shift and add multiplication (#41)

* shift and add multiplication
* test suite for mult_by_const

qlasskit/ast2ast.py

@@ -72,9 +72,9 @@ def _replace_types_annotations(ann, arg=None):
         isinstance(ann, ast.Subscript)
         and isinstance(ann.value, ast.Name)
         and ann.value.id == "Tuple"
-        and hasattr(ann.slice, 'elts')
+        and hasattr(ann.slice, "elts")
     ):
-        _elts = ann.slice.elts 
+        _elts = ann.slice.elts
         _ituple = ast.Tuple(elts=[_replace_types_annotations(el) for el in _elts])
 
         ann = ast.Subscript(
@@ -101,7 +101,7 @@ def _replace_types_annotations(ann, arg=None):
         isinstance(ann, ast.Subscript)
         and isinstance(ann.value, ast.Name)
         and ann.value.id == "Qlist"
-        and hasattr(ann.slice, 'elts')
+        and hasattr(ann.slice, "elts")
     ):
         _elts = ann.slice.elts
         _ituple = ast.Tuple(elts=[copy.deepcopy(_elts[0])] * _elts[1].value)
@@ -116,7 +116,7 @@ def _replace_types_annotations(ann, arg=None):
         isinstance(ann, ast.Subscript)
         and isinstance(ann.value, ast.Name)
         and ann.value.id == "Qmatrix"
-        and hasattr(ann.slice, 'elts')
+        and hasattr(ann.slice, "elts")
     ):
         _elts = ann.slice.elts
         _ituple_row = ast.Tuple(elts=[copy.deepcopy(_elts[0])] * _elts[2].value)
@@ -425,31 +425,31 @@ def visit_For(self, node):  # noqa: C901
             isinstance(iter, ast.Subscript)
             and isinstance(iter.value, ast.Name)
             and iter.value.id in self.env
-            and hasattr(iter.slice, 'value')
+            and hasattr(iter.slice, "value")
         ):
             if isinstance(self.env[iter.value.id], ast.Tuple):
                 new_iter = self.env[iter.value.id].elts[iter.slice.value]
 
-            elif isinstance(self.env[iter.value.id], ast.Subscript):  
-                _elts = self.env[iter.value.id].slice.elts[iter.slice.value]  
+            elif isinstance(self.env[iter.value.id], ast.Subscript):
+                _elts = self.env[iter.value.id].slice.elts[iter.slice.value]
 
                 if isinstance(_elts, ast.Tuple):
                     _elts = _elts.elts
 
                 new_iter = [
                     ast.Subscript(
                         value=ast.Subscript(
-                            value=ast.Name(id=iter.value.id, ctx=ast.Load()), 
-                            slice=ast.Constant(value=iter.slice.value),  
+                            value=ast.Name(id=iter.value.id, ctx=ast.Load()),
+                            slice=ast.Constant(value=iter.slice.value),
                             ctx=ast.Load(),
                         ),
                         slice=ast.Constant(value=e),
                     )
                     for e in range(len(_elts))
                 ]
             else:
-                new_iter = iter 
-                
+                new_iter = iter
+
             iter = new_iter
 
         if isinstance(iter, ast.Constant) and isinstance(iter.value, ast.Tuple):

qlasskit/types/qint.py

@@ -18,7 +18,7 @@
 from sympy.logic import And, Not, Or, Xor, false, true
 
 from . import TypeErrorException, _eq, _full_adder, _neq
-from .qtype import Qtype, TExp, bin_to_bool_list, bool_list_to_bin
+from .qtype import Qtype, TExp, TType, bin_to_bool_list, bool_list_to_bin
 
 
 class QintImp(int, Qtype):
@@ -164,12 +164,86 @@ def add(cls, tleft: TExp, tright: TExp) -> TExp:
 
         return (cls if cls.BIT_SIZE > tleft_e[0].BIT_SIZE else tleft_e[0], sums)
 
+    @staticmethod
+    def mul_even_const(t_num: TExp, const: int, result_type: Qtype) -> TExp:
+        """Multiply by an even const using shift and add
+        (x << 3) + (x << 1) # Here 10*x is computed as x*2^3 + x*2
+        """
+
+        # Multiply t_num by the nearest n | 2**n < t_const
+        n = 1
+        while 2**n <= const:
+            n += 1
+        if 2**n > const:
+            n -= 1
+
+        result_ttype = cast(TType, result_type)
+
+        t_num_r = result_type.shift_left((result_ttype, t_num[1]), n)
+
+        # Shift t_const by t_const - 2**n
+        r = const - 2**n
+        if r > 0:
+            # Add the shift result to t_num
+            res = result_type.add(
+                (result_ttype, t_num_r[1]),
+                result_type.shift_left((result_ttype, t_num[1]), int(r / 2)),
+            )
+        else:
+            res = (result_ttype, t_num_r[1])
+
+        return res
+
     @classmethod
-    def mul(cls, tleft: TExp, tright: TExp) -> TExp:  # noqa: C901
-        # TODO: use RGQFT multiplier
+    def mul(cls, tleft_: TExp, tright_: TExp) -> TExp:  # noqa: C901
+        if not issubclass(tleft_[0], Qtype):
+            raise TypeErrorException(tleft_[0], Qtype)
+        if not issubclass(tright_[0], Qtype):
+            raise TypeErrorException(tright_[0], Qtype)
+
+        def __mul_sizing(n, m):
+            if (n + m) <= 2:
+                return Qint2
+            elif (n + m) > 2 and (n + m) <= 4:
+                return Qint4
+            elif (n + m) > 4 and (n + m) <= 6:
+                return Qint6
+            elif (n + m) > 6 and (n + m) <= 8:
+                return Qint8
+            elif (n + m) > 8 and (n + m) <= 12:
+                return Qint12
+            elif (n + m) > 12 and (n + m) <= 16:
+                return Qint16
+            elif (n + m) > 16:
+                return Qint16
+            else:
+                raise Exception(f"Mul result size is too big ({n+m})")
+
+        # Fill constants so explicit typecast is not needed
+        if cls.is_const(tleft_):
+            tleft = tright_[0].fill(tleft_)
+        else:
+            tleft = tleft_
+
+        if cls.is_const(tright_):
+            tright = tleft_[0].fill(tright_)
+        else:
+            tright = tright_
+
         n = len(tleft[1])
         m = len(tright[1])
 
+        # If one operand is an even constant, use mul_even_const
+        if cls.is_const(tleft) or cls.is_const(tright):
+            t_num = tleft if cls.is_const(tright) else tright
+            t_const = tleft if cls.is_const(tleft) else tright
+            const = cast(int, cast(Qtype, t_const[0]).from_bool(t_const[1]))
+
+            if const % 2 == 0:
+                t = __mul_sizing(n, m)
+                res = cls.mul_even_const(t_num, const, t)
+                return t.crop(t.fill(res))
+
         if n != m:
             raise Exception(f"Mul works only on same size Qint: {n} != {m}")
 
@@ -190,22 +264,8 @@ def mul(cls, tleft: TExp, tright: TExp) -> TExp:  # noqa: C901
             if i + m < n + m:
                 product[i + m] = carry
 
-        if (n + m) <= 2:
-            return Qint2, product
-        elif (n + m) > 2 and (n + m) <= 4:
-            return Qint4, product
-        elif (n + m) > 4 and (n + m) <= 6:
-            return Qint6, product
-        elif (n + m) > 6 and (n + m) <= 8:
-            return Qint8, product
-        elif (n + m) > 8 and (n + m) <= 12:
-            return Qint12, product
-        elif (n + m) > 12 and (n + m) <= 16:
-            return Qint16, product
-        elif (n + m) > 16:
-            return Qint16.crop((Qint16, product))
-
-        raise Exception(f"Mul result size is too big ({n+m})")
+        t = __mul_sizing(n, m)
+        return t.crop(t.fill((t, product)))
 
     @classmethod
     def sub(cls, tleft: TExp, tright: TExp) -> TExp:

qlasskit/types/qtype.py

@@ -187,12 +187,18 @@ def bitwise_not(v: TExp) -> TExp:
     @staticmethod
     def shift_right(v: TExp, i: int = 1) -> TExp:
         """Apply a shift right"""
-        return (v[0], v[1][i:])
+        if not issubclass(v[0], Qtype):
+            raise TypeErrorException(v[0], Qtype)
+
+        return v[0].fill((v[0], v[1][i:]))
 
     @staticmethod
     def shift_left(v: TExp, i: int = 1) -> TExp:
         """Apply a shift left"""
-        return (v[0], [False] * i + v[1])
+        if not issubclass(v[0], Qtype):
+            raise TypeErrorException(v[0], Qtype)
+
+        return v[0].crop((v[0], [False] * i + v[1]))
 
     @staticmethod
     def add(tleft: TExp, tright: TExp) -> TExp:

test/qlassf/test_int.py

@@ -293,13 +293,27 @@ def test_composed_comparators(self):
         qf = qlassf(f, to_compile=COMPILATION_ENABLED, compiler=self.compiler)
         compute_and_compare_results(self, qf)
 
-    def test_shift_left(self):
-        f = "def test(n: Qint[2]) -> Qint[4]: return n << 1"
+    @parameterized.expand(
+        [
+            (1,),
+            (2,),
+            (3,),
+        ]
+    )
+    def test_shift_left(self, v):
+        f = f"def test(n: Qint[4]) -> Qint[4]: return n << {v}"
         qf = qlassf(f, to_compile=COMPILATION_ENABLED, compiler=self.compiler)
         compute_and_compare_results(self, qf)
 
-    def test_shift_right(self):
-        f = "def test(n: Qint[2]) -> Qint[4]: return n >> 1"
+    @parameterized.expand(
+        [
+            (1,),
+            (2,),
+            (3,),
+        ]
+    )
+    def test_shift_right(self, v):
+        f = f"def test(n: Qint[2]) -> Qint[4]: return n >> {v}"
         qf = qlassf(f, to_compile=COMPILATION_ENABLED, compiler=self.compiler)
         compute_and_compare_results(self, qf)
 
@@ -479,3 +493,23 @@ def test_mul5(self):
         qf = qlassf(f, to_compile=COMPILATION_ENABLED, compiler=self.compiler)
         compute_and_compare_results(self, qf)
         self.assertEqual(qf.expressions[0][1], True)
+
+
+@parameterized_class(
+    ("ttype_i", "ttype_o", "const", "compiler"),
+    inject_parameterized_compilers(
+        [
+            (4, 6, 2),
+            (4, 6, 4),
+            (4, 6, 6),
+            (6, 8, 6),
+            (6, 8, 8),
+            (6, 8, 10),
+        ]
+    ),
+)
+class TestQlassfIntMulByConst(unittest.TestCase):
+    def test_mul(self):
+        f = f"def test(a: Qint[{self.ttype_i}]) -> Qint[{self.ttype_o}]: return a * {self.const}"
+        qf = qlassf(f, to_compile=COMPILATION_ENABLED, compiler=self.compiler)
+        compute_and_compare_results(self, qf)

test/utils.py

@@ -223,7 +223,7 @@ def compute_and_compare_results(cls, qf, test_original_f=True, test_qcircuit=Tru
 
     # circ_qi = qf.circuit().export("circuit", "qiskit")
 
-    # update_statistics(qf.circuit().num_qubits, qf.circuit().num_gates)
+    update_statistics(qf.circuit().num_qubits, qf.circuit().num_gates)
 
     # print(qf.expressions)
     # print(circ_qi.draw("text"))