From 22f69adb92bc55987fccdbe6d8fe4b753c3602d7 Mon Sep 17 00:00:00 2001
From: Johan Gunnarsson <johan.gunnarsson@arm.com>
Date: Fri, 24 Jan 2025 13:30:20 +0100
Subject: [PATCH] MLBEDSW-9868: Adjust BufferReader asserts to always allow
 index 0

Index 0 is unstrided so we can always allow reading that index
regardless of stride. Also added a few more asserts.

Signed-off-by: Johan Gunnarsson <johan.gunnarsson@arm.com>
Change-Id: Icf7ac8c46665d4e651232d0c0ba66733dce99dc6
---
 ethosu/regor/common/buffer_view.hpp           |  9 +++--
 .../regor/compiler/tflite_graph_optimiser.cpp | 38 +++++++++----------
 2 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/ethosu/regor/common/buffer_view.hpp b/ethosu/regor/common/buffer_view.hpp
index 81c2575d..3dc282cd 100644
--- a/ethosu/regor/common/buffer_view.hpp
+++ b/ethosu/regor/common/buffer_view.hpp
@@ -1,5 +1,5 @@
 //
-// SPDX-FileCopyrightText: Copyright 2021, 2023-2024 Arm Limited and/or its affiliates <open-source-office@arm.com>
+// SPDX-FileCopyrightText: Copyright 2021, 2023-2025 Arm Limited and/or its affiliates <open-source-office@arm.com>
 //
 // SPDX-License-Identifier: Apache-2.0
 //
@@ -410,7 +410,7 @@ public:
     TYPE operator[](size_t index) const
     {
         assert(index < _count);
-        assert(((_strideBytes.Size() <= 2) || (_count == 1)) && "View does not guarantee linear access");
+        assert(((index == 0) || (_strideBytes.Size() <= 2)) && "View does not guarantee linear access");
         return _get(_data, index * _strideBytes.Depth());
     }
 
@@ -438,6 +438,7 @@ public:
         using iterator_category = std::forward_iterator_tag;
 
     public:
+        iterator_base_t() = default;
         iterator_base_t(const iterator_base_t<VALUE> &other) = default;
         iterator_base_t(GetFunc fn, const void *p, size_t index, size_t strideBytes) :
                 _get(fn), _data(p), _offset(index * strideBytes), _strideBytes(strideBytes)
@@ -520,7 +521,7 @@ public:
     {
         assert(index < _count);
         assert(_strideBytes[-1] == sizeof(TYPE));
-        assert(((_strideBytes.Size() <= 2) || (_count == 1)) && "View does not guarantee linear access");
+        assert(((index == 0) || (_strideBytes.Size() <= 2)) && "View does not guarantee linear access");
         return _data[index];
     }
 
@@ -528,7 +529,7 @@ public:
     {
         assert(index < _count);
         assert(_strideBytes[-1] == sizeof(TYPE));
-        assert(((_strideBytes.Size() <= 2) || (_count == 1)) && "View does not guarantee linear access");
+        assert(((index == 0) || (_strideBytes.Size() <= 2)) && "View does not guarantee linear access");
         return _data[index];
     }
 
diff --git a/ethosu/regor/compiler/tflite_graph_optimiser.cpp b/ethosu/regor/compiler/tflite_graph_optimiser.cpp
index 571aee37..0b3e3de9 100644
--- a/ethosu/regor/compiler/tflite_graph_optimiser.cpp
+++ b/ethosu/regor/compiler/tflite_graph_optimiser.cpp
@@ -2122,25 +2122,24 @@ Operation *TFLiteGraphOptimiser::ConvertPrelu(Graph *const graph, Operation *con
                 int64_t alphaZp = 0;
                 int alphaMin = 0;
                 int alphaMax = 0;
-                if ( params->tensor->Type() == DataType::Int8 )
+                BufferReader<int> reader;
+                switch ( params->tensor->Type() )
                 {
-                    auto *alphaBuf = alpha.Buffer()->Data<int8_t>();
-                    alphaMin = *std::min_element(alphaBuf, alphaBuf + alphaSize);
-                    alphaMax = *std::max_element(alphaBuf, alphaBuf + alphaSize);
-                }
-                else if ( params->tensor->Type() == DataType::UInt8 )
-                {
-                    auto *alphaBuf = alpha.Buffer()->Data<uint8_t>();
-                    alphaMin = *std::min_element(alphaBuf, alphaBuf + alphaSize);
-                    alphaMax = *std::max_element(alphaBuf, alphaBuf + alphaSize);
-                }
-                else if ( params->tensor->Type() == DataType::Int16 )
-                {
-                    auto *alphaBuf = alpha.Buffer()->Data<int16_t>();
-                    alphaMin = *std::min_element(alphaBuf, alphaBuf + alphaSize);
-                    alphaMax = *std::max_element(alphaBuf, alphaBuf + alphaSize);
-                }
-
+                    case DataType::Int8:
+                        reader = alpha.Values<int8_t, int>();
+                        break;
+                    case DataType::UInt8:
+                        reader = alpha.Values<uint8_t, int>();
+                        break;
+                    case DataType::Int16:
+                        reader = alpha.Values<int16_t, int>();
+                        break;
+                    default:
+                        assert(false);
+                };
+                auto alphaMinMax = std::minmax_element(reader.begin(), reader.end());
+                alphaMin = *alphaMinMax.first;
+                alphaMax = *alphaMinMax.second;
                 if ( alphaQuant.zeroPoints.size() )
                 {
                     alphaZp = alphaQuant.zeroPoints[0];
@@ -2163,8 +2162,7 @@ Operation *TFLiteGraphOptimiser::ConvertPrelu(Graph *const graph, Operation *con
                     lreluOp->CopyOutput(TensorUsage::OFM, *ofmConn);
                     auto *attr = lreluOp->Attribute<leaky_relu_attr_t>();
                     attr->alpha = scaledAlphaMin;
-                    // and then optimize LeakyRelU
-                    returnOp = ConvertLeakyRelu(graph, lreluOp.get());
+                    returnOp = lreluOp.get();
                     RecordOptimisation(operation, returnOp);
                     operation->Disconnect();
                     return returnOp;
-- 
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