freebsd-dev/contrib/llvm/lib/Analysis/CGSCCPassManager.cpp
2017-04-16 16:25:46 +00:00

515 lines
21 KiB
C++

//===- CGSCCPassManager.cpp - Managing & running CGSCC passes -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/CGSCCPassManager.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/InstIterator.h"
using namespace llvm;
// Explicit template instantiations and specialization defininitions for core
// template typedefs.
namespace llvm {
// Explicit instantiations for the core proxy templates.
template class AllAnalysesOn<LazyCallGraph::SCC>;
template class AnalysisManager<LazyCallGraph::SCC, LazyCallGraph &>;
template class PassManager<LazyCallGraph::SCC, CGSCCAnalysisManager,
LazyCallGraph &, CGSCCUpdateResult &>;
template class InnerAnalysisManagerProxy<CGSCCAnalysisManager, Module>;
template class OuterAnalysisManagerProxy<ModuleAnalysisManager,
LazyCallGraph::SCC, LazyCallGraph &>;
template class OuterAnalysisManagerProxy<CGSCCAnalysisManager, Function>;
/// Explicitly specialize the pass manager run method to handle call graph
/// updates.
template <>
PreservedAnalyses
PassManager<LazyCallGraph::SCC, CGSCCAnalysisManager, LazyCallGraph &,
CGSCCUpdateResult &>::run(LazyCallGraph::SCC &InitialC,
CGSCCAnalysisManager &AM,
LazyCallGraph &G, CGSCCUpdateResult &UR) {
PreservedAnalyses PA = PreservedAnalyses::all();
if (DebugLogging)
dbgs() << "Starting CGSCC pass manager run.\n";
// The SCC may be refined while we are running passes over it, so set up
// a pointer that we can update.
LazyCallGraph::SCC *C = &InitialC;
for (auto &Pass : Passes) {
if (DebugLogging)
dbgs() << "Running pass: " << Pass->name() << " on " << *C << "\n";
PreservedAnalyses PassPA = Pass->run(*C, AM, G, UR);
// Update the SCC if necessary.
C = UR.UpdatedC ? UR.UpdatedC : C;
// Check that we didn't miss any update scenario.
assert(!UR.InvalidatedSCCs.count(C) && "Processing an invalid SCC!");
assert(C->begin() != C->end() && "Cannot have an empty SCC!");
// Update the analysis manager as each pass runs and potentially
// invalidates analyses.
AM.invalidate(*C, PassPA);
// Finally, we intersect the final preserved analyses to compute the
// aggregate preserved set for this pass manager.
PA.intersect(std::move(PassPA));
// FIXME: Historically, the pass managers all called the LLVM context's
// yield function here. We don't have a generic way to acquire the
// context and it isn't yet clear what the right pattern is for yielding
// in the new pass manager so it is currently omitted.
// ...getContext().yield();
}
// Invaliadtion was handled after each pass in the above loop for the current
// SCC. Therefore, the remaining analysis results in the AnalysisManager are
// preserved. We mark this with a set so that we don't need to inspect each
// one individually.
PA.preserveSet<AllAnalysesOn<LazyCallGraph::SCC>>();
if (DebugLogging)
dbgs() << "Finished CGSCC pass manager run.\n";
return PA;
}
bool CGSCCAnalysisManagerModuleProxy::Result::invalidate(
Module &M, const PreservedAnalyses &PA,
ModuleAnalysisManager::Invalidator &Inv) {
// If literally everything is preserved, we're done.
if (PA.areAllPreserved())
return false; // This is still a valid proxy.
// If this proxy or the call graph is going to be invalidated, we also need
// to clear all the keys coming from that analysis.
//
// We also directly invalidate the FAM's module proxy if necessary, and if
// that proxy isn't preserved we can't preserve this proxy either. We rely on
// it to handle module -> function analysis invalidation in the face of
// structural changes and so if it's unavailable we conservatively clear the
// entire SCC layer as well rather than trying to do invalidation ourselves.
auto PAC = PA.getChecker<CGSCCAnalysisManagerModuleProxy>();
if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Module>>()) ||
Inv.invalidate<LazyCallGraphAnalysis>(M, PA) ||
Inv.invalidate<FunctionAnalysisManagerModuleProxy>(M, PA)) {
InnerAM->clear();
// And the proxy itself should be marked as invalid so that we can observe
// the new call graph. This isn't strictly necessary because we cheat
// above, but is still useful.
return true;
}
// Directly check if the relevant set is preserved so we can short circuit
// invalidating SCCs below.
bool AreSCCAnalysesPreserved =
PA.allAnalysesInSetPreserved<AllAnalysesOn<LazyCallGraph::SCC>>();
// Ok, we have a graph, so we can propagate the invalidation down into it.
G->buildRefSCCs();
for (auto &RC : G->postorder_ref_sccs())
for (auto &C : RC) {
Optional<PreservedAnalyses> InnerPA;
// Check to see whether the preserved set needs to be adjusted based on
// module-level analysis invalidation triggering deferred invalidation
// for this SCC.
if (auto *OuterProxy =
InnerAM->getCachedResult<ModuleAnalysisManagerCGSCCProxy>(C))
for (const auto &OuterInvalidationPair :
OuterProxy->getOuterInvalidations()) {
AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
if (Inv.invalidate(OuterAnalysisID, M, PA)) {
if (!InnerPA)
InnerPA = PA;
for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
InnerPA->abandon(InnerAnalysisID);
}
}
// Check if we needed a custom PA set. If so we'll need to run the inner
// invalidation.
if (InnerPA) {
InnerAM->invalidate(C, *InnerPA);
continue;
}
// Otherwise we only need to do invalidation if the original PA set didn't
// preserve all SCC analyses.
if (!AreSCCAnalysesPreserved)
InnerAM->invalidate(C, PA);
}
// Return false to indicate that this result is still a valid proxy.
return false;
}
template <>
CGSCCAnalysisManagerModuleProxy::Result
CGSCCAnalysisManagerModuleProxy::run(Module &M, ModuleAnalysisManager &AM) {
// Force the Function analysis manager to also be available so that it can
// be accessed in an SCC analysis and proxied onward to function passes.
// FIXME: It is pretty awkward to just drop the result here and assert that
// we can find it again later.
(void)AM.getResult<FunctionAnalysisManagerModuleProxy>(M);
return Result(*InnerAM, AM.getResult<LazyCallGraphAnalysis>(M));
}
AnalysisKey FunctionAnalysisManagerCGSCCProxy::Key;
FunctionAnalysisManagerCGSCCProxy::Result
FunctionAnalysisManagerCGSCCProxy::run(LazyCallGraph::SCC &C,
CGSCCAnalysisManager &AM,
LazyCallGraph &CG) {
// Collect the FunctionAnalysisManager from the Module layer and use that to
// build the proxy result.
//
// This allows us to rely on the FunctionAnalysisMangaerModuleProxy to
// invalidate the function analyses.
auto &MAM = AM.getResult<ModuleAnalysisManagerCGSCCProxy>(C, CG).getManager();
Module &M = *C.begin()->getFunction().getParent();
auto *FAMProxy = MAM.getCachedResult<FunctionAnalysisManagerModuleProxy>(M);
assert(FAMProxy && "The CGSCC pass manager requires that the FAM module "
"proxy is run on the module prior to entering the CGSCC "
"walk.");
// Note that we special-case invalidation handling of this proxy in the CGSCC
// analysis manager's Module proxy. This avoids the need to do anything
// special here to recompute all of this if ever the FAM's module proxy goes
// away.
return Result(FAMProxy->getManager());
}
bool FunctionAnalysisManagerCGSCCProxy::Result::invalidate(
LazyCallGraph::SCC &C, const PreservedAnalyses &PA,
CGSCCAnalysisManager::Invalidator &Inv) {
for (LazyCallGraph::Node &N : C)
FAM->invalidate(N.getFunction(), PA);
// This proxy doesn't need to handle invalidation itself. Instead, the
// module-level CGSCC proxy handles it above by ensuring that if the
// module-level FAM proxy becomes invalid the entire SCC layer, which
// includes this proxy, is cleared.
return false;
}
} // End llvm namespace
namespace {
/// Helper function to update both the \c CGSCCAnalysisManager \p AM and the \c
/// CGSCCPassManager's \c CGSCCUpdateResult \p UR based on a range of newly
/// added SCCs.
///
/// The range of new SCCs must be in postorder already. The SCC they were split
/// out of must be provided as \p C. The current node being mutated and
/// triggering updates must be passed as \p N.
///
/// This function returns the SCC containing \p N. This will be either \p C if
/// no new SCCs have been split out, or it will be the new SCC containing \p N.
template <typename SCCRangeT>
LazyCallGraph::SCC *
incorporateNewSCCRange(const SCCRangeT &NewSCCRange, LazyCallGraph &G,
LazyCallGraph::Node &N, LazyCallGraph::SCC *C,
CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR,
bool DebugLogging = false) {
typedef LazyCallGraph::SCC SCC;
if (NewSCCRange.begin() == NewSCCRange.end())
return C;
// Add the current SCC to the worklist as its shape has changed.
UR.CWorklist.insert(C);
if (DebugLogging)
dbgs() << "Enqueuing the existing SCC in the worklist:" << *C << "\n";
SCC *OldC = C;
(void)OldC;
// Update the current SCC. Note that if we have new SCCs, this must actually
// change the SCC.
assert(C != &*NewSCCRange.begin() &&
"Cannot insert new SCCs without changing current SCC!");
C = &*NewSCCRange.begin();
assert(G.lookupSCC(N) == C && "Failed to update current SCC!");
for (SCC &NewC :
reverse(make_range(std::next(NewSCCRange.begin()), NewSCCRange.end()))) {
assert(C != &NewC && "No need to re-visit the current SCC!");
assert(OldC != &NewC && "Already handled the original SCC!");
UR.CWorklist.insert(&NewC);
if (DebugLogging)
dbgs() << "Enqueuing a newly formed SCC:" << NewC << "\n";
}
return C;
}
}
LazyCallGraph::SCC &llvm::updateCGAndAnalysisManagerForFunctionPass(
LazyCallGraph &G, LazyCallGraph::SCC &InitialC, LazyCallGraph::Node &N,
CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR, bool DebugLogging) {
typedef LazyCallGraph::Node Node;
typedef LazyCallGraph::Edge Edge;
typedef LazyCallGraph::SCC SCC;
typedef LazyCallGraph::RefSCC RefSCC;
RefSCC &InitialRC = InitialC.getOuterRefSCC();
SCC *C = &InitialC;
RefSCC *RC = &InitialRC;
Function &F = N.getFunction();
// Walk the function body and build up the set of retained, promoted, and
// demoted edges.
SmallVector<Constant *, 16> Worklist;
SmallPtrSet<Constant *, 16> Visited;
SmallPtrSet<Node *, 16> RetainedEdges;
SmallSetVector<Node *, 4> PromotedRefTargets;
SmallSetVector<Node *, 4> DemotedCallTargets;
// First walk the function and handle all called functions. We do this first
// because if there is a single call edge, whether there are ref edges is
// irrelevant.
for (Instruction &I : instructions(F))
if (auto CS = CallSite(&I))
if (Function *Callee = CS.getCalledFunction())
if (Visited.insert(Callee).second && !Callee->isDeclaration()) {
Node &CalleeN = *G.lookup(*Callee);
Edge *E = N->lookup(CalleeN);
// FIXME: We should really handle adding new calls. While it will
// make downstream usage more complex, there is no fundamental
// limitation and it will allow passes within the CGSCC to be a bit
// more flexible in what transforms they can do. Until then, we
// verify that new calls haven't been introduced.
assert(E && "No function transformations should introduce *new* "
"call edges! Any new calls should be modeled as "
"promoted existing ref edges!");
RetainedEdges.insert(&CalleeN);
if (!E->isCall())
PromotedRefTargets.insert(&CalleeN);
}
// Now walk all references.
for (Instruction &I : instructions(F))
for (Value *Op : I.operand_values())
if (Constant *C = dyn_cast<Constant>(Op))
if (Visited.insert(C).second)
Worklist.push_back(C);
LazyCallGraph::visitReferences(Worklist, Visited, [&](Function &Referee) {
Node &RefereeN = *G.lookup(Referee);
Edge *E = N->lookup(RefereeN);
// FIXME: Similarly to new calls, we also currently preclude
// introducing new references. See above for details.
assert(E && "No function transformations should introduce *new* ref "
"edges! Any new ref edges would require IPO which "
"function passes aren't allowed to do!");
RetainedEdges.insert(&RefereeN);
if (E->isCall())
DemotedCallTargets.insert(&RefereeN);
});
// First remove all of the edges that are no longer present in this function.
// We have to build a list of dead targets first and then remove them as the
// data structures will all be invalidated by removing them.
SmallVector<PointerIntPair<Node *, 1, Edge::Kind>, 4> DeadTargets;
for (Edge &E : *N)
if (!RetainedEdges.count(&E.getNode()))
DeadTargets.push_back({&E.getNode(), E.getKind()});
for (auto DeadTarget : DeadTargets) {
Node &TargetN = *DeadTarget.getPointer();
bool IsCall = DeadTarget.getInt() == Edge::Call;
SCC &TargetC = *G.lookupSCC(TargetN);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
if (&TargetRC != RC) {
RC->removeOutgoingEdge(N, TargetN);
if (DebugLogging)
dbgs() << "Deleting outgoing edge from '" << N << "' to '" << TargetN
<< "'\n";
continue;
}
if (DebugLogging)
dbgs() << "Deleting internal " << (IsCall ? "call" : "ref")
<< " edge from '" << N << "' to '" << TargetN << "'\n";
if (IsCall) {
if (C != &TargetC) {
// For separate SCCs this is trivial.
RC->switchTrivialInternalEdgeToRef(N, TargetN);
} else {
// Otherwise we may end up re-structuring the call graph. First,
// invalidate any SCC analyses. We have to do this before we split
// functions into new SCCs and lose track of where their analyses are
// cached.
// FIXME: We should accept a more precise preserved set here. For
// example, it might be possible to preserve some function analyses
// even as the SCC structure is changed.
AM.invalidate(*C, PreservedAnalyses::none());
// Now update the call graph.
C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, TargetN), G,
N, C, AM, UR, DebugLogging);
}
}
auto NewRefSCCs = RC->removeInternalRefEdge(N, TargetN);
if (!NewRefSCCs.empty()) {
// Note that we don't bother to invalidate analyses as ref-edge
// connectivity is not really observable in any way and is intended
// exclusively to be used for ordering of transforms rather than for
// analysis conclusions.
// The RC worklist is in reverse postorder, so we first enqueue the
// current RefSCC as it will remain the parent of all split RefSCCs, then
// we enqueue the new ones in RPO except for the one which contains the
// source node as that is the "bottom" we will continue processing in the
// bottom-up walk.
UR.RCWorklist.insert(RC);
if (DebugLogging)
dbgs() << "Enqueuing the existing RefSCC in the update worklist: "
<< *RC << "\n";
// Update the RC to the "bottom".
assert(G.lookupSCC(N) == C && "Changed the SCC when splitting RefSCCs!");
RC = &C->getOuterRefSCC();
assert(G.lookupRefSCC(N) == RC && "Failed to update current RefSCC!");
assert(NewRefSCCs.front() == RC &&
"New current RefSCC not first in the returned list!");
for (RefSCC *NewRC : reverse(
make_range(std::next(NewRefSCCs.begin()), NewRefSCCs.end()))) {
assert(NewRC != RC && "Should not encounter the current RefSCC further "
"in the postorder list of new RefSCCs.");
UR.RCWorklist.insert(NewRC);
if (DebugLogging)
dbgs() << "Enqueuing a new RefSCC in the update worklist: " << *NewRC
<< "\n";
}
}
}
// Next demote all the call edges that are now ref edges. This helps make
// the SCCs small which should minimize the work below as we don't want to
// form cycles that this would break.
for (Node *RefTarget : DemotedCallTargets) {
SCC &TargetC = *G.lookupSCC(*RefTarget);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
// The easy case is when the target RefSCC is not this RefSCC. This is
// only supported when the target RefSCC is a child of this RefSCC.
if (&TargetRC != RC) {
assert(RC->isAncestorOf(TargetRC) &&
"Cannot potentially form RefSCC cycles here!");
RC->switchOutgoingEdgeToRef(N, *RefTarget);
if (DebugLogging)
dbgs() << "Switch outgoing call edge to a ref edge from '" << N
<< "' to '" << *RefTarget << "'\n";
continue;
}
// We are switching an internal call edge to a ref edge. This may split up
// some SCCs.
if (C != &TargetC) {
// For separate SCCs this is trivial.
RC->switchTrivialInternalEdgeToRef(N, *RefTarget);
continue;
}
// Otherwise we may end up re-structuring the call graph. First, invalidate
// any SCC analyses. We have to do this before we split functions into new
// SCCs and lose track of where their analyses are cached.
// FIXME: We should accept a more precise preserved set here. For example,
// it might be possible to preserve some function analyses even as the SCC
// structure is changed.
AM.invalidate(*C, PreservedAnalyses::none());
// Now update the call graph.
C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, *RefTarget), G, N,
C, AM, UR, DebugLogging);
}
// Now promote ref edges into call edges.
for (Node *CallTarget : PromotedRefTargets) {
SCC &TargetC = *G.lookupSCC(*CallTarget);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
// The easy case is when the target RefSCC is not this RefSCC. This is
// only supported when the target RefSCC is a child of this RefSCC.
if (&TargetRC != RC) {
assert(RC->isAncestorOf(TargetRC) &&
"Cannot potentially form RefSCC cycles here!");
RC->switchOutgoingEdgeToCall(N, *CallTarget);
if (DebugLogging)
dbgs() << "Switch outgoing ref edge to a call edge from '" << N
<< "' to '" << *CallTarget << "'\n";
continue;
}
if (DebugLogging)
dbgs() << "Switch an internal ref edge to a call edge from '" << N
<< "' to '" << *CallTarget << "'\n";
// Otherwise we are switching an internal ref edge to a call edge. This
// may merge away some SCCs, and we add those to the UpdateResult. We also
// need to make sure to update the worklist in the event SCCs have moved
// before the current one in the post-order sequence.
auto InitialSCCIndex = RC->find(*C) - RC->begin();
auto InvalidatedSCCs = RC->switchInternalEdgeToCall(N, *CallTarget);
if (!InvalidatedSCCs.empty()) {
C = &TargetC;
assert(G.lookupSCC(N) == C && "Failed to update current SCC!");
// Any analyses cached for this SCC are no longer precise as the shape
// has changed by introducing this cycle.
AM.invalidate(*C, PreservedAnalyses::none());
for (SCC *InvalidatedC : InvalidatedSCCs) {
assert(InvalidatedC != C && "Cannot invalidate the current SCC!");
UR.InvalidatedSCCs.insert(InvalidatedC);
// Also clear any cached analyses for the SCCs that are dead. This
// isn't really necessary for correctness but can release memory.
AM.clear(*InvalidatedC);
}
}
auto NewSCCIndex = RC->find(*C) - RC->begin();
if (InitialSCCIndex < NewSCCIndex) {
// Put our current SCC back onto the worklist as we'll visit other SCCs
// that are now definitively ordered prior to the current one in the
// post-order sequence, and may end up observing more precise context to
// optimize the current SCC.
UR.CWorklist.insert(C);
if (DebugLogging)
dbgs() << "Enqueuing the existing SCC in the worklist: " << *C << "\n";
// Enqueue in reverse order as we pop off the back of the worklist.
for (SCC &MovedC : reverse(make_range(RC->begin() + InitialSCCIndex,
RC->begin() + NewSCCIndex))) {
UR.CWorklist.insert(&MovedC);
if (DebugLogging)
dbgs() << "Enqueuing a newly earlier in post-order SCC: " << MovedC
<< "\n";
}
}
}
assert(!UR.InvalidatedSCCs.count(C) && "Invalidated the current SCC!");
assert(!UR.InvalidatedRefSCCs.count(RC) && "Invalidated the current RefSCC!");
assert(&C->getOuterRefSCC() == RC && "Current SCC not in current RefSCC!");
// Record the current RefSCC and SCC for higher layers of the CGSCC pass
// manager now that all the updates have been applied.
if (RC != &InitialRC)
UR.UpdatedRC = RC;
if (C != &InitialC)
UR.UpdatedC = C;
return *C;
}