From fff79c311028cc8a5cff310a9c493b23af68eb0c Mon Sep 17 00:00:00 2001
From: venkataram-nv <vedavamadath@nvidia.com>
Date: Mon, 1 Jul 2024 16:01:21 -0700
Subject: Support HLSL `.sample` operators for MS textures (#4524)

* Add `.sample` operator for MS texture types
* Adding filecheck tests for `.sample`
---
 source/slang/hlsl.meta.slang             | 33 ++++++++++++++++++++++++++++++++
 tests/hlsl/texture-sample-operator.slang | 27 ++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 tests/hlsl/texture-sample-operator.slang

diff --git a/source/slang/hlsl.meta.slang b/source/slang/hlsl.meta.slang
index 7c65aec5e..f50c63367 100644
--- a/source/slang/hlsl.meta.slang
+++ b/source/slang/hlsl.meta.slang
@@ -3202,6 +3202,7 @@ struct __TextureMip<T, Shape : __ITextureShape, let isArray : int, let isCombine
         get { return tex.Load(__makeVector(pos, mip)); }
     }
 }
+
 struct __TextureMips<T, Shape : __ITextureShape, let isArray : int, let isCombined : int, let format : int>
 {
     __TextureImpl<T, Shape, isArray, 0 /*isMS*/, 0 /*sampleCount*/, 0 /*access*/, 0 /*isShadow*/, isCombined, format> tex;
@@ -3222,6 +3223,38 @@ extension __TextureImpl<T, Shape, isArray, 0 /*isMS*/, 0 /*sampleCount*/, 0 /*ac
     }
 }
 
+// Definitions to support the .sample[][] operator.
+struct __TextureSample<T, Shape : __ITextureShape, let isArray : int, let isCombined : int, let format : int>
+{
+    __TextureImpl<T, Shape, isArray, 1 /*isMS*/, 0 /*sampleCount*/, 0 /*access*/, 0 /*isShadow*/, isCombined, format> tex;
+    int sample;
+    __subscript(vector<int, isArray + Shape.dimensions> pos)->T
+    {
+        [__unsafeForceInlineEarly]
+        get { return tex[pos, sample]; }
+    }
+}
+
+struct __TextureSampleMS<T, Shape : __ITextureShape, let isArray : int, let isCombined : int, let format : int>
+{
+    __TextureImpl<T, Shape, isArray, 1 /*isMS*/, 0 /*sampleCount*/, 0 /*access*/, 0 /*isShadow*/, isCombined, format> tex;
+    __subscript(int sample)->__TextureSample<T, Shape, isArray, isCombined, format>
+    {
+        [__unsafeForceInlineEarly]
+        get { return { tex, sample }; }
+    }
+}
+
+__generic<T, Shape : __ITextureShape, let isArray : int, let isCombined : int, let format : int>
+extension __TextureImpl<T, Shape, isArray, 1 /*isMS*/, 0 /*sampleCount*/, 0 /*access*/, 0 /*isShadow*/, isCombined, format>
+{
+    property __TextureSampleMS<T, Shape, isArray, isCombined, format> sample
+    {
+        [__unsafeForceInlineEarly]
+        get { return { this }; }
+    }
+}
+
 // Texture type aliases.
 // T, Shape: __ITextureShape, let isArray:int, let isMS:int, let sampleCount:int, let access:int, let isShadow:int, let isCombined:int, let format:int
 ${{{{
diff --git a/tests/hlsl/texture-sample-operator.slang b/tests/hlsl/texture-sample-operator.slang
new file mode 100644
index 000000000..175470367
--- /dev/null
+++ b/tests/hlsl/texture-sample-operator.slang
@@ -0,0 +1,27 @@
+//TEST:SIMPLE(filecheck=HLSL): -target hlsl -stage vertex
+//TEST:SIMPLE(filecheck=GLSL): -target glsl -stage vertex
+//TEST:SIMPLE(filecheck=METAL): -target metal -stage vertex
+//TEST:SIMPLE(filecheck=SPIRV): -target spirv -stage vertex
+//TEST:SIMPLE(filecheck=SPIRV): -target spirv-asm -stage vertex
+
+Texture2DMS <int3> t1;
+Texture2DMSArray <float4> t2;
+
+float4 main()
+{
+    // HLSL: .sample
+    // GLSL: texelFetch
+    // SPIRV: OpImageFetch %v4int {{.*}} Sample {{.*}}
+    // METAL: .read
+    uint2 p1 = uint2(1, 2);
+    int3 a1 = t1.sample[7][p1];
+
+    // HLSL: .sample
+    // GLSL: texelFetch
+    // SPIRV: OpImageFetch %v4float {{.*}} Sample {{.*}}
+    // METAL: .read
+    uint p2 = uint(1);
+    float4 a2 = t2.sample[p2][uint3(1, 2, 3)];
+
+    return float4(float3(a1), 0) + a2;
+}
-- 
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