Fix atomic operations on RWBuffer (#593)

* Fix atomic operations on RWBuffer

An earlier change added support for passing true pointers to `__ref` parameters to fix the global `Interlocked*()` functions when applied to `groupshared` variables or `RWStructureBuffer<T>` elements.
That change didn't apply to `RWBuffer<T>` or `RWTexture2D<T>`, etc. because those types had so far only declared `get` and `set` accessors, but not any `ref` accessors (which return a pointer).

The main fixes here are:

* Add `ref` accessors to the subscript oeprations on the `RW*` resource types

* Adjust the logic for emitting calls to subscript accessors so that we don't get quite as eager about invoking a `ref` accessor, and instead try to invoke just a `get` or `set` accessor when these will suffice. This is important for Vulkan cross-compilation, where we don't yet support the semantics of our `ref` accessors.

* Add a test case for atomics on a `RWBuffer`

* Fix up `render-test` so that we can specify a format for a buffer resource, which allows us to use things other than `*StructuredBuffer` and `*ByteAddressBuffer`. The work there is probably not complete; I just did what I could to get the test working.

* A bunch of files got whitespace edits thanks to the fact that I'm using editorconfig and others on the project seemingly arent...

* fixup: remove ifdefed-out code

2 files changed, 32 insertions, 0 deletions

diff --git a/tests/compute/atomics-buffer.slang b/tests/compute/atomics-buffer.slang
new file mode 100644
index 000000000..92f00272d
--- /dev/null
+++ b/tests/compute/atomics-buffer.slang
@@ -0,0 +1,28 @@
+// atomics-buffer.slang
+
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute
+
+// Note: not enabling D3D12 test yet because change
+// was developed on a machine that can run D3D12
+//
+//TEST_DISABLED(compute):COMPARE_COMPUTE_EX:-slang -compute -dx12
+
+//TEST_INPUT:ubuffer(format=R_UInt32, data=[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]):dxbinding(0),glbinding(0),out
+
+RWBuffer<uint> outputBuffer;
+
+void test(uint val)
+{
+    uint originalValue;
+
+	InterlockedAdd(outputBuffer[val], 		val, 		originalValue);
+	InterlockedAdd(outputBuffer[val ^ 1], 	val*16, 	originalValue);
+	InterlockedAdd(outputBuffer[val ^ 2], 	val*16*16, 	originalValue);
+}
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    uint tid = dispatchThreadID.x;
+    test(tid);
+}
\ No newline at end of file
diff --git a/tests/compute/atomics-buffer.slang.expected.txt b/tests/compute/atomics-buffer.slang.expected.txt
new file mode 100644
index 000000000..36caeb8d6
--- /dev/null
+++ b/tests/compute/atomics-buffer.slang.expected.txt
@@ -0,0 +1,4 @@
+210
+301
+32
+123