radv: run nir_opt_shrink_load

LLVM can't shrink loads.

Polaris10:
Totals from affected shaders:
SGPRS: 62528 -> 59955 (-4.11 %)
VGPRS: 44708 -> 44616 (-0.21 %)
Spilled SGPRs: 16 -> 8 (-50.00 %)
Code Size: 1355504 -> 1355172 (-0.02 %) bytes
Max Waves: 11710 -> 11670 (-0.34 %)

Vega10:
Totals from affected shaders:
SGPRS: 51448 -> 50371 (-2.09 %)
VGPRS: 39140 -> 39048 (-0.24 %)
Spilled SGPRs: 16 -> 16 (0.00 %)
Code Size: 1307188 -> 1304296 (-0.22 %) bytes
Max Waves: 11312 -> 11292 (-0.18 %)

This reduces SGPRs spilling in MadMax, and it also reduces
number of SGPRs in DOW3 and F12017. The number of waves slightly
decreases in F1 but I don't see any performance changes after
benchmarking it. Talos and Serious Sam are not affected because
they don't use any push constants.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>

1 files changed, 67 insertions, 0 deletions

diff --git a/src/compiler/nir/nir_opt_shrink_load.c b/src/compiler/nir/nir_opt_shrink_load.c
new file mode 100644
index 00000000000..f97b7f9b67f
--- /dev/null
+++ b/src/compiler/nir/nir_opt_shrink_load.c
@@ -0,0 +1,67 @@
+/*
+ * Copyright © 2018 Valve 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"
+
+static bool
+opt_shrink_load(nir_intrinsic_instr *instr)
+{
+   bool progress = false;
+
+   if (instr->intrinsic == nir_intrinsic_load_push_constant) {
+      unsigned mask = nir_ssa_def_components_read(&instr->dest.ssa);
+
+      if (instr->num_components > util_last_bit(mask)) {
+         instr->num_components = util_last_bit(mask);
+         instr->dest.ssa.num_components = instr->num_components;
+         progress = true;
+      }
+   }
+
+   return progress;
+}
+
+bool
+nir_opt_shrink_load(nir_shader *shader)
+{
+   bool progress = false;
+
+   nir_foreach_function(function, shader) {
+      if (!function->impl)
+         continue;
+
+      nir_foreach_block(block, function->impl) {
+         nir_foreach_instr(instr, block) {
+            if (instr->type != nir_instr_type_intrinsic)
+               continue;
+
+            progress |= opt_shrink_load(nir_instr_as_intrinsic(instr));
+         }
+      }
+
+      nir_metadata_preserve(function->impl, nir_metadata_block_index |
+                                            nir_metadata_dominance);
+   }
+
+   return progress;
+}