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fix: prevent Instruction::Constrains for non-primitive types #3916

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Merged
kevaundray merged 1 commit into from
Jan 2, 2024
Merged

fix: prevent Instruction::Constrains for non-primitive types #3916

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105 changes: 19 additions & 86 deletions compiler/noirc_evaluator/src/ssa/opt/flatten_cfg.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -641,8 +641,25 @@ impl<'f> Context<'f> {
match instruction {
Instruction::Constrain(lhs, rhs, message) => {
// Replace constraint `lhs == rhs` with `condition * lhs == condition * rhs`.
let lhs = self.handle_constrain_arg_side_effects(lhs, condition, &call_stack);
let rhs = self.handle_constrain_arg_side_effects(rhs, condition, &call_stack);

// Condition needs to be cast to argument type in order to multiply them together.
let argument_type = self.inserter.function.dfg.type_of_value(lhs);
// Sanity check that we're not constraining non-primitive types
assert!(matches!(argument_type, Type::Numeric(_)));

let casted_condition = self.insert_instruction(
Instruction::Cast(condition, argument_type),
call_stack.clone(),
);

let lhs = self.insert_instruction(
Instruction::binary(BinaryOp::Mul, lhs, casted_condition),
call_stack.clone(),
);
let rhs = self.insert_instruction(
Instruction::binary(BinaryOp::Mul, rhs, casted_condition),
call_stack,
);

Instruction::Constrain(lhs, rhs, message)
}
Expand Down Expand Up @@ -673,90 +690,6 @@ impl<'f> Context<'f> {
}
}

/// Given the arguments of a constrain instruction, multiplying them by the branch's condition
/// requires special handling in the case of complex types.
fn handle_constrain_arg_side_effects(
&mut self,
argument: ValueId,
condition: ValueId,
call_stack: &CallStack,
) -> ValueId {
let argument_type = self.inserter.function.dfg.type_of_value(argument);

match &argument_type {
Type::Numeric(_) => {
// Condition needs to be cast to argument type in order to multiply them together.
let casted_condition = self.insert_instruction(
Instruction::Cast(condition, argument_type),
call_stack.clone(),
);

self.insert_instruction(
Instruction::binary(BinaryOp::Mul, argument, casted_condition),
call_stack.clone(),
)
}
Type::Array(_, _) => {
self.handle_array_constrain_arg(argument_type, argument, condition, call_stack)
}
Type::Slice(_) => {
panic!("Cannot use slices directly in a constrain statement")
}
Type::Reference(_) => {
panic!("Cannot use references directly in a constrain statement")
}
Type::Function => {
panic!("Cannot use functions directly in a constrain statement")
}
}
}

fn handle_array_constrain_arg(
&mut self,
typ: Type,
argument: ValueId,
condition: ValueId,
call_stack: &CallStack,
) -> ValueId {
let mut new_array = im::Vector::new();

let (element_types, len) = match &typ {
Type::Array(elements, len) => (elements, *len),
_ => panic!("Expected array type"),
};

for i in 0..len {
for (element_index, element_type) in element_types.iter().enumerate() {
let index = ((i * element_types.len() + element_index) as u128).into();
let index = self.inserter.function.dfg.make_constant(index, Type::field());

let typevars = Some(vec![element_type.clone()]);

let mut get_element = |array, typevars| {
let get = Instruction::ArrayGet { array, index };
self.inserter
.function
.dfg
.insert_instruction_and_results(
get,
self.inserter.function.entry_block(),
typevars,
CallStack::new(),
)
.first()
};

let element = get_element(argument, typevars);

new_array.push_back(
self.handle_constrain_arg_side_effects(element, condition, call_stack),
);
}
}

self.inserter.function.dfg.make_array(new_array, typ)
}

fn undo_stores_in_then_branch(&mut self, then_branch: &Branch) {
for (address, store) in &then_branch.store_values {
let address = *address;
Expand Down
24 changes: 5 additions & 19 deletions compiler/noirc_evaluator/src/ssa/ssa_gen/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,8 +8,8 @@ use context::SharedContext;
use iter_extended::{try_vecmap, vecmap};
use noirc_errors::Location;
use noirc_frontend::{
monomorphization::ast::{self, Binary, Expression, Program},
BinaryOpKind, Visibility,
monomorphization::ast::{self, Expression, Program},
Visibility,
};

use crate::{
Expand Down Expand Up @@ -653,24 +653,10 @@ impl<'a> FunctionContext<'a> {
location: Location,
assert_message: Option<String>,
) -> Result<Values, RuntimeError> {
match expr {
// If we're constraining an equality to be true then constrain the two sides directly.
Expression::Binary(Binary { lhs, operator: BinaryOpKind::Equal, rhs, .. }) => {
let lhs = self.codegen_non_tuple_expression(lhs)?;
let rhs = self.codegen_non_tuple_expression(rhs)?;
self.builder.set_location(location).insert_constrain(lhs, rhs, assert_message);
}
let expr = self.codegen_non_tuple_expression(expr)?;
let true_literal = self.builder.numeric_constant(true, Type::bool());
self.builder.set_location(location).insert_constrain(expr, true_literal, assert_message);

_ => {
let expr = self.codegen_non_tuple_expression(expr)?;
let true_literal = self.builder.numeric_constant(true, Type::bool());
self.builder.set_location(location).insert_constrain(
expr,
true_literal,
assert_message,
);
}
}
Ok(Self::unit_value())
}

Expand Down