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Rollup merge of #58000 - oli-obk:fixes_and_cleanups, r=RalfJung 

Fixes and cleanups

Address the points raised in https://github.com/rust-lang/rust/pull/57677/files by @eddyb and @RalfJung
This commit is contained in:
Mazdak Farrokhzad 2019-01-31 02:10:50 +01:00 committed by GitHub
parent bb91a192c0 8c26c590b4
commit 880f6334f7
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GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 77 additions and 45 deletions
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2
src/librustc/mir/interpret/value.rs
View File

@ -14,7 +14,7 @@ pub struct RawConst<'tcx> {
}
/// Represents a constant value in Rust. Scalar and ScalarPair are optimizations which
/// matches the LocalValue optimizations for easy conversions between Value and ConstValue.
/// matches the LocalState optimizations for easy conversions between Value and ConstValue.
#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash)]
pub enum ConstValue<'tcx> {
/// Used only for types with layout::abi::Scalar ABI and ZSTs

72
src/librustc_mir/interpret/eval_context.rs
View File

@ -76,8 +76,7 @@ pub struct Frame<'mir, 'tcx: 'mir, Tag=(), Extra=()> {
/// The locals are stored as `Option<Value>`s.
/// `None` represents a local that is currently dead, while a live local
/// can either directly contain `Scalar` or refer to some part of an `Allocation`.
pub locals: IndexVec<mir::Local, LocalValue<Tag>>,
pub local_layouts: IndexVec<mir::Local, Cell<Option<TyLayout<'tcx>>>>,
pub locals: IndexVec<mir::Local, LocalState<'tcx, Tag>>,
////////////////////////////////////////////////////////////////////////////////
// Current position within the function
@ -106,7 +105,15 @@ pub enum StackPopCleanup {
None { cleanup: bool },
}
// State of a local variable
/// State of a local variable including a memoized layout
#[derive(Clone, PartialEq, Eq)]
pub struct LocalState<'tcx, Tag=(), Id=AllocId> {
pub state: LocalValue<Tag, Id>,
/// Don't modify if `Some`, this is only used to prevent computing the layout twice
pub layout: Cell<Option<TyLayout<'tcx>>>,
}
/// State of a local variable
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
pub enum LocalValue<Tag=(), Id=AllocId> {
Dead,
@ -117,16 +124,16 @@ pub enum LocalValue<Tag=(), Id=AllocId> {
Live(Operand<Tag, Id>),
}
impl<'tcx, Tag> LocalValue<Tag> {
impl<'tcx, Tag> LocalState<'tcx, Tag> {
pub fn access(&self) -> EvalResult<'tcx, &Operand<Tag>> {
match self {
match self.state {
LocalValue::Dead => err!(DeadLocal),
LocalValue::Live(ref val) => Ok(val),
}
}
pub fn access_mut(&mut self) -> EvalResult<'tcx, &mut Operand<Tag>> {
match self {
match self.state {
LocalValue::Dead => err!(DeadLocal),
LocalValue::Live(ref mut val) => Ok(val),
}
@ -310,17 +317,21 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
pub fn layout_of_local(
&self,
frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>,
local: mir::Local
local: mir::Local,
layout: Option<TyLayout<'tcx>>,
) -> EvalResult<'tcx, TyLayout<'tcx>> {
let cell = &frame.local_layouts[local];
if cell.get().is_none() {
let local_ty = frame.mir.local_decls[local].ty;
let local_ty = self.monomorphize_with_substs(local_ty, frame.instance.substs);
let layout = self.layout_of(local_ty)?;
cell.set(Some(layout));
match frame.locals[local].layout.get() {
None => {
let layout = ::interpret::operand::from_known_layout(layout, || {
let local_ty = frame.mir.local_decls[local].ty;
let local_ty = self.monomorphize_with_substs(local_ty, frame.instance.substs);
self.layout_of(local_ty)
})?;
frame.locals[local].layout.set(Some(layout));
Ok(layout)
}
Some(layout) => Ok(layout),
}
Ok(cell.get().unwrap())
}
pub fn str_to_immediate(&mut self, s: &str) -> EvalResult<'tcx, Immediate<M::PointerTag>> {
@ -454,7 +465,6 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
// empty local array, we fill it in below, after we are inside the stack frame and
// all methods actually know about the frame
locals: IndexVec::new(),
local_layouts: IndexVec::from_elem_n(Default::default(), mir.local_decls.len()),
span,
instance,
stmt: 0,
@ -466,12 +476,16 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
// We put some marker immediate into the locals that we later want to initialize.
// This can be anything except for LocalValue::Dead -- because *that* is the
// value we use for things that we know are initially dead.
let dummy =
LocalValue::Live(Operand::Immediate(Immediate::Scalar(ScalarMaybeUndef::Undef)));
let dummy = LocalState {
state: LocalValue::Live(Operand::Immediate(Immediate::Scalar(
ScalarMaybeUndef::Undef,
))),
layout: Cell::new(None),
};
let mut locals = IndexVec::from_elem(dummy, &mir.local_decls);
// Return place is handled specially by the `eval_place` functions, and the
// entry in `locals` should never be used. Make it dead, to be sure.
locals[mir::RETURN_PLACE] = LocalValue::Dead;
locals[mir::RETURN_PLACE].state = LocalValue::Dead;
// Now mark those locals as dead that we do not want to initialize
match self.tcx.describe_def(instance.def_id()) {
// statics and constants don't have `Storage*` statements, no need to look for them
@ -484,7 +498,7 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
match stmt.kind {
StorageLive(local) |
StorageDead(local) => {
locals[local] = LocalValue::Dead;
locals[local].state = LocalValue::Dead;
}
_ => {}
}
@ -494,11 +508,13 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
}
// Finally, properly initialize all those that still have the dummy value
for (idx, local) in locals.iter_enumerated_mut() {
match *local {
match local.state {
LocalValue::Live(_) => {
// This needs to be peoperly initialized.
let layout = self.layout_of_local(self.frame(), idx)?;
*local = LocalValue::Live(self.uninit_operand(layout)?);
// This needs to be properly initialized.
let ty = self.monomorphize(mir.local_decls[idx].ty)?;
let layout = self.layout_of(ty)?;
local.state = LocalValue::Live(self.uninit_operand(layout)?);
local.layout = Cell::new(Some(layout));
}
LocalValue::Dead => {
// Nothing to do
@ -543,7 +559,7 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
}
// Deallocate all locals that are backed by an allocation.
for local in frame.locals {
self.deallocate_local(local)?;
self.deallocate_local(local.state)?;
}
// Validate the return value. Do this after deallocating so that we catch dangling
// references.
@ -591,10 +607,10 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
assert!(local != mir::RETURN_PLACE, "Cannot make return place live");
trace!("{:?} is now live", local);
let layout = self.layout_of_local(self.frame(), local)?;
let layout = self.layout_of_local(self.frame(), local, None)?;
let init = LocalValue::Live(self.uninit_operand(layout)?);
// StorageLive *always* kills the value that's currently stored
Ok(mem::replace(&mut self.frame_mut().locals[local], init))
Ok(mem::replace(&mut self.frame_mut().locals[local].state, init))
}
/// Returns the old value of the local.
@ -603,7 +619,7 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc
assert!(local != mir::RETURN_PLACE, "Cannot make return place dead");
trace!("{:?} is now dead", local);
mem::replace(&mut self.frame_mut().locals[local], LocalValue::Dead)
mem::replace(&mut self.frame_mut().locals[local].state, LocalValue::Dead)
}
pub(super) fn deallocate_local(

2
src/librustc_mir/interpret/mod.rs
View File

@ -18,7 +18,7 @@ mod visitor;
pub use rustc::mir::interpret::*; // have all the `interpret` symbols in one place: here
pub use self::eval_context::{
EvalContext, Frame, StackPopCleanup, LocalValue,
EvalContext, Frame, StackPopCleanup, LocalState, LocalValue,
};
pub use self::place::{Place, PlaceTy, MemPlace, MPlaceTy};

14
src/librustc_mir/interpret/operand.rs
View File

@ -227,7 +227,7 @@ impl<'tcx, Tag> OpTy<'tcx, Tag>
// Use the existing layout if given (but sanity check in debug mode),
// or compute the layout.
#[inline(always)]
fn from_known_layout<'tcx>(
pub(super) fn from_known_layout<'tcx>(
layout: Option<TyLayout<'tcx>>,
compute: impl FnOnce() -> EvalResult<'tcx, TyLayout<'tcx>>
) -> EvalResult<'tcx, TyLayout<'tcx>> {
@ -457,14 +457,15 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
}
/// This is used by [priroda](https://github.com/oli-obk/priroda) to get an OpTy from a local
fn access_local(
pub fn access_local(
&self,
frame: &super::Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>,
local: mir::Local,
layout: Option<TyLayout<'tcx>>,
) -> EvalResult<'tcx, OpTy<'tcx, M::PointerTag>> {
assert_ne!(local, mir::RETURN_PLACE);
let op = *frame.locals[local].access()?;
let layout = self.layout_of_local(frame, local)?;
let layout = self.layout_of_local(frame, local, layout)?;
Ok(OpTy { op, layout })
}
@ -473,14 +474,15 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
fn eval_place_to_op(
&self,
mir_place: &mir::Place<'tcx>,
layout: Option<TyLayout<'tcx>>,
) -> EvalResult<'tcx, OpTy<'tcx, M::PointerTag>> {
use rustc::mir::Place::*;
let op = match *mir_place {
Local(mir::RETURN_PLACE) => return err!(ReadFromReturnPointer),
Local(local) => self.access_local(self.frame(), local)?,
Local(local) => self.access_local(self.frame(), local, layout)?,
Projection(ref proj) => {
let op = self.eval_place_to_op(&proj.base)?;
let op = self.eval_place_to_op(&proj.base, None)?;
self.operand_projection(op, &proj.elem)?
}
@ -504,7 +506,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
// FIXME: do some more logic on `move` to invalidate the old location
Copy(ref place) |
Move(ref place) =>
self.eval_place_to_op(place)?,
self.eval_place_to_op(place, layout)?,
Constant(ref constant) => {
let layout = from_known_layout(layout, || {

6
src/librustc_mir/interpret/place.rs
View File

@ -624,7 +624,7 @@ where
// their layout on return.
PlaceTy {
place: *return_place,
layout: self.layout_of_local(self.frame(), mir::RETURN_PLACE)?,
layout: self.layout_of(self.monomorphize(self.frame().mir.return_ty())?)?,
},
None => return err!(InvalidNullPointerUsage),
},
@ -633,7 +633,7 @@ where
frame: self.cur_frame(),
local,
},
layout: self.layout_of_local(self.frame(), local)?,
layout: self.layout_of_local(self.frame(), local, None)?,
},
Projection(ref proj) => {
@ -901,7 +901,7 @@ where
// We need the layout of the local. We can NOT use the layout we got,
// that might e.g., be an inner field of a struct with `Scalar` layout,
// that has different alignment than the outer field.
let local_layout = self.layout_of_local(&self.stack[frame], local)?;
let local_layout = self.layout_of_local(&self.stack[frame], local, None)?;
let ptr = self.allocate(local_layout, MemoryKind::Stack);
// We don't have to validate as we can assume the local
// was already valid for its type.

22
src/librustc_mir/interpret/snapshot.rs
View File

@ -23,8 +23,8 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use syntax::ast::Mutability;
use syntax::source_map::Span;
use super::eval_context::{LocalValue, StackPopCleanup};
use super::{Frame, Memory, Operand, MemPlace, Place, Immediate, ScalarMaybeUndef};
use super::eval_context::{LocalState, StackPopCleanup};
use super::{Frame, Memory, Operand, MemPlace, Place, Immediate, ScalarMaybeUndef, LocalValue};
use const_eval::CompileTimeInterpreter;
#[derive(Default)]
@ -321,7 +321,6 @@ impl_stable_hash_for!(impl<'mir, 'tcx: 'mir> for struct Frame<'mir, 'tcx> {
return_to_block,
return_place -> (return_place.as_ref().map(|r| &**r)),
locals,
local_layouts -> _,
block,
stmt,
extra,
@ -340,7 +339,6 @@ impl<'a, 'mir, 'tcx, Ctx> Snapshot<'a, Ctx> for &'a Frame<'mir, 'tcx>
return_to_block,
return_place,
locals,
local_layouts: _,
block,
stmt,
extra: _,
@ -358,6 +356,22 @@ impl<'a, 'mir, 'tcx, Ctx> Snapshot<'a, Ctx> for &'a Frame<'mir, 'tcx>
}
}
impl<'a, 'tcx, Ctx> Snapshot<'a, Ctx> for &'a LocalState<'tcx>
where Ctx: SnapshotContext<'a>,
{
type Item = LocalValue<(), AllocIdSnapshot<'a>>;
fn snapshot(&self, ctx: &'a Ctx) -> Self::Item {
let LocalState { state, layout: _ } = self;
state.snapshot(ctx)
}
}
impl_stable_hash_for!(struct LocalState<'tcx> {
state,
layout -> _,
});
impl<'a, 'b, 'mir, 'tcx: 'a+'mir> SnapshotContext<'b>
for Memory<'a, 'mir, 'tcx, CompileTimeInterpreter<'a, 'mir, 'tcx>>
{

4
src/librustc_mir/interpret/terminator.rs
View File

@ -309,7 +309,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
mir.spread_arg,
mir.args_iter()
.map(|local|
(local, self.layout_of_local(self.frame(), local).unwrap().ty)
(local, self.layout_of_local(self.frame(), local, None).unwrap().ty)
)
.collect::<Vec<_>>()
);
@ -383,7 +383,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
}
} else {
let callee_layout =
self.layout_of_local(self.frame(), mir::RETURN_PLACE)?;
self.layout_of_local(self.frame(), mir::RETURN_PLACE, None)?;
if !callee_layout.abi.is_uninhabited() {
return err!(FunctionRetMismatch(
self.tcx.types.never, callee_layout.ty