--- gcc/gimple-lower-bitint.cc.jj	2024-02-23 11:36:06.977015730 +0100
+++ gcc/gimple-lower-bitint.cc	2024-02-23 18:21:09.282751377 +0100
@@ -5305,27 +5305,21 @@ bitint_large_huge::lower_stmt (gimple *s
       else if (TREE_CODE (TREE_TYPE (rhs1)) == BITINT_TYPE
 	       && bitint_precision_kind (TREE_TYPE (rhs1)) >= bitint_prec_large
 	       && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
-		   || POINTER_TYPE_P (TREE_TYPE (lhs))))
+		   || POINTER_TYPE_P (TREE_TYPE (lhs))
+		   || gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR))
 	{
 	  final_cast_p = true;
-	  if (TREE_CODE (TREE_TYPE (lhs)) == INTEGER_TYPE
-	      && TYPE_PRECISION (TREE_TYPE (lhs)) > MAX_FIXED_MODE_SIZE
+	  if (((TREE_CODE (TREE_TYPE (lhs)) == INTEGER_TYPE
+		&& TYPE_PRECISION (TREE_TYPE (lhs)) > MAX_FIXED_MODE_SIZE)
+	       || (!INTEGRAL_TYPE_P (TREE_TYPE (lhs))
+		   && !POINTER_TYPE_P (TREE_TYPE (lhs))))
 	      && gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR)
 	    {
 	      /* Handle VIEW_CONVERT_EXPRs to not generally supported
 		 huge INTEGER_TYPEs like uint256_t or uint512_t.  These
 		 are usually emitted from memcpy folding and backends
-		 support moves with them but that is usually it.  */
-	      if (TREE_CODE (rhs1) == INTEGER_CST)
-		{
-		  rhs1 = fold_unary (VIEW_CONVERT_EXPR, TREE_TYPE (lhs),
-				     rhs1);
-		  gcc_assert (rhs1 && TREE_CODE (rhs1) == INTEGER_CST);
-		  gimple_assign_set_rhs1 (stmt, rhs1);
-		  gimple_assign_set_rhs_code (stmt, INTEGER_CST);
-		  update_stmt (stmt);
-		  return;
-		}
+		 support moves with them but that is usually it.
+		 Similarly handle VCEs to vector/complex types etc.  */
 	      gcc_assert (TREE_CODE (rhs1) == SSA_NAME);
 	      if (SSA_NAME_IS_DEFAULT_DEF (rhs1)
 		  && (!SSA_NAME_VAR (rhs1) || VAR_P (SSA_NAME_VAR (rhs1))))
@@ -5376,6 +5370,18 @@ bitint_large_huge::lower_stmt (gimple *s
 		}
 	    }
 	}
+      else if (TREE_CODE (TREE_TYPE (lhs)) == BITINT_TYPE
+	       && bitint_precision_kind (TREE_TYPE (lhs)) >= bitint_prec_large
+	       && !INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
+	       && !POINTER_TYPE_P (TREE_TYPE (rhs1))
+	       && gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR)
+	{
+	  int part = var_to_partition (m_map, lhs);
+	  gcc_assert (m_vars[part] != NULL_TREE);
+	  lhs = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (rhs1), m_vars[part]);
+	  insert_before (gimple_build_assign (lhs, rhs1));
+	  return;
+	}
     }
   if (gimple_store_p (stmt))
     {
@@ -5411,6 +5417,28 @@ bitint_large_huge::lower_stmt (gimple *s
 	      case IMAGPART_EXPR:
 		lower_cplxpart_stmt (lhs, g);
 		goto handled;
+	      case VIEW_CONVERT_EXPR:
+		{
+		  tree rhs1 = gimple_assign_rhs1 (g);
+		  rhs1 = TREE_OPERAND (rhs1, 0);
+		  if (!INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
+		      && !POINTER_TYPE_P (TREE_TYPE (rhs1)))
+		    {
+		      tree ltype = TREE_TYPE (rhs1);
+		      addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (lhs));
+		      ltype
+			= build_qualified_type (ltype,
+						TYPE_QUALS (TREE_TYPE (lhs))
+						| ENCODE_QUAL_ADDR_SPACE (as));
+		      lhs = build1 (VIEW_CONVERT_EXPR, ltype, lhs);
+		      gimple_assign_set_lhs (stmt, lhs);
+		      gimple_assign_set_rhs1 (stmt, rhs1);
+		      gimple_assign_set_rhs_code (stmt, TREE_CODE (rhs1));
+		      update_stmt (stmt);
+		      return;
+		    }
+		}
+		break;
 	      default:
 		break;
 	      }
@@ -6235,6 +6263,14 @@ gimple_lower_bitint (void)
 	      if (gimple_assign_cast_p (SSA_NAME_DEF_STMT (s)))
 		{
 		  tree rhs1 = gimple_assign_rhs1 (SSA_NAME_DEF_STMT (s));
+		  if (TREE_CODE (rhs1) == VIEW_CONVERT_EXPR)
+		    {
+		      rhs1 = TREE_OPERAND (rhs1, 0);
+		      if (!INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
+			  && !POINTER_TYPE_P (TREE_TYPE (rhs1))
+			  && gimple_store_p (use_stmt))
+			continue;
+		    }
 		  if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
 		      && ((is_gimple_assign (use_stmt)
 			   && (gimple_assign_rhs_code (use_stmt)
@@ -6279,11 +6315,15 @@ gimple_lower_bitint (void)
 			      goto force_name;
 			    break;
 			  case VIEW_CONVERT_EXPR:
-			    /* Don't merge with VIEW_CONVERT_EXPRs to
-			       huge INTEGER_TYPEs used sometimes in memcpy
-			       expansion.  */
 			    {
 			      tree lhs = gimple_assign_lhs (use_stmt);
+			      /* Don't merge with VIEW_CONVERT_EXPRs to
+				 non-integral types.  */
+			      if (!INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
+				goto force_name;
+			      /* Don't merge with VIEW_CONVERT_EXPRs to
+				 huge INTEGER_TYPEs used sometimes in memcpy
+				 expansion.  */
 			      if (TREE_CODE (TREE_TYPE (lhs)) == INTEGER_TYPE
 				  && (TYPE_PRECISION (TREE_TYPE (lhs))
 				      > MAX_FIXED_MODE_SIZE))
--- gcc/testsuite/gcc.dg/bitint-93.c.jj	2024-02-23 17:28:44.761989660 +0100
+++ gcc/testsuite/gcc.dg/bitint-93.c	2024-02-23 17:28:33.092149911 +0100
@@ -0,0 +1,253 @@
+/* PR middle-end/114073 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-O2 -Wno-psabi" } */
+/* { dg-additional-options "-mavx512f" { target i?86-*-* x86_64-*-* } } */
+
+typedef int V __attribute__((vector_size (sizeof (_BitInt(256)))));
+typedef int W __attribute__((vector_size (sizeof (_BitInt(512)))));
+
+#if __BITINT_MAXWIDTH__ >= 256 && defined (__SIZEOF_INT128__)
+_Complex __int128
+f1 (_BitInt(256) x)
+{
+  union U { _BitInt(256) x; _Complex __int128 y; } u;
+  u.x = x;
+  return u.y;
+}
+
+_Complex __int128
+f2 (_BitInt(254) x)
+{
+  union U { _BitInt(254) x; _Complex __int128 y; } u;
+  u.x = x;
+  return u.y;
+}
+
+_BitInt(256)
+f3 (_Complex __int128 x)
+{
+  union U { _BitInt(256) x; _Complex __int128 y; } u;
+  u.y = x;
+  return u.x;
+}
+
+_BitInt(252)
+f4 (_Complex __int128 x)
+{
+  union U { _BitInt(252) x; _Complex __int128 y; } u;
+  u.y = x;
+  return u.x;
+}
+
+_Complex __int128
+f5 (_BitInt(256) x)
+{
+  union U { _BitInt(256) x; _Complex __int128 y; } u;
+  u.x = x + 1;
+  return u.y;
+}
+
+_Complex __int128
+f6 (_BitInt(254) x)
+{
+  union U { _BitInt(254) x; _Complex __int128 y; } u;
+  u.x = x + 1;
+  return u.y;
+}
+
+_Complex __int128
+f7 (_BitInt(256) *x)
+{
+  union U { _BitInt(256) x; _Complex __int128 y; } u;
+  u.x = *x + 1;
+  return u.y;
+}
+
+_Complex __int128
+f8 (_BitInt(254) *x)
+{
+  union U { _BitInt(254) x; _Complex __int128 y; } u;
+  u.x = *x + 1;
+  return u.y;
+}
+
+_BitInt(256)
+f9 (_Complex __int128 x)
+{
+  union U { _BitInt(256) x; _Complex __int128 y; } u;
+  u.y = x;
+  return u.x + 1;
+}
+
+_BitInt(252)
+f10 (_Complex __int128 x)
+{
+  union U { _BitInt(252) x; _Complex __int128 y; } u;
+  u.y = x;
+  return u.x + 1;
+}
+#endif
+
+#if __BITINT_MAXWIDTH__ >= 256
+V
+f11 (_BitInt(256) x)
+{
+  union U { _BitInt(256) x; V y; } u;
+  u.x = x;
+  return u.y;
+}
+
+V
+f12 (_BitInt(254) x)
+{
+  union U { _BitInt(254) x; V y; } u;
+  u.x = x;
+  return u.y;
+}
+
+_BitInt(256)
+f13 (V x)
+{
+  union U { _BitInt(256) x; V y; } u;
+  u.y = x;
+  return u.x;
+}
+
+_BitInt(252)
+f14 (V x)
+{
+  union U { _BitInt(252) x; V y; } u;
+  u.y = x;
+  return u.x;
+}
+
+V
+f15 (_BitInt(256) x)
+{
+  union U { _BitInt(256) x; V y; } u;
+  u.x = x + 1;
+  return u.y;
+}
+
+V
+f16 (_BitInt(254) x)
+{
+  union U { _BitInt(254) x; V y; } u;
+  u.x = x + 1;
+  return u.y;
+}
+
+V
+f17 (_BitInt(256) *x)
+{
+  union U { _BitInt(256) x; V y; } u;
+  u.x = *x + 1;
+  return u.y;
+}
+
+V
+f18 (_BitInt(254) *x)
+{
+  union U { _BitInt(254) x; V y; } u;
+  u.x = *x + 1;
+  return u.y;
+}
+
+_BitInt(256)
+f19 (V x)
+{
+  union U { _BitInt(256) x; V y; } u;
+  u.y = x;
+  return u.x + 1;
+}
+
+_BitInt(252)
+f20 (V x)
+{
+  union U { _BitInt(252) x; V y; } u;
+  u.y = x;
+  return u.x + 1;
+}
+#endif
+
+#if __BITINT_MAXWIDTH__ >= 512
+W
+f21 (_BitInt(512) x)
+{
+  union U { _BitInt(512) x; W y; } u;
+  u.x = x;
+  return u.y;
+}
+
+W
+f22 (_BitInt(509) x)
+{
+  union U { _BitInt(509) x; W y; } u;
+  u.x = x;
+  return u.y;
+}
+
+_BitInt(512)
+f23 (W x)
+{
+  union U { _BitInt(512) x; W y; } u;
+  u.y = x;
+  return u.x;
+}
+
+_BitInt(506)
+f24 (W x)
+{
+  union U { _BitInt(506) x; W y; } u;
+  u.y = x;
+  return u.x;
+}
+
+W
+f25 (_BitInt(512) x)
+{
+  union U { _BitInt(512) x; W y; } u;
+  u.x = x + 1;
+  return u.y;
+}
+
+W
+f26 (_BitInt(509) x)
+{
+  union U { _BitInt(509) x; W y; } u;
+  u.x = x + 1;
+  return u.y;
+}
+
+W
+f27 (_BitInt(512) *x)
+{
+  union U { _BitInt(512) x; W y; } u;
+  u.x = *x + 1;
+  return u.y;
+}
+
+W
+f28 (_BitInt(509) *x)
+{
+  union U { _BitInt(509) x; W y; } u;
+  u.x = *x + 1;
+  return u.y;
+}
+
+_BitInt(512)
+f29 (W x)
+{
+  union U { _BitInt(512) x; W y; } u;
+  u.y = x;
+  return u.x + 1;
+}
+
+_BitInt(506)
+f30 (W x)
+{
+  union U { _BitInt(506) x; W y; } u;
+  u.y = x;
+  return u.x + 1;
+}
+#endif
