Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

feat: Optimize away constant calls to black box functions #1981

Merged
merged 5 commits into from
Aug 2, 2023
Merged

feat: Optimize away constant calls to black box functions #1981

Show file tree
Hide file tree
Changes from 3 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
33b119c
feat: optimize away constant calls to black box functions
TomAFrench Jul 20, 2023
059cfcc
chore: remove `use SimplifyResult::*`
TomAFrench Aug 2, 2023
e83ed7b
chore: remove unnecessary match arms
TomAFrench Aug 2, 2023
06402ff
Update crates/noirc_evaluator/src/ssa_refactor/ir/instruction/call.rs
jfecher Aug 2, 2023
62d4d50
Update crates/noirc_evaluator/src/ssa_refactor/ir/instruction/call.rs
jfecher Aug 2, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
156 changes: 4 additions & 152 deletions crates/noirc_evaluator/src/ssa_refactor/ir/instruction.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,3 @@
use std::rc::Rc;

use acvm::{acir::BlackBoxFunc, FieldElement};
use iter_extended::vecmap;
use num_bigint::BigUint;
Expand All @@ -14,6 +12,10 @@ use super::{
value::{Value, ValueId},
};

mod call;

use call::simplify_call;

/// Reference to an instruction
///
/// Note that InstructionIds are not unique. That is, two InstructionIds
Expand Down Expand Up @@ -385,156 +387,6 @@ fn simplify_cast(value: ValueId, dst_typ: &Type, dfg: &mut DataFlowGraph) -> Sim
}
}

/// Try to simplify this call instruction. If the instruction can be simplified to a known value,
/// that value is returned. Otherwise None is returned.
fn simplify_call(func: ValueId, arguments: &[ValueId], dfg: &mut DataFlowGraph) -> SimplifyResult {
use SimplifyResult::*;
let intrinsic = match &dfg[func] {
Value::Intrinsic(intrinsic) => *intrinsic,
_ => return None,
};

let constant_args: Option<Vec<_>> =
arguments.iter().map(|value_id| dfg.get_numeric_constant(*value_id)).collect();

match intrinsic {
Intrinsic::ToBits(endian) => {
if let Some(constant_args) = constant_args {
let field = constant_args[0];
let limb_count = constant_args[1].to_u128() as u32;
SimplifiedTo(constant_to_radix(endian, field, 2, limb_count, dfg))
} else {
None
}
}
Intrinsic::ToRadix(endian) => {
if let Some(constant_args) = constant_args {
let field = constant_args[0];
let radix = constant_args[1].to_u128() as u32;
let limb_count = constant_args[2].to_u128() as u32;
SimplifiedTo(constant_to_radix(endian, field, radix, limb_count, dfg))
} else {
None
}
}
Intrinsic::ArrayLen => {
let slice = dfg.get_array_constant(arguments[0]);
if let Some((slice, _)) = slice {
SimplifiedTo(dfg.make_constant((slice.len() as u128).into(), Type::field()))
} else if let Some(length) = dfg.try_get_array_length(arguments[0]) {
SimplifiedTo(dfg.make_constant((length as u128).into(), Type::field()))
} else {
None
}
}
Intrinsic::SlicePushBack => {
let slice = dfg.get_array_constant(arguments[0]);
if let (Some((mut slice, element_type)), elem) = (slice, arguments[1]) {
slice.push_back(elem);
let new_slice = dfg.make_array(slice, element_type);
SimplifiedTo(new_slice)
} else {
None
}
}
Intrinsic::SlicePushFront => {
let slice = dfg.get_array_constant(arguments[0]);
if let (Some((mut slice, element_type)), elem) = (slice, arguments[1]) {
slice.push_front(elem);
let new_slice = dfg.make_array(slice, element_type);
SimplifiedTo(new_slice)
} else {
None
}
}
Intrinsic::SlicePopBack => {
let slice = dfg.get_array_constant(arguments[0]);
if let Some((mut slice, element_type)) = slice {
let elem =
slice.pop_back().expect("There are no elements in this slice to be removed");
let new_slice = dfg.make_array(slice, element_type);
SimplifiedToMultiple(vec![new_slice, elem])
} else {
None
}
}
Intrinsic::SlicePopFront => {
let slice = dfg.get_array_constant(arguments[0]);
if let Some((mut slice, element_type)) = slice {
let elem =
slice.pop_front().expect("There are no elements in this slice to be removed");
let new_slice = dfg.make_array(slice, element_type);
SimplifiedToMultiple(vec![elem, new_slice])
} else {
None
}
}
Intrinsic::SliceInsert => {
let slice = dfg.get_array_constant(arguments[0]);
let index = dfg.get_numeric_constant(arguments[1]);
if let (Some((mut slice, element_type)), Some(index), value) =
(slice, index, arguments[2])
{
slice.insert(index.to_u128() as usize, value);
let new_slice = dfg.make_array(slice, element_type);
SimplifiedTo(new_slice)
} else {
None
}
}
Intrinsic::SliceRemove => {
let slice = dfg.get_array_constant(arguments[0]);
let index = dfg.get_numeric_constant(arguments[1]);
if let (Some((mut slice, element_type)), Some(index)) = (slice, index) {
let removed_elem = slice.remove(index.to_u128() as usize);
let new_slice = dfg.make_array(slice, element_type);
SimplifiedToMultiple(vec![new_slice, removed_elem])
} else {
None
}
}
Intrinsic::BlackBox(_) | Intrinsic::Println | Intrinsic::Sort => None,
}
}

/// Returns a Value::Array of constants corresponding to the limbs of the radix decomposition.
fn constant_to_radix(
endian: Endian,
field: FieldElement,
radix: u32,
limb_count: u32,
dfg: &mut DataFlowGraph,
) -> ValueId {
let bit_size = u32::BITS - (radix - 1).leading_zeros();
let radix_big = BigUint::from(radix);
assert_eq!(BigUint::from(2u128).pow(bit_size), radix_big, "ICE: Radix must be a power of 2");
let big_integer = BigUint::from_bytes_be(&field.to_be_bytes());

// Decompose the integer into its radix digits in little endian form.
let decomposed_integer = big_integer.to_radix_le(radix);
let mut limbs = vecmap(0..limb_count, |i| match decomposed_integer.get(i as usize) {
Some(digit) => FieldElement::from_be_bytes_reduce(&[*digit]),
None => FieldElement::zero(),
});
if endian == Endian::Big {
limbs.reverse();
}

// For legacy reasons (see #617) the to_radix interface supports 256 bits even though
// FieldElement::max_num_bits() is only 254 bits. Any limbs beyond the specified count
// become zero padding.
let max_decomposable_bits: u32 = 256;
let limb_count_with_padding = max_decomposable_bits / bit_size;
while limbs.len() < limb_count_with_padding as usize {
limbs.push(FieldElement::zero());
}
let result_constants: im::Vector<ValueId> =
limbs.into_iter().map(|limb| dfg.make_constant(limb, Type::unsigned(bit_size))).collect();

let typ = Type::Array(Rc::new(vec![Type::unsigned(bit_size)]), result_constants.len());
dfg.make_array(result_constants, typ)
}

/// The possible return values for Instruction::return_types
pub(crate) enum InstructionResultType {
/// The result type of this instruction matches that of this operand
Expand Down
Loading