Add legalization for 0-sized arrays. (#7327)

* Add legalization for 0-sized arrays.

* Allow 0-sized arrays in the front-end.

* More tests.

* Add `Conditional<T, hasValue>` type to core module.

* Update toc.

* Fix wording.

* Update test.

1 files changed, 31 insertions, 0 deletions

diff --git a/tests/language-feature/0-array-1.slang b/tests/language-feature/0-array-1.slang
new file mode 100644
index 000000000..327f71444
--- /dev/null
+++ b/tests/language-feature/0-array-1.slang
@@ -0,0 +1,31 @@
+//TEST:SIMPLE(filecheck=SPV): -target spirv
+//TEST:SIMPLE(filecheck=HLSL): -target hlsl -profile cs_6_0 -entry computeMain
+
+struct MyData
+{
+    int a[0][0][0];
+}
+
+uniform MyData* myData;
+uniform int * output;
+
+[numthreads(1, 1, 1)]
+void computeMain()
+{
+    // These are all ill-formed, but we want to still ensure our backend
+    // can handle them gracefully without crashing.
+    // In actual user code, any access to 0-sized arrays should be protected
+    // by a `if` statement that checks the size before accessing.
+    // The condition would then evaluate to false and causing all the accessing
+    // code to be optimized out.
+    InterlockedAdd(myData.a[0][0][0], 1);
+    myData.a[0][0][0] += 1;
+    output[0] = myData.a[0][0][0];
+}
+
+//SPV: OpEntryPoint
+//SPV-NOT: OpAtomic
+//SPV-NOT: OpStore
+//SPV-NOT: OpLoad
+
+//HLSL: computeMain