forked from OSchip/llvm-project
362 lines
15 KiB
C++
362 lines
15 KiB
C++
//===- CGSCCPassManager.cpp - Managing & running CGSCC passes -------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/CGSCCPassManager.h"
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#include "llvm/IR/CallSite.h"
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using namespace llvm;
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namespace llvm {
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// Explicit instantiations for the core proxy templates.
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template class AnalysisManager<LazyCallGraph::SCC, LazyCallGraph &>;
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template class PassManager<LazyCallGraph::SCC, CGSCCAnalysisManager,
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LazyCallGraph &, CGSCCUpdateResult &>;
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template class InnerAnalysisManagerProxy<CGSCCAnalysisManager, Module>;
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template class OuterAnalysisManagerProxy<ModuleAnalysisManager,
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LazyCallGraph::SCC>;
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template class InnerAnalysisManagerProxy<FunctionAnalysisManager,
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LazyCallGraph::SCC>;
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template class OuterAnalysisManagerProxy<CGSCCAnalysisManager, Function>;
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/// Explicitly specialize the pass manager run method to handle call graph
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/// updates.
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template <>
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PreservedAnalyses
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PassManager<LazyCallGraph::SCC, CGSCCAnalysisManager, LazyCallGraph &,
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CGSCCUpdateResult &>::run(LazyCallGraph::SCC &InitialC,
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CGSCCAnalysisManager &AM,
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LazyCallGraph &G, CGSCCUpdateResult &UR) {
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PreservedAnalyses PA = PreservedAnalyses::all();
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if (DebugLogging)
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dbgs() << "Starting CGSCC pass manager run.\n";
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// The SCC may be refined while we are running passes over it, so set up
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// a pointer that we can update.
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LazyCallGraph::SCC *C = &InitialC;
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for (auto &Pass : Passes) {
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if (DebugLogging)
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dbgs() << "Running pass: " << Pass->name() << " on " << *C << "\n";
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PreservedAnalyses PassPA = Pass->run(*C, AM, G, UR);
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// Update the SCC if necessary.
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C = UR.UpdatedC ? UR.UpdatedC : C;
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// Check that we didn't miss any update scenario.
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assert(!UR.InvalidatedSCCs.count(C) && "Processing an invalid SCC!");
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assert(C->begin() != C->end() && "Cannot have an empty SCC!");
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// Update the analysis manager as each pass runs and potentially
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// invalidates analyses. We also update the preserved set of analyses
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// based on what analyses we have already handled the invalidation for
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// here and don't need to invalidate when finished.
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PassPA = AM.invalidate(*C, std::move(PassPA));
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// Finally, we intersect the final preserved analyses to compute the
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// aggregate preserved set for this pass manager.
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PA.intersect(std::move(PassPA));
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// FIXME: Historically, the pass managers all called the LLVM context's
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// yield function here. We don't have a generic way to acquire the
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// context and it isn't yet clear what the right pattern is for yielding
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// in the new pass manager so it is currently omitted.
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// ...getContext().yield();
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}
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if (DebugLogging)
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dbgs() << "Finished CGSCC pass manager run.\n";
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return PA;
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}
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} // End llvm namespace
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namespace {
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/// Helper function to update both the \c CGSCCAnalysisManager \p AM and the \c
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/// CGSCCPassManager's \c CGSCCUpdateResult \p UR based on a range of newly
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/// added SCCs.
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///
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/// The range of new SCCs must be in postorder already. The SCC they were split
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/// out of must be provided as \p C. The current node being mutated and
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/// triggering updates must be passed as \p N.
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///
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/// This function returns the SCC containing \p N. This will be either \p C if
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/// no new SCCs have been split out, or it will be the new SCC containing \p N.
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template <typename SCCRangeT>
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LazyCallGraph::SCC *
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incorporateNewSCCRange(const SCCRangeT &NewSCCRange, LazyCallGraph &G,
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LazyCallGraph::Node &N, LazyCallGraph::SCC *C,
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CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR,
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bool DebugLogging = false) {
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typedef LazyCallGraph::SCC SCC;
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if (NewSCCRange.begin() == NewSCCRange.end())
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return C;
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// Invalidate the analyses of the current SCC and add it to the worklist since
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// it has changed its shape.
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AM.invalidate(*C, PreservedAnalyses::none());
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UR.CWorklist.insert(C);
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if (DebugLogging)
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dbgs() << "Enqueuing the existing SCC in the worklist:" << *C << "\n";
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SCC *OldC = C;
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(void)OldC;
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// Update the current SCC. Note that if we have new SCCs, this must actually
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// change the SCC.
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assert(C != &*NewSCCRange.begin() &&
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"Cannot insert new SCCs without changing current SCC!");
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C = &*NewSCCRange.begin();
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assert(G.lookupSCC(N) == C && "Failed to update current SCC!");
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for (SCC &NewC :
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reverse(make_range(std::next(NewSCCRange.begin()), NewSCCRange.end()))) {
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assert(C != &NewC && "No need to re-visit the current SCC!");
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assert(OldC != &NewC && "Already handled the original SCC!");
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UR.CWorklist.insert(&NewC);
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if (DebugLogging)
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dbgs() << "Enqueuing a newly formed SCC:" << NewC << "\n";
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}
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return C;
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}
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}
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LazyCallGraph::SCC &llvm::updateCGAndAnalysisManagerForFunctionPass(
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LazyCallGraph &G, LazyCallGraph::SCC &InitialC, LazyCallGraph::Node &N,
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CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR, bool DebugLogging) {
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typedef LazyCallGraph::Node Node;
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typedef LazyCallGraph::Edge Edge;
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typedef LazyCallGraph::SCC SCC;
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typedef LazyCallGraph::RefSCC RefSCC;
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RefSCC &InitialRC = InitialC.getOuterRefSCC();
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SCC *C = &InitialC;
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RefSCC *RC = &InitialRC;
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Function &F = N.getFunction();
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// Walk the function body and build up the set of retained, promoted, and
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// demoted edges.
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SmallVector<Constant *, 16> Worklist;
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SmallPtrSet<Constant *, 16> Visited;
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SmallPtrSet<Function *, 16> RetainedEdges;
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SmallSetVector<Function *, 4> PromotedRefTargets;
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SmallSetVector<Function *, 4> DemotedCallTargets;
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// First walk the function and handle all called functions. We do this first
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// because if there is a single call edge, whether there are ref edges is
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// irrelevant.
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for (BasicBlock &BB : F)
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for (Instruction &I : BB)
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if (auto CS = CallSite(&I))
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if (Function *Callee = CS.getCalledFunction())
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if (Visited.insert(Callee).second && !Callee->isDeclaration()) {
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const Edge *E = N.lookup(*Callee);
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// FIXME: We should really handle adding new calls. While it will
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// make downstream usage more complex, there is no fundamental
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// limitation and it will allow passes within the CGSCC to be a bit
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// more flexible in what transforms they can do. Until then, we
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// verify that new calls haven't been introduced.
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assert(E && "No function transformations should introduce *new* "
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"call edges! Any new calls should be modeled as "
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"promoted existing ref edges!");
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RetainedEdges.insert(Callee);
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if (!E->isCall())
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PromotedRefTargets.insert(Callee);
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}
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// Now walk all references.
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for (BasicBlock &BB : F)
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for (Instruction &I : BB) {
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for (Value *Op : I.operand_values())
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if (Constant *C = dyn_cast<Constant>(Op))
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if (Visited.insert(C).second)
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Worklist.push_back(C);
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LazyCallGraph::visitReferences(Worklist, Visited, [&](Function &Referee) {
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// Skip declarations.
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if (Referee.isDeclaration())
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return;
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const Edge *E = N.lookup(Referee);
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// FIXME: Similarly to new calls, we also currently preclude
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// introducing new references. See above for details.
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assert(E && "No function transformations should introduce *new* ref "
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"edges! Any new ref edges would require IPO which "
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"function passes aren't allowed to do!");
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RetainedEdges.insert(&Referee);
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if (E->isCall())
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DemotedCallTargets.insert(&Referee);
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});
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}
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// First remove all of the edges that are no longer present in this function.
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// We have to build a list of dead targets first and then remove them as the
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// data structures will all be invalidated by removing them.
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SmallVector<PointerIntPair<Node *, 1, Edge::Kind>, 4> DeadTargets;
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for (Edge &E : N)
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if (!RetainedEdges.count(&E.getFunction()))
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DeadTargets.push_back({E.getNode(), E.getKind()});
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for (auto DeadTarget : DeadTargets) {
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Node &TargetN = *DeadTarget.getPointer();
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bool IsCall = DeadTarget.getInt() == Edge::Call;
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SCC &TargetC = *G.lookupSCC(TargetN);
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RefSCC &TargetRC = TargetC.getOuterRefSCC();
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if (&TargetRC != RC) {
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RC->removeOutgoingEdge(N, TargetN);
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if (DebugLogging)
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dbgs() << "Deleting outgoing edge from '" << N << "' to '" << TargetN
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<< "'\n";
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continue;
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}
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if (DebugLogging)
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dbgs() << "Deleting internal " << (IsCall ? "call" : "ref")
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<< " edge from '" << N << "' to '" << TargetN << "'\n";
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if (IsCall)
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C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, TargetN), G, N,
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C, AM, UR, DebugLogging);
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auto NewRefSCCs = RC->removeInternalRefEdge(N, TargetN);
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if (!NewRefSCCs.empty()) {
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// Note that we don't bother to invalidate analyses as ref-edge
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// connectivity is not really observable in any way and is intended
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// exclusively to be used for ordering of transforms rather than for
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// analysis conclusions.
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// The RC worklist is in reverse postorder, so we first enqueue the
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// current RefSCC as it will remain the parent of all split RefSCCs, then
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// we enqueue the new ones in RPO except for the one which contains the
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// source node as that is the "bottom" we will continue processing in the
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// bottom-up walk.
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UR.RCWorklist.insert(RC);
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if (DebugLogging)
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dbgs() << "Enqueuing the existing RefSCC in the update worklist: "
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<< *RC << "\n";
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// Update the RC to the "bottom".
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assert(G.lookupSCC(N) == C && "Changed the SCC when splitting RefSCCs!");
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RC = &C->getOuterRefSCC();
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assert(G.lookupRefSCC(N) == RC && "Failed to update current RefSCC!");
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for (RefSCC *NewRC : reverse(NewRefSCCs))
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if (NewRC != RC) {
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UR.RCWorklist.insert(NewRC);
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if (DebugLogging)
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dbgs() << "Enqueuing a new RefSCC in the update worklist: "
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<< *NewRC << "\n";
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}
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}
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}
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// Next demote all the call edges that are now ref edges. This helps make
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// the SCCs small which should minimize the work below as we don't want to
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// form cycles that this would break.
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for (Function *RefTarget : DemotedCallTargets) {
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Node &TargetN = *G.lookup(*RefTarget);
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SCC &TargetC = *G.lookupSCC(TargetN);
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RefSCC &TargetRC = TargetC.getOuterRefSCC();
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// The easy case is when the target RefSCC is not this RefSCC. This is
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// only supported when the target RefSCC is a child of this RefSCC.
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if (&TargetRC != RC) {
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assert(RC->isAncestorOf(TargetRC) &&
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"Cannot potentially form RefSCC cycles here!");
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RC->switchOutgoingEdgeToRef(N, TargetN);
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if (DebugLogging)
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dbgs() << "Switch outgoing call edge to a ref edge from '" << N
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<< "' to '" << TargetN << "'\n";
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continue;
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}
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// Otherwise we are switching an internal call edge to a ref edge. This
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// may split up some SCCs.
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C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, TargetN), G, N, C,
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AM, UR, DebugLogging);
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}
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// Now promote ref edges into call edges.
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for (Function *CallTarget : PromotedRefTargets) {
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Node &TargetN = *G.lookup(*CallTarget);
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SCC &TargetC = *G.lookupSCC(TargetN);
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RefSCC &TargetRC = TargetC.getOuterRefSCC();
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// The easy case is when the target RefSCC is not this RefSCC. This is
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// only supported when the target RefSCC is a child of this RefSCC.
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if (&TargetRC != RC) {
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assert(RC->isAncestorOf(TargetRC) &&
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"Cannot potentially form RefSCC cycles here!");
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RC->switchOutgoingEdgeToCall(N, TargetN);
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if (DebugLogging)
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dbgs() << "Switch outgoing ref edge to a call edge from '" << N
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<< "' to '" << TargetN << "'\n";
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continue;
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}
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if (DebugLogging)
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dbgs() << "Switch an internal ref edge to a call edge from '" << N
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<< "' to '" << TargetN << "'\n";
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// Otherwise we are switching an internal ref edge to a call edge. This
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// may merge away some SCCs, and we add those to the UpdateResult. We also
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// need to make sure to update the worklist in the event SCCs have moved
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// before the current one in the post-order sequence.
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auto InitialSCCIndex = RC->find(*C) - RC->begin();
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auto InvalidatedSCCs = RC->switchInternalEdgeToCall(N, TargetN);
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if (!InvalidatedSCCs.empty()) {
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C = &TargetC;
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assert(G.lookupSCC(N) == C && "Failed to update current SCC!");
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// Any analyses cached for this SCC are no longer precise as the shape
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// has changed by introducing this cycle.
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AM.invalidate(*C, PreservedAnalyses::none());
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for (SCC *InvalidatedC : InvalidatedSCCs) {
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assert(InvalidatedC != C && "Cannot invalidate the current SCC!");
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UR.InvalidatedSCCs.insert(InvalidatedC);
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// Also clear any cached analyses for the SCCs that are dead. This
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// isn't really necessary for correctness but can release memory.
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AM.clear(*InvalidatedC);
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}
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}
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auto NewSCCIndex = RC->find(*C) - RC->begin();
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if (InitialSCCIndex < NewSCCIndex) {
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// Put our current SCC back onto the worklist as we'll visit other SCCs
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// that are now definitively ordered prior to the current one in the
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// post-order sequence, and may end up observing more precise context to
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// optimize the current SCC.
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UR.CWorklist.insert(C);
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if (DebugLogging)
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dbgs() << "Enqueuing the existing SCC in the worklist: " << *C << "\n";
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// Enqueue in reverse order as we pop off the back of the worklist.
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for (SCC &MovedC : reverse(make_range(RC->begin() + InitialSCCIndex,
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RC->begin() + NewSCCIndex))) {
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UR.CWorklist.insert(&MovedC);
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if (DebugLogging)
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dbgs() << "Enqueuing a newly earlier in post-order SCC: " << MovedC
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<< "\n";
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}
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}
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}
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assert(!UR.InvalidatedSCCs.count(C) && "Invalidated the current SCC!");
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assert(!UR.InvalidatedRefSCCs.count(RC) && "Invalidated the current RefSCC!");
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assert(&C->getOuterRefSCC() == RC && "Current SCC not in current RefSCC!");
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// Record the current RefSCC and SCC for higher layers of the CGSCC pass
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// manager now that all the updates have been applied.
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if (RC != &InitialRC)
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UR.UpdatedRC = RC;
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if (C != &InitialC)
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UR.UpdatedC = C;
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return *C;
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}
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