Add bounds checking for out-of-bounds array access with constant indices (#7814)

* Initial plan

* Implement out-of-bounds array access checking

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Add tests and format code for array bounds checking

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Move checkForOutOfBoundAccess to separate file and refactor using InstPassBase

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Optimize out-of-bounds checker to use single IR traversal

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Fix DiagnosticSink forward declaration from struct to class

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Update 0-array-1 test to use runtime indices to avoid bounds checking diagnostic

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Use SV_DispatchThreadID for truly runtime array access in 0-array-1 test

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

2 files changed, 57 insertions, 0 deletions

diff --git a/tests/diagnostics/array-out-of-bounds-2.slang b/tests/diagnostics/array-out-of-bounds-2.slang
new file mode 100644
index 000000000..978f61d9f
--- /dev/null
+++ b/tests/diagnostics/array-out-of-bounds-2.slang
@@ -0,0 +1,29 @@
+// array-out-of-bounds-2.slang
+
+// Test the specific scenario from the issue (array of size 3, accessing index 3)
+
+//TEST:SIMPLE(filecheck=CHECK): -target spirv -entry computeMain -stage compute
+
+struct SH3_t
+{
+    float coeffs[4];
+};
+
+RWStructuredBuffer<float> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    SH3_t a[3];
+    SH3_t b;
+    
+    for (int i = 0; i < 3; ++i)
+    {
+        // This should be fine
+        outputBuffer[i] = a[i].coeffs[0];
+    }
+    
+    // This reproduces the issue - accessing index 3 in array of size 3
+    //CHECK: error 30029: array index '3' is out of bounds for array of size '3'.
+    outputBuffer[3] = a[3].coeffs[0];
+}
\ No newline at end of file
diff --git a/tests/diagnostics/array-out-of-bounds.slang b/tests/diagnostics/array-out-of-bounds.slang
new file mode 100644
index 000000000..81c243031
--- /dev/null
+++ b/tests/diagnostics/array-out-of-bounds.slang
@@ -0,0 +1,28 @@
+// array-out-of-bounds.slang
+
+// Test that out-of-bounds array access with constant indices generates an error
+
+//TEST:SIMPLE(filecheck=CHECK): -target spirv -entry computeMain -stage compute
+
+RWStructuredBuffer<int> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    int a[3];
+    a[0] = 10;
+    a[1] = 20;
+    a[2] = 30;
+    
+    // Valid access - should be fine
+    outputBuffer[0] = a[0];
+    outputBuffer[1] = a[2];
+    
+    // Invalid access - index 3 is out of bounds for array of size 3
+    //CHECK: error 30029: array index '3' is out of bounds for array of size '3'.
+    outputBuffer[2] = a[3];
+    
+    // Invalid access - negative index
+    //CHECK: error 30029: array index '-1' is out of bounds for array of size '3'.
+    outputBuffer[3] = a[-1];
+}
\ No newline at end of file