Fix lower bound violation

src/types.h

Index: src/types.h
diff --git a/src/types.h b/src/types.h
index aafaf07fb5ddc054378ea7a53be68545bb2006ef..f810b3940f0f08400cf2dc4a574aa9342d7b6d2a 100644
--- a/src/types.h
+++ b/src/types.h
@@ -1035,7 +1035,7 @@ struct BoundsImpl {
     TypeHandle lower = Type::Union(b1.lower, b2.lower, region);
     TypeHandle upper = Type::Intersect(b1.upper, b2.upper, region);
     // Lower bounds are considered approximate, correct as necessary.
-    lower = Type::Intersect(lower, upper, region);
+    if (!lower->Is(upper)) lower = upper;
     return BoundsImpl(lower, upper);
   }
 
@@ -1047,14 +1047,16 @@ struct BoundsImpl {
   }
 
   static BoundsImpl NarrowLower(BoundsImpl b, TypeHandle t, Region* region) {
-    // Lower bounds are considered approximate, correct as necessary.
-    t = Type::Intersect(t, b.upper, region);
     TypeHandle lower = Type::Union(b.lower, t, region);
+    // Lower bounds are considered approximate, correct as necessary.
+    if (!lower->Is(b.upper)) lower = b.upper;
     return BoundsImpl(lower, b.upper);
   }
   static BoundsImpl NarrowUpper(BoundsImpl b, TypeHandle t, Region* region) {
-    TypeHandle lower = Type::Intersect(b.lower, t, region);
+    TypeHandle lower = b.lower;
     TypeHandle upper = Type::Intersect(b.upper, t, region);
+    // Lower bounds are considered approximate, correct as necessary.
+    if (!lower->Is(upper)) lower = upper;
     return BoundsImpl(lower, upper);
   }