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refactor execution of branch indicators and function returns

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This commit is contained in:
collin 2020-12-03 13:24:23 -05:00
parent ced02462a0
commit b94c70588e
13 changed files with 145 additions and 118 deletions
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18
compiler/src/console/assert.rs
View File

@ -16,7 +16,13 @@
//! Enforces an assert equals statement in a compiled Leo program.
use crate::{errors::ConsoleError, program::ConstrainedProgram, value::ConstrainedValue, GroupType};
use crate::{
errors::ConsoleError,
get_indicator_value,
program::ConstrainedProgram,
value::ConstrainedValue,
GroupType,
};
use leo_ast::{Expression, Span, Type};
use snarkos_models::{
@ -30,7 +36,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs: &mut CS,
file_scope: &str,
function_scope: &str,
indicator: Option<Boolean>,
indicator: &Boolean,
expression: Expression,
span: &Span,
) -> Result<(), ConsoleError> {
@ -42,12 +48,8 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
// If the indicator bit is false, do not evaluate the assertion
// This is okay since we are not enforcing any constraints
let false_boolean = Boolean::Constant(false);
if let Some(indicator_bool) = indicator {
if indicator_bool.eq(&false_boolean) {
return Ok(()); // continue execution
}
if !get_indicator_value(indicator) {
return Ok(()); // Continue execution.
}
// Unwrap assertion value and handle errors

23
compiler/src/console/console.rs
View File

@ -16,7 +16,7 @@
//! Evaluates a macro in a compiled Leo program.
use crate::{errors::ConsoleError, program::ConstrainedProgram, GroupType};
use crate::{errors::ConsoleError, program::ConstrainedProgram, statement::get_indicator_value, GroupType};
use leo_ast::{ConsoleFunction, ConsoleFunctionCall};
use snarkos_models::{
@ -30,7 +30,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs: &mut CS,
file_scope: &str,
function_scope: &str,
indicator: Option<Boolean>,
indicator: &Boolean,
console: ConsoleFunctionCall,
) -> Result<(), ConsoleError> {
match console.function {
@ -40,21 +40,21 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
ConsoleFunction::Debug(string) => {
let string = self.format(cs, file_scope, function_scope, string)?;
if unwrap_indicator_value(indicator) {
if get_indicator_value(indicator) {
tracing::debug!("{}", string);
}
}
ConsoleFunction::Error(string) => {
let string = self.format(cs, file_scope, function_scope, string)?;
if unwrap_indicator_value(indicator) {
if get_indicator_value(indicator) {
tracing::error!("{}", string);
}
}
ConsoleFunction::Log(string) => {
let string = self.format(cs, file_scope, function_scope, string)?;
if unwrap_indicator_value(indicator) {
if get_indicator_value(indicator) {
tracing::info!("{}", string);
}
}
@ -63,16 +63,3 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
Ok(())
}
}
// Return the indicator boolean gadget value or true if it is None
// This is okay since we are not enforcing any constraints
fn unwrap_indicator_value(indicator: Option<Boolean>) -> bool {
let false_boolean = Boolean::constant(false);
if let Some(indicator_bool) = indicator {
if indicator_bool.eq(&false_boolean) {
return false;
}
}
true
}

16
compiler/src/errors/statement.rs
View File

@ -135,6 +135,22 @@ impl StatementError {
Self::new_from_span(message, span)
}
pub fn multiple_returns(span: Span) -> Self {
let message =
format!("This function returns multiple times and produces unreachable circuits with undefined behavior.");
Self::new_from_span(message, span)
}
pub fn no_returns(expected: Type, span: Span) -> Self {
let message = format!(
"function expected `{}` return type but no valid branches returned a result",
expected
);
Self::new_from_span(message, span)
}
pub fn select_fail(first: String, second: String, span: Span) -> Self {
let message = format!(
"Conditional select gadget failed to select between `{}` or `{}`",

30
compiler/src/function/function.rs
View File

@ -23,11 +23,11 @@ use crate::{
GroupType,
};
use leo_ast::{Expression, Function, FunctionInput, Span, Type};
use leo_ast::{Expression, Function, FunctionInput, Span};
use snarkos_models::{
curves::{Field, PrimeField},
gadgets::r1cs::ConstraintSystem,
gadgets::{r1cs::ConstraintSystem, utilities::boolean::Boolean},
};
pub fn check_arguments_length(expected: usize, actual: usize, span: &Span) -> Result<(), FunctionError> {
@ -89,13 +89,14 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
// Evaluate every statement in the function and save all potential results
let mut results = vec![];
let indicator = Boolean::constant(true);
for statement in function.statements.iter() {
let mut result = self.enforce_statement(
cs,
scope,
&function_name,
None,
&indicator,
statement.clone(),
function.output.clone(),
declared_circuit_reference,
@ -105,26 +106,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
}
// Conditionally select a result based on returned indicators
let mut return_values = ConstrainedValue::Tuple(vec![]);
Self::conditionally_select_result(cs, &mut return_values, results, &function.span)?;
if let ConstrainedValue::Tuple(ref returns) = return_values {
let return_types = match function.output {
Some(Type::Tuple(types)) => types.len(),
Some(_) => 1usize,
None => 0usize,
};
if return_types != returns.len() {
return Err(FunctionError::return_arguments_length(
return_types,
returns.len(),
function.span.clone(),
));
}
}
Ok(return_values)
Self::conditionally_select_result(cs, function.output, results, &function.span)
.map_err(|err| FunctionError::StatementError(err))
}
}

115
compiler/src/function/result/result.rs
View File

@ -16,9 +16,15 @@
//! Enforces that one return value is produced in a compiled Leo program.
use crate::{errors::StatementError, program::ConstrainedProgram, value::ConstrainedValue, GroupType};
use crate::{
errors::StatementError,
get_indicator_value,
program::ConstrainedProgram,
value::ConstrainedValue,
GroupType,
};
use leo_ast::Span;
use leo_ast::{Span, Type};
use snarkos_models::{
curves::{Field, PrimeField},
@ -29,49 +35,84 @@ use snarkos_models::{
};
impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
/// iterates through a vector of results and selects one based off of indicators
///
/// Returns a conditionally selected result from the given possible function returns and
/// given function return type.
///
pub fn conditionally_select_result<CS: ConstraintSystem<F>>(
cs: &mut CS,
return_value: &mut ConstrainedValue<F, G>,
results: Vec<(Option<Boolean>, ConstrainedValue<F, G>)>,
expected_return: Option<Type>,
results: Vec<(Boolean, ConstrainedValue<F, G>)>,
span: &Span,
) -> Result<(), StatementError> {
// if there are no results, continue
if results.is_empty() {
return Ok(());
) -> Result<ConstrainedValue<F, G>, StatementError> {
// Initialize empty return value.
let mut return_value = ConstrainedValue::Tuple(vec![]);
// If the function does not expect a return type, then make sure there are no returned results.
let return_type = match expected_return {
Some(return_type) => return_type,
None => {
if results.is_empty() {
// If the function has no returns, then return an empty tuple.
return Ok(return_value);
} else {
return Err(StatementError::invalid_number_of_returns(
0,
results.len(),
span.to_owned(),
));
}
}
};
// Error if the function or one of its branches does not return.
if let None = results.iter().find(|(indicator, _res)| get_indicator_value(indicator)) {
return Err(StatementError::no_returns(return_type, span.to_owned()));
}
// If all indicators are none, then there are no branch conditions in the function.
// We simply return the last result.
if results.iter().all(|(indicator, _res)| indicator.is_none()) {
let result = &results[results.len() - 1].1;
*return_value = result.clone();
return Ok(());
}
// If there are branches in the function we need to use the `ConditionalSelectGadget` to parse through and select the correct one.
// This can be thought of as de-multiplexing all previous wires that may have returned results into one.
for (i, (indicator, result)) in results.into_iter().enumerate() {
// Set the first value as the starting point
if i == 0 {
*return_value = result.clone();
// Find the return value
let mut ignored = vec![];
let mut found_return = false;
for (indicator, result) in results.into_iter() {
// Error if a statement returned a result with an incorrect type
let result_type = result.to_type(span)?;
if return_type != result_type {
return Err(StatementError::arguments_type(
&return_type,
&result_type,
span.to_owned(),
));
}
let condition = indicator.unwrap_or(Boolean::Constant(true));
let selected_value = ConstrainedValue::conditionally_select(
cs.ns(|| format!("select {} {}:{}", result, span.line, span.start)),
&condition,
&result,
return_value,
)
.map_err(|_| StatementError::select_fail(result.to_string(), return_value.to_string(), span.to_owned()))?;
*return_value = selected_value;
if get_indicator_value(&indicator) {
// Error if we already have a return value.
if found_return {
return Err(StatementError::multiple_returns(span.to_owned()));
} else {
// Set the function return value.
return_value = result;
found_return = true;
}
} else {
// Ignore a possible function return value.
ignored.push((indicator, result))
}
}
Ok(())
// Conditionally select out the ignored results in the circuit.
//
// If there are branches in the function we need to use the `ConditionalSelectGadget` to parse through and select the correct one.
// This can be thought of as de-multiplexing all previous wires that may have returned results into one.
for (i, (indicator, result)) in ignored.into_iter().enumerate() {
return_value = ConstrainedValue::conditionally_select(
cs.ns(|| format!("select result {} {}:{}", i, span.line, span.start)),
&indicator,
&result,
&return_value,
)
.map_err(|_| StatementError::select_fail(result.to_string(), return_value.to_string(), span.to_owned()))?;
}
Ok(return_value)
}
}

8
compiler/src/statement/assign/array.rs
View File

@ -34,14 +34,12 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs: &mut CS,
file_scope: &str,
function_scope: &str,
indicator: Option<Boolean>,
indicator: &Boolean,
name: &str,
range_or_expression: RangeOrExpression,
mut new_value: ConstrainedValue<F, G>,
span: &Span,
) -> Result<(), StatementError> {
let condition = indicator.unwrap_or(Boolean::Constant(true));
// Resolve index so we know if we are assigning to a single value or a range of values
match range_or_expression {
RangeOrExpression::Expression(index) => {
@ -54,7 +52,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
let selected_value = ConstrainedValue::conditionally_select(
cs.ns(|| format!("select {} {}:{}", new_value, span.line, span.start)),
&condition,
indicator,
&new_value,
&old[index],
)
@ -90,7 +88,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
};
let selected_array = ConstrainedValue::conditionally_select(
cs.ns(|| format!("select {} {}:{}", new_array, span.line, span.start)),
&condition,
indicator,
&new_array,
old_array,
)

5
compiler/src/statement/assign/assign.rs
View File

@ -42,7 +42,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
file_scope: &str,
function_scope: &str,
declared_circuit_reference: &str,
indicator: Option<Boolean>,
indicator: &Boolean,
assignee: Assignee,
expression: Expression,
span: &Span,
@ -55,14 +55,13 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
// Mutate the old value into the new value
if assignee.accesses.is_empty() {
let condition = indicator.unwrap_or(Boolean::Constant(true));
let old_value = self.get_mutable_assignee(&variable_name, span)?;
new_value.resolve_type(Some(old_value.to_type(&span)?), span)?;
let selected_value = ConstrainedValue::conditionally_select(
cs.ns(|| format!("select {} {}:{}", new_value, span.line, span.start)),
&condition,
indicator,
&new_value,
old_value,
)

6
compiler/src/statement/assign/circuit_variable.rs
View File

@ -31,14 +31,12 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
pub fn mutate_circuit_variable<CS: ConstraintSystem<F>>(
&mut self,
cs: &mut CS,
indicator: Option<Boolean>,
indicator: &Boolean,
circuit_name: &str,
variable_name: Identifier,
mut new_value: ConstrainedValue<F, G>,
span: &Span,
) -> Result<ConstrainedValue<F, G>, StatementError> {
let condition = indicator.unwrap_or(Boolean::Constant(true));
// Get the mutable circuit by name
match self.get_mutable_assignee(circuit_name, span)? {
ConstrainedValue::CircuitExpression(_variable, members) => {
@ -70,7 +68,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
// Conditionally select the value if this branch is executed.
let mut selected_value = ConstrainedValue::conditionally_select(
cs.ns(|| format!("select {} {}:{}", new_value, span.line, span.start)),
&condition,
indicator,
&new_value,
&member.1,
)

7
compiler/src/statement/assign/tuple.rs
View File

@ -31,15 +31,12 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
pub fn assign_tuple<CS: ConstraintSystem<F>>(
&mut self,
cs: &mut CS,
indicator: Option<Boolean>,
indicator: &Boolean,
name: &str,
index: PositiveNumber,
mut new_value: ConstrainedValue<F, G>,
span: &Span,
) -> Result<(), StatementError> {
// Get the indicator value.
let condition = indicator.unwrap_or(Boolean::Constant(true));
// Parse the index.
let index_usize = parse_index(&index, &span)?;
@ -50,7 +47,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
let selected_value = ConstrainedValue::conditionally_select(
cs.ns(|| format!("select {} {}:{}", new_value, span.line, span.start)),
&condition,
indicator,
&new_value,
&old[index_usize],
)

2
compiler/src/statement/branch/branch.rs
View File

@ -30,7 +30,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs: &mut CS,
file_scope: &str,
function_scope: &str,
indicator: Option<Boolean>,
indicator: &Boolean,
statements: Vec<Statement>,
return_type: Option<Type>,
) -> StatementResult<Vec<IndicatorAndConstrainedValue<F, G>>> {

16
compiler/src/statement/conditional/conditional.rs
View File

@ -49,15 +49,15 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs: &mut CS,
file_scope: &str,
function_scope: &str,
indicator: Option<Boolean>,
indicator: &Boolean,
statement: ConditionalStatement,
return_type: Option<Type>,
span: &Span,
) -> StatementResult<Vec<IndicatorAndConstrainedValue<F, G>>> {
let statement_string = statement.to_string();
// Inherit the indicator from a previous conditional statement or assume that we are the outer parent
let outer_indicator = indicator.unwrap_or(Boolean::Constant(true));
// Inherit an indicator from a previous statement.
let outer_indicator = indicator;
// Evaluate the conditional boolean as the inner indicator
let inner_indicator = match self.enforce_expression(
@ -72,7 +72,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
};
// If outer_indicator && inner_indicator, then select branch 1
let outer_indicator_string = indicator_to_string(&outer_indicator);
let outer_indicator_string = indicator_to_string(outer_indicator);
let inner_indicator_string = indicator_to_string(&inner_indicator);
let branch_1_name = format!(
"branch indicator 1 {} && {}",
@ -80,7 +80,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
);
let branch_1_indicator = Boolean::and(
&mut cs.ns(|| format!("branch 1 {} {}:{}", statement_string, span.line, span.start)),
&outer_indicator,
outer_indicator,
&inner_indicator,
)
.map_err(|_| StatementError::indicator_calculation(branch_1_name, span.to_owned()))?;
@ -92,7 +92,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs,
file_scope,
function_scope,
Some(branch_1_indicator),
&branch_1_indicator,
statement.statements,
return_type.clone(),
)?;
@ -120,7 +120,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs,
file_scope,
function_scope,
Some(branch_2_indicator),
&branch_2_indicator,
*nested,
return_type,
span,
@ -129,7 +129,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs,
file_scope,
function_scope,
Some(branch_2_indicator),
&branch_2_indicator,
statements,
return_type,
)?,

2
compiler/src/statement/iteration/iteration.rs
View File

@ -42,7 +42,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs: &mut CS,
file_scope: &str,
function_scope: &str,
indicator: Option<Boolean>,
indicator: &Boolean,
index: Identifier,
start: Expression,
stop: Expression,

15
compiler/src/statement/statement.rs
View File

@ -25,7 +25,7 @@ use snarkos_models::{
};
pub type StatementResult<T> = Result<T, StatementError>;
pub type IndicatorAndConstrainedValue<T, U> = (Option<Boolean>, ConstrainedValue<T, U>);
pub type IndicatorAndConstrainedValue<T, U> = (Boolean, ConstrainedValue<T, U>);
impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
///
@ -41,7 +41,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
cs: &mut CS,
file_scope: &str,
function_scope: &str,
indicator: Option<Boolean>,
indicator: &Boolean,
statement: Statement,
return_type: Option<Type>,
declared_circuit_reference: &str,
@ -51,7 +51,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
match statement {
Statement::Return(expression, span) => {
let return_value = (
indicator,
indicator.to_owned(),
self.enforce_return_statement(cs, file_scope, function_scope, expression, return_type, &span)?,
);
@ -126,7 +126,7 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
_ => return Err(StatementError::unassigned(expression_string, span)),
}
let result = (indicator, value);
let result = (indicator.to_owned(), value);
results.push(result);
}
@ -135,3 +135,10 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
Ok(results)
}
}
/// Returns the indicator boolean gadget value.
/// We can directly compare a boolean constant to the indicator since we are not enforcing any
/// constraints
pub fn get_indicator_value(indicator: &Boolean) -> bool {
indicator.eq(&Boolean::constant(true))
}