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Introduce pruning in the constant synthesis loop #460

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Introduce pruning in the constant synthesis loop #460

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59 changes: 35 additions & 24 deletions lib/Infer/ExhaustiveSynthesis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -631,35 +631,14 @@ bool isBigQuerySat(SynthesisContext &SC,
return BigQueryIsSat;
}

void generateAndSortGuesses(InstContext &IC, Inst *LHS,
std::vector<Inst *> &Guesses) {
std::vector<Inst *> Inputs;
findCands(LHS, Inputs, /*WidthMustMatch=*/false, /*FilterVars=*/false, MaxLHSCands);
if (DebugLevel > 1)
llvm::errs() << "got " << Inputs.size() << " candidates from LHS\n";

void generateAndSortGuesses(InstContext &IC, Inst *LHS, const std::vector<Inst *> Inputs,
std::vector<Inst *> &Guesses, PruneFunc PruneCallback) {
int LHSCost = souper::cost(LHS, /*IgnoreDepsWithExternalUses=*/true);

int TooExpensive = 0;

dataflow::DataflowPruningManager DataflowPruning
(LHS, Inputs, DebugLevel);
// Cheaper tests go first
std::vector<PruneFunc> PruneFuncs = {CostPrune};
if (EnableDataflowPruning) {
PruneFuncs.push_back(DataflowPruning.getPruneFunc());
}
auto PruneCallback = MkPruneFunc(PruneFuncs);
// TODO(zhengyangl): Refactor the syntactic pruning into a
// prune function here, between Cost and Dataflow
// TODO(manasij7479) : If RHS is concrete, evaluate both sides
// TODO(regehr?) : Solver assisted pruning (should be the last component)

getGuesses(Guesses, Inputs, LHS->Width,
LHSCost, IC, nullptr, nullptr, TooExpensive, PruneCallback);
if (DebugLevel >= 1) {
DataflowPruning.printStats(llvm::outs());
}

// add nops guesses separately
for (auto I : Inputs) {
Expand Down Expand Up @@ -822,7 +801,29 @@ ExhaustiveSynthesis::synthesize(SMTLIBSolver *SMTSolver,

std::vector<Inst *> Guesses;
std::error_code EC;
generateAndSortGuesses(IC, LHS, Guesses);

std::vector<Inst *> Inputs;
findCands(LHS, Inputs, /*WidthMustMatch=*/false, /*FilterVars=*/false, MaxLHSCands);
if (DebugLevel > 1)
llvm::errs() << "got " << Inputs.size() << " candidates from LHS\n";

dataflow::DataflowPruningManager DataflowPruning
(LHS, Inputs, DebugLevel);
// Cheaper tests go first
std::vector<PruneFunc> PruneFuncs = {CostPrune};
if (EnableDataflowPruning) {
PruneFuncs.push_back(DataflowPruning.getPruneFunc());
}
auto PruneCallback = MkPruneFunc(PruneFuncs);
// TODO(zhengyangl): Refactor the syntactic pruning into a
// prune function here, between Cost and Dataflow
// TODO(manasij7479) : If RHS is concrete, evaluate both sides
// TODO(regehr?) : Solver assisted pruning (should be the last component)

generateAndSortGuesses(IC, LHS, Inputs, Guesses, PruneCallback);
if (DebugLevel >= 1) {
DataflowPruning.printStats(llvm::outs());
}

if (Guesses.empty()) {
return EC;
Expand Down Expand Up @@ -883,6 +884,16 @@ ExhaustiveSynthesis::synthesize(SMTLIBSolver *SMTSolver,
// TODO Utilize this for the mysterious constant synthesis 'loop'
}

// Avoids calling isConcreteCandidateSat
std::vector<Inst *> Empty;
if (!PruneCallback(ConcreteRHS, Empty)) {
if (DebugLevel > 3)
llvm::errs() << "Constant proved infeasible with inequivalence checks\n";
Tries++;
if (GuessHasConstant && Tries < MaxTries)
goto again; // TODO: Remove goto.
}

bool SecondSmallQueryIsSat;
EC = isConcreteCandidateSat(SC, ConstMap, ConcreteRHS, SecondSmallQueryIsSat);
if (EC) {
Expand Down