From 936c22a9a938744eb43c310dd82c9c6944f79e87 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Tue, 10 Sep 2024 08:13:21 -0700
Subject: Specialize existential return types when possible. (#5044)

* Fix inccorect dropping of declref during Unification of DeclaredSubtypeWitness.

* Add extension test.

* Specialize existential return types when possible.

* Fix.

* Fix.

* Fix falcor issue.
---
 .../generics/generic-return-type-requirement.slang | 39 ++++++++++++++++++++++
 .../interfaces/default-construct-conformance.slang |  8 ++---
 2 files changed, 41 insertions(+), 6 deletions(-)
 create mode 100644 tests/language-feature/generics/generic-return-type-requirement.slang

(limited to 'tests')

diff --git a/tests/language-feature/generics/generic-return-type-requirement.slang b/tests/language-feature/generics/generic-return-type-requirement.slang
new file mode 100644
index 000000000..945afd808
--- /dev/null
+++ b/tests/language-feature/generics/generic-return-type-requirement.slang
@@ -0,0 +1,39 @@
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-slang -compute -shaderobj -output-using-type
+//TEST(compute, vulkan):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -compute -shaderobj -output-using-type
+//TEST:SIMPLE(filecheck=HLSL): -target hlsl -profile cs_6_0 -entry computeMain
+
+// HLSL-NOT: AnyValue
+
+interface IStack<let D : int>
+{
+    __generic<let N : int>
+    IStack<D - N> popN();
+
+    int get();
+}
+struct StackImpl<let D : int> : IStack<D>
+{
+    // We should be able to specialize the callsites of this function to use
+    // the concrete type instead of resorting to dynamic dispatch.
+    __generic<let N : int>
+    IStack<D - N> popN() { return StackImpl<D-N>(); }
+
+    int get() { return D; }
+}
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+int test<int D, S : IStack<D>>(S stack)
+{
+    return stack.popN<2>().get();
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(int3 dispatchThreadID : SV_DispatchThreadID)
+{
+    StackImpl<5> stack;
+
+    // CHECK: 2
+    outputBuffer[0] = test(stack);
+}
diff --git a/tests/language-feature/interfaces/default-construct-conformance.slang b/tests/language-feature/interfaces/default-construct-conformance.slang
index 00778a9f6..4a6aed869 100644
--- a/tests/language-feature/interfaces/default-construct-conformance.slang
+++ b/tests/language-feature/interfaces/default-construct-conformance.slang
@@ -36,22 +36,18 @@ struct TestAny : ITest
     uint getValue() { return value; }
 }
 
-// CHECK: Tuple{{.*}} makeTest0{{.*}}()
-// CHECK: Tuple{{.*}} = { uint2(0U, 0U), uint2(0U, 0U), packAnyValue4{{.*}} };
 ITest makeTest0()
 {
     return Test0();
 }
 
-// CHECK: Tuple{{.*}} makeTest1{{.*}}()
-// CHECK: Tuple{{.*}} = { uint2(0U, 0U), uint2(1U, 0U), packAnyValue4{{.*}} };
 ITest makeTest1()
 {
     return Test1();
 }
 
-// CHECK: Tuple{{.*}} makeTestAny{{.*}}()
-// CHECK: Tuple{{.*}} = { uint2(0U, 0U), uint2(2U, 0U), packAnyValue4{{.*}} };
+// CHECK: TestAny{{.*}} makeTestAny{{.*}}()
+// CHECK: return TestAny_{{.*}}init{{.*}}()
 ITest makeTestAny()
 {
     return TestAny();
-- 
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