mirror of https://github.com/m-labs/artiq
52 lines
1.7 KiB
Python
52 lines
1.7 KiB
Python
"""
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:class:`LocalDemoter` is a constant propagation transform:
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it replaces reads of any local variable with only one write
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in a function without closures with the value that was written.
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:class:`LocalAccessValidator` must be run before this transform
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to ensure that the transformation it performs is sound.
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"""
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from collections import defaultdict
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from .. import ir
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class LocalDemoter:
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def process(self, functions):
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for func in functions:
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self.process_function(func)
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def process_function(self, func):
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env_safe = {}
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env_gets = defaultdict(lambda: set())
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env_sets = defaultdict(lambda: set())
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for insn in func.instructions():
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if isinstance(insn, (ir.GetLocal, ir.SetLocal)):
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if "$" in insn.var_name:
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continue
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env = insn.environment()
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if env not in env_safe:
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for use in env.uses:
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if not isinstance(use, (ir.GetLocal, ir.SetLocal)):
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env_safe[env] = False
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break
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else:
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env_safe[env] = True
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if not env_safe[env]:
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continue
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if isinstance(insn, ir.SetLocal):
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env_sets[(env, insn.var_name)].add(insn)
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else:
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env_gets[(env, insn.var_name)].add(insn)
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for (env, var_name) in env_sets:
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if len(env_sets[(env, var_name)]) == 1:
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set_insn = next(iter(env_sets[(env, var_name)]))
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for get_insn in env_gets[(env, var_name)]:
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get_insn.replace_all_uses_with(set_insn.value())
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get_insn.erase()
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