Preserve type cast during AST constant folding. (#2912)

* Preserve type cast during AST constant folding.

Fixes #2891.

* Fix.

* Fix truncating.

* fix test.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/source/slang/slang-lower-to-ir.cpp b/source/slang/slang-lower-to-ir.cpp
index b36f0dc94..144875e8c 100644
--- a/source/slang/slang-lower-to-ir.cpp
+++ b/source/slang/slang-lower-to-ir.cpp
@@ -1432,6 +1432,15 @@ struct ValLoweringVisitor : ValVisitor<ValLoweringVisitor, LoweredValInfo, Lower
             tryEnv);
     }
 
+    LoweredValInfo visitTypeCastIntVal(TypeCastIntVal* val)
+    {
+        TryClauseEnvironment tryEnv;
+        auto baseVal = lowerVal(context, val->base);
+        SLANG_ASSERT(baseVal.flavor == LoweredValInfo::Flavor::Simple);
+        auto type = lowerType(context, val->type);
+        return LoweredValInfo::simple(getBuilder()->emitCast(type, baseVal.val));
+    }
+
     LoweredValInfo visitWitnessLookupIntVal(WitnessLookupIntVal* val)
     {
         auto witnessVal = lowerVal(context, val->witness);