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diff --git a/contrib/llvm-project/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp b/contrib/llvm-project/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp
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+//===- BreakCriticalEdges.cpp - Critical Edge Elimination Pass ------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// BreakCriticalEdges pass - Break all of the critical edges in the CFG by
+// inserting a dummy basic block. This pass may be "required" by passes that
+// cannot deal with critical edges. For this usage, the structure type is
+// forward declared. This pass obviously invalidates the CFG, but can update
+// dominator trees.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/BreakCriticalEdges.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/BlockFrequencyInfo.h"
+#include "llvm/Analysis/BranchProbabilityInfo.h"
+#include "llvm/Analysis/CFG.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/MemorySSAUpdater.h"
+#include "llvm/Analysis/PostDominators.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Type.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Transforms/Utils.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/ValueMapper.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "break-crit-edges"
+
+STATISTIC(NumBroken, "Number of blocks inserted");
+
+namespace {
+ struct BreakCriticalEdges : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ BreakCriticalEdges() : FunctionPass(ID) {
+ initializeBreakCriticalEdgesPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnFunction(Function &F) override {
+ auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
+ auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
+
+ auto *PDTWP = getAnalysisIfAvailable<PostDominatorTreeWrapperPass>();
+ auto *PDT = PDTWP ? &PDTWP->getPostDomTree() : nullptr;
+
+ auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
+ auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
+ unsigned N =
+ SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions(DT, LI, nullptr, PDT));
+ NumBroken += N;
+ return N > 0;
+ }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addPreserved<DominatorTreeWrapperPass>();
+ AU.addPreserved<LoopInfoWrapperPass>();
+
+ // No loop canonicalization guarantees are broken by this pass.
+ AU.addPreservedID(LoopSimplifyID);
+ }
+ };
+}
+
+char BreakCriticalEdges::ID = 0;
+INITIALIZE_PASS(BreakCriticalEdges, "break-crit-edges",
+ "Break critical edges in CFG", false, false)
+
+// Publicly exposed interface to pass...
+char &llvm::BreakCriticalEdgesID = BreakCriticalEdges::ID;
+FunctionPass *llvm::createBreakCriticalEdgesPass() {
+ return new BreakCriticalEdges();
+}
+
+PreservedAnalyses BreakCriticalEdgesPass::run(Function &F,
+ FunctionAnalysisManager &AM) {
+ auto *DT = AM.getCachedResult<DominatorTreeAnalysis>(F);
+ auto *LI = AM.getCachedResult<LoopAnalysis>(F);
+ unsigned N = SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions(DT, LI));
+ NumBroken += N;
+ if (N == 0)
+ return PreservedAnalyses::all();
+ PreservedAnalyses PA;
+ PA.preserve<DominatorTreeAnalysis>();
+ PA.preserve<LoopAnalysis>();
+ return PA;
+}
+
+//===----------------------------------------------------------------------===//
+// Implementation of the external critical edge manipulation functions
+//===----------------------------------------------------------------------===//
+
+/// When a loop exit edge is split, LCSSA form may require new PHIs in the new
+/// exit block. This function inserts the new PHIs, as needed. Preds is a list
+/// of preds inside the loop, SplitBB is the new loop exit block, and DestBB is
+/// the old loop exit, now the successor of SplitBB.
+static void createPHIsForSplitLoopExit(ArrayRef<BasicBlock *> Preds,
+ BasicBlock *SplitBB,
+ BasicBlock *DestBB) {
+ // SplitBB shouldn't have anything non-trivial in it yet.
+ assert((SplitBB->getFirstNonPHI() == SplitBB->getTerminator() ||
+ SplitBB->isLandingPad()) && "SplitBB has non-PHI nodes!");
+
+ // For each PHI in the destination block.
+ for (PHINode &PN : DestBB->phis()) {
+ unsigned Idx = PN.getBasicBlockIndex(SplitBB);
+ Value *V = PN.getIncomingValue(Idx);
+
+ // If the input is a PHI which already satisfies LCSSA, don't create
+ // a new one.
+ if (const PHINode *VP = dyn_cast<PHINode>(V))
+ if (VP->getParent() == SplitBB)
+ continue;
+
+ // Otherwise a new PHI is needed. Create one and populate it.
+ PHINode *NewPN = PHINode::Create(
+ PN.getType(), Preds.size(), "split",
+ SplitBB->isLandingPad() ? &SplitBB->front() : SplitBB->getTerminator());
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i)
+ NewPN->addIncoming(V, Preds[i]);
+
+ // Update the original PHI.
+ PN.setIncomingValue(Idx, NewPN);
+ }
+}
+
+BasicBlock *llvm::SplitCriticalEdge(Instruction *TI, unsigned SuccNum,
+ const CriticalEdgeSplittingOptions &Options,
+ const Twine &BBName) {
+ if (!isCriticalEdge(TI, SuccNum, Options.MergeIdenticalEdges))
+ return nullptr;
+
+ assert(!isa<IndirectBrInst>(TI) &&
+ "Cannot split critical edge from IndirectBrInst");
+
+ BasicBlock *TIBB = TI->getParent();
+ BasicBlock *DestBB = TI->getSuccessor(SuccNum);
+
+ // Splitting the critical edge to a pad block is non-trivial. Don't do
+ // it in this generic function.
+ if (DestBB->isEHPad()) return nullptr;
+
+ if (Options.IgnoreUnreachableDests &&
+ isa<UnreachableInst>(DestBB->getFirstNonPHIOrDbgOrLifetime()))
+ return nullptr;
+
+ auto *LI = Options.LI;
+ SmallVector<BasicBlock *, 4> LoopPreds;
+ // Check if extra modifications will be required to preserve loop-simplify
+ // form after splitting. If it would require splitting blocks with IndirectBr
+ // or CallBr terminators, bail out if preserving loop-simplify form is
+ // requested.
+ if (LI) {
+ if (Loop *TIL = LI->getLoopFor(TIBB)) {
+
+ // The only way that we can break LoopSimplify form by splitting a
+ // critical edge is if after the split there exists some edge from TIL to
+ // DestBB *and* the only edge into DestBB from outside of TIL is that of
+ // NewBB. If the first isn't true, then LoopSimplify still holds, NewBB
+ // is the new exit block and it has no non-loop predecessors. If the
+ // second isn't true, then DestBB was not in LoopSimplify form prior to
+ // the split as it had a non-loop predecessor. In both of these cases,
+ // the predecessor must be directly in TIL, not in a subloop, or again
+ // LoopSimplify doesn't hold.
+ for (BasicBlock *P : predecessors(DestBB)) {
+ if (P == TIBB)
+ continue; // The new block is known.
+ if (LI->getLoopFor(P) != TIL) {
+ // No need to re-simplify, it wasn't to start with.
+ LoopPreds.clear();
+ break;
+ }
+ LoopPreds.push_back(P);
+ }
+ // Loop-simplify form can be preserved, if we can split all in-loop
+ // predecessors.
+ if (any_of(LoopPreds, [](BasicBlock *Pred) {
+ const Instruction *T = Pred->getTerminator();
+ if (const auto *CBR = dyn_cast<CallBrInst>(T))
+ return CBR->getDefaultDest() != Pred;
+ return isa<IndirectBrInst>(T);
+ })) {
+ if (Options.PreserveLoopSimplify)
+ return nullptr;
+ LoopPreds.clear();
+ }
+ }
+ }
+
+ // Create a new basic block, linking it into the CFG.
+ BasicBlock *NewBB = nullptr;
+ if (BBName.str() != "")
+ NewBB = BasicBlock::Create(TI->getContext(), BBName);
+ else
+ NewBB = BasicBlock::Create(TI->getContext(), TIBB->getName() + "." +
+ DestBB->getName() +
+ "_crit_edge");
+ // Create our unconditional branch.
+ BranchInst *NewBI = BranchInst::Create(DestBB, NewBB);
+ NewBI->setDebugLoc(TI->getDebugLoc());
+
+ // Insert the block into the function... right after the block TI lives in.
+ Function &F = *TIBB->getParent();
+ Function::iterator FBBI = TIBB->getIterator();
+ F.getBasicBlockList().insert(++FBBI, NewBB);
+
+ // Branch to the new block, breaking the edge.
+ TI->setSuccessor(SuccNum, NewBB);
+
+ // If there are any PHI nodes in DestBB, we need to update them so that they
+ // merge incoming values from NewBB instead of from TIBB.
+ {
+ unsigned BBIdx = 0;
+ for (BasicBlock::iterator I = DestBB->begin(); isa<PHINode>(I); ++I) {
+ // We no longer enter through TIBB, now we come in through NewBB.
+ // Revector exactly one entry in the PHI node that used to come from
+ // TIBB to come from NewBB.
+ PHINode *PN = cast<PHINode>(I);
+
+ // Reuse the previous value of BBIdx if it lines up. In cases where we
+ // have multiple phi nodes with *lots* of predecessors, this is a speed
+ // win because we don't have to scan the PHI looking for TIBB. This
+ // happens because the BB list of PHI nodes are usually in the same
+ // order.
+ if (PN->getIncomingBlock(BBIdx) != TIBB)
+ BBIdx = PN->getBasicBlockIndex(TIBB);
+ PN->setIncomingBlock(BBIdx, NewBB);
+ }
+ }
+
+ // If there are any other edges from TIBB to DestBB, update those to go
+ // through the split block, making those edges non-critical as well (and
+ // reducing the number of phi entries in the DestBB if relevant).
+ if (Options.MergeIdenticalEdges) {
+ for (unsigned i = SuccNum+1, e = TI->getNumSuccessors(); i != e; ++i) {
+ if (TI->getSuccessor(i) != DestBB) continue;
+
+ // Remove an entry for TIBB from DestBB phi nodes.
+ DestBB->removePredecessor(TIBB, Options.KeepOneInputPHIs);
+
+ // We found another edge to DestBB, go to NewBB instead.
+ TI->setSuccessor(i, NewBB);
+ }
+ }
+
+ // If we have nothing to update, just return.
+ auto *DT = Options.DT;
+ auto *PDT = Options.PDT;
+ auto *MSSAU = Options.MSSAU;
+ if (MSSAU)
+ MSSAU->wireOldPredecessorsToNewImmediatePredecessor(
+ DestBB, NewBB, {TIBB}, Options.MergeIdenticalEdges);
+
+ if (!DT && !PDT && !LI)
+ return NewBB;
+
+ if (DT || PDT) {
+ // Update the DominatorTree.
+ // ---> NewBB -----\
+ // / V
+ // TIBB -------\\------> DestBB
+ //
+ // First, inform the DT about the new path from TIBB to DestBB via NewBB,
+ // then delete the old edge from TIBB to DestBB. By doing this in that order
+ // DestBB stays reachable in the DT the whole time and its subtree doesn't
+ // get disconnected.
+ SmallVector<DominatorTree::UpdateType, 3> Updates;
+ Updates.push_back({DominatorTree::Insert, TIBB, NewBB});
+ Updates.push_back({DominatorTree::Insert, NewBB, DestBB});
+ if (!llvm::is_contained(successors(TIBB), DestBB))
+ Updates.push_back({DominatorTree::Delete, TIBB, DestBB});
+
+ if (DT)
+ DT->applyUpdates(Updates);
+ if (PDT)
+ PDT->applyUpdates(Updates);
+ }
+
+ // Update LoopInfo if it is around.
+ if (LI) {
+ if (Loop *TIL = LI->getLoopFor(TIBB)) {
+ // If one or the other blocks were not in a loop, the new block is not
+ // either, and thus LI doesn't need to be updated.
+ if (Loop *DestLoop = LI->getLoopFor(DestBB)) {
+ if (TIL == DestLoop) {
+ // Both in the same loop, the NewBB joins loop.
+ DestLoop->addBasicBlockToLoop(NewBB, *LI);
+ } else if (TIL->contains(DestLoop)) {
+ // Edge from an outer loop to an inner loop. Add to the outer loop.
+ TIL->addBasicBlockToLoop(NewBB, *LI);
+ } else if (DestLoop->contains(TIL)) {
+ // Edge from an inner loop to an outer loop. Add to the outer loop.
+ DestLoop->addBasicBlockToLoop(NewBB, *LI);
+ } else {
+ // Edge from two loops with no containment relation. Because these
+ // are natural loops, we know that the destination block must be the
+ // header of its loop (adding a branch into a loop elsewhere would
+ // create an irreducible loop).
+ assert(DestLoop->getHeader() == DestBB &&
+ "Should not create irreducible loops!");
+ if (Loop *P = DestLoop->getParentLoop())
+ P->addBasicBlockToLoop(NewBB, *LI);
+ }
+ }
+
+ // If TIBB is in a loop and DestBB is outside of that loop, we may need
+ // to update LoopSimplify form and LCSSA form.
+ if (!TIL->contains(DestBB)) {
+ assert(!TIL->contains(NewBB) &&
+ "Split point for loop exit is contained in loop!");
+
+ // Update LCSSA form in the newly created exit block.
+ if (Options.PreserveLCSSA) {
+ createPHIsForSplitLoopExit(TIBB, NewBB, DestBB);
+ }
+
+ if (!LoopPreds.empty()) {
+ assert(!DestBB->isEHPad() && "We don't split edges to EH pads!");
+ BasicBlock *NewExitBB = SplitBlockPredecessors(
+ DestBB, LoopPreds, "split", DT, LI, MSSAU, Options.PreserveLCSSA);
+ if (Options.PreserveLCSSA)
+ createPHIsForSplitLoopExit(LoopPreds, NewExitBB, DestBB);
+ }
+ }
+ }
+ }
+
+ return NewBB;
+}
+
+// Return the unique indirectbr predecessor of a block. This may return null
+// even if such a predecessor exists, if it's not useful for splitting.
+// If a predecessor is found, OtherPreds will contain all other (non-indirectbr)
+// predecessors of BB.
+static BasicBlock *
+findIBRPredecessor(BasicBlock *BB, SmallVectorImpl<BasicBlock *> &OtherPreds) {
+ // If the block doesn't have any PHIs, we don't care about it, since there's
+ // no point in splitting it.
+ PHINode *PN = dyn_cast<PHINode>(BB->begin());
+ if (!PN)
+ return nullptr;
+
+ // Verify we have exactly one IBR predecessor.
+ // Conservatively bail out if one of the other predecessors is not a "regular"
+ // terminator (that is, not a switch or a br).
+ BasicBlock *IBB = nullptr;
+ for (unsigned Pred = 0, E = PN->getNumIncomingValues(); Pred != E; ++Pred) {
+ BasicBlock *PredBB = PN->getIncomingBlock(Pred);
+ Instruction *PredTerm = PredBB->getTerminator();
+ switch (PredTerm->getOpcode()) {
+ case Instruction::IndirectBr:
+ if (IBB)
+ return nullptr;
+ IBB = PredBB;
+ break;
+ case Instruction::Br:
+ case Instruction::Switch:
+ OtherPreds.push_back(PredBB);
+ continue;
+ default:
+ return nullptr;
+ }
+ }
+
+ return IBB;
+}
+
+bool llvm::SplitIndirectBrCriticalEdges(Function &F,
+ BranchProbabilityInfo *BPI,
+ BlockFrequencyInfo *BFI) {
+ // Check whether the function has any indirectbrs, and collect which blocks
+ // they may jump to. Since most functions don't have indirect branches,
+ // this lowers the common case's overhead to O(Blocks) instead of O(Edges).
+ SmallSetVector<BasicBlock *, 16> Targets;
+ for (auto &BB : F) {
+ auto *IBI = dyn_cast<IndirectBrInst>(BB.getTerminator());
+ if (!IBI)
+ continue;
+
+ for (unsigned Succ = 0, E = IBI->getNumSuccessors(); Succ != E; ++Succ)
+ Targets.insert(IBI->getSuccessor(Succ));
+ }
+
+ if (Targets.empty())
+ return false;
+
+ bool ShouldUpdateAnalysis = BPI && BFI;
+ bool Changed = false;
+ for (BasicBlock *Target : Targets) {
+ SmallVector<BasicBlock *, 16> OtherPreds;
+ BasicBlock *IBRPred = findIBRPredecessor(Target, OtherPreds);
+ // If we did not found an indirectbr, or the indirectbr is the only
+ // incoming edge, this isn't the kind of edge we're looking for.
+ if (!IBRPred || OtherPreds.empty())
+ continue;
+
+ // Don't even think about ehpads/landingpads.
+ Instruction *FirstNonPHI = Target->getFirstNonPHI();
+ if (FirstNonPHI->isEHPad() || Target->isLandingPad())
+ continue;
+
+ // Remember edge probabilities if needed.
+ SmallVector<BranchProbability, 4> EdgeProbabilities;
+ if (ShouldUpdateAnalysis) {
+ EdgeProbabilities.reserve(Target->getTerminator()->getNumSuccessors());
+ for (unsigned I = 0, E = Target->getTerminator()->getNumSuccessors();
+ I < E; ++I)
+ EdgeProbabilities.emplace_back(BPI->getEdgeProbability(Target, I));
+ BPI->eraseBlock(Target);
+ }
+
+ BasicBlock *BodyBlock = Target->splitBasicBlock(FirstNonPHI, ".split");
+ if (ShouldUpdateAnalysis) {
+ // Copy the BFI/BPI from Target to BodyBlock.
+ BPI->setEdgeProbability(BodyBlock, EdgeProbabilities);
+ BFI->setBlockFreq(BodyBlock, BFI->getBlockFreq(Target).getFrequency());
+ }
+ // It's possible Target was its own successor through an indirectbr.
+ // In this case, the indirectbr now comes from BodyBlock.
+ if (IBRPred == Target)
+ IBRPred = BodyBlock;
+
+ // At this point Target only has PHIs, and BodyBlock has the rest of the
+ // block's body. Create a copy of Target that will be used by the "direct"
+ // preds.
+ ValueToValueMapTy VMap;
+ BasicBlock *DirectSucc = CloneBasicBlock(Target, VMap, ".clone", &F);
+
+ BlockFrequency BlockFreqForDirectSucc;
+ for (BasicBlock *Pred : OtherPreds) {
+ // If the target is a loop to itself, then the terminator of the split
+ // block (BodyBlock) needs to be updated.
+ BasicBlock *Src = Pred != Target ? Pred : BodyBlock;
+ Src->getTerminator()->replaceUsesOfWith(Target, DirectSucc);
+ if (ShouldUpdateAnalysis)
+ BlockFreqForDirectSucc += BFI->getBlockFreq(Src) *
+ BPI->getEdgeProbability(Src, DirectSucc);
+ }
+ if (ShouldUpdateAnalysis) {
+ BFI->setBlockFreq(DirectSucc, BlockFreqForDirectSucc.getFrequency());
+ BlockFrequency NewBlockFreqForTarget =
+ BFI->getBlockFreq(Target) - BlockFreqForDirectSucc;
+ BFI->setBlockFreq(Target, NewBlockFreqForTarget.getFrequency());
+ }
+
+ // Ok, now fix up the PHIs. We know the two blocks only have PHIs, and that
+ // they are clones, so the number of PHIs are the same.
+ // (a) Remove the edge coming from IBRPred from the "Direct" PHI
+ // (b) Leave that as the only edge in the "Indirect" PHI.
+ // (c) Merge the two in the body block.
+ BasicBlock::iterator Indirect = Target->begin(),
+ End = Target->getFirstNonPHI()->getIterator();
+ BasicBlock::iterator Direct = DirectSucc->begin();
+ BasicBlock::iterator MergeInsert = BodyBlock->getFirstInsertionPt();
+
+ assert(&*End == Target->getTerminator() &&
+ "Block was expected to only contain PHIs");
+
+ while (Indirect != End) {
+ PHINode *DirPHI = cast<PHINode>(Direct);
+ PHINode *IndPHI = cast<PHINode>(Indirect);
+
+ // Now, clean up - the direct block shouldn't get the indirect value,
+ // and vice versa.
+ DirPHI->removeIncomingValue(IBRPred);
+ Direct++;
+
+ // Advance the pointer here, to avoid invalidation issues when the old
+ // PHI is erased.
+ Indirect++;
+
+ PHINode *NewIndPHI = PHINode::Create(IndPHI->getType(), 1, "ind", IndPHI);
+ NewIndPHI->addIncoming(IndPHI->getIncomingValueForBlock(IBRPred),
+ IBRPred);
+
+ // Create a PHI in the body block, to merge the direct and indirect
+ // predecessors.
+ PHINode *MergePHI =
+ PHINode::Create(IndPHI->getType(), 2, "merge", &*MergeInsert);
+ MergePHI->addIncoming(NewIndPHI, Target);
+ MergePHI->addIncoming(DirPHI, DirectSucc);
+
+ IndPHI->replaceAllUsesWith(MergePHI);
+ IndPHI->eraseFromParent();
+ }
+
+ Changed = true;
+ }
+
+ return Changed;
+}
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