vulkan: add vk_spec_info_to_nir_spirv util method

All vulkan drivers have been copying anv's code to convert
VkSpecializationInfo into nir_spirv_specialization.

Recently there was a Vulkan spec change on allowed values for
VkSpecializationInfo, and all drivers got affected.

This commits creates a new helper, and uses it on all Vulkan Mesa
drivers.

v2: use (uint8_t*) castings, instead of void*, to avoid C2036 with
    MSVC (detected by the CI, inspired on what radv was doing)

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Juan A. Suarez <jasuarez@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12047>

src/vulkan/util/meson.build

@@ -113,7 +113,7 @@ libvulkan_util = static_library(
   [files_vulkan_util, vk_common_entrypoints, vk_dispatch_table,
    vk_enum_to_str, vk_extensions],
   include_directories : [inc_include, inc_src, inc_gallium],
-  dependencies : [vulkan_wsi_deps, idep_mesautil],
+  dependencies : [vulkan_wsi_deps, idep_mesautil, idep_nir_headers],
   # For glsl_type_singleton
   link_with : libcompiler,
   c_args : [vulkan_wsi_args],

src/vulkan/util/vk_util.c

@@ -29,6 +29,8 @@
 #include "vk_util.h"
 #include "util/debug.h"
 
+#include "compiler/spirv/nir_spirv.h"
+
 uint32_t vk_get_driver_version(void)
 {
    const char *minor_string = strchr(PACKAGE_VERSION, '.');
@@ -79,3 +81,63 @@ vk_warn_non_conformant_implementation(const char *driver_name)
    fprintf(stderr, "WARNING: %s is not a conformant Vulkan implementation, "
                    "testing use only.\n", driver_name);
 }
+
+struct nir_spirv_specialization*
+vk_spec_info_to_nir_spirv(const VkSpecializationInfo *spec_info,
+                          uint32_t *out_num_spec_entries)
+{
+   if (spec_info == NULL || spec_info->mapEntryCount == 0)
+      return NULL;
+
+   uint32_t num_spec_entries = spec_info->mapEntryCount;
+   struct nir_spirv_specialization *spec_entries =
+      calloc(num_spec_entries, sizeof(*spec_entries));
+
+   for (uint32_t i = 0; i < num_spec_entries; i++) {
+      VkSpecializationMapEntry entry = spec_info->pMapEntries[i];
+      const void *data = (uint8_t *)spec_info->pData + entry.offset;
+      assert((uint8_t *)data + entry.size <=
+             (uint8_t *)spec_info->pData + spec_info->dataSize);
+
+      spec_entries[i].id = spec_info->pMapEntries[i].constantID;
+      switch (entry.size) {
+      case 8:
+         spec_entries[i].value.u64 = *(const uint64_t *)data;
+         break;
+      case 4:
+         spec_entries[i].value.u32 = *(const uint32_t *)data;
+         break;
+      case 2:
+         spec_entries[i].value.u16 = *(const uint16_t *)data;
+         break;
+      case 1:
+         spec_entries[i].value.u8 = *(const uint8_t *)data;
+         break;
+      case 0:
+      default:
+         /* The Vulkan spec says:
+          *
+          *    "For a constantID specialization constant declared in a
+          *    shader, size must match the byte size of the constantID. If
+          *    the specialization constant is of type boolean, size must be
+          *    the byte size of VkBool32."
+          *
+          * Therefore, since only scalars can be decorated as
+          * specialization constants, we can assume that if it doesn't have
+          * a size of 1, 2, 4, or 8, any use in a shader would be invalid
+          * usage.  The spec further says:
+          *
+          *    "If a constantID value is not a specialization constant ID
+          *    used in the shader, that map entry does not affect the
+          *    behavior of the pipeline."
+          *
+          * so we should ignore any invalid specialization constants rather
+          * than crash or error out when we see one.
+          */
+         break;
+      }
+   }
+
+   *out_num_spec_entries = num_spec_entries;
+   return spec_entries;
+}

src/vulkan/util/vk_util.h

@@ -272,6 +272,12 @@ mesa_to_vk_shader_stage(gl_shader_stage mesa_stage)
         (_i)++, (_draw) = (const VkMultiDrawInfoEXT*)((const uint8_t*)(_draw) + (_stride)))
 
 
+struct nir_spirv_specialization;
+
+struct nir_spirv_specialization*
+vk_spec_info_to_nir_spirv(const VkSpecializationInfo *spec_info,
+                          uint32_t *out_num_spec_entries);
+
 #ifdef __cplusplus
 }
 #endif