Add separate get proof steps and execute proof step phase

src/pyk/proof/implies.py

@@ -12,7 +12,7 @@
 from ..prelude.kbool import BOOL, FALSE, TRUE
 from ..prelude.ml import is_bottom, is_top, mlAnd, mlEquals, mlEqualsFalse, mlEqualsTrue
 from ..utils import ensure_dir_path
-from .proof import FailureInfo, Proof, ProofStatus, ProofSummary, Prover, StepResult
+from .proof import FailureInfo, Proof, ProofStatus, ProofStep, ProofSummary, Prover, StepResult
 
 if TYPE_CHECKING:
     from collections.abc import Iterable, Mapping
@@ -26,6 +26,11 @@
 _LOGGER: Final = logging.getLogger(__name__)
 
 
+@dataclass
+class ImpliesProofStep(ProofStep):
+    proof: ImpliesProof
+
+
 class ImpliesProof(Proof):
     antecedent: KInner
     consequent: KInner
@@ -55,6 +60,9 @@ def __init__(
         self.simplified_consequent = simplified_consequent
         self.csubst = csubst
 
+    def get_steps(self) -> Iterable[ProofStep]:
+        return [ImpliesProofStep(self)]
+
     def commit(self, result: StepResult) -> None:
         proof_type = type(self).__name__
         if isinstance(result, ImpliesProofResult):
@@ -404,29 +412,31 @@ def __init__(self, proof: ImpliesProof, kcfg_explore: KCFGExplore):
         super().__init__(kcfg_explore)
         self.proof = proof
 
-    def step_proof(self) -> Iterable[StepResult]:
-        proof_type = type(self.proof).__name__
-        _LOGGER.info(f'Attempting {proof_type} {self.proof.id}')
+    def step_proof(self, step: ProofStep) -> Iterable[StepResult]:
+        assert isinstance(step, ImpliesProofStep)
+
+        proof_type = type(step.proof).__name__
+        _LOGGER.info(f'Attempting {proof_type} {step.proof.id}')
 
-        if self.proof.status is not ProofStatus.PENDING:
-            _LOGGER.info(f'{proof_type} finished {self.proof.id}: {self.proof.status}')
+        if step.proof.status is not ProofStatus.PENDING:
+            _LOGGER.info(f'{proof_type} finished {step.proof.id}: {step.proof.status}')
             return []
 
         # to prove the equality, we check the implication of the form `constraints #Implies LHS #Equals RHS`, i.e.
         # "LHS equals RHS under these constraints"
-        simplified_antecedent, _ = self.kcfg_explore.cterm_symbolic.kast_simplify(self.proof.antecedent)
-        simplified_consequent, _ = self.kcfg_explore.cterm_symbolic.kast_simplify(self.proof.consequent)
+        simplified_antecedent, _ = self.kcfg_explore.cterm_symbolic.kast_simplify(step.proof.antecedent)
+        simplified_consequent, _ = self.kcfg_explore.cterm_symbolic.kast_simplify(step.proof.consequent)
         _LOGGER.info(f'Simplified antecedent: {self.kcfg_explore.pretty_print(simplified_antecedent)}')
         _LOGGER.info(f'Simplified consequent: {self.kcfg_explore.pretty_print(simplified_consequent)}')
 
         csubst: CSubst | None = None
 
         if is_bottom(simplified_antecedent):
-            _LOGGER.warning(f'Antecedent of implication (proof constraints) simplifies to #Bottom {self.proof.id}')
+            _LOGGER.warning(f'Antecedent of implication (proof constraints) simplifies to #Bottom {step.proof.id}')
             csubst = CSubst(Subst({}), ())
 
         elif is_top(simplified_consequent):
-            _LOGGER.warning(f'Consequent of implication (proof equality) simplifies to #Top {self.proof.id}')
+            _LOGGER.warning(f'Consequent of implication (proof equality) simplifies to #Top {step.proof.id}')
             csubst = CSubst(Subst({}), ())
 
         else:
@@ -435,13 +445,13 @@ def step_proof(self) -> Iterable[StepResult]:
             _result = self.kcfg_explore.cterm_symbolic.implies(
                 antecedent=CTerm(config=dummy_config, constraints=[simplified_antecedent]),
                 consequent=CTerm(config=dummy_config, constraints=[simplified_consequent]),
-                bind_universally=self.proof.bind_universally,
+                bind_universally=step.proof.bind_universally,
             )
             result = _result.csubst
             if result is not None:
                 csubst = result
 
-        _LOGGER.info(f'{proof_type} finished {self.proof.id}: {self.proof.status}')
+        _LOGGER.info(f'{proof_type} finished {step.proof.id}: {step.proof.status}')
         return [
             ImpliesProofResult(
                 csubst=csubst, simplified_antecedent=simplified_antecedent, simplified_consequent=simplified_consequent

src/pyk/proof/proof.py

@@ -268,6 +268,9 @@ def lines(self) -> list[str]:
         subproofs_summaries = [subproof.summary for subproof in self.subproofs]
         return CompositeSummary([BaseSummary(self.id, self.status), *subproofs_summaries])
 
+    @abstractmethod
+    def get_steps(self) -> Iterable[ProofStep]: ...
+
 
 class ProofSummary(ABC):
     id: str
@@ -296,6 +299,9 @@ def lines(self) -> list[str]:
         return [line for lines in (summary.lines for summary in self.summaries) for line in lines]
 
 
+class ProofStep: ...
+
+
 class StepResult: ...
 
 
@@ -313,21 +319,23 @@ def __init__(self, kcfg_explore: KCFGExplore):
     def failure_info(self) -> FailureInfo: ...
 
     @abstractmethod
-    def step_proof(self) -> Iterable[StepResult]: ...
+    def step_proof(self, step: ProofStep) -> Iterable[StepResult]: ...
 
     def advance_proof(self, max_iterations: int | None = None, fail_fast: bool = False) -> None:
         iterations = 0
-        while self.proof.can_progress:
-            if fail_fast and self.proof.failed:
-                _LOGGER.warning(f'Terminating proof early because fail_fast is set: {self.proof.id}')
-                self.proof.failure_info = self.failure_info()
-                return
-            if max_iterations is not None and max_iterations <= iterations:
-                return
-            iterations += 1
-            results = self.step_proof()
-            for result in results:
-                self.proof.commit(result)
-            self.proof.write_proof_data()
+        while True:
+            steps = self.proof.get_steps()
+            for step in steps:
+                if fail_fast and self.proof.failed:
+                    _LOGGER.warning(f'Terminating proof early because fail_fast is set: {self.proof.id}')
+                    self.proof.failure_info = self.failure_info()
+                    return
+                if max_iterations is not None and max_iterations <= iterations:
+                    return
+                iterations += 1
+                results = self.step_proof(step)
+                for result in results:
+                    self.proof.commit(result)
+                self.proof.write_proof_data()
         if self.proof.failed:
             self.proof.failure_info = self.failure_info()

src/pyk/proof/reachability.py

@@ -19,7 +19,7 @@
 from ..prelude.ml import mlAnd, mlTop
 from ..utils import FrozenDict, ensure_dir_path, hash_str, shorten_hashes, single
 from .implies import ProofSummary, Prover, RefutationProof
-from .proof import CompositeSummary, FailureInfo, Proof, ProofStatus, StepResult
+from .proof import CompositeSummary, FailureInfo, Proof, ProofStatus, ProofStep, StepResult
 
 if TYPE_CHECKING:
     from collections.abc import Iterable, Mapping
@@ -59,6 +59,12 @@ class APRProofTerminalResult(APRProofResult): ...
 class APRProofBoundedResult(APRProofResult): ...
 
 
+@dataclass
+class APRProofStep(ProofStep):
+    proof: APRProof
+    node_id: int
+
+
 class APRProof(Proof, KCFGExploration):
     """APRProof and APRProver implement all-path reachability logic,
     as introduced by A. Stefanescu and others in their paper 'All-Path Reachability Logic':
@@ -132,6 +138,9 @@ def __init__(
                 assert type(subproof) is RefutationProof
                 self.node_refutations[node_id] = subproof
 
+    def get_steps(self) -> Iterable[APRProofStep]:
+        return [APRProofStep(self, node.id) for node in self.pending]
+
     def commit(self, result: StepResult) -> None:
         if isinstance(result, APRProofExtendResult):
             self.kcfg.extend(result.extend_result, self.kcfg.node(result.node_id), logs=self.logs)
@@ -720,37 +729,37 @@ def _check_subsume(self, node: KCFG.Node) -> CSubst | None:
             _LOGGER.info(f'Subsumed into target node {self.proof.id}: {shorten_hashes((node.id, self.proof.target))}')
         return csubst
 
-    def step_proof(self) -> Iterable[StepResult]:
-        if not self.proof.pending:
-            return []
-        curr_node = self.proof.pending[0]
+    def step_proof(self, step: ProofStep) -> Iterable[StepResult]:
+        assert isinstance(step, APRProofStep)
+
+        curr_node = step.proof.kcfg.node(step.node_id)
 
-        if self.proof.bmc_depth is not None and curr_node.id not in self._checked_for_bounded:
-            _LOGGER.info(f'Checking bmc depth for node {self.proof.id}: {curr_node.id}')
+        if step.proof.bmc_depth is not None and curr_node.id not in self._checked_for_bounded:
+            _LOGGER.info(f'Checking bmc depth for node {step.proof.id}: {curr_node.id}')
             self._checked_for_bounded.add(curr_node.id)
 
             prior_loops = []
-            for succ in reversed(self.proof.shortest_path_to(curr_node.id)):
+            for succ in reversed(step.proof.shortest_path_to(curr_node.id)):
                 if self.kcfg_explore.kcfg_semantics.same_loop(succ.source.cterm, curr_node.cterm):
-                    if succ.source.id in self.proof.prior_loops_cache:
-                        if self.proof.kcfg.zero_depth_between(succ.source.id, curr_node.id):
-                            prior_loops = self.proof.prior_loops_cache[succ.source.id]
+                    if succ.source.id in step.proof.prior_loops_cache:
+                        if step.proof.kcfg.zero_depth_between(succ.source.id, curr_node.id):
+                            prior_loops = step.proof.prior_loops_cache[succ.source.id]
                         else:
-                            prior_loops = self.proof.prior_loops_cache[succ.source.id] + [succ.source.id]
+                            prior_loops = step.proof.prior_loops_cache[succ.source.id] + [succ.source.id]
                         break
                     else:
-                        self.proof.prior_loops_cache[succ.source.id] = []
+                        step.proof.prior_loops_cache[succ.source.id] = []
 
-            self.proof.prior_loops_cache[curr_node.id] = prior_loops
+            step.proof.prior_loops_cache[curr_node.id] = prior_loops
 
-            _LOGGER.info(f'Prior loop heads for node {self.proof.id}: {(curr_node.id, prior_loops)}')
-            if len(prior_loops) > self.proof.bmc_depth:
-                _LOGGER.warning(f'Bounded node {self.proof.id}: {curr_node.id} at bmc depth {self.proof.bmc_depth}')
+            _LOGGER.info(f'Prior loop heads for node {step.proof.id}: {(curr_node.id, prior_loops)}')
+            if len(prior_loops) > step.proof.bmc_depth:
+                _LOGGER.warning(f'Bounded node {step.proof.id}: {curr_node.id} at bmc depth {step.proof.bmc_depth}')
                 return [APRProofBoundedResult(curr_node.id)]
 
         # Terminal checks for current node and target node
         is_terminal = self.kcfg_explore.kcfg_semantics.is_terminal(curr_node.cterm)
-        target_is_terminal = self.proof.is_terminal(self.proof.target)
+        target_is_terminal = step.proof.is_terminal(step.proof.target)
 
         terminal_result = [APRProofTerminalResult(node_id=curr_node.id)] if is_terminal else []
 
@@ -768,7 +777,7 @@ def step_proof(self) -> Iterable[StepResult]:
 
         module_name = self.circularities_module_name if self.nonzero_depth(curr_node) else self.dependencies_module_name
 
-        self.kcfg_explore.check_extendable(self.proof, curr_node)
+        self.kcfg_explore.check_extendable(step.proof, curr_node)
         extend_result = self.kcfg_explore.extend_cterm(
             curr_node.cterm,
             execute_depth=self.execute_depth,