Perform GVN inside coroutines.

Author: cjgillot

compiler/rustc_mir_transform/src/gvn.rs

@@ -362,7 +362,6 @@ struct VnState<'body, 'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     ecx: InterpCx<'tcx, DummyMachine>,
     local_decls: &'body LocalDecls<'tcx>,
-    is_coroutine: bool,
     /// Value stored in each local.
     locals: IndexVec<Local, Option<VnIndex>>,
     /// Locals that are assigned that value.
@@ -403,7 +402,6 @@ impl<'body, 'a, 'tcx> VnState<'body, 'a, 'tcx> {
             tcx,
             ecx: InterpCx::new(tcx, DUMMY_SP, typing_env, DummyMachine),
             local_decls,
-            is_coroutine: body.coroutine.is_some(),
             locals: IndexVec::from_elem(None, local_decls),
             rev_locals: IndexVec::with_capacity(num_values),
             values: ValueSet::new(num_values),
@@ -561,11 +559,7 @@ impl<'body, 'a, 'tcx> VnState<'body, 'a, 'tcx> {
         use Value::*;
         let ty = self.ty(value);
         // Avoid computing layouts inside a coroutine, as that can cause cycles.
-        let ty = if !self.is_coroutine || ty.is_scalar() {
-            self.ecx.layout_of(ty).ok()?
-        } else {
-            return None;
-        };
+        let ty = self.ecx.layout_of(ty).ok()?;
         let op = match self.get(value) {
             _ if ty.is_zst() => ImmTy::uninit(ty).into(),