From 48f093a45b823caa60cad27bf91c0e642857c5ea Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tapani=20P=C3=A4lli?= <tapani.palli@intel.com>
Date: Thu, 2 May 2019 13:49:41 +0300
Subject: [PATCH] nir: HACK - refuse loop unrolling with hacky restrictions
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Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
---
 src/compiler/nir/nir.h                 |  3 ++
 src/compiler/nir/nir_loop_analyze.c    | 38 ++++++++++++++++++++++++++
 src/compiler/nir/nir_opt_loop_unroll.c |  4 +++
 3 files changed, 45 insertions(+)

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 3fc01b798e4..313a10205b8 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -1963,6 +1963,9 @@ typedef struct {
    /* Unroll the loop regardless of its size */
    bool force_unroll;
 
+   /* Do not unroll the loop, no matter what. */
+   bool force_no_unroll;
+
    /* Does the loop contain complex loop terminators, continues or other
     * complex behaviours? If this is true we can't rely on
     * loop_terminator_list to be complete or accurate.
diff --git a/src/compiler/nir/nir_loop_analyze.c b/src/compiler/nir/nir_loop_analyze.c
index 0ae9533e007..45c66fb237b 100644
--- a/src/compiler/nir/nir_loop_analyze.c
+++ b/src/compiler/nir/nir_loop_analyze.c
@@ -1016,6 +1016,35 @@ force_unroll_array_access(loop_info_state *state, nir_deref_instr *deref)
    return false;
 }
 
+static bool
+force_no_unroll_heuristics(loop_info_state *state, nir_block *block)
+{
+   uint32_t unwanted_ops = 0;
+   nir_foreach_instr(instr, block) {
+      switch (instr->type) {
+      case nir_instr_type_alu: {
+         nir_alu_instr *alu = nir_instr_as_alu(instr);
+         switch (alu->op) {
+         case nir_op_u2u8:
+         case nir_op_i2i8:
+            unwanted_ops++;
+            break;
+         default:
+            break;
+         }
+         break;
+      }
+      default:
+         break;
+      }
+   }
+
+   if (unwanted_ops > 10)
+      return true;
+
+   return false;
+}
+
 static bool
 force_unroll_heuristics(loop_info_state *state, nir_block *block)
 {
@@ -1115,6 +1144,15 @@ get_loop_info(loop_info_state *state, nir_function_impl *impl)
          break;
       }
    }
+
+   nir_foreach_block_in_cf_node(block, &state->loop->cf_node) {
+      if (force_no_unroll_heuristics(state, block)) {
+         state->loop->info->force_unroll = false;
+         state->loop->info->force_no_unroll = true;
+         break;
+      }
+   }
+
 }
 
 static loop_info_state *
diff --git a/src/compiler/nir/nir_opt_loop_unroll.c b/src/compiler/nir/nir_opt_loop_unroll.c
index c0198390749..bdb4a7c64d4 100644
--- a/src/compiler/nir/nir_opt_loop_unroll.c
+++ b/src/compiler/nir/nir_opt_loop_unroll.c
@@ -783,6 +783,10 @@ check_unrolling_restrictions(nir_shader *shader, nir_loop *loop)
       return false;
 
    nir_loop_info *li = loop->info;
+
+   if (li->force_no_unroll)
+      return false;
+
    unsigned max_iter = shader->options->max_unroll_iterations;
    unsigned trip_count =
       li->max_trip_count ? li->max_trip_count : li->guessed_trip_count;
-- 
2.20.1