Rollup merge of #66991 - Nashenas88:body_cache_cleanup, r=eddyb

Cleanup BodyCache

After this PR:

- `BodyCache` is renamed to `BodyAndCache`
- `ReadOnlyBodyCache` is renamed to `ReadOnlyBodyAndCache`
- `ReadOnlyBodyAndCache::body` fn is removed and all calls to it are replaced by a deref (possible due to fix of its `Deref` imp in #65947)

cc @eddyb @oli-obk

src/librustc_codegen_ssa/mir/block.rs

@@ -153,7 +153,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
     // a loop.
     fn maybe_sideeffect<Bx: BuilderMethods<'a, 'tcx>>(
         &self,
-        mir: mir::ReadOnlyBodyCache<'tcx, 'tcx>,
+        mir: mir::ReadOnlyBodyAndCache<'tcx, 'tcx>,
         bx: &mut Bx,
         targets: &[mir::BasicBlock],
     ) {

src/librustc_codegen_ssa/mir/mod.rs

@@ -21,7 +21,7 @@ use self::operand::{OperandRef, OperandValue};
 pub struct FunctionCx<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
     instance: Instance<'tcx>,
 
-    mir: mir::ReadOnlyBodyCache<'tcx, 'tcx>,
+    mir: mir::ReadOnlyBodyAndCache<'tcx, 'tcx>,
 
     debug_context: Option<FunctionDebugContext<Bx::DIScope>>,
 
@@ -159,7 +159,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         }).collect();
 
     let (landing_pads, funclets) = create_funclets(&mir, &mut bx, &cleanup_kinds, &block_bxs);
-    let mir_body: &mir::Body<'_> = mir.body();
+    let mir_body: &mir::Body<'_> = *mir;
     let mut fx = FunctionCx {
         instance,
         mir,