codegen: align funclet stubs and likely handling notes

Author: LegNeato

crates/rustc_codegen_spirv/src/builder/builder_methods.rs

@@ -1825,9 +1825,8 @@ impl<'a, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'tcx> {
         self.declare_func_local_var(self.type_array(self.type_i8(), size.bytes()), align)
     }
 
-    fn scalable_alloca(&mut self, elt: u64, align: Align, element_ty: Ty<'_>) -> Self::Value {
-        let _ = (elt, align, element_ty);
-        self.fatal("scalable alloca is not supported in SPIR-V backend")
+    fn scalable_alloca(&mut self, _elt: u64, _align: Align, _element_ty: Ty<'_>) -> Self::Value {
+        bug!("scalable alloca is not supported in SPIR-V backend")
     }
 
     fn load(&mut self, ty: Self::Type, ptr: Self::Value, _align: Align) -> Self::Value {
@@ -3062,15 +3061,15 @@ impl<'a, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'tcx> {
         _parent: Option<Self::Value>,
         _args: &[Self::Value],
     ) -> Self::Funclet {
-        todo!()
+        bug!("Funclets are not supported")
     }
 
     fn cleanup_ret(&mut self, _funclet: &Self::Funclet, _unwind: Option<Self::BasicBlock>) {
-        todo!()
+        bug!("Funclets are not supported")
     }
 
     fn catch_pad(&mut self, _parent: Self::Value, _args: &[Self::Value]) -> Self::Funclet {
-        todo!()
+        bug!("Funclets are not supported")
     }
 
     fn catch_switch(
@@ -3079,7 +3078,7 @@ impl<'a, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'tcx> {
         _unwind: Option<Self::BasicBlock>,
         _handlers: &[Self::BasicBlock],
     ) -> Self::Value {
-        todo!()
+        bug!("Funclets are not supported")
     }
 
     fn get_funclet_cleanuppad(&self, _funclet: &Self::Funclet) -> Self::Value {

crates/rustc_codegen_spirv/src/builder/intrinsics.rs

@@ -83,10 +83,10 @@ impl<'a, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'a, 'tcx> {
         let ret_ty = self.layout_of(sig.output()).spirv_type(self.span(), self);
 
         let value = match name {
-            _ if name == sym::unlikely || name.as_str() == "likely" => {
-                // Ignore these for now.
-                args[0].immediate()
-            }
+            // `sym::likely` no longer exists on newer rustc nightlies, but
+            // the intrinsic name is still `"likely"` in MIR. Ignore both branch
+            // hint intrinsics for now.
+            _ if name == sym::unlikely || name.as_str() == "likely" => args[0].immediate(),
 
             sym::breakpoint => {
                 self.abort();