Add a query to convert from ConstValue to Allocation

Author: Zoxc

src/librustc/dep_graph/dep_node.rs

@@ -621,13 +621,14 @@ define_dep_nodes!( <'tcx>
     [input] UsedCrateSource(CrateNum),
     [input] PostorderCnums,
 
-    // This query is not expected to have inputs -- as a result, it's
-    // not a good candidate for "replay" because it's essentially a
-    // pure function of its input (and hence the expectation is that
-    // no caller would be green **apart** from just this
-    // query). Making it anonymous avoids hashing the result, which
+    // These queries are not expected to have inputs -- as a result, they
+    // are not good candidates for "replay" because they are essentially
+    // pure functions of their input (and hence the expectation is that
+    // no caller would be green **apart** from just these
+    // queries). Making them anonymous avoids hashing the result, which
     // may save a bit of time.
     [anon] EraseRegionsTy { ty: Ty<'tcx> },
+    [anon] ConstValueToAllocation { val: ConstValue<'tcx>, ty: Ty<'tcx> },
 
     [input] Freevars(DefId),
     [input] MaybeUnusedTraitImport(DefId),

src/librustc/ty/maps/config.rs

@@ -137,6 +137,12 @@ impl<'tcx> QueryDescription<'tcx> for queries::super_predicates_of<'tcx> {
     }
 }
 
+impl<'tcx> QueryDescription<'tcx> for queries::const_value_to_allocation<'tcx> {
+    fn describe(_tcx: TyCtxt, (val, ty): (ConstValue<'tcx>, Ty<'tcx>)) -> String {
+        format!("converting value `{:?}` ({}) to an allocation", val, ty)
+    }
+}
+
 impl<'tcx> QueryDescription<'tcx> for queries::erase_regions_ty<'tcx> {
     fn describe(_tcx: TyCtxt, ty: Ty<'tcx>) -> String {
         format!("erasing regions from `{:?}`", ty)

src/librustc/ty/maps/keys.rs

@@ -145,6 +145,15 @@ impl<'tcx> Key for ty::PolyTraitRef<'tcx>{
     }
 }
 
+impl<'tcx> Key for (mir::interpret::ConstValue<'tcx>, Ty<'tcx>) {
+    fn map_crate(&self) -> CrateNum {
+        LOCAL_CRATE
+    }
+    fn default_span(&self, _: TyCtxt) -> Span {
+        DUMMY_SP
+    }
+}
+
 impl<'tcx> Key for Ty<'tcx> {
     fn map_crate(&self) -> CrateNum {
         LOCAL_CRATE

src/librustc/ty/maps/mod.rs

@@ -228,6 +228,11 @@ define_maps! { <'tcx>
     [] fn const_eval: const_eval_dep_node(ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>)
         -> EvalResult<'tcx>,
 
+    /// Converts a constant value to an constant allocation
+    [] fn const_value_to_allocation: const_value_to_allocation(
+        (ConstValue<'tcx>, Ty<'tcx>)
+    ) -> &'tcx Allocation,
+
     [] fn check_match: CheckMatch(DefId)
         -> Result<(), ErrorReported>,
 
@@ -478,6 +483,12 @@ fn erase_regions_ty<'tcx>(ty: Ty<'tcx>) -> DepConstructor<'tcx> {
     DepConstructor::EraseRegionsTy { ty }
 }
 
+fn const_value_to_allocation<'tcx>(
+    (val, ty): (ConstValue<'tcx>, Ty<'tcx>)
+) -> DepConstructor<'tcx> {
+    DepConstructor::ConstValueToAllocation { val, ty }
+}
+
 fn type_param_predicates<'tcx>((item_id, param_id): (DefId, DefId)) -> DepConstructor<'tcx> {
     DepConstructor::TypeParamPredicates {
         item_id,

src/librustc/ty/maps/plumbing.rs

@@ -956,6 +956,7 @@ pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>,
         DepKind::FulfillObligation |
         DepKind::VtableMethods |
         DepKind::EraseRegionsTy |
+        DepKind::ConstValueToAllocation |
         DepKind::NormalizeProjectionTy |
         DepKind::NormalizeTyAfterErasingRegions |
         DepKind::DropckOutlives |

src/librustc_mir/interpret/const_eval.rs

@@ -8,12 +8,13 @@ use rustc::ty::subst::Subst;
 
 use syntax::ast::Mutability;
 use syntax::codemap::Span;
+use syntax::codemap::DUMMY_SP;
 
 use rustc::mir::interpret::{
     EvalResult, EvalError, EvalErrorKind, GlobalId,
     Value, Pointer, PrimVal, AllocId, Allocation, ConstValue,
 };
-use super::{Place, EvalContext, StackPopCleanup, ValTy, PlaceExtra, Memory};
+use super::{Place, EvalContext, StackPopCleanup, ValTy, PlaceExtra, Memory, MemoryKind};
 
 use std::fmt;
 use std::error::Error;
@@ -470,7 +471,6 @@ pub fn const_variant_index<'a, 'tcx>(
     let (ptr, align) = match value {
         Value::ByValPair(..) | Value::ByVal(_) => {
             let layout = ecx.layout_of(ty)?;
-            use super::MemoryKind;
             let ptr = ecx.memory.allocate(layout.size.bytes(), layout.align, Some(MemoryKind::Stack))?;
             let ptr: Pointer = ptr.into();
             ecx.write_value_to_ptr(value, ptr, layout.align, ty)?;
@@ -482,6 +482,30 @@ pub fn const_variant_index<'a, 'tcx>(
     ecx.read_discriminant_as_variant_index(place, ty)
 }
 
+pub fn const_value_to_allocation_provider<'a, 'tcx>(
+    tcx: TyCtxt<'a, 'tcx, 'tcx>,
+    (val, ty): (ConstValue<'tcx>, Ty<'tcx>),
+) -> &'tcx Allocation {
+    match val {
+        ConstValue::ByRef(alloc) => return alloc,
+        _ => ()
+    }
+    let result = || -> EvalResult<'tcx, &'tcx Allocation> {
+        let mut ecx = EvalContext::new(
+            tcx.at(DUMMY_SP),
+            ty::ParamEnv::reveal_all(),
+            CompileTimeEvaluator,
+            ());
+        let value = ecx.const_value_to_value(val, ty)?;
+        let layout = ecx.layout_of(ty)?;
+        let ptr = ecx.memory.allocate(layout.size.bytes(), layout.align, Some(MemoryKind::Stack))?;
+        ecx.write_value_to_ptr(value, ptr.into(), layout.align, ty)?;
+        let alloc = ecx.memory.get(ptr.alloc_id)?;
+        Ok(tcx.intern_const_alloc(alloc.clone()))
+    };
+    result().expect("unable to convert ConstVal to Allocation")
+}
+
 pub fn const_eval_provider<'a, 'tcx>(
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
     key: ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>,

src/librustc_mir/interpret/memory.rs

@@ -1,14 +1,17 @@
 use std::collections::{btree_map, VecDeque};
 use std::ptr;
 
+use rustc::hir::def_id::DefId;
 use rustc::ty::Instance;
+use rustc::ty::ParamEnv;
 use rustc::ty::maps::TyCtxtAt;
 use rustc::ty::layout::{self, Align, TargetDataLayout};
 use syntax::ast::Mutability;
+use rustc::middle::const_val::{ConstVal, ErrKind};
 
 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
 use rustc::mir::interpret::{MemoryPointer, AllocId, Allocation, AccessKind, Value, Pointer,
-                            EvalResult, PrimVal, EvalErrorKind};
+                            EvalResult, PrimVal, EvalErrorKind, GlobalId};
 pub use rustc::mir::interpret::{write_target_uint, write_target_int, read_target_uint};
 
 use super::{EvalContext, Machine};
@@ -274,6 +277,31 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
 
 /// Allocation accessors
 impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
+    fn const_eval_static(&self, def_id: DefId) -> EvalResult<'tcx, &'tcx Allocation> {
+        let instance = Instance::mono(self.tcx.tcx, def_id);
+        let gid = GlobalId {
+            instance,
+            promoted: None,
+        };
+        self.tcx.const_eval(ParamEnv::reveal_all().and(gid)).map_err(|err| {
+            match *err.kind {
+                ErrKind::Miri(ref err, _) => match err.kind {
+                    EvalErrorKind::TypeckError |
+                    EvalErrorKind::Layout(_) => EvalErrorKind::TypeckError.into(),
+                    _ => EvalErrorKind::ReferencedConstant.into(),
+                },
+                ErrKind::TypeckError => EvalErrorKind::TypeckError.into(),
+                ref other => bug!("const eval returned {:?}", other),
+            }
+        }).map(|val| {
+            let const_val = match val.val {
+                ConstVal::Value(val) => val,
+                ConstVal::Unevaluated(..) => bug!("should be evaluated"),
+            };
+            self.tcx.const_value_to_allocation((const_val, val.ty))
+        })
+    }
+
     pub fn get(&self, id: AllocId) -> EvalResult<'tcx, &Allocation> {
         // normal alloc?
         match self.alloc_map.get(&id) {
@@ -283,13 +311,19 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
                 Some(alloc) => Ok(alloc),
                 None => {
                     // static alloc?
-                    self.tcx.interpret_interner.get_alloc(id)
-                        // no alloc? produce an error
-                        .ok_or_else(|| if self.tcx.interpret_interner.get_fn(id).is_some() {
-                            EvalErrorKind::DerefFunctionPointer.into()
-                        } else {
-                            EvalErrorKind::DanglingPointerDeref.into()
-                        })
+                    if let Some(a) = self.tcx.interpret_interner.get_alloc(id) {
+                        return Ok(a);
+                    }
+                    // static variable?
+                    if let Some(did) = self.tcx.interpret_interner.get_static(id) {
+                        return self.const_eval_static(did);
+                    }
+                    // otherwise return an error
+                    Err(if self.tcx.interpret_interner.get_fn(id).is_some() {
+                        EvalErrorKind::DerefFunctionPointer.into()
+                    } else {
+                        EvalErrorKind::DanglingPointerDeref.into()
+                    })
                 },
             },
         }

src/librustc_mir/interpret/mod.rs

@@ -23,6 +23,7 @@ pub use self::const_eval::{
     mk_borrowck_eval_cx,
     eval_body,
     CompileTimeEvaluator,
+    const_value_to_allocation_provider,
     const_eval_provider,
     const_val_field,
     const_variant_index,

src/librustc_mir/lib.rs

@@ -85,6 +85,7 @@ pub fn provide(providers: &mut Providers) {
     shim::provide(providers);
     transform::provide(providers);
     providers.const_eval = interpret::const_eval_provider;
+    providers.const_value_to_allocation = interpret::const_value_to_allocation_provider;
     providers.check_match = hair::pattern::check_match;
 }
 

src/librustc_trans/base.rs

@@ -1373,6 +1373,7 @@ mod temp_stable_hash_impls {
 
 fn fetch_wasm_section(tcx: TyCtxt, id: DefId) -> (String, Vec<u8>) {
     use rustc::mir::interpret::GlobalId;
+    use rustc::middle::const_val::ConstVal;
 
     info!("loading wasm section {:?}", id);
 
@@ -1391,11 +1392,11 @@ fn fetch_wasm_section(tcx: TyCtxt, id: DefId) -> (String, Vec<u8>) {
     let param_env = ty::ParamEnv::reveal_all();
     let val = tcx.const_eval(param_env.and(cid)).unwrap();
 
-    let mem = val.to_ptr().expect("should be pointer");
-    assert_eq!(mem.offset, 0);
-    let alloc = tcx
-        .interpret_interner
-        .get_alloc(mem.alloc_id)
-        .expect("miri allocation never successfully created");
+    let const_val = match val.val {
+        ConstVal::Value(val) => val,
+        ConstVal::Unevaluated(..) => bug!("should be evaluated"),
+    };
+
+    let alloc = tcx.const_value_to_allocation((const_val, val.ty));
     (section.to_string(), alloc.bytes.clone())
 }