i965: Add nir based intrinsic lowering and thread ID uniform

We add a lowering pass for nir intrinsics. This pass can replace nir
intrinsics with driver specific nir lower code.

We lower the gl_LocalInvocationIndex intrinsic based on a uniform
which is loaded with a thread specific ID.

We also lower the gl_LocalInvocationID based on
gl_LocalInvocationIndex.

v2:
 * Create variable during lowering pass. (Ken)

v3:
 * Don't create a variable, but instead just insert an intrisic call
   to load a uniform from the allocated location. (Jason)

v4:
 * Don't run this pass if thread_local_id_index < 0

Cc: "12.0" <[email protected]>
Signed-off-by: Jordan Justen <[email protected]>
Reviewed-by: Jason Ekstrand <[email protected]>

4 files changed, 190 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
index d8711edcf39..f448551cca3 100644
--- a/src/mesa/drivers/dri/i965/Makefile.sources
+++ b/src/mesa/drivers/dri/i965/Makefile.sources
@@ -46,6 +46,7 @@ i965_compiler_FILES = \
 	brw_nir.c \
 	brw_nir_analyze_boolean_resolves.c \
 	brw_nir_attribute_workarounds.c \
+	brw_nir_intrinsics.c \
 	brw_nir_opt_peephole_ffma.c \
 	brw_packed_float.c \
 	brw_predicated_break.cpp \
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 6bd28718280..975ac9eb6ba 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -6599,6 +6599,7 @@ brw_compile_cs(const struct brw_compiler *compiler, void *log_data,
               (unsigned)4 * (prog_data->thread_local_id_index + 1));
    }
 
+   brw_nir_lower_intrinsics(shader, &prog_data->base);
    shader = brw_postprocess_nir(shader, compiler->devinfo, true);
 
    prog_data->local_size[0] = shader->info.cs.local_size[0];
diff --git a/src/mesa/drivers/dri/i965/brw_nir.h b/src/mesa/drivers/dri/i965/brw_nir.h
index 409e49a1a07..74c354f5c82 100644
--- a/src/mesa/drivers/dri/i965/brw_nir.h
+++ b/src/mesa/drivers/dri/i965/brw_nir.h
@@ -91,6 +91,8 @@ void brw_nir_analyze_boolean_resolves(nir_shader *nir);
 nir_shader *brw_preprocess_nir(const struct brw_compiler *compiler,
                                nir_shader *nir);
 
+bool brw_nir_lower_intrinsics(nir_shader *nir,
+                              struct brw_stage_prog_data *prog_data);
 void brw_nir_lower_vs_inputs(nir_shader *nir,
                              const struct brw_device_info *devinfo,
                              bool is_scalar,
diff --git a/src/mesa/drivers/dri/i965/brw_nir_intrinsics.c b/src/mesa/drivers/dri/i965/brw_nir_intrinsics.c
new file mode 100644
index 00000000000..972b1171730
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_nir_intrinsics.c
@@ -0,0 +1,186 @@
+/*
+ * Copyright (c) 2016 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 "brw_nir.h"
+#include "compiler/nir/nir_builder.h"
+
+struct lower_intrinsics_state {
+   nir_shader *nir;
+   union {
+      struct brw_stage_prog_data *prog_data;
+      struct brw_cs_prog_data *cs_prog_data;
+   };
+   nir_function_impl *impl;
+   bool progress;
+   nir_builder builder;
+   bool cs_thread_id_used;
+};
+
+static nir_ssa_def *
+read_thread_local_id(struct lower_intrinsics_state *state)
+{
+   assert(state->cs_prog_data->thread_local_id_index >= 0);
+   state->cs_thread_id_used = true;
+   const int id_index = state->cs_prog_data->thread_local_id_index;
+
+   nir_builder *b = &state->builder;
+   nir_shader *nir = state->nir;
+   nir_intrinsic_instr *load =
+      nir_intrinsic_instr_create(nir, nir_intrinsic_load_uniform);
+   load->num_components = 1;
+   load->src[0] = nir_src_for_ssa(nir_imm_int(b, 0));
+   nir_ssa_dest_init(&load->instr, &load->dest, 1, 32, NULL);
+   nir_intrinsic_set_base(load, id_index * sizeof(uint32_t));
+   nir_intrinsic_set_range(load, sizeof(uint32_t));
+   nir_builder_instr_insert(b, &load->instr);
+   return &load->dest.ssa;
+}
+
+static bool
+lower_cs_intrinsics_convert_block(struct lower_intrinsics_state *state,
+                                  nir_block *block)
+{
+   bool progress = false;
+   nir_builder *b = &state->builder;
+   nir_shader *nir = state->nir;
+
+   nir_foreach_instr_safe(instr, block) {
+      if (instr->type != nir_instr_type_intrinsic)
+         continue;
+
+      nir_intrinsic_instr *intrinsic = nir_instr_as_intrinsic(instr);
+
+      b->cursor = nir_after_instr(&intrinsic->instr);
+
+      nir_ssa_def *sysval;
+      switch (intrinsic->intrinsic) {
+      case nir_intrinsic_load_local_invocation_index: {
+         assert(nir->stage == MESA_SHADER_COMPUTE);
+         /* We construct the local invocation index from:
+          *
+          *    gl_LocalInvocationIndex =
+          *       cs_thread_local_id + channel_num;
+          */
+         nir_ssa_def *thread_local_id = read_thread_local_id(state);
+         nir_ssa_def *channel =
+            nir_load_system_value(b, nir_intrinsic_load_channel_num, 0);
+         sysval = nir_iadd(b, channel, thread_local_id);
+         break;
+      }
+
+      case nir_intrinsic_load_local_invocation_id: {
+         assert(nir->stage == MESA_SHADER_COMPUTE);
+         /* We lower gl_LocalInvocationID from gl_LocalInvocationIndex based
+          * on this formula:
+          *
+          *    gl_LocalInvocationID.x =
+          *       gl_LocalInvocationIndex % gl_WorkGroupSize.x;
+          *    gl_LocalInvocationID.y =
+          *       (gl_LocalInvocationIndex / gl_WorkGroupSize.x) %
+          *       gl_WorkGroupSize.y;
+          *    gl_LocalInvocationID.z =
+          *       (gl_LocalInvocationIndex /
+          *        (gl_WorkGroupSize.x * gl_WorkGroupSize.y)) %
+          *       gl_WorkGroupSize.z;
+          */
+         unsigned *size = nir->info.cs.local_size;
+
+         nir_ssa_def *local_index =
+            nir_load_system_value(b, nir_intrinsic_load_local_invocation_index, 0);
+
+         nir_const_value uvec3;
+         uvec3.u32[0] = 1;
+         uvec3.u32[1] = size[0];
+         uvec3.u32[2] = size[0] * size[1];
+         nir_ssa_def *div_val = nir_build_imm(b, 3, 32, uvec3);
+         uvec3.u32[0] = size[0];
+         uvec3.u32[1] = size[1];
+         uvec3.u32[2] = size[2];
+         nir_ssa_def *mod_val = nir_build_imm(b, 3, 32, uvec3);
+
+         sysval = nir_imod(b, nir_idiv(b, local_index, div_val), mod_val);
+         break;
+      }
+
+      default:
+         continue;
+      }
+
+      nir_ssa_def_rewrite_uses(&intrinsic->dest.ssa, nir_src_for_ssa(sysval));
+      nir_instr_remove(&intrinsic->instr);
+
+      state->progress = true;
+   }
+
+   return progress;
+}
+
+static void
+lower_cs_intrinsics_convert_impl(struct lower_intrinsics_state *state)
+{
+   nir_builder_init(&state->builder, state->impl);
+
+   nir_foreach_block(block, state->impl) {
+      lower_cs_intrinsics_convert_block(state, block);
+   }
+
+   nir_metadata_preserve(state->impl,
+                         nir_metadata_block_index | nir_metadata_dominance);
+}
+
+bool
+brw_nir_lower_intrinsics(nir_shader *nir, struct brw_stage_prog_data *prog_data)
+{
+   /* Currently we only lower intrinsics for compute shaders */
+   if (nir->stage != MESA_SHADER_COMPUTE)
+      return false;
+
+   bool progress = false;
+   struct lower_intrinsics_state state;
+   memset(&state, 0, sizeof(state));
+   state.nir = nir;
+   state.prog_data = prog_data;
+
+   /* Currently this pass only lowers intrinsics using the uniform specified
+    * by thread_local_id_index.
+    */
+   if (nir->stage == MESA_SHADER_COMPUTE &&
+       state.cs_prog_data->thread_local_id_index < 0)
+      return false;
+
+   do {
+      state.progress = false;
+      nir_foreach_function(function, nir) {
+         if (function->impl) {
+            state.impl = function->impl;
+            lower_cs_intrinsics_convert_impl(&state);
+         }
+      }
+      progress |= state.progress;
+   } while (state.progress);
+
+   if (nir->stage == MESA_SHADER_COMPUTE && !state.cs_thread_id_used)
+      state.cs_prog_data->thread_local_id_index = -1;
+
+   return progress;
+}