Add case to `emitVectorReshape` for when using a `vector<M, N>` type with `T` value (#4419)

* Add case to `emitVectorReshape` for `vector<>` type, `scalar` value

1. Add new case
2. Add test

* fix warning

* fix warning

1 files changed, 17 insertions, 1 deletions

diff --git a/source/slang/slang-ir.cpp b/source/slang/slang-ir.cpp
index 22ef4e6be..c0541f4c4 100644
--- a/source/slang/slang-ir.cpp
+++ b/source/slang/slang-ir.cpp
@@ -3894,7 +3894,23 @@ namespace Slang
     {
         auto targetVectorType = as<IRVectorType>(type);
         auto sourceVectorType = as<IRVectorType>(value->getDataType());
-        if (!targetVectorType)
+        if (targetVectorType && !sourceVectorType)
+        {
+            auto elementType = targetVectorType->getElementType();
+            Index elemCount = 1;
+            if(auto intLit = as<IRIntLit>(targetVectorType->getElementCount()))
+            {
+                elemCount = (Index)intLit->getValue();
+            }
+            IRInst* zeroVal = emitDefaultConstruct(elementType);
+            List<IRInst*> defaultVals;
+            defaultVals.reserve(elemCount);
+            defaultVals.add(value);
+            for(auto i = 1; i < elemCount; i++)
+                defaultVals.add(zeroVal);
+            return emitMakeVector(targetVectorType, defaultVals);
+        }
+        else if (!targetVectorType)
         {
             if (!sourceVectorType)
                 return emitCast(targetVectorType, value);