Auto merge of #81114 - bugadani:generator, r=estebank

Box generator-related Body fields

Might save some memory on functions that aren't generators.

compiler/rustc_mir/src/transform/check_consts/validation.rs

@@ -222,7 +222,7 @@ impl Validator<'mir, 'tcx> {
 
         // `async` functions cannot be `const fn`. This is checked during AST lowering, so there's
         // no need to emit duplicate errors here.
-        if is_async_fn(self.ccx) || body.generator_kind.is_some() {
+        if is_async_fn(self.ccx) || body.generator.is_some() {
             tcx.sess.delay_span_bug(body.span, "`async` functions cannot be `const fn`");
             return;
         }

compiler/rustc_mir/src/transform/const_prop.rs

@@ -140,7 +140,7 @@ impl<'tcx> MirPass<'tcx> for ConstProp {
             body.arg_count,
             Default::default(),
             body.span,
-            body.generator_kind,
+            body.generator_kind(),
         );
 
         // FIXME(oli-obk, eddyb) Optimize locals (or even local paths) to hold

compiler/rustc_mir/src/transform/generator.rs

@@ -1111,7 +1111,7 @@ fn create_generator_resume_function<'tcx>(
     cases.insert(0, (UNRESUMED, BasicBlock::new(0)));
 
     // Panic when resumed on the returned or poisoned state
-    let generator_kind = body.generator_kind.unwrap();
+    let generator_kind = body.generator_kind().unwrap();
 
     if can_unwind {
         cases.insert(
@@ -1236,14 +1236,14 @@ fn create_cases<'tcx>(
 
 impl<'tcx> MirPass<'tcx> for StateTransform {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        let yield_ty = if let Some(yield_ty) = body.yield_ty {
+        let yield_ty = if let Some(yield_ty) = body.yield_ty() {
             yield_ty
         } else {
             // This only applies to generators
             return;
         };
 
-        assert!(body.generator_drop.is_none());
+        assert!(body.generator_drop().is_none());
 
         // The first argument is the generator type passed by value
         let gen_ty = body.local_decls.raw[1].ty;
@@ -1340,10 +1340,11 @@ impl<'tcx> MirPass<'tcx> for StateTransform {
         transform.visit_body(body);
 
         // Update our MIR struct to reflect the changes we've made
-        body.yield_ty = None;
         body.arg_count = 2; // self, resume arg
         body.spread_arg = None;
-        body.generator_layout = Some(layout);
+
+        body.generator.as_mut().unwrap().yield_ty = None;
+        body.generator.as_mut().unwrap().generator_layout = Some(layout);
 
         // Insert `drop(generator_struct)` which is used to drop upvars for generators in
         // the unresumed state.
@@ -1362,7 +1363,7 @@ impl<'tcx> MirPass<'tcx> for StateTransform {
         // Create a copy of our MIR and use it to create the drop shim for the generator
         let drop_shim = create_generator_drop_shim(tcx, &transform, gen_ty, body, drop_clean);
 
-        body.generator_drop = Some(box drop_shim);
+        body.generator.as_mut().unwrap().generator_drop = Some(drop_shim);
 
         // Create the Generator::resume function
         create_generator_resume_function(tcx, transform, body, can_return);

compiler/rustc_mir/src/transform/inline.rs

@@ -220,7 +220,7 @@ impl Inliner<'tcx> {
             // since their `optimized_mir` is used for layout computation, which can
             // create a cycle, even when no attempt is made to inline the function
             // in the other direction.
-            if caller_body.generator_kind.is_some() {
+            if caller_body.generator.is_some() {
                 return Err("local generator (query cycle avoidance)");
             }
 

compiler/rustc_mir/src/transform/promote_consts.rs

@@ -1177,7 +1177,7 @@ pub fn promote_candidates<'tcx>(
             0,
             vec![],
             body.span,
-            body.generator_kind,
+            body.generator_kind(),
         );
 
         let promoter = Promoter {