nir: Carve out nir_lower_samplers from GLSL code.

Lowering samplers is needed to produce NIR that can actually be
consumed by some gallium drivers, so it doesn't make sense to
to keep it only in the GLSL code.

This commit introduces nir_lower_samplers to compiler/nir,
while maintains the GL-specific function too.

Signed-off-by: Timur Kristóf <[email protected]>
Reviewed-by: Connor Abbott <[email protected]>

5 files changed, 159 insertions, 127 deletions

diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index edf1b936ac1..ac6c0670444 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -272,6 +272,7 @@ NIR_FILES = \
 	nir/nir_lower_phis_to_scalar.c \
 	nir/nir_lower_regs_to_ssa.c \
 	nir/nir_lower_returns.c \
+	nir/nir_lower_samplers.c \
 	nir/nir_lower_scratch.c \
 	nir/nir_lower_subgroups.c \
 	nir/nir_lower_system_values.c \
diff --git a/src/compiler/glsl/gl_nir_lower_samplers.c b/src/compiler/glsl/gl_nir_lower_samplers.c
index 85535c074dc..08817316b9c 100644
--- a/src/compiler/glsl/gl_nir_lower_samplers.c
+++ b/src/compiler/glsl/gl_nir_lower_samplers.c
@@ -24,142 +24,16 @@
  */
 
 #include "compiler/nir/nir.h"
-#include "compiler/nir/nir_builder.h"
 #include "gl_nir.h"
-#include "ir_uniform.h"
-
-#include "main/compiler.h"
-#include "main/mtypes.h"
-
-static void
-lower_tex_src_to_offset(nir_builder *b,
-                        nir_tex_instr *instr, unsigned src_idx)
-{
-   nir_ssa_def *index = NULL;
-   unsigned base_index = 0;
-   unsigned array_elements = 1;
-   nir_tex_src *src = &instr->src[src_idx];
-   bool is_sampler = src->src_type == nir_tex_src_sampler_deref;
-
-   /* We compute first the offsets */
-   nir_deref_instr *deref = nir_instr_as_deref(src->src.ssa->parent_instr);
-   while (deref->deref_type != nir_deref_type_var) {
-      assert(deref->parent.is_ssa);
-      nir_deref_instr *parent =
-         nir_instr_as_deref(deref->parent.ssa->parent_instr);
-
-      assert(deref->deref_type == nir_deref_type_array);
-
-      if (nir_src_is_const(deref->arr.index) && index == NULL) {
-         /* We're still building a direct index */
-         base_index += nir_src_as_uint(deref->arr.index) * array_elements;
-      } else {
-         if (index == NULL) {
-            /* We used to be direct but not anymore */
-            index = nir_imm_int(b, base_index);
-            base_index = 0;
-         }
-
-         index = nir_iadd(b, index,
-                          nir_imul(b, nir_imm_int(b, array_elements),
-                                   nir_ssa_for_src(b, deref->arr.index, 1)));
-      }
-
-      array_elements *= glsl_get_length(parent->type);
-
-      deref = parent;
-   }
-
-   if (index)
-      index = nir_umin(b, index, nir_imm_int(b, array_elements - 1));
-
-   /* We hit the deref_var.  This is the end of the line */
-   assert(deref->deref_type == nir_deref_type_var);
-
-   base_index += deref->var->data.binding;
-
-   /* We have the offsets, we apply them, rewriting the source or removing
-    * instr if needed
-    */
-   if (index) {
-      nir_instr_rewrite_src(&instr->instr, &src->src,
-                            nir_src_for_ssa(index));
-
-      src->src_type = is_sampler ?
-         nir_tex_src_sampler_offset :
-         nir_tex_src_texture_offset;
-
-      instr->texture_array_size = array_elements;
-   } else {
-      nir_tex_instr_remove_src(instr, src_idx);
-   }
-
-   if (is_sampler) {
-      instr->sampler_index = base_index;
-   } else {
-      instr->texture_index = base_index;
-      instr->texture_array_size = array_elements;
-   }
-}
-
-static bool
-lower_sampler(nir_builder *b, nir_tex_instr *instr)
-{
-   int texture_idx =
-      nir_tex_instr_src_index(instr, nir_tex_src_texture_deref);
-
-   if (texture_idx >= 0) {
-      b->cursor = nir_before_instr(&instr->instr);
-
-      lower_tex_src_to_offset(b, instr, texture_idx);
-   }
-
-   int sampler_idx =
-      nir_tex_instr_src_index(instr, nir_tex_src_sampler_deref);
-
-   if (sampler_idx >= 0) {
-      lower_tex_src_to_offset(b, instr, sampler_idx);
-   }
-
-   if (texture_idx < 0 && sampler_idx < 0)
-      return false;
-
-   return true;
-}
-
-static bool
-lower_impl(nir_function_impl *impl)
-{
-   nir_builder b;
-   nir_builder_init(&b, impl);
-   bool progress = false;
-
-   nir_foreach_block(block, impl) {
-      nir_foreach_instr(instr, block) {
-         if (instr->type == nir_instr_type_tex)
-            progress |= lower_sampler(&b, nir_instr_as_tex(instr));
-      }
-   }
-
-   return progress;
-}
 
 bool
 gl_nir_lower_samplers(nir_shader *shader,
                       const struct gl_shader_program *shader_program)
 {
-   bool progress = false;
-
    /* First, use gl_nir_lower_samplers_as_derefs to set var->data.binding
     * based on the uniforms, and split structures to simplify derefs.
     */
    gl_nir_lower_samplers_as_deref(shader, shader_program);
 
-   /* Next, lower derefs to offsets. */
-   nir_foreach_function(function, shader) {
-      if (function->impl)
-         progress |= lower_impl(function->impl);
-   }
-
-   return progress;
+   return nir_lower_samplers(shader);
 }
diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build
index 04e4f729902..1da26ef561c 100644
--- a/src/compiler/nir/meson.build
+++ b/src/compiler/nir/meson.build
@@ -152,6 +152,7 @@ files_libnir = files(
   'nir_lower_point_size.c',
   'nir_lower_regs_to_ssa.c',
   'nir_lower_returns.c',
+  'nir_lower_samplers.c',
   'nir_lower_scratch.c',
   'nir_lower_subgroups.c',
   'nir_lower_system_values.c',
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index bad1d6af212..ab1aab774a0 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -3938,6 +3938,8 @@ bool nir_lower_phis_to_regs_block(nir_block *block);
 bool nir_lower_ssa_defs_to_regs_block(nir_block *block);
 bool nir_rematerialize_derefs_in_use_blocks_impl(nir_function_impl *impl);
 
+bool nir_lower_samplers(nir_shader *shader);
+
 /* This is here for unit tests. */
 bool nir_opt_comparison_pre_impl(nir_function_impl *impl);
 
diff --git a/src/compiler/nir/nir_lower_samplers.c b/src/compiler/nir/nir_lower_samplers.c
new file mode 100644
index 00000000000..5a440f7117c
--- /dev/null
+++ b/src/compiler/nir/nir_lower_samplers.c
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2005-2007  Brian Paul   All Rights Reserved.
+ * Copyright (C) 2008  VMware, Inc.   All Rights Reserved.
+ * Copyright © 2014 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/nir.h"
+#include "nir_builder.h"
+
+static void
+lower_tex_src_to_offset(nir_builder *b,
+                        nir_tex_instr *instr, unsigned src_idx)
+{
+   nir_ssa_def *index = NULL;
+   unsigned base_index = 0;
+   unsigned array_elements = 1;
+   nir_tex_src *src = &instr->src[src_idx];
+   bool is_sampler = src->src_type == nir_tex_src_sampler_deref;
+
+   /* We compute first the offsets */
+   nir_deref_instr *deref = nir_instr_as_deref(src->src.ssa->parent_instr);
+   while (deref->deref_type != nir_deref_type_var) {
+      assert(deref->parent.is_ssa);
+      nir_deref_instr *parent =
+         nir_instr_as_deref(deref->parent.ssa->parent_instr);
+
+      assert(deref->deref_type == nir_deref_type_array);
+
+      if (nir_src_is_const(deref->arr.index) && index == NULL) {
+         /* We're still building a direct index */
+         base_index += nir_src_as_uint(deref->arr.index) * array_elements;
+      } else {
+         if (index == NULL) {
+            /* We used to be direct but not anymore */
+            index = nir_imm_int(b, base_index);
+            base_index = 0;
+         }
+
+         index = nir_iadd(b, index,
+                          nir_imul(b, nir_imm_int(b, array_elements),
+                                   nir_ssa_for_src(b, deref->arr.index, 1)));
+      }
+
+      array_elements *= glsl_get_length(parent->type);
+
+      deref = parent;
+   }
+
+   if (index)
+      index = nir_umin(b, index, nir_imm_int(b, array_elements - 1));
+
+   /* We hit the deref_var.  This is the end of the line */
+   assert(deref->deref_type == nir_deref_type_var);
+
+   base_index += deref->var->data.binding;
+
+   /* We have the offsets, we apply them, rewriting the source or removing
+    * instr if needed
+    */
+   if (index) {
+      nir_instr_rewrite_src(&instr->instr, &src->src,
+                            nir_src_for_ssa(index));
+
+      src->src_type = is_sampler ?
+         nir_tex_src_sampler_offset :
+         nir_tex_src_texture_offset;
+
+      instr->texture_array_size = array_elements;
+   } else {
+      nir_tex_instr_remove_src(instr, src_idx);
+   }
+
+   if (is_sampler) {
+      instr->sampler_index = base_index;
+   } else {
+      instr->texture_index = base_index;
+      instr->texture_array_size = array_elements;
+   }
+}
+
+static bool
+lower_sampler(nir_builder *b, nir_tex_instr *instr)
+{
+   int texture_idx =
+      nir_tex_instr_src_index(instr, nir_tex_src_texture_deref);
+
+   if (texture_idx >= 0) {
+      b->cursor = nir_before_instr(&instr->instr);
+
+      lower_tex_src_to_offset(b, instr, texture_idx);
+   }
+
+   int sampler_idx =
+      nir_tex_instr_src_index(instr, nir_tex_src_sampler_deref);
+
+   if (sampler_idx >= 0) {
+      lower_tex_src_to_offset(b, instr, sampler_idx);
+   }
+
+   if (texture_idx < 0 && sampler_idx < 0)
+      return false;
+
+   return true;
+}
+
+static bool
+lower_impl(nir_function_impl *impl)
+{
+   nir_builder b;
+   nir_builder_init(&b, impl);
+   bool progress = false;
+
+   nir_foreach_block(block, impl) {
+      nir_foreach_instr(instr, block) {
+         if (instr->type == nir_instr_type_tex)
+            progress |= lower_sampler(&b, nir_instr_as_tex(instr));
+      }
+   }
+
+   return progress;
+}
+
+bool
+nir_lower_samplers(nir_shader *shader)
+{
+   bool progress = false;
+
+   /* Next, lower derefs to offsets. */
+   nir_foreach_function(function, shader) {
+      if (function->impl)
+         progress |= lower_impl(function->impl);
+   }
+
+   return progress;
+}