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@@ -82,6 +82,33 @@ def optimize_graph_flow(entry_point):
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for block in get_all_blocks(entry_point):
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optimize_flow(block)
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+def merge_blocks(entry_point):
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+ """Merges blocks which have exactly one predecessor with said predecessor, if the
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+ predecessor has a jump flow instruction."""
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+ predecessor_map = cfg_dominators.get_all_predecessor_blocks(entry_point)
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+ queue = list(predecessor_map.keys())
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+ def __do_merge(source, target):
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+ for target_param, branch_arg in zip(target.parameters, source.flow.branch.arguments):
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+ source.append_definition(target_param)
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+ target_param.redefine(branch_arg)
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+
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+ for target_def in target.definitions:
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+ source.append_definition(target_def)
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+
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+ source.flow = target.flow
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+ for pred_set in predecessor_map.values():
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+ if target in pred_set:
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+ pred_set.remove(target)
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+ pred_set.add(source)
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+
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+ while len(queue) > 0:
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+ block = queue.pop()
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+ preds = predecessor_map[block]
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+ if len(preds) == 1:
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+ single_pred = next(iter(preds))
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+ if isinstance(single_pred.flow, cfg_ir.JumpFlow):
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+ __do_merge(single_pred, block)
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+
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def elide_local_checks(entry_point):
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"""Tries to elide redundant checks on local variables."""
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# The plan here is to replace all check-local-exists defs by literals if
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@@ -154,3 +181,4 @@ def optimize(entry_point):
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optimize_graph_flow(entry_point)
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eliminate_unused_definitions(entry_point)
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optimize_graph_flow(entry_point)
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+ merge_blocks(entry_point)
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jonathanvdc