fix: use 128 bits for constant bit shift (#3586)

Author: guipublic

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

@@ -282,32 +282,34 @@ impl FunctionBuilder {
     ) -> ValueId {
         let base = self.field_constant(FieldElement::from(2_u128));
         let typ = self.current_function.dfg.type_of_value(lhs);
-        let (max_bit, pow) = if let Some(rhs_constant) =
-            self.current_function.dfg.get_numeric_constant(rhs)
-        {
-            // Happy case is that we know precisely by how many bits the the integer will
-            // increase: lhs_bit_size + rhs
-            let (rhs_bit_size_pow_2, overflows) =
-                2_u32.overflowing_pow(rhs_constant.to_u128() as u32);
-            if overflows {
-                let zero = self.numeric_constant(FieldElement::zero(), typ);
-                return InsertInstructionResult::SimplifiedTo(zero).first();
-            }
-            let pow = self.numeric_constant(FieldElement::from(rhs_bit_size_pow_2 as u128), typ);
-            (bit_size + (rhs_constant.to_u128() as u32), pow)
-        } else {
-            // we use a predicate to nullify the result in case of overflow
-            let bit_size_var =
-                self.numeric_constant(FieldElement::from(bit_size as u128), typ.clone());
-            let overflow = self.insert_binary(rhs, BinaryOp::Lt, bit_size_var);
-            let one = self.numeric_constant(FieldElement::one(), Type::unsigned(1));
-            let predicate = self.insert_binary(overflow, BinaryOp::Eq, one);
-            let predicate = self.insert_cast(predicate, typ.clone());
-
-            let pow = self.pow(base, rhs);
-            let pow = self.insert_cast(pow, typ);
-            (FieldElement::max_num_bits(), self.insert_binary(predicate, BinaryOp::Mul, pow))
-        };
+        let (max_bit, pow) =
+            if let Some(rhs_constant) = self.current_function.dfg.get_numeric_constant(rhs) {
+                // Happy case is that we know precisely by how many bits the the integer will
+                // increase: lhs_bit_size + rhs
+                let (rhs_bit_size_pow_2, overflows) =
+                    2_u128.overflowing_pow(rhs_constant.to_u128() as u32);
+                if overflows {
+                    assert!(bit_size < 128, "ICE - shift left with big integers are not supported");
+                    if bit_size < 128 {
+                        let zero = self.numeric_constant(FieldElement::zero(), typ);
+                        return InsertInstructionResult::SimplifiedTo(zero).first();
+                    }
+                }
+                let pow = self.numeric_constant(FieldElement::from(rhs_bit_size_pow_2), typ);
+                (bit_size + (rhs_constant.to_u128() as u32), pow)
+            } else {
+                // we use a predicate to nullify the result in case of overflow
+                let bit_size_var =
+                    self.numeric_constant(FieldElement::from(bit_size as u128), typ.clone());
+                let overflow = self.insert_binary(rhs, BinaryOp::Lt, bit_size_var);
+                let one = self.numeric_constant(FieldElement::one(), Type::unsigned(1));
+                let predicate = self.insert_binary(overflow, BinaryOp::Eq, one);
+                let predicate = self.insert_cast(predicate, typ.clone());
+
+                let pow = self.pow(base, rhs);
+                let pow = self.insert_cast(pow, typ);
+                (FieldElement::max_num_bits(), self.insert_binary(predicate, BinaryOp::Mul, pow))
+            };
 
         let instruction = Instruction::Binary(Binary { lhs, rhs: pow, operator: BinaryOp::Mul });
         if max_bit <= bit_size {

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

@@ -13,6 +13,8 @@ fn main(x: u64) {
 
     //regression for 3481
     assert(x << 63 == 0);
+
+    assert_eq((1 as u56) << (32 as u56), 0x0100000000);
 }
 
 fn regression_2250() {