initial working state

compiler/rustc_middle/src/mir/abstract_const.rs

@@ -0,0 +1,15 @@
+//! A subset of a mir body used for const evaluatability checking.
+use crate::mir;
+use crate::ty;
+
+/// An index into an `AbstractConst`.
+pub type NodeId = usize;
+
+/// A node of an `AbstractConst`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, HashStable)]
+pub enum Node<'tcx> {
+    Leaf(&'tcx ty::Const<'tcx>),
+    Binop(mir::BinOp, NodeId, NodeId),
+    UnaryOp(mir::UnOp, NodeId),
+    FunctionCall(NodeId, &'tcx [NodeId]),
+}

compiler/rustc_middle/src/mir/mod.rs

@@ -40,6 +40,7 @@ use std::{iter, mem, option};
 use self::predecessors::{PredecessorCache, Predecessors};
 pub use self::query::*;
 
+pub mod abstract_const;
 pub mod coverage;
 pub mod interpret;
 pub mod mono;

compiler/rustc_middle/src/query/mod.rs

@@ -244,6 +244,25 @@ rustc_queries! {
             no_hash
         }
 
+        /// Try to build an abstract representation of the given constant.
+        query mir_abstract_const(
+            key: DefId
+        ) -> Option<&'tcx [mir::abstract_const::Node<'tcx>]> {
+            desc {
+                |tcx| "building an abstract representation for {}", tcx.def_path_str(key),
+            }
+        }
+        /// Try to build an abstract representation of the given constant.
+        query mir_abstract_const_of_const_arg(
+            key: (LocalDefId, DefId)
+        ) -> Option<&'tcx [mir::abstract_const::Node<'tcx>]> {
+            desc {
+                |tcx|
+                "building an abstract representation for the const argument {}",
+                tcx.def_path_str(key.0.to_def_id()),
+            }
+        }
+
         query mir_drops_elaborated_and_const_checked(
             key: ty::WithOptConstParam<LocalDefId>
         ) -> &'tcx Steal<mir::Body<'tcx>> {