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only emit Suspend validation for mutable paths

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This commit is contained in:
Ralf Jung 2017-07-20 15:27:03 -07:00
parent 24a2ac9e46
commit 511b88cdce
1 changed files with 41 additions and 12 deletions
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53
src/librustc_mir/transform/add_validation.rs
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@ -20,6 +20,33 @@ use rustc::mir::transform::{MirPass, MirSource};
pub struct AddValidation;
fn is_lvalue_shared<'a, 'tcx, D>(lval: &Lvalue<'tcx>, local_decls: &D, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> bool
where D: HasLocalDecls<'tcx>
{
use rustc::mir::Lvalue::*;
match *lval {
Local { .. } => false,
Static(_) => true,
Projection(ref proj) => {
// If the base is shared, things stay shared
if is_lvalue_shared(&proj.base, local_decls, tcx) {
return true;
}
// A Deref projection may make things shared
match proj.elem {
ProjectionElem::Deref => {
// Computing the inside the recursion makes this quadratic. We don't expect deep paths though.
let ty = proj.base.ty(local_decls, tcx).to_ty(tcx);
!ty.is_mutable_pointer()
}
_ => false,
}
}
}
}
impl MirPass for AddValidation {
fn run_pass<'a, 'tcx>(&self,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
@ -117,18 +144,20 @@ impl MirPass for AddValidation {
};
block_data.statements.insert(i+1, acquire_stmt);
// The source is released until the region of the borrow ends.
let src_ty = src_lval.ty(&local_decls, tcx).to_ty(tcx);
let op = match re {
&RegionKind::ReScope(ce) => ValidationOp::Suspend(ce),
&RegionKind::ReErased => bug!("AddValidation pass must be run before erasing lifetimes"),
_ => ValidationOp::Release,
};
let release_stmt = Statement {
source_info: block_data.statements[i].source_info,
kind: StatementKind::Validate(op, vec![(src_ty, src_lval)]),
};
block_data.statements.insert(i, release_stmt);
// The source is released until the region of the borrow ends -- but not if it is shared.
if !is_lvalue_shared(&src_lval, &local_decls, tcx) {
let src_ty = src_lval.ty(&local_decls, tcx).to_ty(tcx);
let op = match re {
&RegionKind::ReScope(ce) => ValidationOp::Suspend(ce),
&RegionKind::ReErased => bug!("AddValidation pass must be run before erasing lifetimes"),
_ => ValidationOp::Release,
};
let release_stmt = Statement {
source_info: block_data.statements[i].source_info,
kind: StatementKind::Validate(op, vec![(src_ty, src_lval)]),
};
block_data.statements.insert(i, release_stmt);
}
}
}
}