rustc: expose monomorphic const_eval through on-demand.

Author: eddyb

src/Cargo.lock

@@ -11,9 +11,12 @@
 use self::ConstVal::*;
 pub use rustc_const_math::ConstInt;
 
+use hir;
+use hir::def::Def;
 use hir::def_id::DefId;
-use ty::TyCtxt;
+use ty::{self, TyCtxt};
 use ty::subst::Substs;
+use util::common::ErrorReported;
 use rustc_const_math::*;
 
 use graphviz::IntoCow;
@@ -215,3 +218,35 @@ impl<'a, 'gcx, 'tcx> ConstEvalErr<'tcx> {
         self.struct_error(tcx, primary_span, primary_kind).emit();
     }
 }
+
+/// Returns the value of the length-valued expression
+pub fn eval_length(tcx: TyCtxt,
+                   count: hir::BodyId,
+                   reason: &str)
+                   -> Result<usize, ErrorReported>
+{
+    let count_expr = &tcx.hir.body(count).value;
+    let count_def_id = tcx.hir.body_owner_def_id(count);
+    match ty::queries::monomorphic_const_eval::get(tcx, count_expr.span, count_def_id) {
+        Ok(Integral(Usize(count))) => {
+            let val = count.as_u64(tcx.sess.target.uint_type);
+            assert_eq!(val as usize as u64, val);
+            Ok(val as usize)
+        },
+        Ok(_) |
+        Err(ConstEvalErr { kind: ErrKind::TypeckError, .. }) => Err(ErrorReported),
+        Err(err) => {
+            let mut diag = err.struct_error(tcx, count_expr.span, reason);
+
+            if let hir::ExprPath(hir::QPath::Resolved(None, ref path)) = count_expr.node {
+                if let Def::Local(..) = path.def {
+                    diag.note(&format!("`{}` is a variable",
+                                       tcx.hir.node_to_pretty_string(count_expr.id)));
+                }
+            }
+
+            diag.emit();
+            Err(ErrorReported)
+        }
+    }
+}

src/librustc/middle/const_val.rs

@@ -18,6 +18,7 @@ use rustc::traits;
 use rustc::hir::def::Def;
 use rustc::hir::def_id::DefId;
 use rustc::ty::{self, Ty, TyCtxt};
+use rustc::ty::maps::Providers;
 use rustc::ty::util::IntTypeExt;
 use rustc::ty::subst::{Substs, Subst};
 use rustc::traits::Reveal;
@@ -163,12 +164,6 @@ pub struct ConstContext<'a, 'tcx: 'a> {
 }
 
 impl<'a, 'tcx> ConstContext<'a, 'tcx> {
-    pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>, body: hir::BodyId) -> Self {
-        let def_id = tcx.hir.body_owner_def_id(body);
-        ty::queries::mir_const_qualif::get(tcx, DUMMY_SP, def_id);
-        ConstContext::with_tables(tcx, tcx.item_tables(def_id))
-    }
-
     pub fn with_tables(tcx: TyCtxt<'a, 'tcx, 'tcx>, tables: &'a ty::TypeckTables<'tcx>) -> Self {
         ConstContext {
             tcx: tcx,
@@ -799,34 +794,20 @@ impl<'a, 'tcx> ConstContext<'a, 'tcx> {
     }
 }
 
+pub fn provide(providers: &mut Providers) {
+    *providers = Providers {
+        monomorphic_const_eval,
+        ..*providers
+    };
+}
 
-/// Returns the value of the length-valued expression
-pub fn eval_length<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                             count: hir::BodyId,
-                             reason: &str)
-                             -> Result<usize, ErrorReported>
-{
-    let count_expr = &tcx.hir.body(count).value;
-    match ConstContext::new(tcx, count).eval(count_expr) {
-        Ok(Integral(Usize(count))) => {
-            let val = count.as_u64(tcx.sess.target.uint_type);
-            assert_eq!(val as usize as u64, val);
-            Ok(val as usize)
-        },
-        Ok(_) |
-        Err(ConstEvalErr { kind: TypeckError, .. }) => Err(ErrorReported),
-        Err(err) => {
-            let mut diag = err.struct_error(tcx, count_expr.span, reason);
-
-            if let hir::ExprPath(hir::QPath::Resolved(None, ref path)) = count_expr.node {
-                if let Def::Local(..) = path.def {
-                    diag.note(&format!("`{}` is a variable",
-                                       tcx.hir.node_to_pretty_string(count_expr.id)));
-                }
-            }
+fn monomorphic_const_eval<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
+                                    def_id: DefId)
+                                    -> EvalResult<'tcx> {
+    ty::queries::mir_const_qualif::get(tcx, DUMMY_SP, def_id);
+    let cx = ConstContext::with_tables(tcx, tcx.item_tables(def_id));
 
-            diag.emit();
-            Err(ErrorReported)
-        }
-    }
+    let id = tcx.hir.as_local_node_id(def_id).unwrap();
+    let body = tcx.hir.body_owned_by(id);
+    cx.eval(&tcx.hir.body(body).value)
 }

src/librustc_const_eval/eval.rs

@@ -37,7 +37,7 @@ use rustc_plugin::registry::Registry;
 use rustc_plugin as plugin;
 use rustc_passes::{ast_validation, no_asm, loops, consts,
                    static_recursion, hir_stats, mir_stats};
-use rustc_const_eval::check_match;
+use rustc_const_eval::{self, check_match};
 use super::Compilation;
 
 use serialize::json;
@@ -895,6 +895,7 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
     typeck::provide(&mut local_providers);
     ty::provide(&mut local_providers);
     reachable::provide(&mut local_providers);
+    rustc_const_eval::provide(&mut local_providers);
 
     let mut extern_providers = ty::maps::Providers::default();
     cstore::provide(&mut extern_providers);

src/librustc_driver/driver.rs

@@ -17,7 +17,6 @@ use hair::cx::to_ref::ToRef;
 use rustc::hir::map;
 use rustc::hir::def::{Def, CtorKind};
 use rustc::middle::const_val::ConstVal;
-use rustc_const_eval::ConstContext;
 use rustc::ty::{self, AdtKind, VariantDef, Ty};
 use rustc::ty::cast::CastKind as TyCastKind;
 use rustc::hir;
@@ -592,9 +591,9 @@ fn make_mirror_unadjusted<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>,
 
         // Now comes the rote stuff:
         hir::ExprRepeat(ref v, count) => {
-            let tcx = cx.tcx.global_tcx();
             let c = &cx.tcx.hir.body(count).value;
-            let count = match ConstContext::new(tcx, count).eval(c) {
+            let def_id = cx.tcx.hir.body_owner_def_id(count);
+            let count = match ty::queries::monomorphic_const_eval::get(cx.tcx, c.span, def_id) {
                 Ok(ConstVal::Integral(ConstInt::Usize(u))) => u,
                 Ok(other) => bug!("constant evaluation of repeat count yielded {:?}", other),
                 Err(s) => cx.fatal_const_eval_err(&s, c.span, "expression")

src/librustc_mir/hair/cx/expr.rs

@@ -16,7 +16,6 @@ arena = { path = "../libarena" }
 fmt_macros = { path = "../libfmt_macros" }
 rustc = { path = "../librustc" }
 rustc_back = { path = "../librustc_back" }
-rustc_const_eval = { path = "../librustc_const_eval" }
 rustc_const_math = { path = "../librustc_const_math" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_platform_intrinsics = { path = "../librustc_platform_intrinsics" }

src/librustc_typeck/Cargo.toml

@@ -12,7 +12,7 @@
 //! representation.  The main routine here is `ast_ty_to_ty()`: each use
 //! is parameterized by an instance of `AstConv`.
 
-use rustc_const_eval::eval_length;
+use rustc::middle::const_val::eval_length;
 use rustc_data_structures::accumulate_vec::AccumulateVec;
 use hir;
 use hir::def::Def;
@@ -1208,7 +1208,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                 self.associated_path_def_to_ty(ast_ty.id, ast_ty.span, ty, def, segment).0
             }
             hir::TyArray(ref ty, length) => {
-                if let Ok(length) = eval_length(tcx.global_tcx(), length, "array length") {
+                if let Ok(length) = eval_length(tcx, length, "array length") {
                     tcx.mk_array(self.ast_ty_to_ty(&ty), length)
                 } else {
                     self.tcx().types.err

src/librustc_typeck/astconv.rs

@@ -126,7 +126,7 @@ use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::hir::{self, PatKind};
 use rustc::middle::lang_items;
 use rustc_back::slice;
-use rustc_const_eval::eval_length;
+use rustc::middle::const_val::eval_length;
 use rustc_const_math::ConstInt;
 
 mod assoc;
@@ -3634,7 +3634,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
               tcx.mk_array(element_ty, args.len())
           }
           hir::ExprRepeat(ref element, count) => {
-            let count = eval_length(self.tcx.global_tcx(), count, "repeat count")
+            let count = eval_length(self.tcx, count, "repeat count")
                   .unwrap_or(0);
 
             let uty = match expected {

src/librustc_typeck/check/mod.rs

@@ -59,14 +59,12 @@ use constrained_type_params as ctp;
 use middle::lang_items::SizedTraitLangItem;
 use middle::const_val::ConstVal;
 use middle::resolve_lifetime as rl;
-use rustc_const_eval::ConstContext;
 use rustc::ty::subst::Substs;
 use rustc::ty::{ToPredicate, ReprOptions};
 use rustc::ty::{self, AdtKind, ToPolyTraitRef, Ty, TyCtxt};
 use rustc::ty::maps::Providers;
 use rustc::ty::util::IntTypeExt;
 use rustc::dep_graph::DepNode;
-use util::common::MemoizationMap;
 use util::nodemap::{NodeMap, FxHashMap};
 
 use rustc_const_math::ConstInt;
@@ -600,9 +598,7 @@ fn convert_enum_variant_types<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
         let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr());
         prev_discr = Some(if let Some(e) = variant.node.disr_expr {
             let expr_did = tcx.hir.local_def_id(e.node_id);
-            let result = tcx.maps.monomorphic_const_eval.memoize(expr_did, || {
-                ConstContext::new(tcx, e).eval(&tcx.hir.body(e).value)
-            });
+            let result = ty::queries::monomorphic_const_eval::get(tcx, variant.span, expr_did);
 
             // enum variant evaluation happens before the global constant check
             // so we need to report the real error

src/librustc_typeck/collect.rs

@@ -94,7 +94,6 @@ extern crate fmt_macros;
 extern crate rustc_platform_intrinsics as intrinsics;
 extern crate rustc_back;
 extern crate rustc_const_math;
-extern crate rustc_const_eval;
 extern crate rustc_data_structures;
 extern crate rustc_errors as errors;