Adds zip and dict builtins overloads to support easy literal dict ctor (#992)

* Adds zip and dict builtins overloads to support easy literal dict ctor

Motivation: there's no easy way to create Numba LiteralStrKeyDict
objects for const dicts with many elements. This adds a special overload
for dict builtin that creates LiteralStrKeyDict from tuple of pairs
('col_name', col_data).

* Replacing zip overload builtin with internal sdc_tuple_zip function

Details: zip builtin is already overloaded in Numba and has priority
over user defined overloads, hence in cases when we want zip two single
elements tuples, e.g. zip(('A', ), (1, )) builtin function will match
and type inference will unliteral all tuples, producing iter objects
(that are always homogeneous in Numba). That is, literality of objects
will be lost. Using sdc_zip_tuples explicitly avoid this problem.

* Fixing issue with literal dict ctor with single element

* Fixing refcnt issue and adding tests

* Adding rewrite for dict(zip()) calls

Author: kozlov-alexey

sdc/__init__.py

@@ -70,6 +70,7 @@
 
 import sdc.rewrites.dataframe_constructor
 import sdc.rewrites.read_csv_consts
+import sdc.rewrites.dict_zip_tuples
 import sdc.rewrites.dataframe_getitem_attribute
 import sdc.datatypes.hpat_pandas_functions
 import sdc.datatypes.hpat_pandas_dataframe_functions

sdc/functions/tuple_utils.py

@@ -25,9 +25,14 @@
 # EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 # *****************************************************************************
 
+from textwrap import dedent
+
 from numba import types
-from numba.extending import (intrinsic, )
+from numba.extending import intrinsic
 from numba.core.typing.templates import (signature, )
+from numba.typed.dictobject import build_map
+
+from sdc.utilities.utils import sdc_overload
 
 
 @intrinsic
@@ -205,3 +210,84 @@ def codegen(context, builder, sig, args):
         return context.make_tuple(builder, ret_type, [first_tup, second_tup])
 
     return ret_type(data_type), codegen
+
+
+def sdc_tuple_zip(x, y):
+    pass
+
+
+@sdc_overload(sdc_tuple_zip)
+def sdc_tuple_zip_ovld(x, y):
+    """ This function combines tuple of pairs from two input tuples x and y, preserving
+        literality of elements in them. """
+
+    if not (isinstance(x, types.BaseAnonymousTuple) and isinstance(y, types.BaseAnonymousTuple)):
+        return None
+
+    res_size = min(len(x), len(y))
+    func_impl_name = 'sdc_tuple_zip_impl'
+    tup_elements = ', '.join([f"(x[{i}], y[{i}])" for i in range(res_size)])
+    func_text = dedent(f"""
+    def {func_impl_name}(x, y):
+        return ({tup_elements}{',' if res_size else ''})
+    """)
+    use_globals, use_locals = {}, {}
+    exec(func_text, use_globals, use_locals)
+    return use_locals[func_impl_name]
+
+    # FIXME_Numba#6533: alternatively we could have used sdc_tuple_map_elementwise
+    # to avoid another use of exec, but due to @intrinsic-s not supporting
+    # prefer_literal option below implementation looses literaly of args!
+    # from sdc.functions.tuple_utils import sdc_tuple_map_elementwise
+    # def sdc_tuple_zip_impl(x, y):
+    #     return sdc_tuple_map_elementwise(
+    #         lambda a, b: (a, b),
+    #         x,
+    #         y
+    #     )
+    #
+    # return sdc_tuple_zip_impl
+
+
+@intrinsic
+def literal_dict_ctor(typingctx, items):
+
+    tup_size = len(items)
+    key_order = {p[0].literal_value: i for i, p in enumerate(items)}
+    ret_type = types.LiteralStrKeyDict(dict(items), key_order)
+
+    def codegen(context, builder, sig, args):
+        items_val = args[0]
+
+        # extract elements from the input tuple and repack into a list of variables required by build_map
+        repacked_items = []
+        for i in range(tup_size):
+            elem = builder.extract_value(items_val, i)
+            elem_first = builder.extract_value(elem, 0)
+            elem_second = builder.extract_value(elem, 1)
+            repacked_items.append((elem_first, elem_second))
+        d = build_map(context, builder, ret_type, items, repacked_items)
+        return d
+
+    return ret_type(items), codegen
+
+
+@sdc_overload(dict)
+def dict_from_tuples_ovld(x):
+
+    accepted_tuple_types = (types.Tuple, types.UniTuple)
+    if not isinstance(x, types.BaseAnonymousTuple):
+        return None
+
+    def check_tuple_element(ty):
+        return (isinstance(ty, accepted_tuple_types)
+                and len(ty) == 2
+                and isinstance(ty[0], types.StringLiteral))
+
+    # below checks that elements are tuples with size 2 and first element is literal string
+    if not (len(x) != 0 and all(map(check_tuple_element, x))):
+        assert False, f"Creating LiteralStrKeyDict not supported from pairs of: {x}"
+
+    def dict_from_tuples_impl(x):
+        return literal_dict_ctor(x)
+    return dict_from_tuples_impl

sdc/rewrites/dict_zip_tuples.py

@@ -0,0 +1,78 @@
+# *****************************************************************************
+# Copyright (c) 2019-2021, Intel Corporation All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+#     Redistributions of source code must retain the above copyright notice,
+#     this list of conditions and the following disclaimer.
+#
+#     Redistributions in binary form must reproduce the above copyright notice,
+#     this list of conditions and the following disclaimer in the documentation
+#     and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+# OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+# OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# *****************************************************************************
+
+from numba.core.rewrites import register_rewrite, Rewrite
+from numba.core.ir_utils import guard, get_definition
+from numba import errors
+from numba.core import ir
+
+from sdc.rewrites.ir_utils import find_operations, import_function
+from sdc.functions.tuple_utils import sdc_tuple_zip
+
+
+@register_rewrite('before-inference')
+class RewriteDictZip(Rewrite):
+    """
+    Searches for calls like dict(zip(arg1, arg2)) and replaces zip with sdc_zip.
+    """
+
+    def match(self, func_ir, block, typemap, calltypes):
+
+        self._block = block
+        self._func_ir = func_ir
+        self._calls_to_rewrite = set()
+
+        # Find all assignments with a RHS expr being a call to dict, and where arg
+        # is a call to zip and store these ir.Expr for further modification
+        for inst in find_operations(block=block, op_name='call'):
+            expr = inst.value
+            try:
+                callee = func_ir.infer_constant(expr.func)
+            except errors.ConstantInferenceError:
+                continue
+
+            if (callee is dict and len(expr.args) == 1):
+                dict_arg_expr = guard(get_definition, func_ir, expr.args[0])
+                if (getattr(dict_arg_expr, 'op', None) == 'call'):
+                    called_func = guard(get_definition, func_ir, dict_arg_expr.func)
+                    if (called_func.value is zip and len(dict_arg_expr.args) == 2):
+                        self._calls_to_rewrite.add(dict_arg_expr)
+
+        return len(self._calls_to_rewrite) > 0
+
+    def apply(self):
+        """
+        Replace call to zip in matched expressions with call to sdc_zip.
+        """
+        new_block = self._block.copy()
+        new_block.clear()
+        zip_spec_stmt = import_function(sdc_tuple_zip, new_block, self._func_ir)
+        for inst in self._block.body:
+            if isinstance(inst, ir.Assign) and inst.value in self._calls_to_rewrite:
+                expr = inst.value
+                expr.func = zip_spec_stmt.target  # injects the new function
+            new_block.append(inst)
+        return new_block

sdc/tests/test_basic.py

@@ -30,7 +30,10 @@
 import pandas as pd
 import random
 import unittest
+from itertools import product
+
 from numba import types
+from numba.tests.support import MemoryLeakMixin
 
 import sdc
 from sdc.tests.test_base import TestCase
@@ -43,7 +46,8 @@
                                   dist_IR_contains,
                                   get_rank,
                                   get_start_end,
-                                  skip_numba_jit)
+                                  skip_numba_jit,
+                                  assert_nbtype_for_varname)
 
 
 def get_np_state_ptr():
@@ -540,5 +544,47 @@ def test_rhs(arr_len):
             np.testing.assert_allclose(A, B)
 
 
+class TestPython(MemoryLeakMixin, TestCase):
+
+    def test_literal_dict_ctor(self):
+        """ Verifies that dict builtin creates LiteralStrKeyDict from tuple
+            of pairs ('col_name_i', col_data_i), where col_name_i is literal string """
+
+        def test_impl_1():
+            items = (('A', np.arange(11)), )
+            res = dict(items)
+            return len(res)
+
+        def test_impl_2():
+            items = (('A', np.arange(5)), ('B', np.ones(11)), )
+            res = dict(items)
+            return len(res)
+
+        local_vars = locals()
+        list_tested_fns = [local_vars[k] for k in local_vars.keys() if k.startswith('test_impl')]
+
+        for test_impl in list_tested_fns:
+            with self.subTest(tested_func_name=test_impl.__name__):
+                sdc_func = self.jit(test_impl)
+                self.assertEqual(sdc_func(), test_impl())
+                assert_nbtype_for_varname(self, sdc_func, 'res', types.LiteralStrKeyDict)
+
+    def test_dict_zip_rewrite(self):
+        """ Verifies that a compination of dict(zip()) creates LiteralStrKeyDict when
+            zip is applied to tuples of literal column names and columns data """
+
+        dict_keys = ('A', 'B')
+        dict_values = (np.ones(5), np.array([1, 2, 3]))
+
+        def test_impl():
+            res = dict(zip(dict_keys, dict_values))
+            return len(res)
+
+        sdc_func = self.jit(test_impl)
+        expected = len(dict(zip(dict_keys, dict_values)))
+        self.assertEqual(sdc_func(), expected)
+        assert_nbtype_for_varname(self, sdc_func, 'res', types.LiteralStrKeyDict)
+
+
 if __name__ == "__main__":
     unittest.main()

sdc/tests/test_utils.py

@@ -272,3 +272,10 @@ def _make_func_from_text(func_text, func_name='test_impl', global_vars={}):
     exec(func_text, global_vars, loc_vars)
     test_impl = loc_vars[func_name]
     return test_impl
+
+
+def assert_nbtype_for_varname(self, disp, var, expected_type, fn_sig=None):
+    fn_sig = fn_sig or disp.nopython_signatures[0]
+    cres = disp.get_compile_result(fn_sig)
+    fn_typemap = cres.type_annotation.typemap
+    self.assertIsInstance(fn_typemap[var], expected_type)