From c6e0c062daa55269661b190deaec40e9749198bc Mon Sep 17 00:00:00 2001
From: Rhys Perry <pendingchaos02@gmail.com>
Date: Thu, 27 Feb 2020 19:56:22 +0000
Subject: [PATCH] aco: improve control flow handling in GFX6-9 NOP pass
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Fixes Detroit: Become Human hang. Also affects World of Warships.

pipeline-db (Tahiti):
Totals from affected shaders:
SGPRS: 0 -> 0 (0.00 %)
VGPRS: 0 -> 0 (0.00 %)
Spilled SGPRs: 0 -> 0 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 0 -> 0 (0.00 %) bytes
LDS: 0 -> 0 (0.00 %) blocks
Max Waves: 0 -> 0 (0.00 %)

pipeline-db (Polaris):
Totals from affected shaders:
SGPRS: 17168 -> 17168 (0.00 %)
VGPRS: 11296 -> 11296 (0.00 %)
Spilled SGPRs: 1870 -> 1870 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 1472628 -> 1473292 (0.05 %) bytes
LDS: 0 -> 0 (0.00 %) blocks
Max Waves: 628 -> 628 (0.00 %)

pipeline-db (Vega):
Totals from affected shaders:
SGPRS: 17168 -> 17168 (0.00 %)
VGPRS: 11296 -> 11296 (0.00 %)
Spilled SGPRs: 1870 -> 1870 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 1409716 -> 1410380 (0.05 %) bytes
LDS: 0 -> 0 (0.00 %) blocks
Max Waves: 0 -> 0 (0.00 %)

Max Waves is lower than it should be because of a null winsys bug.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4004>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4004>
---
 src/amd/compiler/aco_insert_NOPs.cpp | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/amd/compiler/aco_insert_NOPs.cpp b/src/amd/compiler/aco_insert_NOPs.cpp
index 4302711ba81..75dbe852174 100644
--- a/src/amd/compiler/aco_insert_NOPs.cpp
+++ b/src/amd/compiler/aco_insert_NOPs.cpp
@@ -225,7 +225,16 @@ int handle_raw_hazard_internal(Program *program, Block *block,
          return 0;
    }
 
-   return 0;
+   int res = 0;
+
+   /* Loops require branch instructions, which count towards the wait
+    * states. So even with loops this should finish unless nops_needed is some
+    * huge value. */
+   for (unsigned lin_pred : block->linear_preds) {
+      res = std::max(res, handle_raw_hazard_internal<Valu, Vintrp, Salu>(
+         program, &program->blocks[lin_pred], nops_needed, reg, mask));
+   }
+   return res;
 }
 
 template <bool Valu, bool Vintrp, bool Salu>
@@ -763,14 +772,10 @@ void mitigate_hazards(Program *program)
 
 void insert_NOPs(Program* program)
 {
-   if (program->chip_class >= GFX10) {
+   if (program->chip_class >= GFX10)
       mitigate_hazards<NOP_ctx_gfx10, handle_instruction_gfx10>(program);
-   } else {
-      for (Block& block : program->blocks) {
-         NOP_ctx_gfx6 ctx;
-         handle_block<NOP_ctx_gfx6, handle_instruction_gfx6>(program, ctx, block);
-      }
-   }
+   else
+      mitigate_hazards<NOP_ctx_gfx6, handle_instruction_gfx6>(program);
 }
 
 }
-- 
2.30.2