Consolidate multiple inouts/outs into struct (#6435)

* Consolidate multiple inout/outs into struct

Fixes #5121

VUID-StandaloneSpirv-IncomingRayPayloadKHR-04700 requires that there be
only one IncomingRayPayloadKHR per entry point. This change does two
things:

1. If an entry point has the one inout or out, or has only ins, then
   stay with current implementation.

2. If there are multiple outs/inouts, then create a new structure to
   consolidate these fields and emit this structure.

These two code paths are split into two separate functions for clarity.
This patch also adds a new test: multipleinout.slang to test this.

* Address review comments

* Refactor code as per review comments

* format code

* fix failing tests

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/tests/vkray/multipleinout.slang b/tests/vkray/multipleinout.slang
new file mode 100644
index 000000000..52e1758b0
--- /dev/null
+++ b/tests/vkray/multipleinout.slang
@@ -0,0 +1,36 @@
+//TEST:SIMPLE(filecheck=CHECK): -stage closesthit -entry main -target spirv -emit-spirv-directly
+
+// This test checks whether the spirv generated when there are multiple inout or out variables, they 
+// all get consolidated into one IncomingRayPayloadKHR.
+
+struct ReflectionRay
+{
+    float4 color;
+};
+
+StructuredBuffer<float4> colors;
+
+[shader("closesthit")]
+void main(
+    BuiltInTriangleIntersectionAttributes attributes,
+    inout ReflectionRay ioPayload,
+    out float3 dummy)
+{
+    uint materialID = (InstanceIndex() << 1)
+        + InstanceID()
+        + PrimitiveIndex()
+        + HitKind();
+
+    ioPayload.color = colors[materialID];
+    dummy = HitTriangleVertexPosition(0);
+}
+
+// CHECK: OpEntryPoint ClosestHitKHR %main "main" %{{.*}} %{{.*}} %gl_PrimitiveID %{{.*}} %gl_InstanceID %colors %{{.*}}
+// CHECK: %_struct_{{.*}} = OpTypeStruct %ReflectionRay %v3float
+// CHECK: %_ptr_IncomingRayPayloadKHR__struct_{{.*}} = OpTypePointer IncomingRayPayloadKHR %_struct_{{.*}}
+// CHECK: %main = OpFunction %void None %{{.*}}
+// CHECK: %materialID = OpIAdd %uint %{{.*}} %{{.*}}
+// CHECK: %{{.*}} = OpAccessChain %_ptr_StorageBuffer_v4float %colors %int_0 %materialID
+// CHECK: %{{.*}} = OpLoad %v4float %{{.*}}
+// CHECK: %{{.*}} = OpAccessChain %_ptr_Input_v3float %{{.*}} %uint_0
+// CHECK: %{{.*}} = OpLoad %v3float %{{.*}}