Fix subtle corner-case with vars getting hoisted out of the loop creating unnecessary loop state (#3165)

* Extend the unit tests for MxLayeredMaterial

* Add breaking loop test

* Fix subtle corner-case with vars getting hoisted out of the loop creating unnecessary loop state

* remove whitespace changes

* Create loop-init.slang.expected.txt

* Add filecheck tests to ensure correct loop state

* Update comment

---------

Co-authored-by: winmad <winmad.wlf@gmail.com>
Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/tests/autodiff/material2/diff-falcor-material-system.slang b/tests/autodiff/material2/diff-falcor-material-system.slang
index 7b0f39ed1..3c7155ec2 100644
--- a/tests/autodiff/material2/diff-falcor-material-system.slang
+++ b/tests/autodiff/material2/diff-falcor-material-system.slang
@@ -2,16 +2,19 @@
 //TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj -output-using-type
 
 // outputBuffer is defined in IBSDF.slang
-//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0], stride=4):out,name=outputBuffer
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
 
 import MaterialSystem;
 import DiffuseMaterial;
 import DiffuseMaterialInstance;
 import GlossyMaterial;
 import GlossyMaterialInstance;
+import MxLayeredMaterial;
+import MxLayeredMaterialInstance;
 
 //TEST_INPUT: type_conformance DiffuseMaterial:IMaterial = 0
 //TEST_INPUT: type_conformance GlossyMaterial:IMaterial = 1
+//TEST_INPUT: type_conformance MxLayeredMaterial:IMaterial = 2
 
 [BackwardDifferentiable]
 float3 evalBSDF(int type)
@@ -44,4 +47,12 @@ void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
         outputBuffer[4] = dp_f.d[1];
         outputBuffer[5] = dp_f.d[2];
     }
+
+    {
+        DifferentialPair<float3> dp_f = __fwd_diff(evalBSDF)(2);
+
+        outputBuffer[6] = dp_f.d[0];
+        outputBuffer[7] = dp_f.d[1];
+        outputBuffer[8] = dp_f.d[2];
+    }
 }