Improved BodyCache body impl so it only returns a sharable ref, add new body_mut method, fix visit macros, simplify usage in codegen_ssa analyzer

Author: Nashenas88

src/librustc/mir/cache.rs

@@ -132,7 +132,7 @@ impl<'a, 'tcx> BodyCache<&'a Body<'tcx>> {
     }
 
     #[inline]
-    pub fn body(&self) -> &Body<'tcx> {
+    pub fn body(&self) -> &'a Body<'tcx> {
         self.body
     }
 
@@ -149,7 +149,8 @@ impl<'a, 'tcx> BodyCache<&'a Body<'tcx>> {
 
 impl<'a, 'tcx> Deref for BodyCache<&'a Body<'tcx>> {
     type Target = Body<'tcx>;
-    fn deref(&self) -> &Body<'tcx> {
+
+    fn deref(&self) -> &Self::Target {
         self.body
     }
 }
@@ -209,7 +210,12 @@ impl<'a, 'b, 'tcx> graph::GraphSuccessors<'b> for BodyCache<&'a Body<'tcx>> {
 
 impl<'a, 'tcx> BodyCache<&'a mut Body<'tcx>> {
     #[inline]
-    pub fn body(&mut self) -> &mut Body<'tcx> {
+    pub fn body(&self) -> &Body<'tcx> {
+        self.body
+    }
+
+    #[inline]
+    pub fn body_mut(&mut self) -> &mut Body<'tcx> {
         self.body
     }
 
@@ -227,7 +233,7 @@ impl<'a, 'tcx> BodyCache<&'a mut Body<'tcx>> {
 impl<'a, 'tcx> Deref for BodyCache<&'a mut Body<'tcx>> {
     type Target = Body<'tcx>;
 
-    fn deref(&self) -> &Body<'tcx> {
+    fn deref(&self) -> &Self::Target {
         self.body
     }
 }

src/librustc/mir/visit.rs

@@ -247,8 +247,12 @@ macro_rules! make_mir_visitor {
                 &mut self,
                 body_cache: & $($mutability)? BodyCache<&'_ $($mutability)? Body<'tcx>>
             ) {
+                macro_rules! body {
+                    (mut) => (body_cache.body_mut());
+                    () => (body_cache.body());
+                }
                 let span = body_cache.body().span;
-                if let Some(yield_ty) = &$($mutability)? body_cache.body().yield_ty {
+                if let Some(yield_ty) = &$($mutability)? body!($($mutability)?).yield_ty {
                     self.visit_ty(yield_ty, TyContext::YieldTy(SourceInfo {
                         span,
                         scope: OUTERMOST_SOURCE_SCOPE,
@@ -266,7 +270,7 @@ macro_rules! make_mir_visitor {
                     self.visit_basic_block_data(bb, data);
                 }
 
-                let body = body_cache.body();
+                let body = body!($($mutability)?);
                 for scope in &$($mutability)? body.source_scopes {
                     self.visit_source_scope_data(scope);
                 }

src/librustc_codegen_ssa/mir/analyze.rs

@@ -4,7 +4,7 @@
 use rustc_index::bit_set::BitSet;
 use rustc_data_structures::graph::dominators::Dominators;
 use rustc_index::vec::{Idx, IndexVec};
-use rustc::mir::{self, BasicBlock, Body, BodyCache, Location, TerminatorKind};
+use rustc::mir::{self, Body, BodyCache, Location, TerminatorKind};
 use rustc::mir::visit::{
     Visitor, PlaceContext, MutatingUseContext, NonMutatingUseContext, NonUseContext,
 };
@@ -20,8 +20,7 @@ pub fn non_ssa_locals<'b, 'a: 'b, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     fx: &mut FunctionCx<'a, 'tcx, Bx>,
     mir: &'b mut BodyCache<&'a Body<'tcx>>,
 ) -> BitSet<mir::Local> {
-    let dominators = mir.dominators();
-    let mut analyzer = LocalAnalyzer::new(fx, mir, dominators);
+    let mut analyzer = LocalAnalyzer::new(fx, mir);
 
     analyzer.visit_body(mir);
 
@@ -68,13 +67,15 @@ struct LocalAnalyzer<'mir, 'a, 'b, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
     first_assignment: IndexVec<mir::Local, Location>,
 }
 
-impl<'mir, 'a, 'b, 'tcx, Bx: BuilderMethods<'a, 'tcx>> LocalAnalyzer<'mir, 'a, 'b, 'tcx, Bx> {
-    fn new(fx: &'mir FunctionCx<'a, 'tcx, Bx>, mir: &'b Body<'tcx>, dominators: Dominators<BasicBlock>) -> Self {
+impl<'mir, 'a, 'b, 'c, 'tcx, Bx: BuilderMethods<'a, 'tcx>> LocalAnalyzer<'mir, 'a, 'b, 'tcx, Bx> {
+    fn new(fx: &'mir FunctionCx<'a, 'tcx, Bx>, mir: &'c mut BodyCache<&'b Body<'tcx>>) -> Self {
         let invalid_location =
             mir::BasicBlock::new(mir.basic_blocks().len()).start_location();
+        let dominators = mir.dominators();
+        let body = mir.body();
         let mut analyzer = LocalAnalyzer {
             fx,
-            mir,
+            mir: body,
             dominators,
             non_ssa_locals: BitSet::new_empty(mir.local_decls.len()),
             first_assignment: IndexVec::from_elem(invalid_location, &mir.local_decls)