Add initial version of value analysis and dataflow constant propagation

Author: jachris

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -113,7 +113,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     }
 
     pub fn misc_cast(
-        &mut self,
+        &self,
         src: &ImmTy<'tcx, M::Provenance>,
         cast_ty: Ty<'tcx>,
     ) -> InterpResult<'tcx, Immediate<M::Provenance>> {

compiler/rustc_graphviz/src/lib.rs

@@ -471,7 +471,11 @@ pub trait Labeller<'a> {
 /// Escape tags in such a way that it is suitable for inclusion in a
 /// Graphviz HTML label.
 pub fn escape_html(s: &str) -> String {
-    s.replace('&', "&amp;").replace('\"', "&quot;").replace('<', "&lt;").replace('>', "&gt;")
+    s.replace('&', "&amp;")
+        .replace('\"', "&quot;")
+        .replace('<', "&lt;")
+        .replace('>', "&gt;")
+        .replace('\n', "<br align=\"left\"/>")
 }
 
 impl<'a> LabelText<'a> {

compiler/rustc_mir_dataflow/src/framework/graphviz.rs

@@ -475,7 +475,10 @@ where
                 r#"<td colspan="{colspan}" {fmt} align="left">{state}</td>"#,
                 colspan = this.style.num_state_columns(),
                 fmt = fmt,
-                state = format!("{:?}", DebugWithAdapter { this: state, ctxt: analysis }),
+                state = dot::escape_html(&format!(
+                    "{:?}",
+                    DebugWithAdapter { this: state, ctxt: analysis }
+                )),
             )
         })
     }

compiler/rustc_mir_dataflow/src/lib.rs

@@ -42,6 +42,7 @@ pub mod move_paths;
 pub mod rustc_peek;
 pub mod storage;
 pub mod un_derefer;
+pub mod value_analysis;
 
 pub(crate) mod indexes {
     pub(crate) use super::move_paths::MovePathIndex;