From 857b9f428ea6009da98dae447cbcb7a86b17bf2b Mon Sep 17 00:00:00 2001
From: Rhys Perry <pendingchaos02@gmail.com>
Date: Thu, 3 Dec 2020 19:55:10 +0000
Subject: [PATCH] aco: don't assume src=lower when splitting self-intersecting
 copies
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Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Fixes: 09c584caeb2 ("aco: split self-intersecting copies instead of swapping")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7798>
(cherry picked from commit 2c40846ab6f8bf161dc79ed99b51702055c6d538)
---
 .pick_status.json                          |  2 +-
 src/amd/compiler/aco_lower_to_hw_instr.cpp | 29 ++++++++++------------
 2 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 6fbb3bd2c6a..cbd1216abd0 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -589,7 +589,7 @@
         "description": "aco: don't assume src=lower when splitting self-intersecting copies",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": "09c584caeb2a1e7446ac2016ce7a7d8f0586774b"
     },
diff --git a/src/amd/compiler/aco_lower_to_hw_instr.cpp b/src/amd/compiler/aco_lower_to_hw_instr.cpp
index 1962c17032f..acbe52e99cb 100644
--- a/src/amd/compiler/aco_lower_to_hw_instr.cpp
+++ b/src/amd/compiler/aco_lower_to_hw_instr.cpp
@@ -1532,31 +1532,28 @@ void handle_operands(std::map<PhysReg, copy_operation>& copy_map, lower_context*
 
       /* if this is self-intersecting, we have to split it because
        * self-intersecting swaps don't make sense */
-      PhysReg lower = swap.def.physReg();
-      PhysReg higher = swap.op.physReg();
-      if (lower.reg_b > higher.reg_b)
-         std::swap(lower, higher);
-      if (higher.reg_b - lower.reg_b < (int)swap.bytes) {
-         unsigned offset = higher.reg_b - lower.reg_b;
+      PhysReg src = swap.op.physReg(), dst = swap.def.physReg();
+      if (abs((int)src.reg_b - (int)dst.reg_b) < (int)swap.bytes) {
+         unsigned offset = abs((int)src.reg_b - (int)dst.reg_b);
          RegType type = swap.def.regClass().type();
 
          copy_operation middle;
-         lower.reg_b += offset;
-         higher.reg_b += offset;
+         src.reg_b += offset;
+         dst.reg_b += offset;
          middle.bytes = swap.bytes - offset * 2;
          memcpy(middle.uses, swap.uses + offset, middle.bytes);
-         middle.op = Operand(lower, RegClass::get(type, middle.bytes));
-         middle.def = Definition(higher, RegClass::get(type, middle.bytes));
-         copy_map[higher] = middle;
+         middle.op = Operand(src, RegClass::get(type, middle.bytes));
+         middle.def = Definition(dst, RegClass::get(type, middle.bytes));
+         copy_map[dst] = middle;
 
          copy_operation end;
-         lower.reg_b += middle.bytes;
-         higher.reg_b += middle.bytes;
+         src.reg_b += middle.bytes;
+         dst.reg_b += middle.bytes;
          end.bytes = swap.bytes - (offset + middle.bytes);
          memcpy(end.uses, swap.uses + offset + middle.bytes, end.bytes);
-         end.op = Operand(lower, RegClass::get(type, end.bytes));
-         end.def = Definition(higher, RegClass::get(type, end.bytes));
-         copy_map[higher] = end;
+         end.op = Operand(src, RegClass::get(type, end.bytes));
+         end.def = Definition(dst, RegClass::get(type, end.bytes));
+         copy_map[dst] = end;
 
          memset(swap.uses + offset, 0, swap.bytes - offset);
          swap.bytes = offset;