feat: signed arithmetic (#2748)

compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs

@@ -1059,18 +1059,14 @@ impl Context {
                 // Casting into a Field as a no-op
                 Ok(variable)
             }
-            NumericType::Unsigned { bit_size } => {
-                if incoming_type.is_signed() {
-                    todo!("Cast from unsigned to signed")
-                }
+            NumericType::Unsigned { bit_size } | NumericType::Signed { bit_size } => {
                 let max_bit_size = incoming_type.bit_size();
                 if max_bit_size <= *bit_size {
                     // Incoming variable already fits into target bit size -  this is a no-op
                     return Ok(variable);
                 }
                 self.acir_context.truncate_var(variable, *bit_size, max_bit_size)
             }
-            NumericType::Signed { .. } => todo!("Cast into signed"),
         }
     }
 

tooling/nargo_cli/tests/execution_success/signed_arithmetic/Nargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "signed_arithmetic"
+type = "bin"
+authors = [""]
+compiler_version = "0.1"
+
+[dependencies]

tooling/nargo_cli/tests/execution_success/signed_arithmetic/Prover.toml

@@ -0,0 +1,3 @@
+x = "5"
+y = "8"
+z = "-15"

tooling/nargo_cli/tests/execution_success/signed_arithmetic/src/main.nr

@@ -0,0 +1,32 @@
+fn main(mut x: i32, mut y: i32, z: i32) {
+    let mut s1: i8 = 5;
+    let mut s2: i8 = 8;
+    assert(s1+s2 == 13);
+    assert(x + y == 13);
+
+    s2= -8;
+    y = -y;
+    assert(s1+s2 == -3);
+    assert(x + y == -3);
+
+    s1 = -15;
+    assert(s1-s2 == -7);
+    assert(z-y == -7);
+
+    s1 = -5;
+    s2 = 8;
+    x = -x;
+    y = -y;
+    assert(s1-s2 == -13);
+    assert(x-y == -13);
+
+    s2 = -8;
+    y = -y;
+    assert(s1*s2 == 40);
+    assert(x*y == 40);
+
+    s1 = 1;
+    s2 = -8;
+    assert(s1*s2 == -8);
+    assert(x/x*y == -8);
+}

tooling/noirc_abi/src/input_parser/mod.rs

@@ -1,5 +1,5 @@
-use num_bigint::BigUint;
-use num_traits::Num;
+use num_bigint::{BigInt, BigUint};
+use num_traits::{Num, Zero};
 use std::collections::BTreeMap;
 
 use acvm::FieldElement;
@@ -201,10 +201,48 @@ fn parse_str_to_field(value: &str) -> Result<FieldElement, InputParserError> {
     }
 }
 
+fn parse_str_to_signed(value: &str, witdh: u32) -> Result<FieldElement, InputParserError> {
+    if value.starts_with("0x") {
+        FieldElement::from_hex(value).ok_or_else(|| InputParserError::ParseHexStr(value.to_owned()))
+    } else {
+        BigInt::from_str_radix(value, 10)
+            .map_err(|err_msg| InputParserError::ParseStr(err_msg.to_string()))
+            .and_then(|bigint| {
+                let modulus: BigInt = FieldElement::modulus().into();
+                let bigint = if bigint.sign() == num_bigint::Sign::Minus {
+                    BigInt::from(2).pow(witdh) + bigint
+                } else {
+                    bigint
+                };
+                if bigint.is_zero() || (bigint.sign() == num_bigint::Sign::Plus && bigint < modulus)
+                {
+                    Ok(field_from_big_int(bigint))
+                } else {
+                    Err(InputParserError::ParseStr(format!(
+                        "Input exceeds field modulus. Values must fall within [0, {})",
+                        FieldElement::modulus(),
+                    )))
+                }
+            })
+    }
+}
+
 fn field_from_big_uint(bigint: BigUint) -> FieldElement {
     FieldElement::from_be_bytes_reduce(&bigint.to_bytes_be())
 }
 
+fn field_from_big_int(bigint: BigInt) -> FieldElement {
+    match bigint.sign() {
+        num_bigint::Sign::Minus => {
+            unreachable!(
+                "Unsupported negative value; it should only be called with a positive value"
+            )
+        }
+        num_bigint::Sign::NoSign => FieldElement::zero(),
+        num_bigint::Sign::Plus => FieldElement::from_be_bytes_reduce(&bigint.to_bytes_be().1),
+    }
+}
+
 #[cfg(test)]
 mod test {
     use acvm::FieldElement;

tooling/noirc_abi/src/input_parser/toml.rs

@@ -1,4 +1,4 @@
-use super::{parse_str_to_field, InputValue};
+use super::{parse_str_to_field, parse_str_to_signed, InputValue};
 use crate::{errors::InputParserError, Abi, AbiType, MAIN_RETURN_NAME};
 use acvm::FieldElement;
 use iter_extended::{try_btree_map, try_vecmap};
@@ -118,9 +118,13 @@ impl InputValue {
             (TomlTypes::String(string), AbiType::String { .. }) => InputValue::String(string),
             (
                 TomlTypes::String(string),
-                AbiType::Field | AbiType::Integer { .. } | AbiType::Boolean,
+                AbiType::Field
+                | AbiType::Integer { sign: crate::Sign::Unsigned, .. }
+                | AbiType::Boolean,
             ) => InputValue::Field(parse_str_to_field(&string)?),
-
+            (TomlTypes::String(string), AbiType::Integer { sign: crate::Sign::Signed, width }) => {
+                InputValue::Field(parse_str_to_signed(&string, *width)?)
+            }
             (
                 TomlTypes::Integer(integer),
                 AbiType::Field | AbiType::Integer { .. } | AbiType::Boolean,