nir: Add a SSA type gathering pass

This new pass (which isn't even compile-tested) attempts to determine
the ALU type of all the SSA values in a function impl.  It takes a
greedy approach and assigns intness or floatness to everything it thinks
can possibly contain an int or a float.  Some values will be labled as
both int and float and some will be labled as neither and it is up to
the caller to decide what to do with this information.  However, for a
"nice" shader where the original source contained no bit-casts and no
implicit bit-casts were introduced by optimizations, there shouldn't be
any overlap in the two sets save for the odd CSEd zero constant.

Reviewed-by: Vasily Khoruzhick <[email protected]>

3 files changed, 222 insertions, 0 deletions

diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build
index f79752df663..a8faeb9c018 100644
--- a/src/compiler/nir/meson.build
+++ b/src/compiler/nir/meson.build
@@ -100,6 +100,7 @@ files_libnir = files(
   'nir_format_convert.h',
   'nir_from_ssa.c',
   'nir_gather_info.c',
+  'nir_gather_ssa_types.c',
   'nir_gather_xfb_info.c',
   'nir_gs_count_vertices.c',
   'nir_inline_functions.c',
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 3083adbfcd9..ed21032e5e1 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -3044,6 +3044,10 @@ bool nir_lower_vars_to_scratch(nir_shader *shader,
 
 void nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint);
 
+void nir_gather_ssa_types(nir_function_impl *impl,
+                          BITSET_WORD *float_types,
+                          BITSET_WORD *int_types);
+
 void nir_assign_var_locations(struct exec_list *var_list, unsigned *size,
                               int (*type_size)(const struct glsl_type *, bool));
 
diff --git a/src/compiler/nir/nir_gather_ssa_types.c b/src/compiler/nir/nir_gather_ssa_types.c
new file mode 100644
index 00000000000..73bd0f9bc6a
--- /dev/null
+++ b/src/compiler/nir/nir_gather_ssa_types.c
@@ -0,0 +1,217 @@
+/*
+ * 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 "util/bitset.h"
+
+static void
+set_type(unsigned idx, nir_alu_type type, BITSET_WORD *float_types,
+         BITSET_WORD *int_types, bool *progress)
+{
+   switch (nir_alu_type_get_base_type(type)) {
+   case nir_type_bool:
+   case nir_type_int:
+   case nir_type_uint:
+      if (int_types && !BITSET_TEST(int_types, idx)) {
+         *progress = true;
+         BITSET_SET(int_types, idx);
+      }
+      break;
+
+   case nir_type_float:
+      if (float_types && !BITSET_TEST(float_types, idx)) {
+         *progress = true;
+         BITSET_SET(float_types, idx);
+      }
+      break;
+
+   default:
+      unreachable("Invalid base nir_alu_type");
+   }
+}
+
+static void
+copy_types(unsigned a, unsigned b, BITSET_WORD *float_types,
+           BITSET_WORD *int_types, bool *progress)
+{
+   /* If the bits do not agree then one of them is set but not both.  Flag
+    * progress and set both bits.
+    */
+   if (float_types && (BITSET_TEST(float_types, a) !=
+                       BITSET_TEST(float_types, b))) {
+      *progress = true;
+      BITSET_SET(float_types, a);
+      BITSET_SET(float_types, b);
+   }
+
+   if (int_types && (BITSET_TEST(int_types, a) !=
+                     BITSET_TEST(int_types, b))) {
+      *progress = true;
+      BITSET_SET(int_types, a);
+      BITSET_SET(int_types, b);
+   }
+}
+
+/** Gather up ALU types for SSA values
+ *
+ * This pass attempts to determine, for each SSA value, the type of data (int
+ * or float) that will be stored in it.  The pass is greedy in the sense that
+ * it just assigns intness or floatness to types without any attempt to sort
+ * out the interesting cases where a given type may be both.
+ *
+ * The output of the pass is a pair of bitsets which has the intness or
+ * floatness of each SSA value recorded by index.  It is the responsibility of
+ * the caller to index the SSA defs using nir_index_ssa_defs and allocate the
+ * bitsets.  Either bitset is allowed to be NULL in which case no data is
+ * recorded for that type.
+ */
+void
+nir_gather_ssa_types(nir_function_impl *impl,
+                     BITSET_WORD *float_types,
+                     BITSET_WORD *int_types)
+{
+   bool progress;
+   do {
+      progress = false;
+
+      nir_foreach_block(block, impl) {
+         nir_foreach_instr(instr, block) {
+            switch (instr->type) {
+            case nir_instr_type_alu: {
+               nir_alu_instr *alu = nir_instr_as_alu(instr);
+               assert(alu->dest.dest.is_ssa);
+               const nir_op_info *info = &nir_op_infos[alu->op];
+               switch (alu->op) {
+               case nir_op_imov:
+               case nir_op_fmov:
+               case nir_op_vec2:
+               case nir_op_vec3:
+               case nir_op_vec4:
+                  for (unsigned i = 0; i < info->num_inputs; i++) {
+                     assert(alu->src[i].src.is_ssa);
+                     copy_types(alu->src[i].src.ssa->index,
+                                alu->dest.dest.ssa.index,
+                                float_types, int_types, &progress);
+                  }
+                  break;
+
+               case nir_op_bcsel:
+               case nir_op_b32csel:
+                  set_type(alu->src[0].src.ssa->index, nir_type_bool,
+                           float_types, int_types, &progress);
+                  copy_types(alu->src[1].src.ssa->index,
+                             alu->dest.dest.ssa.index,
+                             float_types, int_types, &progress);
+                  copy_types(alu->src[2].src.ssa->index,
+                             alu->dest.dest.ssa.index,
+                             float_types, int_types, &progress);
+                  break;
+
+               default:
+                  for (unsigned i = 0; i < info->num_inputs; i++) {
+                     assert(alu->src[i].src.is_ssa);
+                     set_type(alu->src[i].src.ssa->index, info->input_types[i],
+                              float_types, int_types, &progress);
+                  }
+                  set_type(alu->dest.dest.ssa.index, info->output_type,
+                           float_types, int_types, &progress);
+               }
+               break;
+            }
+
+            case nir_instr_type_tex: {
+               nir_tex_instr *tex = nir_instr_as_tex(instr);
+               for (unsigned i = 0; i < tex->num_srcs; i++) {
+                  assert(tex->src[i].src.is_ssa);
+                  set_type(tex->src[i].src.ssa->index,
+                           nir_tex_instr_src_type(tex, i),
+                           float_types, int_types, &progress);
+               }
+               assert(tex->dest.is_ssa);
+               set_type(tex->dest.ssa.index, tex->dest_type,
+                        float_types, int_types, &progress);
+               break;
+            }
+
+            case nir_instr_type_intrinsic: {
+               nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+               /* We could go nuts here, but we'll just handle a few simple
+                * cases and let everything else be untyped.
+                */
+               switch (intrin->intrinsic) {
+               case nir_intrinsic_load_deref: {
+                  nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
+
+                  assert(intrin->dest.is_ssa);
+                  set_type(intrin->dest.ssa.index,
+                           nir_get_nir_type_for_glsl_type(deref->type),
+                           float_types, int_types, &progress);
+                  break;
+               }
+
+               case nir_intrinsic_store_deref: {
+                  nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
+
+                  assert(intrin->src[1].is_ssa);
+                  set_type(intrin->src[1].ssa->index,
+                           nir_get_nir_type_for_glsl_type(deref->type),
+                           float_types, int_types, &progress);
+                  break;
+               }
+
+               default: {
+                  /* For the most part, we leave other intrinsics alone.  Most
+                   * of them don't matter in OpenGL ES 2.0 drivers anyway.
+                   * However, we should at least check if this is some sort of
+                   * IO intrinsic and flag it's offset and index sources.
+                   */
+                  nir_src *offset_src = nir_get_io_offset_src(intrin);
+                  if (offset_src) {
+                     assert(offset_src->is_ssa);
+                     set_type(offset_src->ssa->index, nir_type_int,
+                              float_types, int_types, &progress);
+                  }
+                  break;
+               }
+               }
+               break;
+            }
+
+            case nir_instr_type_phi: {
+               nir_phi_instr *phi = nir_instr_as_phi(instr);
+               assert(phi->dest.is_ssa);
+               nir_foreach_phi_src(src, phi) {
+                  assert(src->src.is_ssa);
+                  copy_types(src->src.ssa->index, phi->dest.ssa.index,
+                             float_types, int_types, &progress);
+               }
+               break;
+            }
+
+            default:
+               break;
+            }
+         }
+      }
+   } while (progress);
+}