fix: Do not emit range check for multiplication by bool

compiler/noirc_evaluator/src/acir/mod.rs

@@ -2028,7 +2028,11 @@ impl<'a> Context<'a> {
                 "attempt to subtract with overflow".to_string()
             }
             BinaryOp::Mul => {
-                if bit_size == 1 || max_lhs_bits + max_rhs_bits <= bit_size {
+                if bit_size == 1
+                    || max_lhs_bits + max_rhs_bits <= bit_size
+                    || max_lhs_bits == 1
+                    || max_rhs_bits == 1
+                {
                     // Either performing boolean multiplication (which cannot overflow),
                     // or `lhs` and `rhs` have both been casted up from smaller types and so cannot overflow.
                     return Ok(());
@@ -2888,8 +2892,9 @@ mod test {
     use acvm::{
         acir::{
             circuit::{
-                brillig::BrilligFunctionId, opcodes::AcirFunctionId, ExpressionWidth, Opcode,
-                OpcodeLocation,
+                brillig::BrilligFunctionId,
+                opcodes::{AcirFunctionId, BlackBoxFuncCall},
+                ExpressionWidth, Opcode, OpcodeLocation,
             },
             native_types::Witness,
         },
@@ -2913,6 +2918,8 @@ mod test {
         },
     };
 
+    use super::Ssa;
+
     fn build_basic_foo_with_return(
         builder: &mut FunctionBuilder,
         foo_id: FunctionId,
@@ -3659,4 +3666,36 @@ mod test {
             "Should have {expected_num_normal_calls} BrilligCall opcodes to normal Brillig functions but got {num_normal_brillig_calls}"
         );
     }
+
+    #[test]
+    fn multiply_with_bool_should_not_emit_range_check() {
+        let src = "
+            acir(inline) fn main f0 {
+            b0(v0: bool, v1: u32):
+                enable_side_effects v0
+                v2 = cast v0 as u32
+                v3 = mul v2, v1
+                return v3
+            }
+        ";
+        let ssa = Ssa::from_str(src).unwrap();
+        let brillig = ssa.to_brillig(false);
+
+        let (mut acir_functions, _brillig_functions, _, _) = ssa
+            .into_acir(&brillig, ExpressionWidth::default())
+            .expect("Should compile manually written SSA into ACIR");
+
+        assert_eq!(acir_functions.len(), 1);
+
+        let opcodes = acir_functions[0].take_opcodes();
+
+        for opcode in opcodes {
+            if let Opcode::BlackBoxFuncCall(BlackBoxFuncCall::RANGE { input }) = opcode {
+                assert!(
+                    input.to_witness().0 <= 1,
+                    "only input witnesses should have range checks: {opcode:?}"
+                );
+            }
+        }
+    }
 }