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Add ability to unit-test dataflow results via rustc_peek intrinsic.

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(The static semantics of `rustc_peek` is derived from attributes
attached to the function being compiled; in this case,
`rustc_peek(&expr)` observes the dataflow state for the l-value
`expr`.)
This commit is contained in:
Felix S. Klock II 2016-05-11 22:03:57 +02:00
parent 3bb598429a
commit 5839e6bb10
2 changed files with 208 additions and 3 deletions
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193
src/librustc_borrowck/borrowck/mir/dataflow/sanity_check.rs Normal file
View file

@ -0,0 +1,193 @@
// Copyright 2012-2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use syntax::abi::{Abi};
use syntax::ast;
use rustc::ty::{self, TyCtxt};
use rustc::mir::repr::{self, Mir};
use bitslice::BitSlice;
use super::super::gather_moves::MovePath;
use super::{bitwise, Union, Subtract};
use super::BitDenotation;
use super::DataflowResults;
use super::HasMoveData;
pub fn sanity_check_via_rustc_peek<'a, 'tcx, O>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
mir: &Mir<'tcx>,
id: ast::NodeId,
_attributes: &[ast::Attribute],
flow_ctxt: &O::Ctxt,
results: &DataflowResults<O>)
where O: BitDenotation<Bit=MovePath<'tcx>>, O::Ctxt: HasMoveData<'tcx>
{
debug!("sanity_check_via_rustc_peek id: {:?}", id);
// FIXME: this is not DRY. Figure out way to abstract this and
// `dataflow::build_sets`. (But see note below about how the
// behavior of this traversal is a bit different than that
// performed by `build_sets`.)
let blocks = mir.all_basic_blocks();
'next_block: for bb in blocks {
let bb_data = mir.basic_block_data(bb);
let &repr::BasicBlockData { ref statements,
ref terminator,
is_cleanup: _ } = bb_data;
let (args, span) = if let Some(repr::Terminator { ref kind, span, .. }) = *terminator {
if let repr::TerminatorKind::Call { func: ref oper, ref args, .. } = *kind
{
if let repr::Operand::Constant(ref func) = *oper
{
if let ty::TyFnDef(def_id, _, &ty::BareFnTy { abi, .. }) = func.ty.sty
{
let name = tcx.item_name(def_id);
if abi == Abi::RustIntrinsic || abi == Abi::PlatformIntrinsic {
if name.as_str() == "rustc_peek" {
(args, span)
} else {
continue;
}
} else {
continue;
}
} else {
continue;
}
} else {
continue;
}
} else {
continue;
}
} else {
continue;
};
assert!(args.len() == 1);
let peek_arg_lval = match args[0] {
repr::Operand::Consume(ref lval @ repr::Lvalue::Temp(_)) => {
lval
}
repr::Operand::Consume(_) => {
bug!("dataflow::sanity_check cannot feed a non-temp to rustc_peek.");
}
repr::Operand::Constant(_) => {
bug!("dataflow::sanity_check cannot feed a constant to rustc_peek.");
}
};
let mut entry = results.0.sets.on_entry_set_for(bb.index()).to_owned();
let mut gen = results.0.sets.gen_set_for(bb.index()).to_owned();
let mut kill = results.0.sets.kill_set_for(bb.index()).to_owned();
let move_data = flow_ctxt.move_data();
// Emulate effect of all statements in the block up to (but
// not including) the assignment to `peek_arg_lval`. Do *not*
// include terminator (since we are peeking the state of the
// argument at time immediate preceding Call to `rustc_peek`).
let mut sets = super::BlockSets { on_entry: &mut entry[..],
gen_set: &mut gen[..],
kill_set: &mut kill[..] };
// Unfortunately if we just re-do the same thing that dataflow does, then
// it will always appear like Lvalues are initialized; e.g. in
// a case like:
//
// <bitset maps var1 to 0>
// tmp13 = var1;
// tmp14 = &tmp13;
// rustc_peek(tmp14)
//
// The gen_set for normal dataflow would treat tmp13 as
// initialized, even though it's source expression is
// uninitialized.
//
// Work around this for rustc_peek by explicitly propagating
// the relevant bitvector state when computing the effect of a
// statement.
for (j, stmt) in statements.iter().enumerate() {
debug!("rustc_peek: ({:?},{}) {:?}", bb, j, stmt);
let (lvalue, rvalue) = match stmt.kind {
repr::StatementKind::Assign(ref lvalue, ref rvalue) => {
(lvalue, rvalue)
}
};
if lvalue == peek_arg_lval {
if let repr::Rvalue::Ref(_,
repr::BorrowKind::Shared,
ref peeking_at_lval) = *rvalue {
// Okay, our search is over.
let peek_mpi = move_data.rev_lookup.find(peeking_at_lval);
let bit_state = sets.on_entry.get_bit(peek_mpi.idx());
debug!("rustc_peek({:?} = &{:?}) bit_state: {}",
lvalue, peeking_at_lval, bit_state);
if !bit_state {
tcx.sess.span_err(span, &format!("rustc_peek: bit not set"));
}
continue 'next_block;
} else {
// Our search should have been over, but the input
// does not match expectations of `rustc_peek` for
// this sanity_check.
tcx.sess.span_err(span, &format!("rustc_peek: argument expression \
must be immediate borrow of form `&expr`"));
}
}
enum Effect<'a, 'tcx:'a> { Propagate(&'a repr::Lvalue<'tcx>), Compute }
let lvalue_effect: Effect = match *rvalue {
// tmp = rhs
repr::Rvalue::Use(repr::Operand::Consume(ref rhs_lval)) =>
Effect::Propagate(rhs_lval),
repr::Rvalue::Use(repr::Operand::Constant(_)) =>
Effect::Compute,
_ => {
// (fall back to BitDenotation for all other kinds of Rvalues
Effect::Compute
}
};
let lhs_mpi = move_data.rev_lookup.find(lvalue);
if let Effect::Propagate(rhs_lval) = lvalue_effect {
let rhs_mpi = move_data.rev_lookup.find(rhs_lval);
let state = sets.on_entry.get_bit(rhs_mpi.idx());
debug!("rustc_peek: propagate into lvalue {:?} ({:?}) from rhs: {:?} state: {}",
lvalue, lhs_mpi, rhs_lval, state);
if state {
sets.on_entry.set_bit(lhs_mpi.idx());
} else {
sets.on_entry.clear_bit(lhs_mpi.idx());
}
} else {
debug!("rustc_peek: computing effect on lvalue: {:?} ({:?}) in stmt: {:?}",
lvalue, lhs_mpi, stmt);
// reset GEN and KILL sets before emulating their effect.
for e in &mut sets.gen_set[..] { *e = 0; }
for e in &mut sets.kill_set[..] { *e = 0; }
results.0.operator.statement_effect(flow_ctxt, &mut sets, bb, j);
bitwise(sets.on_entry, sets.gen_set, &Union);
bitwise(sets.on_entry, sets.kill_set, &Subtract);
}
}
tcx.sess.span_err(span, &format!("rustc_peek: MIR did not match \
anticipated pattern; note that \
rustc_peek expects input of \
form `&expr`"));
}
}

18
src/librustc_borrowck/borrowck/mir/mod.rs
View file

@ -75,9 +75,21 @@ pub fn borrowck_mir<'a, 'tcx: 'a>(
let move_data = MoveData::gather_moves(mir, tcx);
let ctxt = (tcx, mir, move_data);
let (ctxt, flow_inits) =
do_dataflow(bcx, mir, id, attributes, ctxt, MaybeInitializedLvals::default());
let ((_, _, move_data), flow_uninits) =
do_dataflow(bcx, mir, id, attributes, ctxt, MaybeUninitializedLvals::default());
do_dataflow(tcx, mir, id, attributes, ctxt, MaybeInitializedLvals::default());
let (ctxt, flow_uninits) =
do_dataflow(tcx, mir, id, attributes, ctxt, MaybeUninitializedLvals::default());
if has_rustc_mir_with(attributes, "rustc_peek_maybe_init").is_some() {
dataflow::sanity_check_via_rustc_peek(bcx.tcx, mir, id, attributes, &ctxt, &flow_inits);
}
if has_rustc_mir_with(attributes, "rustc_peek_maybe_uninit").is_some() {
dataflow::sanity_check_via_rustc_peek(bcx.tcx, mir, id, attributes, &ctxt, &flow_uninits);
}
let move_data = ctxt.2;
if has_rustc_mir_with(attributes, "stop_after_dataflow").is_some() {
bcx.tcx.sess.fatal("stop_after_dataflow ended compilation");
}
let mut mbcx = MirBorrowckCtxt {
bcx: bcx,