forked from OSchip/llvm-project
361 lines
13 KiB
C++
361 lines
13 KiB
C++
//===--- DAGDeltaAlgorithm.cpp - A DAG Minimization Algorithm --*- C++ -*--===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// The algorithm we use attempts to exploit the dependency information by
|
|
// minimizing top-down. We start by constructing an initial root set R, and
|
|
// then iteratively:
|
|
//
|
|
// 1. Minimize the set R using the test predicate:
|
|
// P'(S) = P(S union pred*(S))
|
|
//
|
|
// 2. Extend R to R' = R union pred(R).
|
|
//
|
|
// until a fixed point is reached.
|
|
//
|
|
// The idea is that we want to quickly prune entire portions of the graph, so we
|
|
// try to find high-level nodes that can be eliminated with all of their
|
|
// dependents.
|
|
//
|
|
// FIXME: The current algorithm doesn't actually provide a strong guarantee
|
|
// about the minimality of the result. The problem is that after adding nodes to
|
|
// the required set, we no longer consider them for elimination. For strictly
|
|
// well formed predicates, this doesn't happen, but it commonly occurs in
|
|
// practice when there are unmodelled dependencies. I believe we can resolve
|
|
// this by allowing the required set to be minimized as well, but need more test
|
|
// cases first.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/ADT/DAGDeltaAlgorithm.h"
|
|
#include "llvm/ADT/DeltaAlgorithm.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/Format.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include <algorithm>
|
|
#include <cassert>
|
|
#include <iterator>
|
|
#include <map>
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
|
|
class DAGDeltaAlgorithmImpl {
|
|
friend class DeltaActiveSetHelper;
|
|
|
|
public:
|
|
typedef DAGDeltaAlgorithm::change_ty change_ty;
|
|
typedef DAGDeltaAlgorithm::changeset_ty changeset_ty;
|
|
typedef DAGDeltaAlgorithm::changesetlist_ty changesetlist_ty;
|
|
typedef DAGDeltaAlgorithm::edge_ty edge_ty;
|
|
|
|
private:
|
|
typedef std::vector<change_ty>::iterator pred_iterator_ty;
|
|
typedef std::vector<change_ty>::iterator succ_iterator_ty;
|
|
typedef std::set<change_ty>::iterator pred_closure_iterator_ty;
|
|
typedef std::set<change_ty>::iterator succ_closure_iterator_ty;
|
|
|
|
DAGDeltaAlgorithm &DDA;
|
|
|
|
const changeset_ty &Changes;
|
|
const std::vector<edge_ty> &Dependencies;
|
|
|
|
std::vector<change_ty> Roots;
|
|
|
|
/// Cache of failed test results. Successful test results are never cached
|
|
/// since we always reduce following a success. We maintain an independent
|
|
/// cache from that used by the individual delta passes because we may get
|
|
/// hits across multiple individual delta invocations.
|
|
mutable std::set<changeset_ty> FailedTestsCache;
|
|
|
|
// FIXME: Gross.
|
|
std::map<change_ty, std::vector<change_ty> > Predecessors;
|
|
std::map<change_ty, std::vector<change_ty> > Successors;
|
|
|
|
std::map<change_ty, std::set<change_ty> > PredClosure;
|
|
std::map<change_ty, std::set<change_ty> > SuccClosure;
|
|
|
|
private:
|
|
pred_iterator_ty pred_begin(change_ty Node) {
|
|
assert(Predecessors.count(Node) && "Invalid node!");
|
|
return Predecessors[Node].begin();
|
|
}
|
|
pred_iterator_ty pred_end(change_ty Node) {
|
|
assert(Predecessors.count(Node) && "Invalid node!");
|
|
return Predecessors[Node].end();
|
|
}
|
|
|
|
pred_closure_iterator_ty pred_closure_begin(change_ty Node) {
|
|
assert(PredClosure.count(Node) && "Invalid node!");
|
|
return PredClosure[Node].begin();
|
|
}
|
|
pred_closure_iterator_ty pred_closure_end(change_ty Node) {
|
|
assert(PredClosure.count(Node) && "Invalid node!");
|
|
return PredClosure[Node].end();
|
|
}
|
|
|
|
succ_iterator_ty succ_begin(change_ty Node) {
|
|
assert(Successors.count(Node) && "Invalid node!");
|
|
return Successors[Node].begin();
|
|
}
|
|
succ_iterator_ty succ_end(change_ty Node) {
|
|
assert(Successors.count(Node) && "Invalid node!");
|
|
return Successors[Node].end();
|
|
}
|
|
|
|
succ_closure_iterator_ty succ_closure_begin(change_ty Node) {
|
|
assert(SuccClosure.count(Node) && "Invalid node!");
|
|
return SuccClosure[Node].begin();
|
|
}
|
|
succ_closure_iterator_ty succ_closure_end(change_ty Node) {
|
|
assert(SuccClosure.count(Node) && "Invalid node!");
|
|
return SuccClosure[Node].end();
|
|
}
|
|
|
|
void UpdatedSearchState(const changeset_ty &Changes,
|
|
const changesetlist_ty &Sets,
|
|
const changeset_ty &Required) {
|
|
DDA.UpdatedSearchState(Changes, Sets, Required);
|
|
}
|
|
|
|
/// ExecuteOneTest - Execute a single test predicate on the change set \p S.
|
|
bool ExecuteOneTest(const changeset_ty &S) {
|
|
// Check dependencies invariant.
|
|
DEBUG({
|
|
for (changeset_ty::const_iterator it = S.begin(),
|
|
ie = S.end(); it != ie; ++it)
|
|
for (succ_iterator_ty it2 = succ_begin(*it),
|
|
ie2 = succ_end(*it); it2 != ie2; ++it2)
|
|
assert(S.count(*it2) && "Attempt to run invalid changeset!");
|
|
});
|
|
|
|
return DDA.ExecuteOneTest(S);
|
|
}
|
|
|
|
public:
|
|
DAGDeltaAlgorithmImpl(DAGDeltaAlgorithm &_DDA,
|
|
const changeset_ty &_Changes,
|
|
const std::vector<edge_ty> &_Dependencies);
|
|
|
|
changeset_ty Run();
|
|
|
|
/// GetTestResult - Get the test result for the active set \p Changes with
|
|
/// \p Required changes from the cache, executing the test if necessary.
|
|
///
|
|
/// \param Changes - The set of active changes being minimized, which should
|
|
/// have their pred closure included in the test.
|
|
/// \param Required - The set of changes which have previously been
|
|
/// established to be required.
|
|
/// \return - The test result.
|
|
bool GetTestResult(const changeset_ty &Changes, const changeset_ty &Required);
|
|
};
|
|
|
|
/// Helper object for minimizing an active set of changes.
|
|
class DeltaActiveSetHelper : public DeltaAlgorithm {
|
|
DAGDeltaAlgorithmImpl &DDAI;
|
|
|
|
const changeset_ty &Required;
|
|
|
|
protected:
|
|
/// UpdatedSearchState - Callback used when the search state changes.
|
|
virtual void UpdatedSearchState(const changeset_ty &Changes,
|
|
const changesetlist_ty &Sets) LLVM_OVERRIDE {
|
|
DDAI.UpdatedSearchState(Changes, Sets, Required);
|
|
}
|
|
|
|
virtual bool ExecuteOneTest(const changeset_ty &S) LLVM_OVERRIDE {
|
|
return DDAI.GetTestResult(S, Required);
|
|
}
|
|
|
|
public:
|
|
DeltaActiveSetHelper(DAGDeltaAlgorithmImpl &_DDAI,
|
|
const changeset_ty &_Required)
|
|
: DDAI(_DDAI), Required(_Required) {}
|
|
};
|
|
|
|
}
|
|
|
|
DAGDeltaAlgorithmImpl::DAGDeltaAlgorithmImpl(DAGDeltaAlgorithm &_DDA,
|
|
const changeset_ty &_Changes,
|
|
const std::vector<edge_ty>
|
|
&_Dependencies)
|
|
: DDA(_DDA),
|
|
Changes(_Changes),
|
|
Dependencies(_Dependencies)
|
|
{
|
|
for (changeset_ty::const_iterator it = Changes.begin(),
|
|
ie = Changes.end(); it != ie; ++it) {
|
|
Predecessors.insert(std::make_pair(*it, std::vector<change_ty>()));
|
|
Successors.insert(std::make_pair(*it, std::vector<change_ty>()));
|
|
}
|
|
for (std::vector<edge_ty>::const_iterator it = Dependencies.begin(),
|
|
ie = Dependencies.end(); it != ie; ++it) {
|
|
Predecessors[it->second].push_back(it->first);
|
|
Successors[it->first].push_back(it->second);
|
|
}
|
|
|
|
// Compute the roots.
|
|
for (changeset_ty::const_iterator it = Changes.begin(),
|
|
ie = Changes.end(); it != ie; ++it)
|
|
if (succ_begin(*it) == succ_end(*it))
|
|
Roots.push_back(*it);
|
|
|
|
// Pre-compute the closure of the successor relation.
|
|
std::vector<change_ty> Worklist(Roots.begin(), Roots.end());
|
|
while (!Worklist.empty()) {
|
|
change_ty Change = Worklist.back();
|
|
Worklist.pop_back();
|
|
|
|
std::set<change_ty> &ChangeSuccs = SuccClosure[Change];
|
|
for (pred_iterator_ty it = pred_begin(Change),
|
|
ie = pred_end(Change); it != ie; ++it) {
|
|
SuccClosure[*it].insert(Change);
|
|
SuccClosure[*it].insert(ChangeSuccs.begin(), ChangeSuccs.end());
|
|
Worklist.push_back(*it);
|
|
}
|
|
}
|
|
|
|
// Invert to form the predecessor closure map.
|
|
for (changeset_ty::const_iterator it = Changes.begin(),
|
|
ie = Changes.end(); it != ie; ++it)
|
|
PredClosure.insert(std::make_pair(*it, std::set<change_ty>()));
|
|
for (changeset_ty::const_iterator it = Changes.begin(),
|
|
ie = Changes.end(); it != ie; ++it)
|
|
for (succ_closure_iterator_ty it2 = succ_closure_begin(*it),
|
|
ie2 = succ_closure_end(*it); it2 != ie2; ++it2)
|
|
PredClosure[*it2].insert(*it);
|
|
|
|
// Dump useful debug info.
|
|
DEBUG({
|
|
llvm::errs() << "-- DAGDeltaAlgorithmImpl --\n";
|
|
llvm::errs() << "Changes: [";
|
|
for (changeset_ty::const_iterator it = Changes.begin(),
|
|
ie = Changes.end(); it != ie; ++it) {
|
|
if (it != Changes.begin()) llvm::errs() << ", ";
|
|
llvm::errs() << *it;
|
|
|
|
if (succ_begin(*it) != succ_end(*it)) {
|
|
llvm::errs() << "(";
|
|
for (succ_iterator_ty it2 = succ_begin(*it),
|
|
ie2 = succ_end(*it); it2 != ie2; ++it2) {
|
|
if (it2 != succ_begin(*it)) llvm::errs() << ", ";
|
|
llvm::errs() << "->" << *it2;
|
|
}
|
|
llvm::errs() << ")";
|
|
}
|
|
}
|
|
llvm::errs() << "]\n";
|
|
|
|
llvm::errs() << "Roots: [";
|
|
for (std::vector<change_ty>::const_iterator it = Roots.begin(),
|
|
ie = Roots.end(); it != ie; ++it) {
|
|
if (it != Roots.begin()) llvm::errs() << ", ";
|
|
llvm::errs() << *it;
|
|
}
|
|
llvm::errs() << "]\n";
|
|
|
|
llvm::errs() << "Predecessor Closure:\n";
|
|
for (changeset_ty::const_iterator it = Changes.begin(),
|
|
ie = Changes.end(); it != ie; ++it) {
|
|
llvm::errs() << format(" %-4d: [", *it);
|
|
for (pred_closure_iterator_ty it2 = pred_closure_begin(*it),
|
|
ie2 = pred_closure_end(*it); it2 != ie2; ++it2) {
|
|
if (it2 != pred_closure_begin(*it)) llvm::errs() << ", ";
|
|
llvm::errs() << *it2;
|
|
}
|
|
llvm::errs() << "]\n";
|
|
}
|
|
|
|
llvm::errs() << "Successor Closure:\n";
|
|
for (changeset_ty::const_iterator it = Changes.begin(),
|
|
ie = Changes.end(); it != ie; ++it) {
|
|
llvm::errs() << format(" %-4d: [", *it);
|
|
for (succ_closure_iterator_ty it2 = succ_closure_begin(*it),
|
|
ie2 = succ_closure_end(*it); it2 != ie2; ++it2) {
|
|
if (it2 != succ_closure_begin(*it)) llvm::errs() << ", ";
|
|
llvm::errs() << *it2;
|
|
}
|
|
llvm::errs() << "]\n";
|
|
}
|
|
|
|
llvm::errs() << "\n\n";
|
|
});
|
|
}
|
|
|
|
bool DAGDeltaAlgorithmImpl::GetTestResult(const changeset_ty &Changes,
|
|
const changeset_ty &Required) {
|
|
changeset_ty Extended(Required);
|
|
Extended.insert(Changes.begin(), Changes.end());
|
|
for (changeset_ty::const_iterator it = Changes.begin(),
|
|
ie = Changes.end(); it != ie; ++it)
|
|
Extended.insert(pred_closure_begin(*it), pred_closure_end(*it));
|
|
|
|
if (FailedTestsCache.count(Extended))
|
|
return false;
|
|
|
|
bool Result = ExecuteOneTest(Extended);
|
|
if (!Result)
|
|
FailedTestsCache.insert(Extended);
|
|
|
|
return Result;
|
|
}
|
|
|
|
DAGDeltaAlgorithm::changeset_ty
|
|
DAGDeltaAlgorithmImpl::Run() {
|
|
// The current set of changes we are minimizing, starting at the roots.
|
|
changeset_ty CurrentSet(Roots.begin(), Roots.end());
|
|
|
|
// The set of required changes.
|
|
changeset_ty Required;
|
|
|
|
// Iterate until the active set of changes is empty. Convergence is guaranteed
|
|
// assuming input was a DAG.
|
|
//
|
|
// Invariant: CurrentSet intersect Required == {}
|
|
// Invariant: Required == (Required union succ*(Required))
|
|
while (!CurrentSet.empty()) {
|
|
DEBUG({
|
|
llvm::errs() << "DAG_DD - " << CurrentSet.size() << " active changes, "
|
|
<< Required.size() << " required changes\n";
|
|
});
|
|
|
|
// Minimize the current set of changes.
|
|
DeltaActiveSetHelper Helper(*this, Required);
|
|
changeset_ty CurrentMinSet = Helper.Run(CurrentSet);
|
|
|
|
// Update the set of required changes. Since
|
|
// CurrentMinSet subset CurrentSet
|
|
// and after the last iteration,
|
|
// succ(CurrentSet) subset Required
|
|
// then
|
|
// succ(CurrentMinSet) subset Required
|
|
// and our invariant on Required is maintained.
|
|
Required.insert(CurrentMinSet.begin(), CurrentMinSet.end());
|
|
|
|
// Replace the current set with the predecssors of the minimized set of
|
|
// active changes.
|
|
CurrentSet.clear();
|
|
for (changeset_ty::const_iterator it = CurrentMinSet.begin(),
|
|
ie = CurrentMinSet.end(); it != ie; ++it)
|
|
CurrentSet.insert(pred_begin(*it), pred_end(*it));
|
|
|
|
// FIXME: We could enforce CurrentSet intersect Required == {} here if we
|
|
// wanted to protect against cyclic graphs.
|
|
}
|
|
|
|
return Required;
|
|
}
|
|
|
|
void DAGDeltaAlgorithm::anchor() {
|
|
}
|
|
|
|
DAGDeltaAlgorithm::changeset_ty
|
|
DAGDeltaAlgorithm::Run(const changeset_ty &Changes,
|
|
const std::vector<edge_ty> &Dependencies) {
|
|
return DAGDeltaAlgorithmImpl(*this, Changes, Dependencies).Run();
|
|
}
|