Metal fix (#6413)

Partially fix #6378

* Fix invalid access mode for texture_buffer

* Fix texture view create issue in metal

In newTextureView, levelRange should represent the mipmap level range,
while sliceRange should represent the texture layer range for texture
array. But the implement inverse those two wrongly.

Author: kaizhangNV

source/slang/slang-emit-metal.cpp

@@ -136,8 +136,15 @@ void MetalSourceEmitter::_emitHLSLTextureType(IRTextureTypeBase* texType)
     switch (texType->getAccess())
     {
     case SLANG_RESOURCE_ACCESS_READ:
-        m_writer->emit("access::sample");
-        break;
+        {
+            // Metal does not support access::sample for texture buffers, so we need to emit
+            // access::read instead.
+            if (texType->GetBaseShape() == SLANG_TEXTURE_BUFFER)
+                m_writer->emit("access::read");
+            else
+                m_writer->emit("access::sample");
+            break;
+        }
 
     case SLANG_RESOURCE_ACCESS_WRITE:
         m_writer->emit("access::write");

tests/metal/test_buffer.slang

@@ -0,0 +1,17 @@
+// Test that Buffer<T> maps to texture_buffer<uint, access::read> in Metal
+
+//TEST:SIMPLE(filecheck=METAL): -stage compute -entry computeMain -target metal
+
+
+// METAL: texture_buffer<uint, access::read> inputBuffer_{{.*}}
+Buffer<uint> inputBuffer;
+
+RWStructuredBuffer<uint> outputBuffer;
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dtid : SV_DispatchThreadID)
+{
+    uint idx = dtid.x;
+    // Load values from the buffer to verify correct access
+    outputBuffer[idx] = inputBuffer.Load(idx);
+}

tools/gfx/metal/metal-device.cpp

@@ -653,8 +653,8 @@ Result DeviceImpl::createTextureView(
     MTL::PixelFormat pixelFormat = desc.format == Format::Unknown
                                        ? textureImpl->m_pixelFormat
                                        : MetalUtil::translatePixelFormat(desc.format);
-    NS::Range levelRange(sr.baseArrayLayer, sr.layerCount);
-    NS::Range sliceRange(sr.mipLevel, sr.mipLevelCount);
+    NS::Range sliceRange(sr.baseArrayLayer, sr.layerCount);
+    NS::Range levelRange(sr.mipLevel, sr.mipLevelCount);
 
     viewImpl->m_textureView = NS::TransferPtr(textureImpl->m_texture->newTextureView(
         pixelFormat,