chore: Basic test for MSM in Noir to catch performance improvements a…

…nd regressions (#7341)

Co-authored-by: Tom French <15848336+TomAFrench@users.noreply.github.com>

test_programs/execution_success/multi_scalar_mul/Nargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "multi_scalar_mul"
+type = "bin"
+authors = [""]
+
+[dependencies]

test_programs/execution_success/multi_scalar_mul/Prover.toml

@@ -0,0 +1,26 @@
+scalars = ["0", "0", "0", "0", "0"]
+
+[[points]]
+is_infinite = "0"
+x = "0x0000000000000000000000000000000000000000000000000000000000000001"
+y = "0x0000000000000002cf135e7506a45d632d270d45f1181294833fc48d823f272c"
+
+[[points]]
+is_infinite = "0"
+x = "0x0000000000000000000000000000000000000000000000000000000000000001"
+y = "0x0000000000000002cf135e7506a45d632d270d45f1181294833fc48d823f272c"
+
+[[points]]
+is_infinite = "0"
+x = "0x0000000000000000000000000000000000000000000000000000000000000001"
+y = "0x0000000000000002cf135e7506a45d632d270d45f1181294833fc48d823f272c"
+
+[[points]]
+is_infinite = "0"
+x = "0x0000000000000000000000000000000000000000000000000000000000000001"
+y = "0x0000000000000002cf135e7506a45d632d270d45f1181294833fc48d823f272c"
+
+[[points]]
+is_infinite = "0"
+x = "0x0000000000000000000000000000000000000000000000000000000000000001"
+y = "0x0000000000000002cf135e7506a45d632d270d45f1181294833fc48d823f272c"

test_programs/execution_success/multi_scalar_mul/src/main.nr

@@ -0,0 +1,45 @@
+// This test provides a basic implementation of a MSM in Noir, that allows us to check
+// performance improvements and regressions.
+use std::embedded_curve_ops::embedded_curve_add_unsafe;
+use std::embedded_curve_ops::EmbeddedCurvePoint;
+
+// `main` must be marked unconstrained as the function uses `break` internally
+unconstrained fn main(
+    points: [EmbeddedCurvePoint; 5],
+    scalars: [Field; 5],
+) -> pub EmbeddedCurvePoint {
+    // EmbeddedCurveScalar are two 128-bit numbers
+    let mut acc = EmbeddedCurvePoint::point_at_infinity();
+    for i in 0..1 {
+        // These should probably be EmbeddedCurveScalars
+        // let full_scalar: Field = scalars[i].hi * 2.pow_32(128) + scalars[i].lo;
+        let full_scalar = scalars[i];
+        let full_scalar_bits: [u1; 254] = full_scalar.to_be_bits();
+        let mut index_of_msb = 0;
+        // Iterates in BE
+        for j in 0..254 {
+            if full_scalar_bits[j] == 1 {
+                index_of_msb = j;
+                break;
+            }
+        }
+
+        let mut temp = points[i];
+        let mut res = EmbeddedCurvePoint::point_at_infinity();
+        // When iterative backwards we want to go to bits.len() - 2
+        for j in 0..(254 - index_of_msb) {
+            let k = 253 - j;
+
+            // Add
+            if full_scalar_bits[k] == 1 {
+                res = embedded_curve_add_unsafe(res, temp);
+            }
+            // Double
+            temp = embedded_curve_add_unsafe(temp, temp);
+        }
+
+        acc = embedded_curve_add_unsafe(acc, res);
+    }
+    acc
+}
+