From 61ff1ba8459d70cbc887040c530b5ce1a125ec77 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Mon, 5 Sep 2022 13:57:06 -0700
Subject: Fix resource inout param specialization. (#2394)

Co-authored-by: Yong He <yhe@nvidia.com>
---
 source/slang/slang-ir-specialize-resources.cpp     |  1 +
 .../mutating/resource-specialization-inout.slang   | 36 ++++++++++++++++++++++
 ...esource-specialization-inout.slang.expected.txt |  4 +++
 3 files changed, 41 insertions(+)
 create mode 100644 tests/bugs/mutating/resource-specialization-inout.slang
 create mode 100644 tests/bugs/mutating/resource-specialization-inout.slang.expected.txt

diff --git a/source/slang/slang-ir-specialize-resources.cpp b/source/slang/slang-ir-specialize-resources.cpp
index 734315911..31e214e46 100644
--- a/source/slang/slang-ir-specialize-resources.cpp
+++ b/source/slang/slang-ir-specialize-resources.cpp
@@ -774,6 +774,7 @@ struct ResourceOutputSpecializationPass
             // `InOut<T>`.
             //
             IRInst* newParam = paramsBuilder.createParam(valueType);
+            newParam->insertBefore(param);
             param->transferDecorationsTo(newParam);
 
             // The start of the function body should assign
diff --git a/tests/bugs/mutating/resource-specialization-inout.slang b/tests/bugs/mutating/resource-specialization-inout.slang
new file mode 100644
index 000000000..541ecd8ac
--- /dev/null
+++ b/tests/bugs/mutating/resource-specialization-inout.slang
@@ -0,0 +1,36 @@
+// Bug related to resource specialization on unused resource typed fields.
+
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj
+
+//TEST_INPUT: Texture2D(size=4, content = one):name t2D
+Texture2D t2D;
+
+struct MyType
+{
+    Texture2D tex;
+    int data;
+    [mutating]
+    void f(int val)
+    {
+        data += val;
+    }
+}
+
+int test(int val)
+{
+    MyType t = {t2D, 0};
+    t.f(val);
+    return t.data;
+}
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=gOutputBuffer
+RWStructuredBuffer<int> gOutputBuffer;
+
+[numthreads(4, 1, 1)]
+void computeMain(int3 dispatchThreadID : SV_DispatchThreadID)
+{
+    int tid = dispatchThreadID.x;
+    int inputVal = tid;
+    int outputVal = test(inputVal);
+    gOutputBuffer[tid] = outputVal;
+}
\ No newline at end of file
diff --git a/tests/bugs/mutating/resource-specialization-inout.slang.expected.txt b/tests/bugs/mutating/resource-specialization-inout.slang.expected.txt
new file mode 100644
index 000000000..bc856dafa
--- /dev/null
+++ b/tests/bugs/mutating/resource-specialization-inout.slang.expected.txt
@@ -0,0 +1,4 @@
+0
+1
+2
+3
-- 
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