update cranelift to match new write_bytes signature

Author: the8472

compiler/rustc_codegen_cranelift/example/mini_core.rs

@@ -666,7 +666,7 @@ pub mod intrinsics {
     #[rustc_intrinsic]
     pub fn bswap<T>(x: T) -> T;
     #[rustc_intrinsic]
-    pub unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
+    pub unsafe fn write_bytes<T, B>(dst: *mut T, val: B, count: usize);
     #[rustc_intrinsic]
     pub unsafe fn unreachable() -> !;
 }

compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs

@@ -125,7 +125,7 @@ static NUM_REF: &'static u8 = unsafe { &*&raw const NUM };
 
 unsafe fn zeroed<T>() -> T {
     let mut uninit = MaybeUninit { uninit: () };
-    intrinsics::write_bytes(&mut uninit.value.value as *mut T, 0, 1);
+    intrinsics::write_bytes(&mut uninit.value.value as *mut T, 0u8, 1);
     uninit.value.value
 }
 

compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs

@@ -685,6 +685,12 @@ fn codegen_regular_intrinsic_call<'tcx>(
 
         sym::write_bytes | sym::volatile_set_memory => {
             intrinsic_args!(fx, args => (dst, val, count); intrinsic);
+            if val.layout().size.bytes() != 1 {
+                // incorrect sizes can be encountered on dead branches
+                fx.bcx.ins().trap(TrapCode::user(1).unwrap());
+                return Ok(());
+            };
+
             let val = val.load_scalar(fx);
             let count = count.load_scalar(fx);