From b7ce613873a88a8349b95e041ec4983971d7affb Mon Sep 17 00:00:00 2001
From: Rickard Bolin <rickard.bolin@arm.com>
Date: Tue, 25 Feb 2025 16:54:23 +0000
Subject: [PATCH] MLBEDSW-10240: Prohibit fusing on DMA ops

Also prohibit fusing on Ethos-U55 Transpose operators

Change-Id: I6ab104659e7b5ae3706a1b8d18c97a564e060e39
Signed-off-by: Rickard Bolin <rickard.bolin@arm.com>
---
 ethosu/regor/architecture/ethosu55/ethos_u55.cpp | 10 +++++++++-
 ethosu/regor/architecture/ethosu85/ethos_u85.cpp |  6 ++++++
 ethosu/regor/architecture/ethosu85/ethos_u85.hpp |  1 +
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/ethosu/regor/architecture/ethosu55/ethos_u55.cpp b/ethosu/regor/architecture/ethosu55/ethos_u55.cpp
index 3fea9e9f..39c81120 100644
--- a/ethosu/regor/architecture/ethosu55/ethos_u55.cpp
+++ b/ethosu/regor/architecture/ethosu55/ethos_u55.cpp
@@ -727,12 +727,20 @@ void ArchEthosU55::Call(std::function<void(const std::string &)> callBack)
 int EthosU55OpGroup::Add(const ArchitectureOpGroupQuery &op, const std::vector<int> &dependsOn)
 {
     LOG_TRACE1("Trying to add op {}\n", OpTypeToString(op.type));
-
     if ( _opsCount >= 2 )
     {
         // Can only fuse 2 ops
         return 0;
     }
+    else if ( _opsCount == 1 )
+    {
+        // Can not fuse to DMA or Compound operators
+        auto hwOp = ArchEthosU55::GetHWOp(_ops[0].type);
+        if ( hwOp == EthosU55NpuOp::Dma || hwOp == EthosU55NpuOp::Compound )
+        {
+            return 0;
+        }
+    }
 
     if ( !CanRunOnNPU(op) )
     {
diff --git a/ethosu/regor/architecture/ethosu85/ethos_u85.cpp b/ethosu/regor/architecture/ethosu85/ethos_u85.cpp
index 45e15874..5ff35454 100644
--- a/ethosu/regor/architecture/ethosu85/ethos_u85.cpp
+++ b/ethosu/regor/architecture/ethosu85/ethos_u85.cpp
@@ -1419,6 +1419,11 @@ int EthosU85OpGroup::ExternalIfms(const ArchitectureOpGroupQuery &op)
 bool EthosU85OpGroup::Fuse(const ArchitectureOpGroupQuery &op, const std::vector<int> &dependsOn)
 {
     assert(_opsCount > 0);
+    if ( !_supportsFusing )
+    {
+        return false;
+    }
+
     if ( _chainLength > 1 )
     {
         // TODO MLBEDSW-9142: support fusing on chained ops
@@ -1584,6 +1589,7 @@ int EthosU85OpGroup::Add(const ArchitectureOpGroupQuery &op, const std::vector<i
     if ( _opsCount == 0 )
     {
         _supportsChaining = CanStartChain(op);
+        _supportsFusing = ArchEthosU85::GetHWOp(op.type) != EthosU85NpuOp::Dma;
         _externalIfms = externalInputs;
         _chainLength = 1;
         _hasFusedActivation = IsActivation(op.type);
diff --git a/ethosu/regor/architecture/ethosu85/ethos_u85.hpp b/ethosu/regor/architecture/ethosu85/ethos_u85.hpp
index ba0bde25..c4cbbad2 100644
--- a/ethosu/regor/architecture/ethosu85/ethos_u85.hpp
+++ b/ethosu/regor/architecture/ethosu85/ethos_u85.hpp
@@ -125,6 +125,7 @@ private:
     int _externalIfms = 0;
     int _chainIdx = 0;
     bool _supportsChaining = false;
+    bool _supportsFusing = false;
     bool _hasFusedActivation = false;
     bool _hasFusedTranspose = false;
     bool _hasFusedReverse = false;
-- 
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