def do_prune(take_truebr, blk): keep = branch.truebr if take_truebr else branch.falsebr # replace the branch with a direct jump jmp = ir.Jump(keep, loc=branch.loc) blk.body[-1] = jmp return 1 if keep == branch.truebr else 0
def op_JUMP_FORWARD(self, inst): jmp = ir.Jump(inst.get_jump_target(), loc=self.loc) self.current_block.append(jmp)
def test_jump(self): a = ir.Jump(1, self.loc1) b = ir.Jump(1, self.loc1) c = ir.Jump(1, self.loc2) d = ir.Jump(2, self.loc1) self.check(a, same=[b, c], different=[d])
def _create_gufunc_for_parfor_body( lowerer, parfor, typemap, typingctx, targetctx, flags, loop_ranges, locals, has_aliases, index_var_typ, races, ): """ Takes a parfor and creates a gufunc function for its body. There are two parts to this function: 1) Code to iterate across the iteration space as defined by the schedule. 2) The parfor body that does the work for a single point in the iteration space. Part 1 is created as Python text for simplicity with a sentinel assignment to mark the point in the IR where the parfor body should be added. This Python text is 'exec'ed into existence and its IR retrieved with run_frontend. The IR is scanned for the sentinel assignment where that basic block is split and the IR for the parfor body inserted. """ loc = parfor.init_block.loc # The parfor body and the main function body share ir.Var nodes. # We have to do some replacements of Var names in the parfor body # to make them legal parameter names. If we don't copy then the # Vars in the main function also would incorrectly change their name. loop_body = copy.copy(parfor.loop_body) remove_dels(loop_body) parfor_dim = len(parfor.loop_nests) loop_indices = [l.index_variable.name for l in parfor.loop_nests] # Get all the parfor params. parfor_params = parfor.params for start, stop, step in loop_ranges: if isinstance(start, ir.Var): parfor_params.add(start.name) if isinstance(stop, ir.Var): parfor_params.add(stop.name) # Get just the outputs of the parfor. parfor_outputs = numba.parfors.parfor.get_parfor_outputs( parfor, parfor_params) # Get all parfor reduction vars, and operators. typemap = lowerer.fndesc.typemap parfor_redvars, parfor_reddict = numba.parfors.parfor.get_parfor_reductions( lowerer.func_ir, parfor, parfor_params, lowerer.fndesc.calltypes) has_reduction = False if len(parfor_redvars) == 0 else True if has_reduction: _create_gufunc_for_reduction_parfor() # Compute just the parfor inputs as a set difference. parfor_inputs = sorted(list(set(parfor_params) - set(parfor_outputs))) for race in races: msg = ("Variable %s used in parallel loop may be written " "to simultaneously by multiple workers and may result " "in non-deterministic or unintended results." % race) warnings.warn(NumbaParallelSafetyWarning(msg, loc)) replace_var_with_array(races, loop_body, typemap, lowerer.fndesc.calltypes) if config.DEBUG_ARRAY_OPT >= 1: print("parfor_params = ", parfor_params, type(parfor_params)) print("parfor_outputs = ", parfor_outputs, type(parfor_outputs)) print("parfor_inputs = ", parfor_inputs, type(parfor_inputs)) # Reorder all the params so that inputs go first then outputs. parfor_params = parfor_inputs + parfor_outputs def addrspace_from(params, def_addr): addrspaces = [] for p in params: if isinstance(to_scalar_from_0d(typemap[p]), types.npytypes.Array): addrspaces.append(def_addr) else: addrspaces.append(None) return addrspaces addrspaces = addrspace_from(parfor_params, address_space.GLOBAL) if config.DEBUG_ARRAY_OPT >= 1: print("parfor_params = ", parfor_params, type(parfor_params)) print("loop_indices = ", loop_indices, type(loop_indices)) print("loop_body = ", loop_body, type(loop_body)) _print_body(loop_body) # Some Var are not legal parameter names so create a dict of # potentially illegal param name to guaranteed legal name. param_dict = legalize_names_with_typemap(parfor_params, typemap) if config.DEBUG_ARRAY_OPT >= 1: print("param_dict = ", sorted(param_dict.items()), type(param_dict)) # Some loop_indices are not legal parameter names so create a dict # of potentially illegal loop index to guaranteed legal name. ind_dict = legalize_names_with_typemap(loop_indices, typemap) # Compute a new list of legal loop index names. legal_loop_indices = [ind_dict[v] for v in loop_indices] if config.DEBUG_ARRAY_OPT >= 1: print("ind_dict = ", sorted(ind_dict.items()), type(ind_dict)) print( "legal_loop_indices = ", legal_loop_indices, type(legal_loop_indices), ) for pd in parfor_params: print("pd = ", pd) print("pd type = ", typemap[pd], type(typemap[pd])) # Get the types of each parameter. param_types = [to_scalar_from_0d(typemap[v]) for v in parfor_params] param_types_addrspaces = copy.copy(param_types) # Calculate types of args passed to gufunc. func_arg_types = [typemap[v] for v in (parfor_inputs + parfor_outputs)] assert len(param_types_addrspaces) == len(addrspaces) for i in range(len(param_types_addrspaces)): if addrspaces[i] is not None: # Convert Numba's npytype.Array to DPPYArray data type. DPPYArray # allows us to specify an address space for the data and other # pointer arguments for the array. param_types_addrspaces[i] = npytypes_array_to_dppy_array( param_types_addrspaces[i], addrspaces[i]) def print_arg_with_addrspaces(args): for a in args: print(a, type(a)) if isinstance(a, types.npytypes.Array): print("addrspace:", a.addrspace) if config.DEBUG_ARRAY_OPT >= 1: print_arg_with_addrspaces(param_types) print("func_arg_types = ", func_arg_types, type(func_arg_types)) # Replace illegal parameter names in the loop body with legal ones. replace_var_names(loop_body, param_dict) # remember the name before legalizing as the actual arguments parfor_args = parfor_params # Change parfor_params to be legal names. parfor_params = [param_dict[v] for v in parfor_params] parfor_params_orig = parfor_params parfor_params = [] ascontig = False for pindex in range(len(parfor_params_orig)): if (ascontig and pindex < len(parfor_inputs) and isinstance(param_types[pindex], types.npytypes.Array)): parfor_params.append(parfor_params_orig[pindex] + "param") else: parfor_params.append(parfor_params_orig[pindex]) # Change parfor body to replace illegal loop index vars with legal ones. replace_var_names(loop_body, ind_dict) loop_body_var_table = get_name_var_table(loop_body) sentinel_name = get_unused_var_name("__sentinel__", loop_body_var_table) if config.DEBUG_ARRAY_OPT >= 1: print("legal parfor_params = ", parfor_params, type(parfor_params)) # Determine the unique names of the scheduling and gufunc functions. gufunc_name = "__numba_parfor_gufunc_%s" % (parfor.id) if config.DEBUG_ARRAY_OPT: # print("sched_func_name ", type(sched_func_name), sched_func_name) print("gufunc_name ", type(gufunc_name), gufunc_name) gufunc_txt = "" # Create the gufunc function. gufunc_txt += "def " + gufunc_name gufunc_txt += "(" + (", ".join(parfor_params)) + "):\n" gufunc_txt += _schedule_loop(parfor_dim, legal_loop_indices, loop_ranges, param_dict) # Add the sentinel assignment so that we can find the loop body position # in the IR. gufunc_txt += " " gufunc_txt += sentinel_name + " = 0\n" # gufunc returns nothing gufunc_txt += " return None\n" if config.DEBUG_ARRAY_OPT: print("gufunc_txt = ", type(gufunc_txt), "\n", gufunc_txt) sys.stdout.flush() # Force gufunc outline into existence. globls = {"np": np, "numba": numba, "dppy": dppy} locls = {} exec(gufunc_txt, globls, locls) gufunc_func = locls[gufunc_name] if config.DEBUG_ARRAY_OPT: print("gufunc_func = ", type(gufunc_func), "\n", gufunc_func) # Get the IR for the gufunc outline. gufunc_ir = compiler.run_frontend(gufunc_func) if config.DEBUG_ARRAY_OPT: print("gufunc_ir dump ", type(gufunc_ir)) gufunc_ir.dump() print("loop_body dump ", type(loop_body)) _print_body(loop_body) # rename all variables in gufunc_ir afresh var_table = get_name_var_table(gufunc_ir.blocks) new_var_dict = {} reserved_names = ([sentinel_name] + list(param_dict.values()) + legal_loop_indices) for name, var in var_table.items(): if not (name in reserved_names): new_var_dict[name] = mk_unique_var(name) replace_var_names(gufunc_ir.blocks, new_var_dict) if config.DEBUG_ARRAY_OPT: print("gufunc_ir dump after renaming ") gufunc_ir.dump() prs_dict = {} pss_dict = {} pspmd_dict = {} gufunc_param_types = param_types if config.DEBUG_ARRAY_OPT: print( "gufunc_param_types = ", type(gufunc_param_types), "\n", gufunc_param_types, ) gufunc_stub_last_label = max(gufunc_ir.blocks.keys()) + 1 # Add gufunc stub last label to each parfor.loop_body label to prevent # label conflicts. loop_body = add_offset_to_labels(loop_body, gufunc_stub_last_label) # new label for splitting sentinel block new_label = max(loop_body.keys()) + 1 # If enabled, add a print statement after every assignment. if config.DEBUG_ARRAY_OPT_RUNTIME: _dbgprint_after_each_array_assignments(lowerer, loop_body, typemap) if config.DEBUG_ARRAY_OPT: print("parfor loop body") _print_body(loop_body) wrapped_blocks = wrap_loop_body(loop_body) # hoisted, not_hoisted = hoist(parfor_params, loop_body, # typemap, wrapped_blocks) setitems = set() find_setitems_body(setitems, loop_body, typemap) hoisted = [] not_hoisted = [] start_block = gufunc_ir.blocks[min(gufunc_ir.blocks.keys())] start_block.body = start_block.body[:-1] + hoisted + [start_block.body[-1]] unwrap_loop_body(loop_body) # store hoisted into diagnostics diagnostics = lowerer.metadata["parfor_diagnostics"] diagnostics.hoist_info[parfor.id] = { "hoisted": hoisted, "not_hoisted": not_hoisted, } lowerer.metadata["parfor_diagnostics"].extra_info[str(parfor.id)] = str( dpctl.get_current_queue().get_sycl_device().name) if config.DEBUG_ARRAY_OPT: print("After hoisting") _print_body(loop_body) # Search all the block in the gufunc outline for the sentinel assignment. for label, block in gufunc_ir.blocks.items(): for i, inst in enumerate(block.body): if (isinstance(inst, ir.Assign) and inst.target.name == sentinel_name): # We found the sentinel assignment. loc = inst.loc scope = block.scope # split block across __sentinel__ # A new block is allocated for the statements prior to the # sentinel but the new block maintains the current block label. prev_block = ir.Block(scope, loc) prev_block.body = block.body[:i] # The current block is used for statements after the sentinel. block.body = block.body[i + 1:] # But the current block gets a new label. body_first_label = min(loop_body.keys()) # The previous block jumps to the minimum labelled block of the # parfor body. prev_block.append(ir.Jump(body_first_label, loc)) # Add all the parfor loop body blocks to the gufunc function's # IR. for (l, b) in loop_body.items(): gufunc_ir.blocks[l] = b body_last_label = max(loop_body.keys()) gufunc_ir.blocks[new_label] = block gufunc_ir.blocks[label] = prev_block # Add a jump from the last parfor body block to the block # containing statements after the sentinel. gufunc_ir.blocks[body_last_label].append( ir.Jump(new_label, loc)) break else: continue break if config.DEBUG_ARRAY_OPT: print("gufunc_ir last dump before renaming") gufunc_ir.dump() gufunc_ir.blocks = rename_labels(gufunc_ir.blocks) remove_dels(gufunc_ir.blocks) if config.DEBUG_ARRAY_OPT: sys.stdout.flush() if config.DEBUG_ARRAY_OPT: print("gufunc_ir last dump") gufunc_ir.dump() print("flags", flags) print("typemap", typemap) old_alias = flags.noalias if not has_aliases: if config.DEBUG_ARRAY_OPT: print("No aliases found so adding noalias flag.") flags.noalias = True remove_dead(gufunc_ir.blocks, gufunc_ir.arg_names, gufunc_ir, typemap) if config.DEBUG_ARRAY_OPT: print("gufunc_ir after remove dead") gufunc_ir.dump() kernel_sig = signature(types.none, *gufunc_param_types) if config.DEBUG_ARRAY_OPT: sys.stdout.flush() if config.DEBUG_ARRAY_OPT: print("before DUFunc inlining".center(80, "-")) gufunc_ir.dump() # Inlining all DUFuncs dufunc_inliner( gufunc_ir, lowerer.fndesc.calltypes, typemap, lowerer.context.typing_context, lowerer.context, ) if config.DEBUG_ARRAY_OPT: print("after DUFunc inline".center(80, "-")) gufunc_ir.dump() kernel_func = numba_dppy.compiler.compile_kernel_parfor( dpctl.get_current_queue(), gufunc_ir, gufunc_param_types, param_types_addrspaces, debug=flags.debuginfo, ) flags.noalias = old_alias if config.DEBUG_ARRAY_OPT: print("kernel_sig = ", kernel_sig) return kernel_func, parfor_args, kernel_sig, func_arg_types, setitems
def _stencil_wrapper(self, result, sigret, return_type, typemap, calltypes, *args): # Overall approach: # 1) Construct a string containing a function definition for the stencil function # that will execute the stencil kernel. This function definition includes a # unique stencil function name, the parameters to the stencil kernel, loop # nests across the dimensions of the input array. Those loop nests use the # computed stencil kernel size so as not to try to compute elements where # elements outside the bounds of the input array would be needed. # 2) The but of the loop nest in this new function is a special sentinel # assignment. # 3) Get the IR of this new function. # 4) Split the block containing the sentinel assignment and remove the sentinel # assignment. Insert the stencil kernel IR into the stencil function IR # after label and variable renaming of the stencil kernel IR to prevent # conflicts with the stencil function IR. # 5) Compile the combined stencil function IR + stencil kernel IR into existence. # Copy the kernel so that our changes for this callsite # won't effect other callsites. (kernel_copy, copy_calltypes) = self.copy_ir_with_calltypes(self.kernel_ir, calltypes) # The stencil kernel body becomes the body of a loop, for which args aren't needed. ir_utils.remove_args(kernel_copy.blocks) first_arg = kernel_copy.arg_names[0] in_cps, out_cps = ir_utils.copy_propagate(kernel_copy.blocks, typemap) name_var_table = ir_utils.get_name_var_table(kernel_copy.blocks) ir_utils.apply_copy_propagate(kernel_copy.blocks, in_cps, name_var_table, typemap, copy_calltypes) if "out" in name_var_table: raise ValueError( "Cannot use the reserved word 'out' in stencil kernels.") sentinel_name = ir_utils.get_unused_var_name("__sentinel__", name_var_table) if config.DEBUG_ARRAY_OPT >= 1: print("name_var_table", name_var_table, sentinel_name) the_array = args[0] if config.DEBUG_ARRAY_OPT >= 1: print("_stencil_wrapper", return_type, return_type.dtype, type(return_type.dtype), args) ir_utils.dump_blocks(kernel_copy.blocks) # We generate a Numba function to execute this stencil and here # create the unique name of this function. stencil_func_name = "__numba_stencil_%s_%s" % (hex( id(the_array)).replace("-", "_"), self.id) # We will put a loop nest in the generated function for each # dimension in the input array. Here we create the name for # the index variable for each dimension. index0, index1, ... index_vars = [] for i in range(the_array.ndim): index_var_name = ir_utils.get_unused_var_name( "index" + str(i), name_var_table) index_vars += [index_var_name] # Create extra signature for out and neighborhood. out_name = ir_utils.get_unused_var_name("out", name_var_table) neighborhood_name = ir_utils.get_unused_var_name( "neighborhood", name_var_table) sig_extra = "" if result is not None: sig_extra += ", {}=None".format(out_name) if "neighborhood" in dict(self.kws): sig_extra += ", {}=None".format(neighborhood_name) # Get a list of the standard indexed array names. standard_indexed = self.options.get("standard_indexing", []) if first_arg in standard_indexed: raise ValueError("The first argument to a stencil kernel must " "use relative indexing, not standard indexing.") if len(set(standard_indexed) - set(kernel_copy.arg_names)) != 0: raise ValueError("Standard indexing requested for an array name " "not present in the stencil kernel definition.") # Add index variables to getitems in the IR to transition the accesses # in the kernel from relative to regular Python indexing. Returns the # computed size of the stencil kernel and a list of the relatively indexed # arrays. kernel_size, relatively_indexed = self.add_indices_to_kernel( kernel_copy, index_vars, the_array.ndim, self.neighborhood, standard_indexed, typemap, copy_calltypes) if self.neighborhood is None: self.neighborhood = kernel_size if config.DEBUG_ARRAY_OPT >= 1: print("After add_indices_to_kernel") ir_utils.dump_blocks(kernel_copy.blocks) # The return in the stencil kernel becomes a setitem for that # particular point in the iteration space. ret_blocks = self.replace_return_with_setitem(kernel_copy.blocks, index_vars, out_name) if config.DEBUG_ARRAY_OPT >= 1: print("After replace_return_with_setitem", ret_blocks) ir_utils.dump_blocks(kernel_copy.blocks) # Start to form the new function to execute the stencil kernel. func_text = "def {}({}{}):\n".format(stencil_func_name, ",".join(kernel_copy.arg_names), sig_extra) # Get loop ranges for each dimension, which could be either int # or variable. In the latter case we'll use the extra neighborhood # argument to the function. ranges = [] for i in range(the_array.ndim): if isinstance(kernel_size[i][0], int): lo = kernel_size[i][0] hi = kernel_size[i][1] else: lo = "{}[{}][0]".format(neighborhood_name, i) hi = "{}[{}][1]".format(neighborhood_name, i) ranges.append((lo, hi)) # If there are more than one relatively indexed arrays, add a call to # a function that will raise an error if any of the relatively indexed # arrays are of different size than the first input array. if len(relatively_indexed) > 1: func_text += " raise_if_incompatible_array_sizes(" + first_arg for other_array in relatively_indexed: if other_array != first_arg: func_text += "," + other_array func_text += ")\n" # Get the shape of the first input array. shape_name = ir_utils.get_unused_var_name("full_shape", name_var_table) func_text += " {} = {}.shape\n".format(shape_name, first_arg) # If we have to allocate the output array (the out argument was not used) # then us numpy.full if the user specified a cval stencil decorator option # or np.zeros if they didn't to allocate the array. if result is None: return_type_name = numpy_support.as_dtype( return_type.dtype).type.__name__ if "cval" in self.options: cval = self.options["cval"] if return_type.dtype != typing.typeof.typeof(cval): raise ValueError( "cval type does not match stencil return type.") out_init = "{} = np.full({}, {}, dtype=np.{})\n".format( out_name, shape_name, cval, return_type_name) else: out_init = "{} = np.zeros({}, dtype=np.{})\n".format( out_name, shape_name, return_type_name) func_text += " " + out_init else: # result is present, if cval is set then use it if "cval" in self.options: cval = self.options["cval"] cval_ty = typing.typeof.typeof(cval) if not self._typingctx.can_convert(cval_ty, return_type.dtype): msg = "cval type does not match stencil return type." raise ValueError(msg) out_init = "{}[:] = {}\n".format(out_name, cval) func_text += " " + out_init offset = 1 # Add the loop nests to the new function. for i in range(the_array.ndim): for j in range(offset): func_text += " " # ranges[i][0] is the minimum index used in the i'th dimension # but minimum's greater than 0 don't preclude any entry in the array. # So, take the minimum of 0 and the minimum index found in the kernel # and this will be a negative number (potentially -0). Then, we do # unary - on that to get the positive offset in this dimension whose # use is precluded. # ranges[i][1] is the maximum of 0 and the observed maximum index # in this dimension because negative maximums would not cause us to # preclude any entry in the array from being used. func_text += ("for {} in range(-min(0,{})," "{}[{}]-max(0,{})):\n").format( index_vars[i], ranges[i][0], shape_name, i, ranges[i][1]) offset += 1 for j in range(offset): func_text += " " # Put a sentinel in the code so we can locate it in the IR. We will # remove this sentinel assignment and replace it with the IR for the # stencil kernel body. func_text += "{} = 0\n".format(sentinel_name) func_text += " return {}\n".format(out_name) if config.DEBUG_ARRAY_OPT >= 1: print("new stencil func text") print(func_text) # Force the new stencil function into existence. exec(func_text) in globals(), locals() stencil_func = eval(stencil_func_name) if sigret is not None: pysig = utils.pysignature(stencil_func) sigret.pysig = pysig # Get the IR for the newly created stencil function. from numba.core import compiler stencil_ir = compiler.run_frontend(stencil_func) ir_utils.remove_dels(stencil_ir.blocks) # rename all variables in stencil_ir afresh var_table = ir_utils.get_name_var_table(stencil_ir.blocks) new_var_dict = {} reserved_names = ( [sentinel_name, out_name, neighborhood_name, shape_name] + kernel_copy.arg_names + index_vars) for name, var in var_table.items(): if not name in reserved_names: new_var_dict[name] = ir_utils.mk_unique_var(name) ir_utils.replace_var_names(stencil_ir.blocks, new_var_dict) stencil_stub_last_label = max(stencil_ir.blocks.keys()) + 1 # Shift labels in the kernel copy so they are guaranteed unique # and don't conflict with any labels in the stencil_ir. kernel_copy.blocks = ir_utils.add_offset_to_labels( kernel_copy.blocks, stencil_stub_last_label) new_label = max(kernel_copy.blocks.keys()) + 1 # Adjust ret_blocks to account for addition of the offset. ret_blocks = [x + stencil_stub_last_label for x in ret_blocks] if config.DEBUG_ARRAY_OPT >= 1: print("ret_blocks w/ offsets", ret_blocks, stencil_stub_last_label) print("before replace sentinel stencil_ir") ir_utils.dump_blocks(stencil_ir.blocks) print("before replace sentinel kernel_copy") ir_utils.dump_blocks(kernel_copy.blocks) # Search all the block in the stencil outline for the sentinel. for label, block in stencil_ir.blocks.items(): for i, inst in enumerate(block.body): if (isinstance(inst, ir.Assign) and inst.target.name == sentinel_name): # We found the sentinel assignment. loc = inst.loc scope = block.scope # split block across __sentinel__ # A new block is allocated for the statements prior to the # sentinel but the new block maintains the current block # label. prev_block = ir.Block(scope, loc) prev_block.body = block.body[:i] # The current block is used for statements after sentinel. block.body = block.body[i + 1:] # But the current block gets a new label. body_first_label = min(kernel_copy.blocks.keys()) # The previous block jumps to the minimum labelled block of # the parfor body. prev_block.append(ir.Jump(body_first_label, loc)) # Add all the parfor loop body blocks to the gufunc # function's IR. for (l, b) in kernel_copy.blocks.items(): stencil_ir.blocks[l] = b stencil_ir.blocks[new_label] = block stencil_ir.blocks[label] = prev_block # Add a jump from all the blocks that previously contained # a return in the stencil kernel to the block # containing statements after the sentinel. for ret_block in ret_blocks: stencil_ir.blocks[ret_block].append( ir.Jump(new_label, loc)) break else: continue break stencil_ir.blocks = ir_utils.rename_labels(stencil_ir.blocks) ir_utils.remove_dels(stencil_ir.blocks) assert (isinstance(the_array, types.Type)) array_types = args new_stencil_param_types = list(array_types) if config.DEBUG_ARRAY_OPT >= 1: print("new_stencil_param_types", new_stencil_param_types) ir_utils.dump_blocks(stencil_ir.blocks) # Compile the combined stencil function with the replaced loop # body in it. new_func = compiler.compile_ir(self._typingctx, self._targetctx, stencil_ir, new_stencil_param_types, None, compiler.DEFAULT_FLAGS, {}) return new_func
def _fix_multi_exit_blocks(func_ir, exit_nodes, *, split_condition=None): """Modify the FunctionIR to create a single common exit node given the original exit nodes. Parameters ---------- func_ir : The FunctionIR. Mutated inplace. exit_nodes : The original exit nodes. A sequence of block keys. split_condition : callable or None If not None, it is a callable with the signature `split_condition(statement)` that determines if the `statement` is the splitting point (e.g. `POP_BLOCK`) in an exit node. If it's None, the exit node is not split. """ # Convert the following: # # | | # +-------+ +-------+ # | exit0 | | exit1 | # +-------+ +-------+ # | | # +-------+ +-------+ # | after0| | after1| # +-------+ +-------+ # | | # # To roughly: # # | | # +-------+ +-------+ # | exit0 | | exit1 | # +-------+ +-------+ # | | # +-----+-----+ # | # +---------+ # | common | # +---------+ # | # +-------+ # | post | # +-------+ # | # +-----+-----+ # | | # +-------+ +-------+ # | after0| | after1| # +-------+ +-------+ blocks = func_ir.blocks # Getting the scope any_blk = min(func_ir.blocks.values()) scope = any_blk.scope # Getting the maximum block label max_label = max(func_ir.blocks) + 1 # Define the new common block for the new exit. common_block = ir.Block(any_blk.scope, loc=ir.unknown_loc) common_label = max_label max_label += 1 blocks[common_label] = common_block # Define the new block after the exit. post_block = ir.Block(any_blk.scope, loc=ir.unknown_loc) post_label = max_label max_label += 1 blocks[post_label] = post_block # Adjust each exit node remainings = [] for i, k in enumerate(exit_nodes): blk = blocks[k] # split the block if needed if split_condition is not None: for pt, stmt in enumerate(blk.body): if split_condition(stmt): break else: # no splitting pt = -1 before = blk.body[:pt] after = blk.body[pt:] remainings.append(after) # Add control-point variable to mark which exit block this is. blk.body = before loc = blk.loc blk.body.append( ir.Assign(value=ir.Const(i, loc=loc), target=scope.get_or_define("$cp", loc=loc), loc=loc)) # Replace terminator with a jump to the common block assert not blk.is_terminated blk.body.append(ir.Jump(common_label, loc=ir.unknown_loc)) if split_condition is not None: # Move the splitting statement to the common block common_block.body.append(remainings[0][0]) assert not common_block.is_terminated # Append jump from common block to post block common_block.body.append(ir.Jump(post_label, loc=loc)) # Make if-else tree to jump to target remain_blocks = [] for remain in remainings: remain_blocks.append(max_label) max_label += 1 switch_block = post_block loc = ir.unknown_loc for i, remain in enumerate(remainings): match_expr = scope.redefine("$cp_check", loc=loc) match_rhs = scope.redefine("$cp_rhs", loc=loc) # Do comparison to match control-point variable to the exit block switch_block.body.append( ir.Assign(value=ir.Const(i, loc=loc), target=match_rhs, loc=loc), ) # Add assignment for the comparison switch_block.body.append( ir.Assign(value=ir.Expr.binop( fn=operator.eq, lhs=scope.get("$cp"), rhs=match_rhs, loc=loc, ), target=match_expr, loc=loc), ) # Insert jump to the next case [jump_target] = remain[-1].get_targets() switch_block.body.append( ir.Branch(match_expr, jump_target, remain_blocks[i], loc=loc), ) switch_block = ir.Block(scope=scope, loc=loc) blocks[remain_blocks[i]] = switch_block # Add the final jump switch_block.body.append(ir.Jump(jump_target, loc=loc)) return func_ir, common_label
def _rewrite_return(func_ir, target_block_label): """Rewrite a return block inside a with statement. Arguments --------- func_ir: Function IR the CFG to transform target_block_label: int the block index/label of the block containing the POP_BLOCK statement This implements a CFG transformation to insert a block between two other blocks. The input situation is: ┌───────────────┐ │ top │ │ POP_BLOCK │ │ bottom │ └───────┬───────┘ │ ┌───────▼───────┐ │ │ │ RETURN │ │ │ └───────────────┘ If such a pattern is detected in IR, it means there is a `return` statement within a `with` context. The basic idea is to rewrite the CFG as follows: ┌───────────────┐ │ top │ │ POP_BLOCK │ │ │ └───────┬───────┘ │ ┌───────▼───────┐ │ │ │ bottom │ │ │ └───────┬───────┘ │ ┌───────▼───────┐ │ │ │ RETURN │ │ │ └───────────────┘ We split the block that contains the `POP_BLOCK` statement into two blocks. Everything from the beginning of the block up to and including the `POP_BLOCK` statement is considered the 'top' and everything below is considered 'bottom'. Finally the jump statements are re-wired to make sure the CFG remains valid. """ # the block itself from the index target_block = func_ir.blocks[target_block_label] # get the index of the block containing the return target_block_successor_label = target_block.terminator.get_targets()[0] # the return block target_block_successor = func_ir.blocks[target_block_successor_label] # create the new return block with an appropriate label max_label = ir_utils.find_max_label(func_ir.blocks) new_label = max_label + 1 # create the new return block new_block_loc = target_block_successor.loc new_block_scope = ir.Scope(None, loc=new_block_loc) new_block = ir.Block(new_block_scope, loc=new_block_loc) # Split the block containing the POP_BLOCK into top and bottom # Block must be of the form: # ----------------- # <some stmts> # POP_BLOCK # <some more stmts> # JUMP # ----------------- top_body, bottom_body = [], [] pop_blocks = [*target_block.find_insts(ir.PopBlock)] assert len(pop_blocks) == 1 assert len([*target_block.find_insts(ir.Jump)]) == 1 assert isinstance(target_block.body[-1], ir.Jump) pb_marker = pop_blocks[0] pb_is = target_block.body.index(pb_marker) top_body.extend(target_block.body[:pb_is]) top_body.append(ir.Jump(target_block_successor_label, target_block.loc)) bottom_body.extend(target_block.body[pb_is:-1]) bottom_body.append(ir.Jump(new_label, target_block.loc)) # get the contents of the return block return_body = func_ir.blocks[target_block_successor_label].body # finally, re-assign all blocks new_block.body.extend(return_body) target_block_successor.body.clear() target_block_successor.body.extend(bottom_body) target_block.body.clear() target_block.body.extend(top_body) # finally, append the new return block and rebuild the IR properties func_ir.blocks[new_label] = new_block func_ir._definitions = ir_utils.build_definitions(func_ir.blocks) return func_ir