Fix for missing signedness cast in SwizzleIR (#7448)

* Cast if there is a signedness mismatch on the swizzle

* Move isSignedType to slang-util and add test

---------

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

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/spirv/swizzle-signed-typecast.slang b/tests/spirv/swizzle-signed-typecast.slang
new file mode 100644
index 000000000..459dd3860
--- /dev/null
+++ b/tests/spirv/swizzle-signed-typecast.slang
@@ -0,0 +1,26 @@
+//TEST:SIMPLE(filecheck=CHECK): -target spirv
+
+// CHECK: %{{.*}} = OpBitcast %v2uint %{{.*}}
+
+RWTexture2D<uint3> tex;
+void fn(inout int2 origPos, uint offset)
+{
+  origPos.x += offset;
+  origPos.y += offset;
+}
+
+uint3 id(float3 coord)
+{
+  return uint3(coord);
+}
+
+[shader("compute")]
+[numthreads(1,1,1)]
+void main(uint3 threadId : SV_DispatchThreadID)
+{
+    uint3 index = id(threadId);
+    // Passing a uint3 swizzle as a parameter to a function expecting a int2 should result
+    // in an explicit typecast from unsigned to signed
+    fn(index.xy, 1);
+    tex[threadId.xy] = index;
+}
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