Add `IRWArray` interface, and make StructuredBuffer conform to them. (#5097)

* Add `IRWArray` interface, and make StructuredBuffer conform to them.

* Update user guide.

* Fix.

* Fixes.

2 files changed, 34 insertions, 74 deletions

diff --git a/tests/diagnostics/inout-never-written.slang b/tests/diagnostics/inout-never-written.slang
deleted file mode 100644
index f4d4bce7e..000000000
--- a/tests/diagnostics/inout-never-written.slang
+++ /dev/null
@@ -1,74 +0,0 @@
-//TEST:SIMPLE(filecheck=CHK): -target spirv
-
-struct State
-{
-    float3 v;
-    float3 n;
-    int rnd;
-};
-
-//CHK-DAG: ([[# @LINE + 1]]): warning 41022: inout parameter 'x' is never written to
-void int_never_assigned(inout int x) {}
-
-//CHK-DAG: ([[# @LINE + 1]]): warning 41022: inout parameter 'state' is never written to
-void state_never_assigned(inout State state, inout float v)
-{
-    v = state.v.x;
-}
-
-void state_assigned(inout State state)
-{
-    state.rnd = (int) dot(state.v, state.n);
-}
-
-struct A
-{
-    int state;
-
-    //CHK-DAG: ([[# @LINE + 1]]): warning 41023: method marked `[mutable]` but never modifies `this`
-    [mutating] int next() { return state; }
-    
-    [mutating] int progress()
-    {
-        unmodified(state);
-        return state;
-    }
-};
-
-__generic <T>
-struct B
-{
-    int state;
-
-    //CHK-DAG: ([[# @LINE + 1]]): warning 41023: method marked `[mutable]` but never modifies `this`
-    [mutating] int next() { return state; }
-};
-
-// Sometimes an inOutImplicitCast is done,
-// this needs to be tracked as an alias;
-// none of the following functions should 
-// generate warnings
-uint lcg(inout uint prev)
-{
-    const uint LCG_A = 1664525u;
-    const uint LCG_C = 1013904223u;
-    prev = (LCG_A * prev + LCG_C);
-    return prev & 0x00FFFFFF;
-}
-
-float rnd(inout uint prev)
-{
-    return ((float) lcg(prev) / (float) 0x01000000);
-}
-
-float3 sample(inout int seed)
-{
-    float3 xi;
-    xi.x = rnd(seed);
-    xi.y = rnd(seed);
-    xi.z = rnd(seed);
-    return xi.z;
-}
-
-//CHK-NOT: warning 41022
-//CHK-NOT: warning 41023
diff --git a/tests/language-feature/generics/irwarray.slang b/tests/language-feature/generics/irwarray.slang
new file mode 100644
index 000000000..47109f7b0
--- /dev/null
+++ b/tests/language-feature/generics/irwarray.slang
@@ -0,0 +1,34 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -shaderobj -output-using-type
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -vk -shaderobj -output-using-type
+
+void writeToArray<U, T : IRWArray<U>>(inout T array, int index, U value) { array[index] = value; }
+void writeToBuffer<U, T : IRWArray<U>>(T array, int index, U value) { array[index] = value; }
+U readFromArray<U, T:IArray<U>>(T array, int index) { return array[index]; }
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain(int3 dispatchThreadID: SV_DispatchThreadID)
+{
+    float arr[3] = { 1.0, 2.0, 3.0 };
+    float4 v = float4(1.0, 2.0, 3.0, 4.0);
+    float2x2 m = float2x2(1.0, 2.0, 3.0, 4.0);
+
+    // CHECK: 1.0
+    writeToBuffer(outputBuffer, 0, 1.0f);
+
+    // CHECK: 4.0
+    writeToArray(arr, 0, 4.0f);
+    outputBuffer[1] = readFromArray(arr, 0);
+
+    // CHECK: 3.0
+    writeToArray(v, 3, 3.0f);
+    outputBuffer[2] = readFromArray(v, 3);
+
+    // CHECK: 30.0
+    writeToArray(m, 1, float2(10.0f, 20.0f));
+    outputBuffer[3] = readFromArray(m, 1).x + readFromArray(m, 1).y;
+
+    writeToBuffer(outputBuffer, 0, readFromArray(outputBuffer, 0));
+}