RHI: Cache ShaderResourceBindings for Metal

We current have lots of redundant state bindings for things like
SamplerState that could reduced by checking if the state is already set.
ShaderResourceBindings are fairly involved to cache since they are done
in batches. This patch stores the current ShaderResourceBindings state
and checkes the current state before setting a new one.

Change-Id: If15ebd2b8b14b016f492d881197e423773c30ef7
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 156 insertions, 89 deletions

diff --git a/src/gui/rhi/qrhimetal.mm b/src/gui/rhi/qrhimetal.mm
index 2fab17d70f..f0b8fcac78 100644
--- a/src/gui/rhi/qrhimetal.mm
+++ b/src/gui/rhi/qrhimetal.mm
@@ -232,6 +232,32 @@ struct QMetalSamplerData
     id<MTLSamplerState> samplerState = nil;
 };
 
+struct QMetalShaderResourceBindingsData {
+    struct Stage {
+        struct Buffer {
+            int nativeBinding;
+            id<MTLBuffer> mtlbuf;
+            quint32 offset;
+        };
+        struct Texture {
+            int nativeBinding;
+            id<MTLTexture> mtltex;
+        };
+        struct Sampler {
+            int nativeBinding;
+            id<MTLSamplerState> mtlsampler;
+        };
+        QVarLengthArray<Buffer, 8> buffers;
+        QVarLengthArray<Texture, 8> textures;
+        QVarLengthArray<Sampler, 8> samplers;
+        QRhiBatchedBindings<id<MTLBuffer> > bufferBatches;
+        QRhiBatchedBindings<NSUInteger> bufferOffsetBatches;
+        QRhiBatchedBindings<id<MTLTexture> > textureBatches;
+        QRhiBatchedBindings<id<MTLSamplerState> > samplerBatches;
+    } res[QRhiMetal::SUPPORTED_STAGES];
+    enum { VERTEX = 0, FRAGMENT = 1, COMPUTE = 2 };
+};
+
 struct QMetalCommandBufferData
 {
     id<MTLCommandBuffer> cb;
@@ -242,6 +268,7 @@ struct QMetalCommandBufferData
     QRhiBatchedBindings<id<MTLBuffer> > currentVertexInputsBuffers;
     QRhiBatchedBindings<NSUInteger> currentVertexInputOffsets;
     id<MTLDepthStencilState> currentDepthStencilState;
+    QMetalShaderResourceBindingsData currentShaderResourceBindingState;
 };
 
 struct QMetalRenderTargetData
@@ -792,6 +819,46 @@ static inline int mapBinding(int binding,
     return -1;
 }
 
+static inline bool areBufferBatchesEqual(const QRhiBatchedBindings<id<MTLBuffer> >::Batch &batch1,
+                                         const QRhiBatchedBindings<NSUInteger>::Batch &offsetBatch1,
+                                         const QRhiBatchedBindings<id<MTLBuffer> >::Batch &batch2,
+                                         const QRhiBatchedBindings<NSUInteger>::Batch &offsetBatch2)
+{
+    if (batch1.startBinding != batch2.startBinding)
+        return false;
+    if (batch1.resources.count() != batch2.resources.count())
+        return false;
+    if (batch1 != batch2)
+        return false;
+    if (offsetBatch1 != offsetBatch2)
+        return false;
+    return true;
+}
+
+static inline bool areTextureBatchesEqual(const QRhiBatchedBindings<id<MTLTexture> >::Batch &batch1,
+                                          const QRhiBatchedBindings<id<MTLTexture> >::Batch &batch2)
+{
+    if (batch1.startBinding != batch2.startBinding)
+        return false;
+    if (batch1.resources.count() != batch2.resources.count())
+        return false;
+    if (batch1 != batch2)
+        return false;
+    return true;
+};
+
+static inline bool areSamplerBatchesEqual(const QRhiBatchedBindings<id<MTLSamplerState> >::Batch &batch1,
+                                          const QRhiBatchedBindings<id<MTLSamplerState> >::Batch &batch2)
+{
+    if (batch1.startBinding != batch2.startBinding)
+        return false;
+    if (batch1.resources.count() != batch2.resources.count())
+        return false;
+    if (batch1 != batch2)
+        return false;
+    return true;
+};
+
 void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD,
                                               QMetalCommandBuffer *cbD,
                                               int dynamicOffsetCount,
@@ -799,29 +866,7 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
                                               bool offsetOnlyChange,
                                               const QShader::NativeResourceBindingMap *nativeResourceBindingMaps[SUPPORTED_STAGES])
 {
-    struct Stage {
-        struct Buffer {
-            int nativeBinding;
-            id<MTLBuffer> mtlbuf;
-            quint32 offset;
-        };
-        struct Texture {
-            int nativeBinding;
-            id<MTLTexture> mtltex;
-        };
-        struct Sampler {
-            int nativeBinding;
-            id<MTLSamplerState> mtlsampler;
-        };
-        QVarLengthArray<Buffer, 8> buffers;
-        QVarLengthArray<Texture, 8> textures;
-        QVarLengthArray<Sampler, 8> samplers;
-        QRhiBatchedBindings<id<MTLBuffer> > bufferBatches;
-        QRhiBatchedBindings<NSUInteger> bufferOffsetBatches;
-        QRhiBatchedBindings<id<MTLTexture> > textureBatches;
-        QRhiBatchedBindings<id<MTLSamplerState> > samplerBatches;
-    } res[SUPPORTED_STAGES];
-    enum { VERTEX = 0, FRAGMENT = 1, COMPUTE = 2 };
+    QMetalShaderResourceBindingsData bindingData;
 
     for (const QRhiShaderResourceBinding &binding : qAsConst(srbD->sortedBindings)) {
         const QRhiShaderResourceBinding::Data *b = binding.data();
@@ -839,19 +884,19 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
                 }
             }
             if (b->stage.testFlag(QRhiShaderResourceBinding::VertexStage)) {
-                const int nativeBinding = mapBinding(b->binding, VERTEX, nativeResourceBindingMaps, BindingType::Buffer);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::VERTEX, nativeResourceBindingMaps, BindingType::Buffer);
                 if (nativeBinding >= 0)
-                    res[VERTEX].buffers.append({ nativeBinding, mtlbuf, offset });
+                    bindingData.res[QMetalShaderResourceBindingsData::VERTEX].buffers.append({ nativeBinding, mtlbuf, offset });
             }
             if (b->stage.testFlag(QRhiShaderResourceBinding::FragmentStage)) {
-                const int nativeBinding = mapBinding(b->binding, FRAGMENT, nativeResourceBindingMaps, BindingType::Buffer);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::FRAGMENT, nativeResourceBindingMaps, BindingType::Buffer);
                 if (nativeBinding >= 0)
-                    res[FRAGMENT].buffers.append({ nativeBinding, mtlbuf, offset });
+                    bindingData.res[QMetalShaderResourceBindingsData::FRAGMENT].buffers.append({ nativeBinding, mtlbuf, offset });
             }
             if (b->stage.testFlag(QRhiShaderResourceBinding::ComputeStage)) {
-                const int nativeBinding = mapBinding(b->binding, COMPUTE, nativeResourceBindingMaps, BindingType::Buffer);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::COMPUTE, nativeResourceBindingMaps, BindingType::Buffer);
                 if (nativeBinding >= 0)
-                    res[COMPUTE].buffers.append({ nativeBinding, mtlbuf, offset });
+                    bindingData.res[QMetalShaderResourceBindingsData::COMPUTE].buffers.append({ nativeBinding, mtlbuf, offset });
             }
         }
             break;
@@ -868,31 +913,31 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
                     //   first = texture binding, second = sampler binding
                     //   first = texture binding
                     //   first = sampler binding (i.e. BindingType::Texture...)
-                    const int textureBinding = mapBinding(b->binding, VERTEX, nativeResourceBindingMaps, BindingType::Texture);
-                    const int samplerBinding = texD && samplerD ? mapBinding(b->binding, VERTEX, nativeResourceBindingMaps, BindingType::Sampler)
-                                                                : (samplerD ? mapBinding(b->binding, VERTEX, nativeResourceBindingMaps, BindingType::Texture) : -1);
+                    const int textureBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::VERTEX, nativeResourceBindingMaps, BindingType::Texture);
+                    const int samplerBinding = texD && samplerD ? mapBinding(b->binding, QMetalShaderResourceBindingsData::VERTEX, nativeResourceBindingMaps, BindingType::Sampler)
+                                                                : (samplerD ? mapBinding(b->binding, QMetalShaderResourceBindingsData::VERTEX, nativeResourceBindingMaps, BindingType::Texture) : -1);
                     if (textureBinding >= 0 && texD)
-                        res[VERTEX].textures.append({ textureBinding + elem, texD->d->tex });
+                        bindingData.res[QMetalShaderResourceBindingsData::VERTEX].textures.append({ textureBinding + elem, texD->d->tex });
                     if (samplerBinding >= 0)
-                        res[VERTEX].samplers.append({ samplerBinding + elem, samplerD->d->samplerState });
+                        bindingData.res[QMetalShaderResourceBindingsData::VERTEX].samplers.append({ samplerBinding + elem, samplerD->d->samplerState });
                 }
                 if (b->stage.testFlag(QRhiShaderResourceBinding::FragmentStage)) {
-                    const int textureBinding = mapBinding(b->binding, FRAGMENT, nativeResourceBindingMaps, BindingType::Texture);
-                    const int samplerBinding = texD && samplerD ? mapBinding(b->binding, FRAGMENT, nativeResourceBindingMaps, BindingType::Sampler)
-                                                                : (samplerD ? mapBinding(b->binding, FRAGMENT, nativeResourceBindingMaps, BindingType::Texture) : -1);
+                    const int textureBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::FRAGMENT, nativeResourceBindingMaps, BindingType::Texture);
+                    const int samplerBinding = texD && samplerD ? mapBinding(b->binding, QMetalShaderResourceBindingsData::FRAGMENT, nativeResourceBindingMaps, BindingType::Sampler)
+                                                                : (samplerD ? mapBinding(b->binding, QMetalShaderResourceBindingsData::FRAGMENT, nativeResourceBindingMaps, BindingType::Texture) : -1);
                     if (textureBinding >= 0 && texD)
-                        res[FRAGMENT].textures.append({ textureBinding + elem, texD->d->tex });
+                        bindingData.res[QMetalShaderResourceBindingsData::FRAGMENT].textures.append({ textureBinding + elem, texD->d->tex });
                     if (samplerBinding >= 0)
-                        res[FRAGMENT].samplers.append({ samplerBinding + elem, samplerD->d->samplerState });
+                        bindingData.res[QMetalShaderResourceBindingsData::FRAGMENT].samplers.append({ samplerBinding + elem, samplerD->d->samplerState });
                 }
                 if (b->stage.testFlag(QRhiShaderResourceBinding::ComputeStage)) {
-                    const int textureBinding = mapBinding(b->binding, COMPUTE, nativeResourceBindingMaps, BindingType::Texture);
-                    const int samplerBinding = texD && samplerD ? mapBinding(b->binding, COMPUTE, nativeResourceBindingMaps, BindingType::Sampler)
-                                                                : (samplerD ? mapBinding(b->binding, COMPUTE, nativeResourceBindingMaps, BindingType::Texture) : -1);
+                    const int textureBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::COMPUTE, nativeResourceBindingMaps, BindingType::Texture);
+                    const int samplerBinding = texD && samplerD ? mapBinding(b->binding, QMetalShaderResourceBindingsData::COMPUTE, nativeResourceBindingMaps, BindingType::Sampler)
+                                                                : (samplerD ? mapBinding(b->binding, QMetalShaderResourceBindingsData::COMPUTE, nativeResourceBindingMaps, BindingType::Texture) : -1);
                     if (textureBinding >= 0 && texD)
-                        res[COMPUTE].textures.append({ textureBinding + elem, texD->d->tex });
+                        bindingData.res[QMetalShaderResourceBindingsData::COMPUTE].textures.append({ textureBinding + elem, texD->d->tex });
                     if (samplerBinding >= 0)
-                        res[COMPUTE].samplers.append({ samplerBinding + elem, samplerD->d->samplerState });
+                        bindingData.res[QMetalShaderResourceBindingsData::COMPUTE].samplers.append({ samplerBinding + elem, samplerD->d->samplerState });
                 }
             }
         }
@@ -904,19 +949,19 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
             QMetalTexture *texD = QRHI_RES(QMetalTexture, b->u.simage.tex);
             id<MTLTexture> t = texD->d->viewForLevel(b->u.simage.level);
             if (b->stage.testFlag(QRhiShaderResourceBinding::VertexStage)) {
-                const int nativeBinding = mapBinding(b->binding, VERTEX, nativeResourceBindingMaps, BindingType::Texture);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::VERTEX, nativeResourceBindingMaps, BindingType::Texture);
                 if (nativeBinding >= 0)
-                    res[VERTEX].textures.append({ nativeBinding, t });
+                    bindingData.res[QMetalShaderResourceBindingsData::VERTEX].textures.append({ nativeBinding, t });
             }
             if (b->stage.testFlag(QRhiShaderResourceBinding::FragmentStage)) {
-                const int nativeBinding = mapBinding(b->binding, FRAGMENT, nativeResourceBindingMaps, BindingType::Texture);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::FRAGMENT, nativeResourceBindingMaps, BindingType::Texture);
                 if (nativeBinding >= 0)
-                    res[FRAGMENT].textures.append({ nativeBinding, t });
+                    bindingData.res[QMetalShaderResourceBindingsData::FRAGMENT].textures.append({ nativeBinding, t });
             }
             if (b->stage.testFlag(QRhiShaderResourceBinding::ComputeStage)) {
-                const int nativeBinding = mapBinding(b->binding, COMPUTE, nativeResourceBindingMaps, BindingType::Texture);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::COMPUTE, nativeResourceBindingMaps, BindingType::Texture);
                 if (nativeBinding >= 0)
-                    res[COMPUTE].textures.append({ nativeBinding, t });
+                    bindingData.res[QMetalShaderResourceBindingsData::COMPUTE].textures.append({ nativeBinding, t });
             }
         }
             break;
@@ -928,19 +973,19 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
             id<MTLBuffer> mtlbuf = bufD->d->buf[0];
             quint32 offset = b->u.sbuf.offset;
             if (b->stage.testFlag(QRhiShaderResourceBinding::VertexStage)) {
-                const int nativeBinding = mapBinding(b->binding, VERTEX, nativeResourceBindingMaps, BindingType::Buffer);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::VERTEX, nativeResourceBindingMaps, BindingType::Buffer);
                 if (nativeBinding >= 0)
-                    res[VERTEX].buffers.append({ nativeBinding, mtlbuf, offset });
+                    bindingData.res[QMetalShaderResourceBindingsData::VERTEX].buffers.append({ nativeBinding, mtlbuf, offset });
             }
             if (b->stage.testFlag(QRhiShaderResourceBinding::FragmentStage)) {
-                const int nativeBinding = mapBinding(b->binding, FRAGMENT, nativeResourceBindingMaps, BindingType::Buffer);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::FRAGMENT, nativeResourceBindingMaps, BindingType::Buffer);
                 if (nativeBinding >= 0)
-                    res[FRAGMENT].buffers.append({ nativeBinding, mtlbuf, offset });
+                    bindingData.res[QMetalShaderResourceBindingsData::FRAGMENT].buffers.append({ nativeBinding, mtlbuf, offset });
             }
             if (b->stage.testFlag(QRhiShaderResourceBinding::ComputeStage)) {
-                const int nativeBinding = mapBinding(b->binding, COMPUTE, nativeResourceBindingMaps, BindingType::Buffer);
+                const int nativeBinding = mapBinding(b->binding, QMetalShaderResourceBindingsData::COMPUTE, nativeResourceBindingMaps, BindingType::Buffer);
                 if (nativeBinding >= 0)
-                    res[COMPUTE].buffers.append({ nativeBinding, mtlbuf, offset });
+                    bindingData.res[QMetalShaderResourceBindingsData::COMPUTE].buffers.append({ nativeBinding, mtlbuf, offset });
             }
         }
             break;
@@ -951,9 +996,9 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
     }
 
     for (int stage = 0; stage < SUPPORTED_STAGES; ++stage) {
-        if (cbD->recordingPass != QMetalCommandBuffer::RenderPass && (stage == VERTEX || stage == FRAGMENT))
+        if (cbD->recordingPass != QMetalCommandBuffer::RenderPass && (stage == QMetalShaderResourceBindingsData::VERTEX || stage == QMetalShaderResourceBindingsData::FRAGMENT))
             continue;
-        if (cbD->recordingPass != QMetalCommandBuffer::ComputePass && stage == COMPUTE)
+        if (cbD->recordingPass != QMetalCommandBuffer::ComputePass && stage == QMetalShaderResourceBindingsData::COMPUTE)
             continue;
 
         // QRhiBatchedBindings works with the native bindings and expects
@@ -961,33 +1006,42 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
         // on the QRhi (SPIR-V) binding) is not helpful in this regard, so we
         // have to sort here every time.
 
-        std::sort(res[stage].buffers.begin(), res[stage].buffers.end(), [](const Stage::Buffer &a, const Stage::Buffer &b) {
+        std::sort(bindingData.res[stage].buffers.begin(), bindingData.res[stage].buffers.end(), [](const QMetalShaderResourceBindingsData::Stage::Buffer &a, const QMetalShaderResourceBindingsData::Stage::Buffer &b) {
             return a.nativeBinding < b.nativeBinding;
         });
 
-        for (const Stage::Buffer &buf : qAsConst(res[stage].buffers)) {
-            res[stage].bufferBatches.feed(buf.nativeBinding, buf.mtlbuf);
-            res[stage].bufferOffsetBatches.feed(buf.nativeBinding, buf.offset);
+        for (const QMetalShaderResourceBindingsData::Stage::Buffer &buf : qAsConst(bindingData.res[stage].buffers)) {
+            bindingData.res[stage].bufferBatches.feed(buf.nativeBinding, buf.mtlbuf);
+            bindingData.res[stage].bufferOffsetBatches.feed(buf.nativeBinding, buf.offset);
         }
 
-        res[stage].bufferBatches.finish();
-        res[stage].bufferOffsetBatches.finish();
-
-        for (int i = 0, ie = res[stage].bufferBatches.batches.count(); i != ie; ++i) {
-            const auto &bufferBatch(res[stage].bufferBatches.batches[i]);
-            const auto &offsetBatch(res[stage].bufferOffsetBatches.batches[i]);
+        bindingData.res[stage].bufferBatches.finish();
+        bindingData.res[stage].bufferOffsetBatches.finish();
+
+        for (int i = 0, ie = bindingData.res[stage].bufferBatches.batches.count(); i != ie; ++i) {
+            const auto &bufferBatch(bindingData.res[stage].bufferBatches.batches[i]);
+            const auto &offsetBatch(bindingData.res[stage].bufferOffsetBatches.batches[i]);
+            // skip setting Buffer binding if the current state is already correct
+            if (cbD->d->currentShaderResourceBindingState.res[stage].bufferBatches.batches.count() > i &&
+                cbD->d->currentShaderResourceBindingState.res[stage].bufferOffsetBatches.batches.count() > i &&
+                areBufferBatchesEqual(bufferBatch,
+                                      offsetBatch,
+                                      cbD->d->currentShaderResourceBindingState.res[stage].bufferBatches.batches[i],
+                                      cbD->d->currentShaderResourceBindingState.res[stage].bufferOffsetBatches.batches[i])) {
+                continue;
+            }
             switch (stage) {
-            case VERTEX:
+            case QMetalShaderResourceBindingsData::VERTEX:
                 [cbD->d->currentRenderPassEncoder setVertexBuffers: bufferBatch.resources.constData()
                   offsets: offsetBatch.resources.constData()
                   withRange: NSMakeRange(bufferBatch.startBinding, NSUInteger(bufferBatch.resources.count()))];
                 break;
-            case FRAGMENT:
+            case QMetalShaderResourceBindingsData::FRAGMENT:
                 [cbD->d->currentRenderPassEncoder setFragmentBuffers: bufferBatch.resources.constData()
                   offsets: offsetBatch.resources.constData()
                   withRange: NSMakeRange(bufferBatch.startBinding, NSUInteger(bufferBatch.resources.count()))];
                 break;
-            case COMPUTE:
+            case QMetalShaderResourceBindingsData::COMPUTE:
                 [cbD->d->currentComputePassEncoder setBuffers: bufferBatch.resources.constData()
                   offsets: offsetBatch.resources.constData()
                   withRange: NSMakeRange(bufferBatch.startBinding, NSUInteger(bufferBatch.resources.count()))];
@@ -1001,35 +1055,40 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
         if (offsetOnlyChange)
             continue;
 
-        std::sort(res[stage].textures.begin(), res[stage].textures.end(), [](const Stage::Texture &a, const Stage::Texture &b) {
+        std::sort(bindingData.res[stage].textures.begin(), bindingData.res[stage].textures.end(), [](const QMetalShaderResourceBindingsData::Stage::Texture &a, const QMetalShaderResourceBindingsData::Stage::Texture &b) {
             return a.nativeBinding < b.nativeBinding;
         });
 
-        std::sort(res[stage].samplers.begin(), res[stage].samplers.end(), [](const Stage::Sampler &a, const Stage::Sampler &b) {
+        std::sort(bindingData.res[stage].samplers.begin(), bindingData.res[stage].samplers.end(), [](const QMetalShaderResourceBindingsData::Stage::Sampler &a, const QMetalShaderResourceBindingsData::Stage::Sampler &b) {
             return a.nativeBinding < b.nativeBinding;
         });
 
-        for (const Stage::Texture &t : qAsConst(res[stage].textures))
-            res[stage].textureBatches.feed(t.nativeBinding, t.mtltex);
+        for (const QMetalShaderResourceBindingsData::Stage::Texture &t : qAsConst(bindingData.res[stage].textures))
+            bindingData.res[stage].textureBatches.feed(t.nativeBinding, t.mtltex);
 
-        for (const Stage::Sampler &s : qAsConst(res[stage].samplers))
-            res[stage].samplerBatches.feed(s.nativeBinding, s.mtlsampler);
+        for (const QMetalShaderResourceBindingsData::Stage::Sampler &s : qAsConst(bindingData.res[stage].samplers))
+            bindingData.res[stage].samplerBatches.feed(s.nativeBinding, s.mtlsampler);
 
-        res[stage].textureBatches.finish();
-        res[stage].samplerBatches.finish();
+        bindingData.res[stage].textureBatches.finish();
+        bindingData.res[stage].samplerBatches.finish();
 
-        for (int i = 0, ie = res[stage].textureBatches.batches.count(); i != ie; ++i) {
-            const auto &batch(res[stage].textureBatches.batches[i]);
+        for (int i = 0, ie = bindingData.res[stage].textureBatches.batches.count(); i != ie; ++i) {
+            const auto &batch(bindingData.res[stage].textureBatches.batches[i]);
+            // skip setting Texture binding if the current state is already correct
+            if (cbD->d->currentShaderResourceBindingState.res[stage].textureBatches.batches.count() > i &&
+                areTextureBatchesEqual(batch, cbD->d->currentShaderResourceBindingState.res[stage].textureBatches.batches[i])) {
+                continue;
+            }
             switch (stage) {
-            case VERTEX:
+            case QMetalShaderResourceBindingsData::VERTEX:
                 [cbD->d->currentRenderPassEncoder setVertexTextures: batch.resources.constData()
                   withRange: NSMakeRange(batch.startBinding, NSUInteger(batch.resources.count()))];
                 break;
-            case FRAGMENT:
+            case QMetalShaderResourceBindingsData::FRAGMENT:
                 [cbD->d->currentRenderPassEncoder setFragmentTextures: batch.resources.constData()
                   withRange: NSMakeRange(batch.startBinding, NSUInteger(batch.resources.count()))];
                 break;
-            case COMPUTE:
+            case QMetalShaderResourceBindingsData::COMPUTE:
                 [cbD->d->currentComputePassEncoder setTextures: batch.resources.constData()
                   withRange: NSMakeRange(batch.startBinding, NSUInteger(batch.resources.count()))];
                 break;
@@ -1038,18 +1097,24 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
                 break;
             }
         }
-        for (int i = 0, ie = res[stage].samplerBatches.batches.count(); i != ie; ++i) {
-            const auto &batch(res[stage].samplerBatches.batches[i]);
+
+        for (int i = 0, ie = bindingData.res[stage].samplerBatches.batches.count(); i != ie; ++i) {
+            const auto &batch(bindingData.res[stage].samplerBatches.batches[i]);
+            // skip setting Sampler State if the current state is already correct
+            if (cbD->d->currentShaderResourceBindingState.res[stage].samplerBatches.batches.count() > i &&
+                areSamplerBatchesEqual(batch, cbD->d->currentShaderResourceBindingState.res[stage].samplerBatches.batches[i])) {
+                continue;
+            }
             switch (stage) {
-            case VERTEX:
+            case QMetalShaderResourceBindingsData::VERTEX:
                 [cbD->d->currentRenderPassEncoder setVertexSamplerStates: batch.resources.constData()
                   withRange: NSMakeRange(batch.startBinding, NSUInteger(batch.resources.count()))];
                 break;
-            case FRAGMENT:
+            case QMetalShaderResourceBindingsData::FRAGMENT:
                 [cbD->d->currentRenderPassEncoder setFragmentSamplerStates: batch.resources.constData()
                   withRange: NSMakeRange(batch.startBinding, NSUInteger(batch.resources.count()))];
                 break;
-            case COMPUTE:
+            case QMetalShaderResourceBindingsData::COMPUTE:
                 [cbD->d->currentComputePassEncoder setSamplerStates: batch.resources.constData()
                   withRange: NSMakeRange(batch.startBinding, NSUInteger(batch.resources.count()))];
                 break;
@@ -1059,6 +1124,7 @@ void QRhiMetal::enqueueShaderResourceBindings(QMetalShaderResourceBindings *srbD
             }
         }
     }
+    cbD->d->currentShaderResourceBindingState = bindingData;
 }
 
 void QRhiMetal::setGraphicsPipeline(QRhiCommandBuffer *cb, QRhiGraphicsPipeline *ps)
@@ -4086,6 +4152,7 @@ void QMetalCommandBuffer::resetPerPassCachedState()
     currentFrontFaceWinding = -1;
     currentDepthBiasValues = { 0.0f, 0.0f };
 
+    d->currentShaderResourceBindingState = {};
     d->currentDepthStencilState = nil;
     d->currentFirstVertexBinding = -1;
     d->currentVertexInputsBuffers.clear();