j < sh_num_blocks; j++) {
+         int index = link_cross_validate_uniform_block(prog->data, &blks,
+                                                       num_blks, sh_blks[j]);
+
+         if (index == -1) {
+            /* We use the binding as we are ignoring the names */
+            linker_error(prog, "buffer block with binding `%i' has mismatching "
+                         "definitions\n", sh_blks[j]->Binding);
+
+            for (unsigned k = 0; k <= i; k++) {
+               free(interfaceBlockStageIndex[k]);
+            }
+
+            /* Reset the block count. This will help avoid various segfaults
+             * from api calls that assume the array exists due to the count
+             * being non-zero.
+             */
+            *num_blks = 0;
+            return false;
+         }
+
+         interfaceBlockStageIndex[i][index] = j;
+      }
+   }
+
+   /* Update per stage block pointers to point to the program list.
+    */
+   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
+      for (unsigned j = 0; j < *num_blks; j++) {
+         int stage_index = interfaceBlockStageIndex[i][j];
+
+         if (stage_index != -1) {
+            struct gl_linked_shader *sh = prog->_LinkedShaders[i];
+
+            struct gl_uniform_block **sh_blks = block_type == BLOCK_SSBO ?
+               sh->Program->sh.ShaderStorageBlocks :
+               sh->Program->sh.UniformBlocks;
+
+            blks[j].stageref |= sh_blks[stage_index]->stageref;
+            sh_blks[stage_index] = &blks[j];
+         }
+      }
+   }
+
+   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
+      free(interfaceBlockStageIndex[i]);
+   }
+
+   if (block_type == BLOCK_SSBO)
+      prog->data->ShaderStorageBlocks = blks;
+   else
+      prog->data->UniformBlocks = blks;
+
+   return true;
+}
+
+/*
+ * Iterates @type in order to compute how many individual leaf variables
+ * contains.
+ */
+static void
+iterate_type_count_variables(const struct glsl_type *type,
+                             unsigned int *num_variables)
+{
+   for (unsigned i = 0; i < glsl_get_length(type); i++) {
+      const struct glsl_type *field_type;
+
+      if (glsl_type_is_struct_or_ifc(type))
+         field_type = glsl_get_struct_field(type, i);
+      else
+         field_type = glsl_get_array_element(type);
+
+      if (glsl_type_is_leaf(field_type))
+         (*num_variables)++;
+      else
+         iterate_type_count_variables(field_type, num_variables);
+   }
+}
+
+
+static void
+fill_individual_variable(const struct glsl_type *type,
+                         struct gl_uniform_buffer_variable *variables,
+                         unsigned int *variable_index,
+                         unsigned int *offset,
+                         struct gl_shader_program *prog,
+                         struct gl_uniform_block *block)
+{
+   /* ARB_gl_spirv: allowed to ignore names. Thus, we don't need to initialize
+    * the variable's Name or IndexName.
+    */
+   variables[*variable_index].Type = type;
+
+   if (glsl_type_is_matrix(type)) {
+      variables[*variable_index].RowMajor = glsl_matrix_type_is_row_major(type);
+   } else {
+      /* default value, better that potential meaningless garbage */
+      variables[*variable_index].RowMajor = false;
+   }
+
+   /**
+    * Although ARB_gl_spirv points that the offsets need to be included (see
+    * "Mappings of layouts"), in the end those are only valid for
+    * root-variables, and we would need to recompute offsets when we iterate
+    * over non-trivial types, like aoa. So we compute the offset always.
+    */
+   variables[*variable_index].Offset = *offset;
+   (*offset) += glsl_get_explicit_size(type, true);
+
+   (*variable_index)++;
+}
+
+static void
+iterate_type_fill_variables(const struct glsl_type *type,
+                            struct gl_uniform_buffer_variable *variables,
+                            unsigned int *variable_index,
+                            unsigned int *offset,
+                            struct gl_shader_program *prog,
+                            struct gl_uniform_block *block)
+{
+   unsigned int struct_base_offset;
+
+   for (unsigned i = 0; i < glsl_get_length(type); i++) {
+      const struct glsl_type *field_type;
+
+      if (glsl_type_is_struct_or_ifc(type)) {
+         field_type = glsl_get_struct_field(type, i);
+
+         if (i == 0) {
+            struct_base_offset = *offset;
+         }
+
+         *offset = struct_base_offset + glsl_get_struct_field_offset(type, i);
+      } else {
+         field_type = glsl_get_array_element(type);
+      }
+
+      if (glsl_type_is_leaf(field_type)) {
+         fill_individual_variable(field_type, variables, variable_index,
+                                  offset, prog, block);
+      } else {
+         iterate_type_fill_variables(field_type, variables, variable_index,
+                                     offset, prog, block);
+      }
+   }
+}
+
+/*
+ * In opposite to the equivalent glsl one, this one only allocates the needed
+ * space. We do a initial count here, just to avoid re-allocating for each one
+ * we find.
+ */
+static void
+allocate_uniform_blocks(void *mem_ctx,
+                        struct gl_linked_shader *shader,
+                        struct gl_uniform_block **out_blks, unsigned *num_blocks,
+                        struct gl_uniform_buffer_variable **out_variables,
+                        unsigned *num_variables,
+                        enum block_type block_type)
+{
+   *num_variables = 0;
+   *num_blocks = 0;
+
+   nir_foreach_variable(var, &shader->Program->nir->uniforms) {
+      if (block_type == BLOCK_UBO && !nir_variable_is_in_ubo(var))
+         continue;
+
+      if (block_type == BLOCK_SSBO && !nir_variable_is_in_ssbo(var))
+         continue;
+
+      const struct glsl_type *type = glsl_without_array(var->type);
+      unsigned aoa_size = glsl_get_aoa_size(var->type);
+      unsigned buffer_count = aoa_size == 0 ? 1 : aoa_size;
+
+      *num_blocks += buffer_count;
+
+      unsigned int block_variables = 0;
+      iterate_type_count_variables(type, &block_variables);
+
+      *num_variables += block_variables * buffer_count;
+   }
+
+   if (*num_blocks == 0) {
+      assert(*num_variables == 0);
+      return;
+   }
+
+   assert(*num_variables != 0);
+
+   struct gl_uniform_block *blocks =
+      rzalloc_array(mem_ctx, struct gl_uniform_block, *num_blocks);
+
+   struct gl_uniform_buffer_variable *variables =
+      rzalloc_array(blocks, struct gl_uniform_buffer_variable, *num_variables);
+
+   *out_blks = blocks;
+   *out_variables = variables;
+}
+
+static void
+fill_block(struct gl_uniform_block *block,
+           nir_variable *var,
+           struct gl_uniform_buffer_variable *variables,
+           unsigned *variable_index,
+           unsigned array_index,
+           struct gl_shader_program *prog,
+           const gl_shader_stage stage)
+{
+   const struct glsl_type *type = glsl_without_array(var->type);
+
+   block->Name = NULL; /* ARB_gl_spirv: allowed to ignore names */
+   /* From ARB_gl_spirv spec:
+    *    "Vulkan uses only one binding point for a resource array,
+    *     while OpenGL still uses multiple binding points, so binding
+    *     numbers are counted differently for SPIR-V used in Vulkan
+    *     and OpenGL
+    */
+   block->Binding = var->data.binding + array_index;
+   block->Uniforms = &variables[*variable_index];
+   block->stageref = 1U << stage;
+
+   /* From SPIR-V 1.0 spec, 3.20, Decoration:
+    *    "RowMajor
+    *     Applies only to a member of a structure type.
+    *     Only valid on a matrix or array whose most basic
+    *     element is a matrix. Indicates that components
+    *     within a row are contiguous in memory."
+    *
+    * So the SPIR-V binary doesn't report if the block was defined as RowMajor
+    * or not. In any case, for the components it is mandatory to set it, so it
+    * is not needed a default RowMajor value to know it.
+    *
+    * Setting to the default, but it should be ignored.
+    */
+   block->_RowMajor = false;
+
+   /* From ARB_gl_spirv spec:
+    *     "Mapping of layouts
+    *
+    *       std140/std430 -> explicit *Offset*, *ArrayStride*, and
+    *                        *MatrixStride* Decoration on struct members
+    *       shared/packed  ->  not allowed"
+    *
+    * So we would not have a value for _Packing, and in fact it would be
+    * useless so far. Using a default value. It should be ignored.
+    */
+   block->_Packing = 0;
+   block->linearized_array_index = array_index;
+
+   unsigned old_variable_index = *variable_index;
+   unsigned offset = 0;
+   iterate_type_fill_variables(type, variables, variable_index, &offset, prog, block);
+   block->NumUniforms = *variable_index - old_variable_index;
+
+   block->UniformBufferSize =  glsl_get_explicit_size(type, false);
+
+   /* From OpenGL 4.6 spec, section 7.6.2.3, "SPIR-V Uniform Offsets and
+    * strides"
+    *
+    *   "If the variable is decorated as a BufferBlock , its offsets and
+    *    strides must not contradict std430 alignment and minimum offset
+    *    requirements. Otherwise, its offsets and strides must not contradict
+    *    std140 alignment and minimum offset requirements."
+    *
+    * So although we are computing the size based on the offsets and
+    * array/matrix strides, at the end we need to ensure that the alignment is
+    * the same that with std140. From ARB_uniform_buffer_object spec:
+    *
+    *   "For uniform blocks laid out according to [std140] rules, the minimum
+    *    buffer object size returned by the UNIFORM_BLOCK_DATA_SIZE query is
+    *    derived by taking the offset of the last basic machine unit consumed
+    *    by the last uniform of the uniform block (including any end-of-array
+    *    or end-of-structure padding), adding one, and rounding up to the next
+    *    multiple of the base alignment required for a vec4."
+    */
+   block->UniformBufferSize = glsl_align(block->UniformBufferSize, 16);
+}
+
+/*
+ * Link ubos/ssbos for a given linked_shader/stage.
+ */
+static void
+link_linked_shader_uniform_blocks(void *mem_ctx,
+                                  struct gl_context *ctx,
+                                  struct gl_shader_program *prog,
+                                  struct gl_linked_shader *shader,
+                                  struct gl_uniform_block **blocks,
+                                  unsigned *num_blocks,
+                                  enum block_type block_type)
+{
+   struct gl_uniform_buffer_variable *variables = NULL;
+   unsigned num_variables = 0;
+
+   allocate_uniform_blocks(mem_ctx, shader,
+                           blocks, num_blocks,
+                           &variables, &num_variables,
+                           block_type);
+
+   /* Fill the content of uniforms and variables */
+   unsigned block_index = 0;
+   unsigned variable_index = 0;
+   struct gl_uniform_block *blks = *blocks;
+
+   nir_foreach_variable(var, &shader->Program->nir->uniforms) {
+      if (block_type == BLOCK_UBO && !nir_variable_is_in_ubo(var))
+         continue;
+
+      if (block_type == BLOCK_SSBO && !nir_variable_is_in_ssbo(var))
+         continue;
+
+      unsigned aoa_size = glsl_get_aoa_size(var->type);
+      unsigned buffer_count = aoa_size == 0 ? 1 : aoa_size;
+
+      for (unsigned array_index = 0; array_index < buffer_count; array_index++) {
+         fill_block(&blks[block_index], var, variables, &variable_index,
+                    array_index, prog, shader->Stage);
+         block_index++;
+      }
+   }
+
+   assert(block_index == *num_blocks);
+   assert(variable_index == num_variables);
+}
+
+bool
+gl_nir_link_uniform_blocks(struct gl_context *ctx,
+                           struct gl_shader_program *prog)
+{
+   void *mem_ctx = ralloc_context(NULL);
+
+   for (int stage = 0; stage < MESA_SHADER_STAGES; stage++) {
+      struct gl_linked_shader *const linked = prog->_LinkedShaders[stage];
+      struct gl_uniform_block *ubo_blocks = NULL;
+      unsigned num_ubo_blocks = 0;
+      struct gl_uniform_block *ssbo_blocks = NULL;
+      unsigned num_ssbo_blocks = 0;
+
+      if (!linked)
+         continue;
+
+      link_linked_shader_uniform_blocks(mem_ctx, ctx, prog, linked,
+                                        &ubo_blocks, &num_ubo_blocks,
+                                        BLOCK_UBO);
+
+      link_linked_shader_uniform_blocks(mem_ctx, ctx, prog, linked,
+                                        &ssbo_blocks, &num_ssbo_blocks,
+                                        BLOCK_SSBO);
+
+      if (!prog->data->LinkStatus) {
+         return false;
+      }
+
+      prog->data->linked_stages |= 1 << stage;
+
+      /* Copy ubo blocks to linked shader list */
+      linked->Program->sh.UniformBlocks =
+         ralloc_array(linked, struct gl_uniform_block *, num_ubo_blocks);
+      ralloc_steal(linked, ubo_blocks);
+      for (unsigned i = 0; i < num_ubo_blocks; i++) {
+         linked->Program->sh.UniformBlocks[i] = &ubo_blocks[i];
+      }
+
+      /* We need to set it twice to avoid the value being overwritten by the
+       * one from nir in brw_shader_gather_info. TODO: get a way to set the
+       * info once, and being able to gather properly the info.
+       */
+      linked->Program->nir->info.num_ubos = num_ubo_blocks;
+      linked->Program->info.num_ubos = num_ubo_blocks;
+
+      /* Copy ssbo blocks to linked shader list */
+      linked->Program->sh.ShaderStorageBlocks =
+         ralloc_array(linked, struct gl_uniform_block *, num_ssbo_blocks);
+      ralloc_steal(linked, ssbo_blocks);
+      for (unsigned i = 0; i < num_ssbo_blocks; i++) {
+         linked->Program->sh.ShaderStorageBlocks[i] = &ssbo_blocks[i];
+      }
+
+      /* See previous comment on num_ubo_blocks */
+      linked->Program->nir->info.num_ssbos = num_ssbo_blocks;
+      linked->Program->info.num_ssbos = num_ssbo_blocks;
+   }
+
+   if (!nir_interstage_cross_validate_uniform_blocks(prog, BLOCK_UBO))
+      return false;
+
+   if (!nir_interstage_cross_validate_uniform_blocks(prog, BLOCK_SSBO))
+      return false;
+
+   return true;
+}
diff --git a/src/compiler/glsl/gl_nir_linker.h b/src/compiler/glsl/gl_nir_linker.h
index 29ca27d3df8..20ed35fa0e4 100644
--- a/src/compiler/glsl/gl_nir_linker.h
+++ b/src/compiler/glsl/gl_nir_linker.h
@@ -46,6 +46,9 @@ void gl_nir_link_assign_atomic_counter_resources(struct gl_context *ctx,
 void gl_nir_link_assign_xfb_resources(struct gl_context *ctx,
                                       struct gl_shader_program *prog);
 
+bool gl_nir_link_uniform_blocks(struct gl_context *ctx,
+                                struct gl_shader_program *prog);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/src/compiler/glsl/meson.build b/src/compiler/glsl/meson.build
index 615c1ad1761..fe1dc8ffe6a 100644
--- a/src/compiler/glsl/meson.build
+++ b/src/compiler/glsl/meson.build
@@ -79,6 +79,7 @@ files_libglsl = files(
   'gl_nir_lower_samplers.c',
   'gl_nir_lower_samplers_as_deref.c',
   'gl_nir_link_atomics.c',
+  'gl_nir_link_uniform_blocks.c',
   'gl_nir_link_uniform_initializers.c',
   'gl_nir_link_uniforms.c',
   'gl_nir_link_xfb.c',