Fix ABI issue with f128 to small integer cast

Author: bjorn3

example/std_example.rs

@@ -1,5 +1,12 @@
-#![feature(core_intrinsics, coroutines, coroutine_trait, repr_simd, tuple_trait, unboxed_closures)]
 #![allow(internal_features)]
+#![feature(cfg_target_has_reliable_f16_f128)]
+#![feature(core_intrinsics)]
+#![feature(coroutine_trait)]
+#![feature(coroutines)]
+#![feature(f128)]
+#![feature(repr_simd)]
+#![feature(tuple_trait)]
+#![feature(unboxed_closures)]
 
 #[cfg(target_arch = "x86_64")]
 use std::arch::x86_64::*;
@@ -91,6 +98,8 @@ fn main() {
     assert_eq!(houndred_f32 as i128, 100);
     assert_eq!(houndred_f64 as i128, 100);
     assert_eq!(1u128.rotate_left(2), 4);
+    #[cfg(target_has_reliable_f128)]
+    assert_eq!(std::hint::black_box(300.0f128) as u8, 255);
 
     assert_eq!(black_box(f32::NAN) as i128, 0);
     assert_eq!(black_box(f32::NAN) as u128, 0);

src/codegen_f16_f128.rs

@@ -259,7 +259,7 @@ pub(crate) fn codegen_cast(
             },
         );
         let ret =
-            fx.lib_call(&name, vec![AbiParam::new(from_ty)], vec![AbiParam::new(to_ty)], &[from])
+            fx.lib_call(&name, vec![AbiParam::new(from_ty)], vec![AbiParam::new(ret_ty)], &[from])
                 [0];
         let val = if ret_ty == to_ty {
             ret