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use crate::{
error::{ErrorEmitted, Handler},
expr::{BinaryOp, Expr, ExternalIntrinsic, IntrinsicKind, UnaryOp},
predicate::{ConstraintDecl, Contract, ExprKey, PredKey, Variable},
span::empty_span,
types::{PrimitiveKind, Type},
};
use fxhash::{FxHashMap, FxHashSet};
/// In a given contract, insert constraints that enforce that all storage vector accesses are
/// within bounds.
pub(crate) fn legalize_vector_accesses(
handler: &Handler,
contract: &mut Contract,
) -> Result<(), ErrorEmitted> {
for pred_key in contract.preds.keys().collect::<Vec<_>>() {
legalize_vector_accesses_in_predicate(handler, contract, pred_key)?;
}
Ok(())
}
/// In a given predicate, insert constraints that enforce that all storage vector accesses are
/// within bounds.
///
/// Currently, this only assumes single dimensional storage vectors
pub(crate) fn legalize_vector_accesses_in_predicate(
_handler: &Handler,
contract: &mut Contract,
pred_key: PredKey,
) -> Result<(), ErrorEmitted> {
let int_ty = Type::Primitive {
kind: PrimitiveKind::Int,
span: empty_span(),
};
let bool_ty = Type::Primitive {
kind: PrimitiveKind::Bool,
span: empty_span(),
};
// Collect all variable variables that are initialized to index expressions to storage vector
let variable_vector_accesses = contract
.preds
.get(pred_key)
.unwrap()
.variables()
.filter_map(|(_, variable)| {
let Variable {
name: variable_var_name,
expr: init_expr,
..
} = variable;
if let Expr::Index {
expr: storage_vec_expr,
index,
..
} = init_expr.get(contract)
{
if let Expr::LocalStorageAccess {
name: storage_vec_name,
..
} = storage_vec_expr.get(contract)
{
if contract.storage_var(storage_vec_name).1.ty.is_vector() {
return Some((
variable_var_name.clone(),
(storage_vec_name.clone(), *index, *storage_vec_expr),
));
}
}
}
None
})
.collect::<FxHashMap<String, (String, ExprKey, ExprKey)>>();
// Collect all `Path` expressions that reference one of the variable variables collected in
// `variable_vector_accesses` and are "primed", i.e., they are used in a `NextState` unary op
// expression
let primed_exprs = contract
.exprs(pred_key)
.filter_map(|expr| {
if let Expr::UnaryOp {
op: UnaryOp::NextState,
expr: primed_expr,
..
} = expr.get(contract)
{
if let Expr::Path(name, _) = primed_expr.get(contract) {
if let Some((storage_vec_name, index, storage_vec_expr)) =
variable_vector_accesses.get(name)
{
return Some((
*primed_expr,
(storage_vec_name.clone(), *index, *storage_vec_expr),
));
}
}
}
None
})
.collect::<FxHashMap<ExprKey, (String, ExprKey, ExprKey)>>();
// Collect all `Path` expression that reference one of the variable variables collected in
// `variable_vector_accesses` and are *not* "primed".
//
// The I'm doing this is probably okay but I think can fail in situations where the `Path`
// expression key is used in a prime expression AND outside a prime expression.
let non_primed_exprs = contract
.exprs(pred_key)
.filter_map(|expr| {
if let Expr::Path(name, _) = expr.get(contract) {
if let Some((storage_vec_name, index, storage_vec_expr)) =
variable_vector_accesses.get(name)
{
if !primed_exprs.contains_key(&expr) {
return Some((storage_vec_name.clone(), *index, *storage_vec_expr));
}
}
}
None
})
.collect::<FxHashSet<(String, ExprKey, ExprKey)>>();
// This is a helper closure that creates a `variable` variable initialized the `__vec_len` of a
// storage access expression to storage variable named `storage_vec_name` and with type
// `storage_access_ty`
let create_vec_len_variable_var =
|contract: &mut Contract,
vec_len_name: String,
storage_vec_name: &String,
storage_access_ty: &Type| {
let vector_storage_access = contract.exprs.insert(
Expr::LocalStorageAccess {
name: storage_vec_name.clone(),
span: empty_span(),
},
storage_access_ty.clone(),
);
let intrinsic = contract.exprs.insert(
Expr::IntrinsicCall {
kind: (
IntrinsicKind::External(ExternalIntrinsic::VecLen),
empty_span(),
),
args: vec![vector_storage_access],
span: empty_span(),
},
Type::Optional {
ty: Box::new(int_ty.clone()),
span: empty_span(),
},
);
if let Some(pred) = contract.preds.get_mut(pred_key) {
pred.variables.insert(
Variable {
name: vec_len_name,
expr: intrinsic,
span: empty_span(),
},
Type::Optional {
ty: Box::new(int_ty.clone()),
span: empty_span(),
},
);
}
};
// Keep track of all created vector length `variable` variables so that we don't create them
// again.
let mut vec_len_variable_var_names = FxHashSet::default();
// Handle "non" primed vector first
for (storage_vec_name, index, storage_vec_expr) in &non_primed_exprs {
let vec_len_variable_var_name = "__".to_owned() + storage_vec_name + "_len";
// Insert a new variable variable that contains the length of the vector being accessed
if vec_len_variable_var_names.insert(vec_len_variable_var_name.clone()) {
let ty = storage_vec_expr.get_ty(contract).clone();
create_vec_len_variable_var(
contract,
vec_len_variable_var_name.clone(),
storage_vec_name,
&ty,
);
}
// Now create insert a new constraint that ensures that the index is smaller than the
// current length of the vector
let vec_len_path = contract.exprs.insert(
Expr::Path(vec_len_variable_var_name.clone(), empty_span()),
Type::Optional {
ty: Box::new(int_ty.clone()),
span: empty_span(),
},
);
let unwrap = contract.exprs.insert(
Expr::UnaryOp {
op: UnaryOp::Unwrap,
expr: vec_len_path,
span: empty_span(),
},
int_ty.clone(),
);
let index_less_than_vec_len = contract.exprs.insert(
Expr::BinaryOp {
op: BinaryOp::LessThan,
lhs: *index,
rhs: unwrap,
span: empty_span(),
},
bool_ty.clone(),
);
if let Some(pred) = contract.preds.get_mut(pred_key) {
pred.constraints.push(ConstraintDecl {
expr: index_less_than_vec_len,
span: empty_span(),
});
}
}
// Now handle primed vector first
for (storage_vec_name, index, storage_vec_expr) in primed_exprs.values() {
let vec_len_variable_var_name = "__".to_owned() + storage_vec_name + "_len";
// Insert a new variable variable that contains the length of the vector being accessed
if vec_len_variable_var_names.insert(vec_len_variable_var_name.clone()) {
let ty = storage_vec_expr.get_ty(contract).clone();
create_vec_len_variable_var(
contract,
vec_len_variable_var_name.clone(),
storage_vec_name,
&ty,
);
}
// Now create insert a new constraint that ensures that the index is smaller than the
// future length of the vector
let vec_len_path = contract.exprs.insert(
Expr::Path(vec_len_variable_var_name.clone(), empty_span()),
int_ty.clone(),
);
let vec_len_path_prime = contract.exprs.insert(
Expr::UnaryOp {
op: UnaryOp::NextState,
expr: vec_len_path,
span: empty_span(),
},
Type::Optional {
ty: Box::new(int_ty.clone()),
span: empty_span(),
},
);
let unwrap = contract.exprs.insert(
Expr::UnaryOp {
op: UnaryOp::Unwrap,
expr: vec_len_path_prime,
span: empty_span(),
},
int_ty.clone(),
);
let index_less_than_vec_len_prime = contract.exprs.insert(
Expr::BinaryOp {
op: BinaryOp::LessThan,
lhs: *index,
rhs: unwrap,
span: empty_span(),
},
bool_ty.clone(),
);
if let Some(pred) = contract.preds.get_mut(pred_key) {
pred.constraints.push(ConstraintDecl {
expr: index_less_than_vec_len_prime,
span: empty_span(),
});
}
}
Ok(())
}