From 0b57cec536236d46e3dba9bd041533462f33dbb7 Mon Sep 17 00:00:00 2001 From: Dimitry Andric Date: Fri, 20 Dec 2019 19:53:05 +0000 Subject: Move all sources from the llvm project into contrib/llvm-project. This uses the new layout of the upstream repository, which was recently migrated to GitHub, and converted into a "monorepo". That is, most of the earlier separate sub-projects with their own branches and tags were consolidated into one top-level directory, and are now branched and tagged together. Updating the vendor area to match this layout is next. --- contrib/llvm/lib/Transforms/Utils/Local.cpp | 2956 --------------------------- 1 file changed, 2956 deletions(-) delete mode 100644 contrib/llvm/lib/Transforms/Utils/Local.cpp (limited to 'contrib/llvm/lib/Transforms/Utils/Local.cpp') diff --git a/contrib/llvm/lib/Transforms/Utils/Local.cpp b/contrib/llvm/lib/Transforms/Utils/Local.cpp deleted file mode 100644 index 39b6b889f91c..000000000000 --- a/contrib/llvm/lib/Transforms/Utils/Local.cpp +++ /dev/null @@ -1,2956 +0,0 @@ -//===- Local.cpp - Functions to perform local transformations -------------===// -// -// 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 -// -//===----------------------------------------------------------------------===// -// -// This family of functions perform various local transformations to the -// program. -// -//===----------------------------------------------------------------------===// - -#include "llvm/Transforms/Utils/Local.h" -#include "llvm/ADT/APInt.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/DenseMapInfo.h" -#include "llvm/ADT/DenseSet.h" -#include "llvm/ADT/Hashing.h" -#include "llvm/ADT/None.h" -#include "llvm/ADT/Optional.h" -#include "llvm/ADT/STLExtras.h" -#include "llvm/ADT/SetVector.h" -#include "llvm/ADT/SmallPtrSet.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/ADT/TinyPtrVector.h" -#include "llvm/Analysis/ConstantFolding.h" -#include "llvm/Analysis/DomTreeUpdater.h" -#include "llvm/Analysis/EHPersonalities.h" -#include "llvm/Analysis/InstructionSimplify.h" -#include "llvm/Analysis/LazyValueInfo.h" -#include "llvm/Analysis/MemoryBuiltins.h" -#include "llvm/Analysis/MemorySSAUpdater.h" -#include "llvm/Analysis/TargetLibraryInfo.h" -#include "llvm/Analysis/ValueTracking.h" -#include "llvm/Analysis/VectorUtils.h" -#include "llvm/BinaryFormat/Dwarf.h" -#include "llvm/IR/Argument.h" -#include "llvm/IR/Attributes.h" -#include "llvm/IR/BasicBlock.h" -#include "llvm/IR/CFG.h" -#include "llvm/IR/CallSite.h" -#include "llvm/IR/Constant.h" -#include "llvm/IR/ConstantRange.h" -#include "llvm/IR/Constants.h" -#include "llvm/IR/DIBuilder.h" -#include "llvm/IR/DataLayout.h" -#include "llvm/IR/DebugInfoMetadata.h" -#include "llvm/IR/DebugLoc.h" -#include "llvm/IR/DerivedTypes.h" -#include "llvm/IR/Dominators.h" -#include "llvm/IR/Function.h" -#include "llvm/IR/GetElementPtrTypeIterator.h" -#include "llvm/IR/GlobalObject.h" -#include "llvm/IR/IRBuilder.h" -#include "llvm/IR/InstrTypes.h" -#include "llvm/IR/Instruction.h" -#include "llvm/IR/Instructions.h" -#include "llvm/IR/IntrinsicInst.h" -#include "llvm/IR/Intrinsics.h" -#include "llvm/IR/LLVMContext.h" -#include "llvm/IR/MDBuilder.h" -#include "llvm/IR/Metadata.h" -#include "llvm/IR/Module.h" -#include "llvm/IR/Operator.h" -#include "llvm/IR/PatternMatch.h" -#include "llvm/IR/Type.h" -#include "llvm/IR/Use.h" -#include "llvm/IR/User.h" -#include "llvm/IR/Value.h" -#include "llvm/IR/ValueHandle.h" -#include "llvm/Support/Casting.h" -#include "llvm/Support/Debug.h" -#include "llvm/Support/ErrorHandling.h" -#include "llvm/Support/KnownBits.h" -#include "llvm/Support/raw_ostream.h" -#include "llvm/Transforms/Utils/ValueMapper.h" -#include -#include -#include -#include -#include -#include -#include - -using namespace llvm; -using namespace llvm::PatternMatch; - -#define DEBUG_TYPE "local" - -STATISTIC(NumRemoved, "Number of unreachable basic blocks removed"); - -// Max recursion depth for collectBitParts used when detecting bswap and -// bitreverse idioms -static const unsigned BitPartRecursionMaxDepth = 64; - -//===----------------------------------------------------------------------===// -// Local constant propagation. -// - -/// ConstantFoldTerminator - If a terminator instruction is predicated on a -/// constant value, convert it into an unconditional branch to the constant -/// destination. This is a nontrivial operation because the successors of this -/// basic block must have their PHI nodes updated. -/// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch -/// conditions and indirectbr addresses this might make dead if -/// DeleteDeadConditions is true. -bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions, - const TargetLibraryInfo *TLI, - DomTreeUpdater *DTU) { - Instruction *T = BB->getTerminator(); - IRBuilder<> Builder(T); - - // Branch - See if we are conditional jumping on constant - if (auto *BI = dyn_cast(T)) { - if (BI->isUnconditional()) return false; // Can't optimize uncond branch - BasicBlock *Dest1 = BI->getSuccessor(0); - BasicBlock *Dest2 = BI->getSuccessor(1); - - if (auto *Cond = dyn_cast(BI->getCondition())) { - // Are we branching on constant? - // YES. Change to unconditional branch... - BasicBlock *Destination = Cond->getZExtValue() ? Dest1 : Dest2; - BasicBlock *OldDest = Cond->getZExtValue() ? Dest2 : Dest1; - - // Let the basic block know that we are letting go of it. Based on this, - // it will adjust it's PHI nodes. - OldDest->removePredecessor(BB); - - // Replace the conditional branch with an unconditional one. - Builder.CreateBr(Destination); - BI->eraseFromParent(); - if (DTU) - DTU->applyUpdatesPermissive({{DominatorTree::Delete, BB, OldDest}}); - return true; - } - - if (Dest2 == Dest1) { // Conditional branch to same location? - // This branch matches something like this: - // br bool %cond, label %Dest, label %Dest - // and changes it into: br label %Dest - - // Let the basic block know that we are letting go of one copy of it. - assert(BI->getParent() && "Terminator not inserted in block!"); - Dest1->removePredecessor(BI->getParent()); - - // Replace the conditional branch with an unconditional one. - Builder.CreateBr(Dest1); - Value *Cond = BI->getCondition(); - BI->eraseFromParent(); - if (DeleteDeadConditions) - RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI); - return true; - } - return false; - } - - if (auto *SI = dyn_cast(T)) { - // If we are switching on a constant, we can convert the switch to an - // unconditional branch. - auto *CI = dyn_cast(SI->getCondition()); - BasicBlock *DefaultDest = SI->getDefaultDest(); - BasicBlock *TheOnlyDest = DefaultDest; - - // If the default is unreachable, ignore it when searching for TheOnlyDest. - if (isa(DefaultDest->getFirstNonPHIOrDbg()) && - SI->getNumCases() > 0) { - TheOnlyDest = SI->case_begin()->getCaseSuccessor(); - } - - // Figure out which case it goes to. - for (auto i = SI->case_begin(), e = SI->case_end(); i != e;) { - // Found case matching a constant operand? - if (i->getCaseValue() == CI) { - TheOnlyDest = i->getCaseSuccessor(); - break; - } - - // Check to see if this branch is going to the same place as the default - // dest. If so, eliminate it as an explicit compare. - if (i->getCaseSuccessor() == DefaultDest) { - MDNode *MD = SI->getMetadata(LLVMContext::MD_prof); - unsigned NCases = SI->getNumCases(); - // Fold the case metadata into the default if there will be any branches - // left, unless the metadata doesn't match the switch. - if (NCases > 1 && MD && MD->getNumOperands() == 2 + NCases) { - // Collect branch weights into a vector. - SmallVector Weights; - for (unsigned MD_i = 1, MD_e = MD->getNumOperands(); MD_i < MD_e; - ++MD_i) { - auto *CI = mdconst::extract(MD->getOperand(MD_i)); - Weights.push_back(CI->getValue().getZExtValue()); - } - // Merge weight of this case to the default weight. - unsigned idx = i->getCaseIndex(); - Weights[0] += Weights[idx+1]; - // Remove weight for this case. - std::swap(Weights[idx+1], Weights.back()); - Weights.pop_back(); - SI->setMetadata(LLVMContext::MD_prof, - MDBuilder(BB->getContext()). - createBranchWeights(Weights)); - } - // Remove this entry. - BasicBlock *ParentBB = SI->getParent(); - DefaultDest->removePredecessor(ParentBB); - i = SI->removeCase(i); - e = SI->case_end(); - if (DTU) - DTU->applyUpdatesPermissive( - {{DominatorTree::Delete, ParentBB, DefaultDest}}); - continue; - } - - // Otherwise, check to see if the switch only branches to one destination. - // We do this by reseting "TheOnlyDest" to null when we find two non-equal - // destinations. - if (i->getCaseSuccessor() != TheOnlyDest) - TheOnlyDest = nullptr; - - // Increment this iterator as we haven't removed the case. - ++i; - } - - if (CI && !TheOnlyDest) { - // Branching on a constant, but not any of the cases, go to the default - // successor. - TheOnlyDest = SI->getDefaultDest(); - } - - // If we found a single destination that we can fold the switch into, do so - // now. - if (TheOnlyDest) { - // Insert the new branch. - Builder.CreateBr(TheOnlyDest); - BasicBlock *BB = SI->getParent(); - std::vector Updates; - if (DTU) - Updates.reserve(SI->getNumSuccessors() - 1); - - // Remove entries from PHI nodes which we no longer branch to... - for (BasicBlock *Succ : successors(SI)) { - // Found case matching a constant operand? - if (Succ == TheOnlyDest) { - TheOnlyDest = nullptr; // Don't modify the first branch to TheOnlyDest - } else { - Succ->removePredecessor(BB); - if (DTU) - Updates.push_back({DominatorTree::Delete, BB, Succ}); - } - } - - // Delete the old switch. - Value *Cond = SI->getCondition(); - SI->eraseFromParent(); - if (DeleteDeadConditions) - RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI); - if (DTU) - DTU->applyUpdatesPermissive(Updates); - return true; - } - - if (SI->getNumCases() == 1) { - // Otherwise, we can fold this switch into a conditional branch - // instruction if it has only one non-default destination. - auto FirstCase = *SI->case_begin(); - Value *Cond = Builder.CreateICmpEQ(SI->getCondition(), - FirstCase.getCaseValue(), "cond"); - - // Insert the new branch. - BranchInst *NewBr = Builder.CreateCondBr(Cond, - FirstCase.getCaseSuccessor(), - SI->getDefaultDest()); - MDNode *MD = SI->getMetadata(LLVMContext::MD_prof); - if (MD && MD->getNumOperands() == 3) { - ConstantInt *SICase = - mdconst::dyn_extract(MD->getOperand(2)); - ConstantInt *SIDef = - mdconst::dyn_extract(MD->getOperand(1)); - assert(SICase && SIDef); - // The TrueWeight should be the weight for the single case of SI. - NewBr->setMetadata(LLVMContext::MD_prof, - MDBuilder(BB->getContext()). - createBranchWeights(SICase->getValue().getZExtValue(), - SIDef->getValue().getZExtValue())); - } - - // Update make.implicit metadata to the newly-created conditional branch. - MDNode *MakeImplicitMD = SI->getMetadata(LLVMContext::MD_make_implicit); - if (MakeImplicitMD) - NewBr->setMetadata(LLVMContext::MD_make_implicit, MakeImplicitMD); - - // Delete the old switch. - SI->eraseFromParent(); - return true; - } - return false; - } - - if (auto *IBI = dyn_cast(T)) { - // indirectbr blockaddress(@F, @BB) -> br label @BB - if (auto *BA = - dyn_cast(IBI->getAddress()->stripPointerCasts())) { - BasicBlock *TheOnlyDest = BA->getBasicBlock(); - std::vector Updates; - if (DTU) - Updates.reserve(IBI->getNumDestinations() - 1); - - // Insert the new branch. - Builder.CreateBr(TheOnlyDest); - - for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) { - if (IBI->getDestination(i) == TheOnlyDest) { - TheOnlyDest = nullptr; - } else { - BasicBlock *ParentBB = IBI->getParent(); - BasicBlock *DestBB = IBI->getDestination(i); - DestBB->removePredecessor(ParentBB); - if (DTU) - Updates.push_back({DominatorTree::Delete, ParentBB, DestBB}); - } - } - Value *Address = IBI->getAddress(); - IBI->eraseFromParent(); - if (DeleteDeadConditions) - RecursivelyDeleteTriviallyDeadInstructions(Address, TLI); - - // If we didn't find our destination in the IBI successor list, then we - // have undefined behavior. Replace the unconditional branch with an - // 'unreachable' instruction. - if (TheOnlyDest) { - BB->getTerminator()->eraseFromParent(); - new UnreachableInst(BB->getContext(), BB); - } - - if (DTU) - DTU->applyUpdatesPermissive(Updates); - return true; - } - } - - return false; -} - -//===----------------------------------------------------------------------===// -// Local dead code elimination. -// - -/// isInstructionTriviallyDead - Return true if the result produced by the -/// instruction is not used, and the instruction has no side effects. -/// -bool llvm::isInstructionTriviallyDead(Instruction *I, - const TargetLibraryInfo *TLI) { - if (!I->use_empty()) - return false; - return wouldInstructionBeTriviallyDead(I, TLI); -} - -bool llvm::wouldInstructionBeTriviallyDead(Instruction *I, - const TargetLibraryInfo *TLI) { - if (I->isTerminator()) - return false; - - // We don't want the landingpad-like instructions removed by anything this - // general. - if (I->isEHPad()) - return false; - - // We don't want debug info removed by anything this general, unless - // debug info is empty. - if (DbgDeclareInst *DDI = dyn_cast(I)) { - if (DDI->getAddress()) - return false; - return true; - } - if (DbgValueInst *DVI = dyn_cast(I)) { - if (DVI->getValue()) - return false; - return true; - } - if (DbgLabelInst *DLI = dyn_cast(I)) { - if (DLI->getLabel()) - return false; - return true; - } - - if (!I->mayHaveSideEffects()) - return true; - - // Special case intrinsics that "may have side effects" but can be deleted - // when dead. - if (IntrinsicInst *II = dyn_cast(I)) { - // Safe to delete llvm.stacksave and launder.invariant.group if dead. - if (II->getIntrinsicID() == Intrinsic::stacksave || - II->getIntrinsicID() == Intrinsic::launder_invariant_group) - return true; - - // Lifetime intrinsics are dead when their right-hand is undef. - if (II->isLifetimeStartOrEnd()) - return isa(II->getArgOperand(1)); - - // Assumptions are dead if their condition is trivially true. Guards on - // true are operationally no-ops. In the future we can consider more - // sophisticated tradeoffs for guards considering potential for check - // widening, but for now we keep things simple. - if (II->getIntrinsicID() == Intrinsic::assume || - II->getIntrinsicID() == Intrinsic::experimental_guard) { - if (ConstantInt *Cond = dyn_cast(II->getArgOperand(0))) - return !Cond->isZero(); - - return false; - } - } - - if (isAllocLikeFn(I, TLI)) - return true; - - if (CallInst *CI = isFreeCall(I, TLI)) - if (Constant *C = dyn_cast(CI->getArgOperand(0))) - return C->isNullValue() || isa(C); - - if (auto *Call = dyn_cast(I)) - if (isMathLibCallNoop(Call, TLI)) - return true; - - return false; -} - -/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a -/// trivially dead instruction, delete it. If that makes any of its operands -/// trivially dead, delete them too, recursively. Return true if any -/// instructions were deleted. -bool llvm::RecursivelyDeleteTriviallyDeadInstructions( - Value *V, const TargetLibraryInfo *TLI, MemorySSAUpdater *MSSAU) { - Instruction *I = dyn_cast(V); - if (!I || !isInstructionTriviallyDead(I, TLI)) - return false; - - SmallVector DeadInsts; - DeadInsts.push_back(I); - RecursivelyDeleteTriviallyDeadInstructions(DeadInsts, TLI, MSSAU); - - return true; -} - -void llvm::RecursivelyDeleteTriviallyDeadInstructions( - SmallVectorImpl &DeadInsts, const TargetLibraryInfo *TLI, - MemorySSAUpdater *MSSAU) { - // Process the dead instruction list until empty. - while (!DeadInsts.empty()) { - Instruction &I = *DeadInsts.pop_back_val(); - assert(I.use_empty() && "Instructions with uses are not dead."); - assert(isInstructionTriviallyDead(&I, TLI) && - "Live instruction found in dead worklist!"); - - // Don't lose the debug info while deleting the instructions. - salvageDebugInfo(I); - - // Null out all of the instruction's operands to see if any operand becomes - // dead as we go. - for (Use &OpU : I.operands()) { - Value *OpV = OpU.get(); - OpU.set(nullptr); - - if (!OpV->use_empty()) - continue; - - // If the operand is an instruction that became dead as we nulled out the - // operand, and if it is 'trivially' dead, delete it in a future loop - // iteration. - if (Instruction *OpI = dyn_cast(OpV)) - if (isInstructionTriviallyDead(OpI, TLI)) - DeadInsts.push_back(OpI); - } - if (MSSAU) - MSSAU->removeMemoryAccess(&I); - - I.eraseFromParent(); - } -} - -bool llvm::replaceDbgUsesWithUndef(Instruction *I) { - SmallVector DbgUsers; - findDbgUsers(DbgUsers, I); - for (auto *DII : DbgUsers) { - Value *Undef = UndefValue::get(I->getType()); - DII->setOperand(0, MetadataAsValue::get(DII->getContext(), - ValueAsMetadata::get(Undef))); - } - return !DbgUsers.empty(); -} - -/// areAllUsesEqual - Check whether the uses of a value are all the same. -/// This is similar to Instruction::hasOneUse() except this will also return -/// true when there are no uses or multiple uses that all refer to the same -/// value. -static bool areAllUsesEqual(Instruction *I) { - Value::user_iterator UI = I->user_begin(); - Value::user_iterator UE = I->user_end(); - if (UI == UE) - return true; - - User *TheUse = *UI; - for (++UI; UI != UE; ++UI) { - if (*UI != TheUse) - return false; - } - return true; -} - -/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively -/// dead PHI node, due to being a def-use chain of single-use nodes that -/// either forms a cycle or is terminated by a trivially dead instruction, -/// delete it. If that makes any of its operands trivially dead, delete them -/// too, recursively. Return true if a change was made. -bool llvm::RecursivelyDeleteDeadPHINode(PHINode *PN, - const TargetLibraryInfo *TLI) { - SmallPtrSet Visited; - for (Instruction *I = PN; areAllUsesEqual(I) && !I->mayHaveSideEffects(); - I = cast(*I->user_begin())) { - if (I->use_empty()) - return RecursivelyDeleteTriviallyDeadInstructions(I, TLI); - - // If we find an instruction more than once, we're on a cycle that - // won't prove fruitful. - if (!Visited.insert(I).second) { - // Break the cycle and delete the instruction and its operands. - I->replaceAllUsesWith(UndefValue::get(I->getType())); - (void)RecursivelyDeleteTriviallyDeadInstructions(I, TLI); - return true; - } - } - return false; -} - -static bool -simplifyAndDCEInstruction(Instruction *I, - SmallSetVector &WorkList, - const DataLayout &DL, - const TargetLibraryInfo *TLI) { - if (isInstructionTriviallyDead(I, TLI)) { - salvageDebugInfo(*I); - - // Null out all of the instruction's operands to see if any operand becomes - // dead as we go. - for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { - Value *OpV = I->getOperand(i); - I->setOperand(i, nullptr); - - if (!OpV->use_empty() || I == OpV) - continue; - - // If the operand is an instruction that became dead as we nulled out the - // operand, and if it is 'trivially' dead, delete it in a future loop - // iteration. - if (Instruction *OpI = dyn_cast(OpV)) - if (isInstructionTriviallyDead(OpI, TLI)) - WorkList.insert(OpI); - } - - I->eraseFromParent(); - - return true; - } - - if (Value *SimpleV = SimplifyInstruction(I, DL)) { - // Add the users to the worklist. CAREFUL: an instruction can use itself, - // in the case of a phi node. - for (User *U : I->users()) { - if (U != I) { - WorkList.insert(cast(U)); - } - } - - // Replace the instruction with its simplified value. - bool Changed = false; - if (!I->use_empty()) { - I->replaceAllUsesWith(SimpleV); - Changed = true; - } - if (isInstructionTriviallyDead(I, TLI)) { - I->eraseFromParent(); - Changed = true; - } - return Changed; - } - return false; -} - -/// SimplifyInstructionsInBlock - Scan the specified basic block and try to -/// simplify any instructions in it and recursively delete dead instructions. -/// -/// This returns true if it changed the code, note that it can delete -/// instructions in other blocks as well in this block. -bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB, - const TargetLibraryInfo *TLI) { - bool MadeChange = false; - const DataLayout &DL = BB->getModule()->getDataLayout(); - -#ifndef NDEBUG - // In debug builds, ensure that the terminator of the block is never replaced - // or deleted by these simplifications. The idea of simplification is that it - // cannot introduce new instructions, and there is no way to replace the - // terminator of a block without introducing a new instruction. - AssertingVH TerminatorVH(&BB->back()); -#endif - - SmallSetVector WorkList; - // Iterate over the original function, only adding insts to the worklist - // if they actually need to be revisited. This avoids having to pre-init - // the worklist with the entire function's worth of instructions. - for (BasicBlock::iterator BI = BB->begin(), E = std::prev(BB->end()); - BI != E;) { - assert(!BI->isTerminator()); - Instruction *I = &*BI; - ++BI; - - // We're visiting this instruction now, so make sure it's not in the - // worklist from an earlier visit. - if (!WorkList.count(I)) - MadeChange |= simplifyAndDCEInstruction(I, WorkList, DL, TLI); - } - - while (!WorkList.empty()) { - Instruction *I = WorkList.pop_back_val(); - MadeChange |= simplifyAndDCEInstruction(I, WorkList, DL, TLI); - } - return MadeChange; -} - -//===----------------------------------------------------------------------===// -// Control Flow Graph Restructuring. -// - -/// RemovePredecessorAndSimplify - Like BasicBlock::removePredecessor, this -/// method is called when we're about to delete Pred as a predecessor of BB. If -/// BB contains any PHI nodes, this drops the entries in the PHI nodes for Pred. -/// -/// Unlike the removePredecessor method, this attempts to simplify uses of PHI -/// nodes that collapse into identity values. For example, if we have: -/// x = phi(1, 0, 0, 0) -/// y = and x, z -/// -/// .. and delete the predecessor corresponding to the '1', this will attempt to -/// recursively fold the and to 0. -void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred, - DomTreeUpdater *DTU) { - // This only adjusts blocks with PHI nodes. - if (!isa(BB->begin())) - return; - - // Remove the entries for Pred from the PHI nodes in BB, but do not simplify - // them down. This will leave us with single entry phi nodes and other phis - // that can be removed. - BB->removePredecessor(Pred, true); - - WeakTrackingVH PhiIt = &BB->front(); - while (PHINode *PN = dyn_cast(PhiIt)) { - PhiIt = &*++BasicBlock::iterator(cast(PhiIt)); - Value *OldPhiIt = PhiIt; - - if (!recursivelySimplifyInstruction(PN)) - continue; - - // If recursive simplification ended up deleting the next PHI node we would - // iterate to, then our iterator is invalid, restart scanning from the top - // of the block. - if (PhiIt != OldPhiIt) PhiIt = &BB->front(); - } - if (DTU) - DTU->applyUpdatesPermissive({{DominatorTree::Delete, Pred, BB}}); -} - -/// MergeBasicBlockIntoOnlyPred - DestBB is a block with one predecessor and its -/// predecessor is known to have one successor (DestBB!). Eliminate the edge -/// between them, moving the instructions in the predecessor into DestBB and -/// deleting the predecessor block. -void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, - DomTreeUpdater *DTU) { - - // If BB has single-entry PHI nodes, fold them. - while (PHINode *PN = dyn_cast(DestBB->begin())) { - Value *NewVal = PN->getIncomingValue(0); - // Replace self referencing PHI with undef, it must be dead. - if (NewVal == PN) NewVal = UndefValue::get(PN->getType()); - PN->replaceAllUsesWith(NewVal); - PN->eraseFromParent(); - } - - BasicBlock *PredBB = DestBB->getSinglePredecessor(); - assert(PredBB && "Block doesn't have a single predecessor!"); - - bool ReplaceEntryBB = false; - if (PredBB == &DestBB->getParent()->getEntryBlock()) - ReplaceEntryBB = true; - - // DTU updates: Collect all the edges that enter - // PredBB. These dominator edges will be redirected to DestBB. - SmallVector Updates; - - if (DTU) { - Updates.push_back({DominatorTree::Delete, PredBB, DestBB}); - for (auto I = pred_begin(PredBB), E = pred_end(PredBB); I != E; ++I) { - Updates.push_back({DominatorTree::Delete, *I, PredBB}); - // This predecessor of PredBB may already have DestBB as a successor. - if (llvm::find(successors(*I), DestBB) == succ_end(*I)) - Updates.push_back({DominatorTree::Insert, *I, DestBB}); - } - } - - // Zap anything that took the address of DestBB. Not doing this will give the - // address an invalid value. - if (DestBB->hasAddressTaken()) { - BlockAddress *BA = BlockAddress::get(DestBB); - Constant *Replacement = - ConstantInt::get(Type::getInt32Ty(BA->getContext()), 1); - BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement, - BA->getType())); - BA->destroyConstant(); - } - - // Anything that branched to PredBB now branches to DestBB. - PredBB->replaceAllUsesWith(DestBB); - - // Splice all the instructions from PredBB to DestBB. - PredBB->getTerminator()->eraseFromParent(); - DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList()); - new UnreachableInst(PredBB->getContext(), PredBB); - - // If the PredBB is the entry block of the function, move DestBB up to - // become the entry block after we erase PredBB. - if (ReplaceEntryBB) - DestBB->moveAfter(PredBB); - - if (DTU) { - assert(PredBB->getInstList().size() == 1 && - isa(PredBB->getTerminator()) && - "The successor list of PredBB isn't empty before " - "applying corresponding DTU updates."); - DTU->applyUpdatesPermissive(Updates); - DTU->deleteBB(PredBB); - // Recalculation of DomTree is needed when updating a forward DomTree and - // the Entry BB is replaced. - if (ReplaceEntryBB && DTU->hasDomTree()) { - // The entry block was removed and there is no external interface for - // the dominator tree to be notified of this change. In this corner-case - // we recalculate the entire tree. - DTU->recalculate(*(DestBB->getParent())); - } - } - - else { - PredBB->eraseFromParent(); // Nuke BB if DTU is nullptr. - } -} - -/// CanMergeValues - Return true if we can choose one of these values to use -/// in place of the other. Note that we will always choose the non-undef -/// value to keep. -static bool CanMergeValues(Value *First, Value *Second) { - return First == Second || isa(First) || isa(Second); -} - -/// CanPropagatePredecessorsForPHIs - Return true if we can fold BB, an -/// almost-empty BB ending in an unconditional branch to Succ, into Succ. -/// -/// Assumption: Succ is the single successor for BB. -static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) { - assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!"); - - LLVM_DEBUG(dbgs() << "Looking to fold " << BB->getName() << " into " - << Succ->getName() << "\n"); - // Shortcut, if there is only a single predecessor it must be BB and merging - // is always safe - if (Succ->getSinglePredecessor()) return true; - - // Make a list of the predecessors of BB - SmallPtrSet BBPreds(pred_begin(BB), pred_end(BB)); - - // Look at all the phi nodes in Succ, to see if they present a conflict when - // merging these blocks - for (BasicBlock::iterator I = Succ->begin(); isa(I); ++I) { - PHINode *PN = cast(I); - - // If the incoming value from BB is again a PHINode in - // BB which has the same incoming value for *PI as PN does, we can - // merge the phi nodes and then the blocks can still be merged - PHINode *BBPN = dyn_cast(PN->getIncomingValueForBlock(BB)); - if (BBPN && BBPN->getParent() == BB) { - for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) { - BasicBlock *IBB = PN->getIncomingBlock(PI); - if (BBPreds.count(IBB) && - !CanMergeValues(BBPN->getIncomingValueForBlock(IBB), - PN->getIncomingValue(PI))) { - LLVM_DEBUG(dbgs() - << "Can't fold, phi node " << PN->getName() << " in " - << Succ->getName() << " is conflicting with " - << BBPN->getName() << " with regard to common predecessor " - << IBB->getName() << "\n"); - return false; - } - } - } else { - Value* Val = PN->getIncomingValueForBlock(BB); - for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) { - // See if the incoming value for the common predecessor is equal to the - // one for BB, in which case this phi node will not prevent the merging - // of the block. - BasicBlock *IBB = PN->getIncomingBlock(PI); - if (BBPreds.count(IBB) && - !CanMergeValues(Val, PN->getIncomingValue(PI))) { - LLVM_DEBUG(dbgs() << "Can't fold, phi node " << PN->getName() - << " in " << Succ->getName() - << " is conflicting with regard to common " - << "predecessor " << IBB->getName() << "\n"); - return false; - } - } - } - } - - return true; -} - -using PredBlockVector = SmallVector; -using IncomingValueMap = DenseMap; - -/// Determines the value to use as the phi node input for a block. -/// -/// Select between \p OldVal any value that we know flows from \p BB -/// to a particular phi on the basis of which one (if either) is not -/// undef. Update IncomingValues based on the selected value. -/// -/// \param OldVal The value we are considering selecting. -/// \param BB The block that the value flows in from. -/// \param IncomingValues A map from block-to-value for other phi inputs -/// that we have examined. -/// -/// \returns the selected value. -static Value *selectIncomingValueForBlock(Value *OldVal, BasicBlock *BB, - IncomingValueMap &IncomingValues) { - if (!isa(OldVal)) { - assert((!IncomingValues.count(BB) || - IncomingValues.find(BB)->second == OldVal) && - "Expected OldVal to match incoming value from BB!"); - - IncomingValues.insert(std::make_pair(BB, OldVal)); - return OldVal; - } - - IncomingValueMap::const_iterator It = IncomingValues.find(BB); - if (It != IncomingValues.end()) return It->second; - - return OldVal; -} - -/// Create a map from block to value for the operands of a -/// given phi. -/// -/// Create a map from block to value for each non-undef value flowing -/// into \p PN. -/// -/// \param PN The phi we are collecting the map for. -/// \param IncomingValues [out] The map from block to value for this phi. -static void gatherIncomingValuesToPhi(PHINode *PN, - IncomingValueMap &IncomingValues) { - for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { - BasicBlock *BB = PN->getIncomingBlock(i); - Value *V = PN->getIncomingValue(i); - - if (!isa(V)) - IncomingValues.insert(std::make_pair(BB, V)); - } -} - -/// Replace the incoming undef values to a phi with the values -/// from a block-to-value map. -/// -/// \param PN The phi we are replacing the undefs in. -/// \param IncomingValues A map from block to value. -static void replaceUndefValuesInPhi(PHINode *PN, - const IncomingValueMap &IncomingValues) { - for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { - Value *V = PN->getIncomingValue(i); - - if (!isa(V)) continue; - - BasicBlock *BB = PN->getIncomingBlock(i); - IncomingValueMap::const_iterator It = IncomingValues.find(BB); - if (It == IncomingValues.end()) continue; - - PN->setIncomingValue(i, It->second); - } -} - -/// Replace a value flowing from a block to a phi with -/// potentially multiple instances of that value flowing from the -/// block's predecessors to the phi. -/// -/// \param BB The block with the value flowing into the phi. -/// \param BBPreds The predecessors of BB. -/// \param PN The phi that we are updating. -static void redirectValuesFromPredecessorsToPhi(BasicBlock *BB, - const PredBlockVector &BBPreds, - PHINode *PN) { - Value *OldVal = PN->removeIncomingValue(BB, false); - assert(OldVal && "No entry in PHI for Pred BB!"); - - IncomingValueMap IncomingValues; - - // We are merging two blocks - BB, and the block containing PN - and - // as a result we need to redirect edges from the predecessors of BB - // to go to the block containing PN, and update PN - // accordingly. Since we allow merging blocks in the case where the - // predecessor and successor blocks both share some predecessors, - // and where some of those common predecessors might have undef - // values flowing into PN, we want to rewrite those values to be - // consistent with the non-undef values. - - gatherIncomingValuesToPhi(PN, IncomingValues); - - // If this incoming value is one of the PHI nodes in BB, the new entries - // in the PHI node are the entries from the old PHI. - if (isa(OldVal) && cast(OldVal)->getParent() == BB) { - PHINode *OldValPN = cast(OldVal); - for (unsigned i = 0, e = OldValPN->getNumIncomingValues(); i != e; ++i) { - // Note that, since we are merging phi nodes and BB and Succ might - // have common predecessors, we could end up with a phi node with - // identical incoming branches. This will be cleaned up later (and - // will trigger asserts if we try to clean it up now, without also - // simplifying the corresponding conditional branch). - BasicBlock *PredBB = OldValPN->getIncomingBlock(i); - Value *PredVal = OldValPN->getIncomingValue(i); - Value *Selected = selectIncomingValueForBlock(PredVal, PredBB, - IncomingValues); - - // And add a new incoming value for this predecessor for the - // newly retargeted branch. - PN->addIncoming(Selected, PredBB); - } - } else { - for (unsigned i = 0, e = BBPreds.size(); i != e; ++i) { - // Update existing incoming values in PN for this - // predecessor of BB. - BasicBlock *PredBB = BBPreds[i]; - Value *Selected = selectIncomingValueForBlock(OldVal, PredBB, - IncomingValues); - - // And add a new incoming value for this predecessor for the - // newly retargeted branch. - PN->addIncoming(Selected, PredBB); - } - } - - replaceUndefValuesInPhi(PN, IncomingValues); -} - -/// TryToSimplifyUncondBranchFromEmptyBlock - BB is known to contain an -/// unconditional branch, and contains no instructions other than PHI nodes, -/// potential side-effect free intrinsics and the branch. If possible, -/// eliminate BB by rewriting all the predecessors to branch to the successor -/// block and return true. If we can't transform, return false. -bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB, - DomTreeUpdater *DTU) { - assert(BB != &BB->getParent()->getEntryBlock() && - "TryToSimplifyUncondBranchFromEmptyBlock called on entry block!"); - - // We can't eliminate infinite loops. - BasicBlock *Succ = cast(BB->getTerminator())->getSuccessor(0); - if (BB == Succ) return false; - - // Check to see if merging these blocks would cause conflicts for any of the - // phi nodes in BB or Succ. If not, we can safely merge. - if (!CanPropagatePredecessorsForPHIs(BB, Succ)) return false; - - // Check for cases where Succ has multiple predecessors and a PHI node in BB - // has uses which will not disappear when the PHI nodes are merged. It is - // possible to handle such cases, but difficult: it requires checking whether - // BB dominates Succ, which is non-trivial to calculate in the case where - // Succ has multiple predecessors. Also, it requires checking whether - // constructing the necessary self-referential PHI node doesn't introduce any - // conflicts; this isn't too difficult, but the previous code for doing this - // was incorrect. - // - // Note that if this check finds a live use, BB dominates Succ, so BB is - // something like a loop pre-header (or rarely, a part of an irreducible CFG); - // folding the branch isn't profitable in that case anyway. - if (!Succ->getSinglePredecessor()) { - BasicBlock::iterator BBI = BB->begin(); - while (isa(*BBI)) { - for (Use &U : BBI->uses()) { - if (PHINode* PN = dyn_cast(U.getUser())) { - if (PN->getIncomingBlock(U) != BB) - return false; - } else { - return false; - } - } - ++BBI; - } - } - - // We cannot fold the block if it's a branch to an already present callbr - // successor because that creates duplicate successors. - for (auto I = pred_begin(BB), E = pred_end(BB); I != E; ++I) { - if (auto *CBI = dyn_cast((*I)->getTerminator())) { - if (Succ == CBI->getDefaultDest()) - return false; - for (unsigned i = 0, e = CBI->getNumIndirectDests(); i != e; ++i) - if (Succ == CBI->getIndirectDest(i)) - return false; - } - } - - LLVM_DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB); - - SmallVector Updates; - if (DTU) { - Updates.push_back({DominatorTree::Delete, BB, Succ}); - // All predecessors of BB will be moved to Succ. - for (auto I = pred_begin(BB), E = pred_end(BB); I != E; ++I) { - Updates.push_back({DominatorTree::Delete, *I, BB}); - // This predecessor of BB may already have Succ as a successor. - if (llvm::find(successors(*I), Succ) == succ_end(*I)) - Updates.push_back({DominatorTree::Insert, *I, Succ}); - } - } - - if (isa(Succ->begin())) { - // If there is more than one pred of succ, and there are PHI nodes in - // the successor, then we need to add incoming edges for the PHI nodes - // - const PredBlockVector BBPreds(pred_begin(BB), pred_end(BB)); - - // Loop over all of the PHI nodes in the successor of BB. - for (BasicBlock::iterator I = Succ->begin(); isa(I); ++I) { - PHINode *PN = cast(I); - - redirectValuesFromPredecessorsToPhi(BB, BBPreds, PN); - } - } - - if (Succ->getSinglePredecessor()) { - // BB is the only predecessor of Succ, so Succ will end up with exactly - // the same predecessors BB had. - - // Copy over any phi, debug or lifetime instruction. - BB->getTerminator()->eraseFromParent(); - Succ->getInstList().splice(Succ->getFirstNonPHI()->getIterator(), - BB->getInstList()); - } else { - while (PHINode *PN = dyn_cast(&BB->front())) { - // We explicitly check for such uses in CanPropagatePredecessorsForPHIs. - assert(PN->use_empty() && "There shouldn't be any uses here!"); - PN->eraseFromParent(); - } - } - - // If the unconditional branch we replaced contains llvm.loop metadata, we - // add the metadata to the branch instructions in the predecessors. - unsigned LoopMDKind = BB->getContext().getMDKindID("llvm.loop"); - Instruction *TI = BB->getTerminator(); - if (TI) - if (MDNode *LoopMD = TI->getMetadata(LoopMDKind)) - for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { - BasicBlock *Pred = *PI; - Pred->getTerminator()->setMetadata(LoopMDKind, LoopMD); - } - - // Everything that jumped to BB now goes to Succ. - BB->replaceAllUsesWith(Succ); - if (!Succ->hasName()) Succ->takeName(BB); - - // Clear the successor list of BB to match updates applying to DTU later. - if (BB->getTerminator()) - BB->getInstList().pop_back(); - new UnreachableInst(BB->getContext(), BB); - assert(succ_empty(BB) && "The successor list of BB isn't empty before " - "applying corresponding DTU updates."); - - if (DTU) { - DTU->applyUpdatesPermissive(Updates); - DTU->deleteBB(BB); - } else { - BB->eraseFromParent(); // Delete the old basic block. - } - return true; -} - -/// EliminateDuplicatePHINodes - Check for and eliminate duplicate PHI -/// nodes in this block. This doesn't try to be clever about PHI nodes -/// which differ only in the order of the incoming values, but instcombine -/// orders them so it usually won't matter. -bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB) { - // This implementation doesn't currently consider undef operands - // specially. Theoretically, two phis which are identical except for - // one having an undef where the other doesn't could be collapsed. - - struct PHIDenseMapInfo { - static PHINode *getEmptyKey() { - return DenseMapInfo::getEmptyKey(); - } - - static PHINode *getTombstoneKey() { - return DenseMapInfo::getTombstoneKey(); - } - - static unsigned getHashValue(PHINode *PN) { - // Compute a hash value on the operands. Instcombine will likely have - // sorted them, which helps expose duplicates, but we have to check all - // the operands to be safe in case instcombine hasn't run. - return static_cast(hash_combine( - hash_combine_range(PN->value_op_begin(), PN->value_op_end()), - hash_combine_range(PN->block_begin(), PN->block_end()))); - } - - static bool isEqual(PHINode *LHS, PHINode *RHS) { - if (LHS == getEmptyKey() || LHS == getTombstoneKey() || - RHS == getEmptyKey() || RHS == getTombstoneKey()) - return LHS == RHS; - return LHS->isIdenticalTo(RHS); - } - }; - - // Set of unique PHINodes. - DenseSet PHISet; - - // Examine each PHI. - bool Changed = false; - for (auto I = BB->begin(); PHINode *PN = dyn_cast(I++);) { - auto Inserted = PHISet.insert(PN); - if (!Inserted.second) { - // A duplicate. Replace this PHI with its duplicate. - PN->replaceAllUsesWith(*Inserted.first); - PN->eraseFromParent(); - Changed = true; - - // The RAUW can change PHIs that we already visited. Start over from the - // beginning. - PHISet.clear(); - I = BB->begin(); - } - } - - return Changed; -} - -/// enforceKnownAlignment - If the specified pointer points to an object that -/// we control, modify the object's alignment to PrefAlign. This isn't -/// often possible though. If alignment is important, a more reliable approach -/// is to simply align all global variables and allocation instructions to -/// their preferred alignment from the beginning. -static unsigned enforceKnownAlignment(Value *V, unsigned Align, - unsigned PrefAlign, - const DataLayout &DL) { - assert(PrefAlign > Align); - - V = V->stripPointerCasts(); - - if (AllocaInst *AI = dyn_cast(V)) { - // TODO: ideally, computeKnownBits ought to have used - // AllocaInst::getAlignment() in its computation already, making - // the below max redundant. But, as it turns out, - // stripPointerCasts recurses through infinite layers of bitcasts, - // while computeKnownBits is not allowed to traverse more than 6 - // levels. - Align = std::max(AI->getAlignment(), Align); - if (PrefAlign <= Align) - return Align; - - // If the preferred alignment is greater than the natural stack alignment - // then don't round up. This avoids dynamic stack realignment. - if (DL.exceedsNaturalStackAlignment(PrefAlign)) - return Align; - AI->setAlignment(PrefAlign); - return PrefAlign; - } - - if (auto *GO = dyn_cast(V)) { - // TODO: as above, this shouldn't be necessary. - Align = std::max(GO->getAlignment(), Align); - if (PrefAlign <= Align) - return Align; - - // If there is a large requested alignment and we can, bump up the alignment - // of the global. If the memory we set aside for the global may not be the - // memory used by the final program then it is impossible for us to reliably - // enforce the preferred alignment. - if (!GO->canIncreaseAlignment()) - return Align; - - GO->setAlignment(PrefAlign); - return PrefAlign; - } - - return Align; -} - -unsigned llvm::getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign, - const DataLayout &DL, - const Instruction *CxtI, - AssumptionCache *AC, - const DominatorTree *DT) { - assert(V->getType()->isPointerTy() && - "getOrEnforceKnownAlignment expects a pointer!"); - - KnownBits Known = computeKnownBits(V, DL, 0, AC, CxtI, DT); - unsigned TrailZ = Known.countMinTrailingZeros(); - - // Avoid trouble with ridiculously large TrailZ values, such as - // those computed from a null pointer. - TrailZ = std::min(TrailZ, unsigned(sizeof(unsigned) * CHAR_BIT - 1)); - - unsigned Align = 1u << std::min(Known.getBitWidth() - 1, TrailZ); - - // LLVM doesn't support alignments larger than this currently. - Align = std::min(Align, +Value::MaximumAlignment); - - if (PrefAlign > Align) - Align = enforceKnownAlignment(V, Align, PrefAlign, DL); - - // We don't need to make any adjustment. - return Align; -} - -///===---------------------------------------------------------------------===// -/// Dbg Intrinsic utilities -/// - -/// See if there is a dbg.value intrinsic for DIVar before I. -static bool LdStHasDebugValue(DILocalVariable *DIVar, DIExpression *DIExpr, - Instruction *I) { - // Since we can't guarantee that the original dbg.declare instrinsic - // is removed by LowerDbgDeclare(), we need to make sure that we are - // not inserting the same dbg.value intrinsic over and over. - BasicBlock::InstListType::iterator PrevI(I); - if (PrevI != I->getParent()->getInstList().begin()) { - --PrevI; - if (DbgValueInst *DVI = dyn_cast(PrevI)) - if (DVI->getValue() == I->getOperand(0) && - DVI->getVariable() == DIVar && - DVI->getExpression() == DIExpr) - return true; - } - return false; -} - -/// See if there is a dbg.value intrinsic for DIVar for the PHI node. -static bool PhiHasDebugValue(DILocalVariable *DIVar, - DIExpression *DIExpr, - PHINode *APN) { - // Since we can't guarantee that the original dbg.declare instrinsic - // is removed by LowerDbgDeclare(), we need to make sure that we are - // not inserting the same dbg.value intrinsic over and over. - SmallVector DbgValues; - findDbgValues(DbgValues, APN); - for (auto *DVI : DbgValues) { - assert(DVI->getValue() == APN); - if ((DVI->getVariable() == DIVar) && (DVI->getExpression() == DIExpr)) - return true; - } - return false; -} - -/// Check if the alloc size of \p ValTy is large enough to cover the variable -/// (or fragment of the variable) described by \p DII. -/// -/// This is primarily intended as a helper for the different -/// ConvertDebugDeclareToDebugValue functions. The dbg.declare/dbg.addr that is -/// converted describes an alloca'd variable, so we need to use the -/// alloc size of the value when doing the comparison. E.g. an i1 value will be -/// identified as covering an n-bit fragment, if the store size of i1 is at -/// least n bits. -static bool valueCoversEntireFragment(Type *ValTy, DbgVariableIntrinsic *DII) { - const DataLayout &DL = DII->getModule()->getDataLayout(); - uint64_t ValueSize = DL.getTypeAllocSizeInBits(ValTy); - if (auto FragmentSize = DII->getFragmentSizeInBits()) - return ValueSize >= *FragmentSize; - // We can't always calculate the size of the DI variable (e.g. if it is a - // VLA). Try to use the size of the alloca that the dbg intrinsic describes - // intead. - if (DII->isAddressOfVariable()) - if (auto *AI = dyn_cast_or_null(DII->getVariableLocation())) - if (auto FragmentSize = AI->getAllocationSizeInBits(DL)) - return ValueSize >= *FragmentSize; - // Could not determine size of variable. Conservatively return false. - return false; -} - -/// Produce a DebugLoc to use for each dbg.declare/inst pair that are promoted -/// to a dbg.value. Because no machine insts can come from debug intrinsics, -/// only the scope and inlinedAt is significant. Zero line numbers are used in -/// case this DebugLoc leaks into any adjacent instructions. -static DebugLoc getDebugValueLoc(DbgVariableIntrinsic *DII, Instruction *Src) { - // Original dbg.declare must have a location. - DebugLoc DeclareLoc = DII->getDebugLoc(); - MDNode *Scope = DeclareLoc.getScope(); - DILocation *InlinedAt = DeclareLoc.getInlinedAt(); - // Produce an unknown location with the correct scope / inlinedAt fields. - return DebugLoc::get(0, 0, Scope, InlinedAt); -} - -/// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value -/// that has an associated llvm.dbg.declare or llvm.dbg.addr intrinsic. -void llvm::ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII, - StoreInst *SI, DIBuilder &Builder) { - assert(DII->isAddressOfVariable()); - auto *DIVar = DII->getVariable(); - assert(DIVar && "Missing variable"); - auto *DIExpr = DII->getExpression(); - Value *DV = SI->getValueOperand(); - - DebugLoc NewLoc = getDebugValueLoc(DII, SI); - - if (!valueCoversEntireFragment(DV->getType(), DII)) { - // FIXME: If storing to a part of the variable described by the dbg.declare, - // then we want to insert a dbg.value for the corresponding fragment. - LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: " - << *DII << '\n'); - // For now, when there is a store to parts of the variable (but we do not - // know which part) we insert an dbg.value instrinsic to indicate that we - // know nothing about the variable's content. - DV = UndefValue::get(DV->getType()); - if (!LdStHasDebugValue(DIVar, DIExpr, SI)) - Builder.insertDbgValueIntrinsic(DV, DIVar, DIExpr, NewLoc, SI); - return; - } - - if (!LdStHasDebugValue(DIVar, DIExpr, SI)) - Builder.insertDbgValueIntrinsic(DV, DIVar, DIExpr, NewLoc, SI); -} - -/// Inserts a llvm.dbg.value intrinsic before a load of an alloca'd value -/// that has an associated llvm.dbg.declare or llvm.dbg.addr intrinsic. -void llvm::ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII, - LoadInst *LI, DIBuilder &Builder) { - auto *DIVar = DII->getVariable(); - auto *DIExpr = DII->getExpression(); - assert(DIVar && "Missing variable"); - - if (LdStHasDebugValue(DIVar, DIExpr, LI)) - return; - - if (!valueCoversEntireFragment(LI->getType(), DII)) { - // FIXME: If only referring to a part of the variable described by the - // dbg.declare, then we want to insert a dbg.value for the corresponding - // fragment. - LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: " - << *DII << '\n'); - return; - } - - DebugLoc NewLoc = getDebugValueLoc(DII, nullptr); - - // We are now tracking the loaded value instead of the address. In the - // future if multi-location support is added to the IR, it might be - // preferable to keep tracking both the loaded value and the original - // address in case the alloca can not be elided. - Instruction *DbgValue = Builder.insertDbgValueIntrinsic( - LI, DIVar, DIExpr, NewLoc, (Instruction *)nullptr); - DbgValue->insertAfter(LI); -} - -/// Inserts a llvm.dbg.value intrinsic after a phi that has an associated -/// llvm.dbg.declare or llvm.dbg.addr intrinsic. -void llvm::ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII, - PHINode *APN, DIBuilder &Builder) { - auto *DIVar = DII->getVariable(); - auto *DIExpr = DII->getExpression(); - assert(DIVar && "Missing variable"); - - if (PhiHasDebugValue(DIVar, DIExpr, APN)) - return; - - if (!valueCoversEntireFragment(APN->getType(), DII)) { - // FIXME: If only referring to a part of the variable described by the - // dbg.declare, then we want to insert a dbg.value for the corresponding - // fragment. - LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: " - << *DII << '\n'); - return; - } - - BasicBlock *BB = APN->getParent(); - auto InsertionPt = BB->getFirstInsertionPt(); - - DebugLoc NewLoc = getDebugValueLoc(DII, nullptr); - - // The block may be a catchswitch block, which does not have a valid - // insertion point. - // FIXME: Insert dbg.value markers in the successors when appropriate. - if (InsertionPt != BB->end()) - Builder.insertDbgValueIntrinsic(APN, DIVar, DIExpr, NewLoc, &*InsertionPt); -} - -/// Determine whether this alloca is either a VLA or an array. -static bool isArray(AllocaInst *AI) { - return AI->isArrayAllocation() || - AI->getType()->getElementType()->isArrayTy(); -} - -/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set -/// of llvm.dbg.value intrinsics. -bool llvm::LowerDbgDeclare(Function &F) { - DIBuilder DIB(*F.getParent(), /*AllowUnresolved*/ false); - SmallVector Dbgs; - for (auto &FI : F) - for (Instruction &BI : FI) - if (auto DDI = dyn_cast(&BI)) - Dbgs.push_back(DDI); - - if (Dbgs.empty()) - return false; - - for (auto &I : Dbgs) { - DbgDeclareInst *DDI = I; - AllocaInst *AI = dyn_cast_or_null(DDI->getAddress()); - // If this is an alloca for a scalar variable, insert a dbg.value - // at each load and store to the alloca and erase the dbg.declare. - // The dbg.values allow tracking a variable even if it is not - // stored on the stack, while the dbg.declare can only describe - // the stack slot (and at a lexical-scope granularity). Later - // passes will attempt to elide the stack slot. - if (!AI || isArray(AI)) - continue; - - // A volatile load/store means that the alloca can't be elided anyway. - if (llvm::any_of(AI->users(), [](User *U) -> bool { - if (LoadInst *LI = dyn_cast(U)) - return LI->isVolatile(); - if (StoreInst *SI = dyn_cast(U)) - return SI->isVolatile(); - return false; - })) - continue; - - for (auto &AIUse : AI->uses()) { - User *U = AIUse.getUser(); - if (StoreInst *SI = dyn_cast(U)) { - if (AIUse.getOperandNo() == 1) - ConvertDebugDeclareToDebugValue(DDI, SI, DIB); - } else if (LoadInst *LI = dyn_cast(U)) { - ConvertDebugDeclareToDebugValue(DDI, LI, DIB); - } else if (CallInst *CI = dyn_cast(U)) { - // This is a call by-value or some other instruction that takes a - // pointer to the variable. Insert a *value* intrinsic that describes - // the variable by dereferencing the alloca. - DebugLoc NewLoc = getDebugValueLoc(DDI, nullptr); - auto *DerefExpr = - DIExpression::append(DDI->getExpression(), dwarf::DW_OP_deref); - DIB.insertDbgValueIntrinsic(AI, DDI->getVariable(), DerefExpr, NewLoc, - CI); - } - } - DDI->eraseFromParent(); - } - return true; -} - -/// Propagate dbg.value intrinsics through the newly inserted PHIs. -void llvm::insertDebugValuesForPHIs(BasicBlock *BB, - SmallVectorImpl &InsertedPHIs) { - assert(BB && "No BasicBlock to clone dbg.value(s) from."); - if (InsertedPHIs.size() == 0) - return; - - // Map existing PHI nodes to their dbg.values. - ValueToValueMapTy DbgValueMap; - for (auto &I : *BB) { - if (auto DbgII = dyn_cast(&I)) { - if (auto *Loc = dyn_cast_or_null(DbgII->getVariableLocation())) - DbgValueMap.insert({Loc, DbgII}); - } - } - if (DbgValueMap.size() == 0) - return; - - // Then iterate through the new PHIs and look to see if they use one of the - // previously mapped PHIs. If so, insert a new dbg.value intrinsic that will - // propagate the info through the new PHI. - LLVMContext &C = BB->getContext(); - for (auto PHI : InsertedPHIs) { - BasicBlock *Parent = PHI->getParent(); - // Avoid inserting an intrinsic into an EH block. - if (Parent->getFirstNonPHI()->isEHPad()) - continue; - auto PhiMAV = MetadataAsValue::get(C, ValueAsMetadata::get(PHI)); - for (auto VI : PHI->operand_values()) { - auto V = DbgValueMap.find(VI); - if (V != DbgValueMap.end()) { - auto *DbgII = cast(V->second); - Instruction *NewDbgII = DbgII->clone(); - NewDbgII->setOperand(0, PhiMAV); - auto InsertionPt = Parent->getFirstInsertionPt(); - assert(InsertionPt != Parent->end() && "Ill-formed basic block"); - NewDbgII->insertBefore(&*InsertionPt); - } - } - } -} - -/// Finds all intrinsics declaring local variables as living in the memory that -/// 'V' points to. This may include a mix of dbg.declare and -/// dbg.addr intrinsics. -TinyPtrVector llvm::FindDbgAddrUses(Value *V) { - // This function is hot. Check whether the value has any metadata to avoid a - // DenseMap lookup. - if (!V->isUsedByMetadata()) - return {}; - auto *L = LocalAsMetadata::getIfExists(V); - if (!L) - return {}; - auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L); - if (!MDV) - return {}; - - TinyPtrVector Declares; - for (User *U : MDV->users()) { - if (auto *DII = dyn_cast(U)) - if (DII->isAddressOfVariable()) - Declares.push_back(DII); - } - - return Declares; -} - -void llvm::findDbgValues(SmallVectorImpl &DbgValues, Value *V) { - // This function is hot. Check whether the value has any metadata to avoid a - // DenseMap lookup. - if (!V->isUsedByMetadata()) - return; - if (auto *L = LocalAsMetadata::getIfExists(V)) - if (auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L)) - for (User *U : MDV->users()) - if (DbgValueInst *DVI = dyn_cast(U)) - DbgValues.push_back(DVI); -} - -void llvm::findDbgUsers(SmallVectorImpl &DbgUsers, - Value *V) { - // This function is hot. Check whether the value has any metadata to avoid a - // DenseMap lookup. - if (!V->isUsedByMetadata()) - return; - if (auto *L = LocalAsMetadata::getIfExists(V)) - if (auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L)) - for (User *U : MDV->users()) - if (DbgVariableIntrinsic *DII = dyn_cast(U)) - DbgUsers.push_back(DII); -} - -bool llvm::replaceDbgDeclare(Value *Address, Value *NewAddress, - Instruction *InsertBefore, DIBuilder &Builder, - uint8_t DIExprFlags, int Offset) { - auto DbgAddrs = FindDbgAddrUses(Address); - for (DbgVariableIntrinsic *DII : DbgAddrs) { - DebugLoc Loc = DII->getDebugLoc(); - auto *DIVar = DII->getVariable(); - auto *DIExpr = DII->getExpression(); - assert(DIVar && "Missing variable"); - DIExpr = DIExpression::prepend(DIExpr, DIExprFlags, Offset); - // Insert llvm.dbg.declare immediately before InsertBefore, and remove old - // llvm.dbg.declare. - Builder.insertDeclare(NewAddress, DIVar, DIExpr, Loc, InsertBefore); - if (DII == InsertBefore) - InsertBefore = InsertBefore->getNextNode(); - DII->eraseFromParent(); - } - return !DbgAddrs.empty(); -} - -bool llvm::replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress, - DIBuilder &Builder, uint8_t DIExprFlags, - int Offset) { - return replaceDbgDeclare(AI, NewAllocaAddress, AI->getNextNode(), Builder, - DIExprFlags, Offset); -} - -static void replaceOneDbgValueForAlloca(DbgValueInst *DVI, Value *NewAddress, - DIBuilder &Builder, int Offset) { - DebugLoc Loc = DVI->getDebugLoc(); - auto *DIVar = DVI->getVariable(); - auto *DIExpr = DVI->getExpression(); - assert(DIVar && "Missing variable"); - - // This is an alloca-based llvm.dbg.value. The first thing it should do with - // the alloca pointer is dereference it. Otherwise we don't know how to handle - // it and give up. - if (!DIExpr || DIExpr->getNumElements() < 1 || - DIExpr->getElement(0) != dwarf::DW_OP_deref) - return; - - // Insert the offset immediately after the first deref. - // We could just change the offset argument of dbg.value, but it's unsigned... - if (Offset) { - SmallVector Ops; - Ops.push_back(dwarf::DW_OP_deref); - DIExpression::appendOffset(Ops, Offset); - Ops.append(DIExpr->elements_begin() + 1, DIExpr->elements_end()); - DIExpr = Builder.createExpression(Ops); - } - - Builder.insertDbgValueIntrinsic(NewAddress, DIVar, DIExpr, Loc, DVI); - DVI->eraseFromParent(); -} - -void llvm::replaceDbgValueForAlloca(AllocaInst *AI, Value *NewAllocaAddress, - DIBuilder &Builder, int Offset) { - if (auto *L = LocalAsMetadata::getIfExists(AI)) - if (auto *MDV = MetadataAsValue::getIfExists(AI->getContext(), L)) - for (auto UI = MDV->use_begin(), UE = MDV->use_end(); UI != UE;) { - Use &U = *UI++; - if (auto *DVI = dyn_cast(U.getUser())) - replaceOneDbgValueForAlloca(DVI, NewAllocaAddress, Builder, Offset); - } -} - -/// Wrap \p V in a ValueAsMetadata instance. -static MetadataAsValue *wrapValueInMetadata(LLVMContext &C, Value *V) { - return MetadataAsValue::get(C, ValueAsMetadata::get(V)); -} - -bool llvm::salvageDebugInfo(Instruction &I) { - SmallVector DbgUsers; - findDbgUsers(DbgUsers, &I); - if (DbgUsers.empty()) - return false; - - return salvageDebugInfoForDbgValues(I, DbgUsers); -} - -bool llvm::salvageDebugInfoForDbgValues( - Instruction &I, ArrayRef DbgUsers) { - auto &Ctx = I.getContext(); - auto wrapMD = [&](Value *V) { return wrapValueInMetadata(Ctx, V); }; - - for (auto *DII : DbgUsers) { - // Do not add DW_OP_stack_value for DbgDeclare and DbgAddr, because they - // are implicitly pointing out the value as a DWARF memory location - // description. - bool StackValue = isa(DII); - - DIExpression *DIExpr = - salvageDebugInfoImpl(I, DII->getExpression(), StackValue); - - // salvageDebugInfoImpl should fail on examining the first element of - // DbgUsers, or none of them. - if (!DIExpr) - return false; - - DII->setOperand(0, wrapMD(I.getOperand(0))); - DII->setOperand(2, MetadataAsValue::get(Ctx, DIExpr)); - LLVM_DEBUG(dbgs() << "SALVAGE: " << *DII << '\n'); - } - - return true; -} - -DIExpression *llvm::salvageDebugInfoImpl(Instruction &I, - DIExpression *SrcDIExpr, - bool WithStackValue) { - auto &M = *I.getModule(); - auto &DL = M.getDataLayout(); - - // Apply a vector of opcodes to the source DIExpression. - auto doSalvage = [&](SmallVectorImpl &Ops) -> DIExpression * { - DIExpression *DIExpr = SrcDIExpr; - if (!Ops.empty()) { - DIExpr = DIExpression::prependOpcodes(DIExpr, Ops, WithStackValue); - } - return DIExpr; - }; - - // Apply the given offset to the source DIExpression. - auto applyOffset = [&](uint64_t Offset) -> DIExpression * { - SmallVector Ops; - DIExpression::appendOffset(Ops, Offset); - return doSalvage(Ops); - }; - - // initializer-list helper for applying operators to the source DIExpression. - auto applyOps = - [&](std::initializer_list Opcodes) -> DIExpression * { - SmallVector Ops(Opcodes); - return doSalvage(Ops); - }; - - if (auto *CI = dyn_cast(&I)) { - // No-op casts and zexts are irrelevant for debug info. - if (CI->isNoopCast(DL) || isa(&I)) - return SrcDIExpr; - return nullptr; - } else if (auto *GEP = dyn_cast(&I)) { - unsigned BitWidth = - M.getDataLayout().getIndexSizeInBits(GEP->getPointerAddressSpace()); - // Rewrite a constant GEP into a DIExpression. - APInt Offset(BitWidth, 0); - if (GEP->accumulateConstantOffset(M.getDataLayout(), Offset)) { - return applyOffset(Offset.getSExtValue()); - } else { - return nullptr; - } - } else if (auto *BI = dyn_cast(&I)) { - // Rewrite binary operations with constant integer operands. - auto *ConstInt = dyn_cast(I.getOperand(1)); - if (!ConstInt || ConstInt->getBitWidth() > 64) - return nullptr; - - uint64_t Val = ConstInt->getSExtValue(); - switch (BI->getOpcode()) { - case Instruction::Add: - return applyOffset(Val); - case Instruction::Sub: - return applyOffset(-int64_t(Val)); - case Instruction::Mul: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_mul}); - case Instruction::SDiv: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_div}); - case Instruction::SRem: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_mod}); - case Instruction::Or: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_or}); - case Instruction::And: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_and}); - case Instruction::Xor: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_xor}); - case Instruction::Shl: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_shl}); - case Instruction::LShr: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_shr}); - case Instruction::AShr: - return applyOps({dwarf::DW_OP_constu, Val, dwarf::DW_OP_shra}); - default: - // TODO: Salvage constants from each kind of binop we know about. - return nullptr; - } - // *Not* to do: we should not attempt to salvage load instructions, - // because the validity and lifetime of a dbg.value containing - // DW_OP_deref becomes difficult to analyze. See PR40628 for examples. - } - return nullptr; -} - -/// A replacement for a dbg.value expression. -using DbgValReplacement = Optional; - -/// Point debug users of \p From to \p To using exprs given by \p RewriteExpr, -/// possibly moving/deleting users to prevent use-before-def. Returns true if -/// changes are made. -static bool rewriteDebugUsers( - Instruction &From, Value &To, Instruction &DomPoint, DominatorTree &DT, - function_ref RewriteExpr) { - // Find debug users of From. - SmallVector Users; - findDbgUsers(Users, &From); - if (Users.empty()) - return false; - - // Prevent use-before-def of To. - bool Changed = false; - SmallPtrSet DeleteOrSalvage; - if (isa(&To)) { - bool DomPointAfterFrom = From.getNextNonDebugInstruction() == &DomPoint; - - for (auto *DII : Users) { - // It's common to see a debug user between From and DomPoint. Move it - // after DomPoint to preserve the variable update without any reordering. - if (DomPointAfterFrom && DII->getNextNonDebugInstruction() == &DomPoint) { - LLVM_DEBUG(dbgs() << "MOVE: " << *DII << '\n'); - DII->moveAfter(&DomPoint); - Changed = true; - - // Users which otherwise aren't dominated by the replacement value must - // be salvaged or deleted. - } else if (!DT.dominates(&DomPoint, DII)) { - DeleteOrSalvage.insert(DII); - } - } - } - - // Update debug users without use-before-def risk. - for (auto *DII : Users) { - if (DeleteOrSalvage.count(DII)) - continue; - - LLVMContext &Ctx = DII->getContext(); - DbgValReplacement DVR = RewriteExpr(*DII); - if (!DVR) - continue; - - DII->setOperand(0, wrapValueInMetadata(Ctx, &To)); - DII->setOperand(2, MetadataAsValue::get(Ctx, *DVR)); - LLVM_DEBUG(dbgs() << "REWRITE: " << *DII << '\n'); - Changed = true; - } - - if (!DeleteOrSalvage.empty()) { - // Try to salvage the remaining debug users. - Changed |= salvageDebugInfo(From); - - // Delete the debug users which weren't salvaged. - for (auto *DII : DeleteOrSalvage) { - if (DII->getVariableLocation() == &From) { - LLVM_DEBUG(dbgs() << "Erased UseBeforeDef: " << *DII << '\n'); - DII->eraseFromParent(); - Changed = true; - } - } - } - - return Changed; -} - -/// Check if a bitcast between a value of type \p FromTy to type \p ToTy would -/// losslessly preserve the bits and semantics of the value. This predicate is -/// symmetric, i.e swapping \p FromTy and \p ToTy should give the same result. -/// -/// Note that Type::canLosslesslyBitCastTo is not suitable here because it -/// allows semantically unequivalent bitcasts, such as <2 x i64> -> <4 x i32>, -/// and also does not allow lossless pointer <-> integer conversions. -static bool isBitCastSemanticsPreserving(const DataLayout &DL, Type *FromTy, - Type *ToTy) { - // Trivially compatible types. - if (FromTy == ToTy) - return true; - - // Handle compatible pointer <-> integer conversions. - if (FromTy->isIntOrPtrTy() && ToTy->isIntOrPtrTy()) { - bool SameSize = DL.getTypeSizeInBits(FromTy) == DL.getTypeSizeInBits(ToTy); - bool LosslessConversion = !DL.isNonIntegralPointerType(FromTy) && - !DL.isNonIntegralPointerType(ToTy); - return SameSize && LosslessConversion; - } - - // TODO: This is not exhaustive. - return false; -} - -bool llvm::replaceAllDbgUsesWith(Instruction &From, Value &To, - Instruction &DomPoint, DominatorTree &DT) { - // Exit early if From has no debug users. - if (!From.isUsedByMetadata()) - return false; - - assert(&From != &To && "Can't replace something with itself"); - - Type *FromTy = From.getType(); - Type *ToTy = To.getType(); - - auto Identity = [&](DbgVariableIntrinsic &DII) -> DbgValReplacement { - return DII.getExpression(); - }; - - // Handle no-op conversions. - Module &M = *From.getModule(); - const DataLayout &DL = M.getDataLayout(); - if (isBitCastSemanticsPreserving(DL, FromTy, ToTy)) - return rewriteDebugUsers(From, To, DomPoint, DT, Identity); - - // Handle integer-to-integer widening and narrowing. - // FIXME: Use DW_OP_convert when it's available everywhere. - if (FromTy->isIntegerTy() && ToTy->isIntegerTy()) { - uint64_t FromBits = FromTy->getPrimitiveSizeInBits(); - uint64_t ToBits = ToTy->getPrimitiveSizeInBits(); - assert(FromBits != ToBits && "Unexpected no-op conversion"); - - // When the width of the result grows, assume that a debugger will only - // access the low `FromBits` bits when inspecting the source variable. - if (FromBits < ToBits) - return rewriteDebugUsers(From, To, DomPoint, DT, Identity); - - // The width of the result has shrunk. Use sign/zero extension to describe - // the source variable's high bits. - auto SignOrZeroExt = [&](DbgVariableIntrinsic &DII) -> DbgValReplacement { - DILocalVariable *Var = DII.getVariable(); - - // Without knowing signedness, sign/zero extension isn't possible. - auto Signedness = Var->getSignedness(); - if (!Signedness) - return None; - - bool Signed = *Signedness == DIBasicType::Signedness::Signed; - dwarf::TypeKind TK = Signed ? dwarf::DW_ATE_signed : dwarf::DW_ATE_unsigned; - SmallVector Ops({dwarf::DW_OP_LLVM_convert, ToBits, TK, - dwarf::DW_OP_LLVM_convert, FromBits, TK}); - return DIExpression::appendToStack(DII.getExpression(), Ops); - }; - return rewriteDebugUsers(From, To, DomPoint, DT, SignOrZeroExt); - } - - // TODO: Floating-point conversions, vectors. - return false; -} - -unsigned llvm::removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB) { - unsigned NumDeadInst = 0; - // Delete the instructions backwards, as it has a reduced likelihood of - // having to update as many def-use and use-def chains. - Instruction *EndInst = BB->getTerminator(); // Last not to be deleted. - while (EndInst != &BB->front()) { - // Delete the next to last instruction. - Instruction *Inst = &*--EndInst->getIterator(); - if (!Inst->use_empty() && !Inst->getType()->isTokenTy()) - Inst->replaceAllUsesWith(UndefValue::get(Inst->getType())); - if (Inst->isEHPad() || Inst->getType()->isTokenTy()) { - EndInst = Inst; - continue; - } - if (!isa(Inst)) - ++NumDeadInst; - Inst->eraseFromParent(); - } - return NumDeadInst; -} - -unsigned llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap, - bool PreserveLCSSA, DomTreeUpdater *DTU, - MemorySSAUpdater *MSSAU) { - BasicBlock *BB = I->getParent(); - std::vector Updates; - - if (MSSAU) - MSSAU->changeToUnreachable(I); - - // Loop over all of the successors, removing BB's entry from any PHI - // nodes. - if (DTU) - Updates.reserve(BB->getTerminator()->getNumSuccessors()); - for (BasicBlock *Successor : successors(BB)) { - Successor->removePredecessor(BB, PreserveLCSSA); - if (DTU) - Updates.push_back({DominatorTree::Delete, BB, Successor}); - } - // Insert a call to llvm.trap right before this. This turns the undefined - // behavior into a hard fail instead of falling through into random code. - if (UseLLVMTrap) { - Function *TrapFn = - Intrinsic::getDeclaration(BB->getParent()->getParent(), Intrinsic::trap); - CallInst *CallTrap = CallInst::Create(TrapFn, "", I); - CallTrap->setDebugLoc(I->getDebugLoc()); - } - auto *UI = new UnreachableInst(I->getContext(), I); - UI->setDebugLoc(I->getDebugLoc()); - - // All instructions after this are dead. - unsigned NumInstrsRemoved = 0; - BasicBlock::iterator BBI = I->getIterator(), BBE = BB->end(); - while (BBI != BBE) { - if (!BBI->use_empty()) - BBI->replaceAllUsesWith(UndefValue::get(BBI->getType())); - BB->getInstList().erase(BBI++); - ++NumInstrsRemoved; - } - if (DTU) - DTU->applyUpdatesPermissive(Updates); - return NumInstrsRemoved; -} - -/// changeToCall - Convert the specified invoke into a normal call. -static void changeToCall(InvokeInst *II, DomTreeUpdater *DTU = nullptr) { - SmallVector Args(II->arg_begin(), II->arg_end()); - SmallVector OpBundles; - II->getOperandBundlesAsDefs(OpBundles); - CallInst *NewCall = CallInst::Create( - II->getFunctionType(), II->getCalledValue(), Args, OpBundles, "", II); - NewCall->takeName(II); - NewCall->setCallingConv(II->getCallingConv()); - NewCall->setAttributes(II->getAttributes()); - NewCall->setDebugLoc(II->getDebugLoc()); - NewCall->copyMetadata(*II); - II->replaceAllUsesWith(NewCall); - - // Follow the call by a branch to the normal destination. - BasicBlock *NormalDestBB = II->getNormalDest(); - BranchInst::Create(NormalDestBB, II); - - // Update PHI nodes in the unwind destination - BasicBlock *BB = II->getParent(); - BasicBlock *UnwindDestBB = II->getUnwindDest(); - UnwindDestBB->removePredecessor(BB); - II->eraseFromParent(); - if (DTU) - DTU->applyUpdatesPermissive({{DominatorTree::Delete, BB, UnwindDestBB}}); -} - -BasicBlock *llvm::changeToInvokeAndSplitBasicBlock(CallInst *CI, - BasicBlock *UnwindEdge) { - BasicBlock *BB = CI->getParent(); - - // Convert this function call into an invoke instruction. First, split the - // basic block. - BasicBlock *Split = - BB->splitBasicBlock(CI->getIterator(), CI->getName() + ".noexc"); - - // Delete the unconditional branch inserted by splitBasicBlock - BB->getInstList().pop_back(); - - // Create the new invoke instruction. - SmallVector InvokeArgs(CI->arg_begin(), CI->arg_end()); - SmallVector OpBundles; - - CI->getOperandBundlesAsDefs(OpBundles); - - // Note: we're round tripping operand bundles through memory here, and that - // can potentially be avoided with a cleverer API design that we do not have - // as of this time. - - InvokeInst *II = - InvokeInst::Create(CI->getFunctionType(), CI->getCalledValue(), Split, - UnwindEdge, InvokeArgs, OpBundles, CI->getName(), BB); - II->setDebugLoc(CI->getDebugLoc()); - II->setCallingConv(CI->getCallingConv()); - II->setAttributes(CI->getAttributes()); - - // Make sure that anything using the call now uses the invoke! This also - // updates the CallGraph if present, because it uses a WeakTrackingVH. - CI->replaceAllUsesWith(II); - - // Delete the original call - Split->getInstList().pop_front(); - return Split; -} - -static bool markAliveBlocks(Function &F, - SmallPtrSetImpl &Reachable, - DomTreeUpdater *DTU = nullptr) { - SmallVector Worklist; - BasicBlock *BB = &F.front(); - Worklist.push_back(BB); - Reachable.insert(BB); - bool Changed = false; - do { - BB = Worklist.pop_back_val(); - - // Do a quick scan of the basic block, turning any obviously unreachable - // instructions into LLVM unreachable insts. The instruction combining pass - // canonicalizes unreachable insts into stores to null or undef. - for (Instruction &I : *BB) { - if (auto *CI = dyn_cast(&I)) { - Value *Callee = CI->getCalledValue(); - // Handle intrinsic calls. - if (Function *F = dyn_cast(Callee)) { - auto IntrinsicID = F->getIntrinsicID(); - // Assumptions that are known to be false are equivalent to - // unreachable. Also, if the condition is undefined, then we make the - // choice most beneficial to the optimizer, and choose that to also be - // unreachable. - if (IntrinsicID == Intrinsic::assume) { - if (match(CI->getArgOperand(0), m_CombineOr(m_Zero(), m_Undef()))) { - // Don't insert a call to llvm.trap right before the unreachable. - changeToUnreachable(CI, false, false, DTU); - Changed = true; - break; - } - } else if (IntrinsicID == Intrinsic::experimental_guard) { - // A call to the guard intrinsic bails out of the current - // compilation unit if the predicate passed to it is false. If the - // predicate is a constant false, then we know the guard will bail - // out of the current compile unconditionally, so all code following - // it is dead. - // - // Note: unlike in llvm.assume, it is not "obviously profitable" for - // guards to treat `undef` as `false` since a guard on `undef` can - // still be useful for widening. - if (match(CI->getArgOperand(0), m_Zero())) - if (!isa(CI->getNextNode())) { - changeToUnreachable(CI->getNextNode(), /*UseLLVMTrap=*/false, - false, DTU); - Changed = true; - break; - } - } - } else if ((isa(Callee) && - !NullPointerIsDefined(CI->getFunction())) || - isa(Callee)) { - changeToUnreachable(CI, /*UseLLVMTrap=*/false, false, DTU); - Changed = true; - break; - } - if (CI->doesNotReturn() && !CI->isMustTailCall()) { - // If we found a call to a no-return function, insert an unreachable - // instruction after it. Make sure there isn't *already* one there - // though. - if (!isa(CI->getNextNode())) { - // Don't insert a call to llvm.trap right before the unreachable. - changeToUnreachable(CI->getNextNode(), false, false, DTU); - Changed = true; - } - break; - } - } else if (auto *SI = dyn_cast(&I)) { - // Store to undef and store to null are undefined and used to signal - // that they should be changed to unreachable by passes that can't - // modify the CFG. - - // Don't touch volatile stores. - if (SI->isVolatile()) continue; - - Value *Ptr = SI->getOperand(1); - - if (isa(Ptr) || - (isa(Ptr) && - !NullPointerIsDefined(SI->getFunction(), - SI->getPointerAddressSpace()))) { - changeToUnreachable(SI, true, false, DTU); - Changed = true; - break; - } - } - } - - Instruction *Terminator = BB->getTerminator(); - if (auto *II = dyn_cast(Terminator)) { - // Turn invokes that call 'nounwind' functions into ordinary calls. - Value *Callee = II->getCalledValue(); - if ((isa(Callee) && - !NullPointerIsDefined(BB->getParent())) || - isa(Callee)) { - changeToUnreachable(II, true, false, DTU); - Changed = true; - } else if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(&F)) { - if (II->use_empty() && II->onlyReadsMemory()) { - // jump to the normal destination branch. - BasicBlock *NormalDestBB = II->getNormalDest(); - BasicBlock *UnwindDestBB = II->getUnwindDest(); - BranchInst::Create(NormalDestBB, II); - UnwindDestBB->removePredecessor(II->getParent()); - II->eraseFromParent(); - if (DTU) - DTU->applyUpdatesPermissive( - {{DominatorTree::Delete, BB, UnwindDestBB}}); - } else - changeToCall(II, DTU); - Changed = true; - } - } else if (auto *CatchSwitch = dyn_cast(Terminator)) { - // Remove catchpads which cannot be reached. - struct CatchPadDenseMapInfo { - static CatchPadInst *getEmptyKey() { - return DenseMapInfo::getEmptyKey(); - } - - static CatchPadInst *getTombstoneKey() { - return DenseMapInfo::getTombstoneKey(); - } - - static unsigned getHashValue(CatchPadInst *CatchPad) { - return static_cast(hash_combine_range( - CatchPad->value_op_begin(), CatchPad->value_op_end())); - } - - static bool isEqual(CatchPadInst *LHS, CatchPadInst *RHS) { - if (LHS == getEmptyKey() || LHS == getTombstoneKey() || - RHS == getEmptyKey() || RHS == getTombstoneKey()) - return LHS == RHS; - return LHS->isIdenticalTo(RHS); - } - }; - - // Set of unique CatchPads. - SmallDenseMap> - HandlerSet; - detail::DenseSetEmpty Empty; - for (CatchSwitchInst::handler_iterator I = CatchSwitch->handler_begin(), - E = CatchSwitch->handler_end(); - I != E; ++I) { - BasicBlock *HandlerBB = *I; - auto *CatchPad = cast(HandlerBB->getFirstNonPHI()); - if (!HandlerSet.insert({CatchPad, Empty}).second) { - CatchSwitch->removeHandler(I); - --I; - --E; - Changed = true; - } - } - } - - Changed |= ConstantFoldTerminator(BB, true, nullptr, DTU); - for (BasicBlock *Successor : successors(BB)) - if (Reachable.insert(Successor).second) - Worklist.push_back(Successor); - } while (!Worklist.empty()); - return Changed; -} - -void llvm::removeUnwindEdge(BasicBlock *BB, DomTreeUpdater *DTU) { - Instruction *TI = BB->getTerminator(); - - if (auto *II = dyn_cast(TI)) { - changeToCall(II, DTU); - return; - } - - Instruction *NewTI; - BasicBlock *UnwindDest; - - if (auto *CRI = dyn_cast(TI)) { - NewTI = CleanupReturnInst::Create(CRI->getCleanupPad(), nullptr, CRI); - UnwindDest = CRI->getUnwindDest(); - } else if (auto *CatchSwitch = dyn_cast(TI)) { - auto *NewCatchSwitch = CatchSwitchInst::Create( - CatchSwitch->getParentPad(), nullptr, CatchSwitch->getNumHandlers(), - CatchSwitch->getName(), CatchSwitch); - for (BasicBlock *PadBB : CatchSwitch->handlers()) - NewCatchSwitch->addHandler(PadBB); - - NewTI = NewCatchSwitch; - UnwindDest = CatchSwitch->getUnwindDest(); - } else { - llvm_unreachable("Could not find unwind successor"); - } - - NewTI->takeName(TI); - NewTI->setDebugLoc(TI->getDebugLoc()); - UnwindDest->removePredecessor(BB); - TI->replaceAllUsesWith(NewTI); - TI->eraseFromParent(); - if (DTU) - DTU->applyUpdatesPermissive({{DominatorTree::Delete, BB, UnwindDest}}); -} - -/// removeUnreachableBlocks - Remove blocks that are not reachable, even -/// if they are in a dead cycle. Return true if a change was made, false -/// otherwise. If `LVI` is passed, this function preserves LazyValueInfo -/// after modifying the CFG. -bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI, - DomTreeUpdater *DTU, - MemorySSAUpdater *MSSAU) { - SmallPtrSet Reachable; - bool Changed = markAliveBlocks(F, Reachable, DTU); - - // If there are unreachable blocks in the CFG... - if (Reachable.size() == F.size()) - return Changed; - - assert(Reachable.size() < F.size()); - NumRemoved += F.size()-Reachable.size(); - - SmallSetVector DeadBlockSet; - for (Function::iterator I = ++F.begin(), E = F.end(); I != E; ++I) { - auto *BB = &*I; - if (Reachable.count(BB)) - continue; - DeadBlockSet.insert(BB); - } - - if (MSSAU) - MSSAU->removeBlocks(DeadBlockSet); - - // Loop over all of the basic blocks that are not reachable, dropping all of - // their internal references. Update DTU and LVI if available. - std::vector Updates; - for (auto *BB : DeadBlockSet) { - for (BasicBlock *Successor : successors(BB)) { - if (!DeadBlockSet.count(Successor)) - Successor->removePredecessor(BB); - if (DTU) - Updates.push_back({DominatorTree::Delete, BB, Successor}); - } - if (LVI) - LVI->eraseBlock(BB); - BB->dropAllReferences(); - } - for (Function::iterator I = ++F.begin(); I != F.end();) { - auto *BB = &*I; - if (Reachable.count(BB)) { - ++I; - continue; - } - if (DTU) { - // Remove the terminator of BB to clear the successor list of BB. - if (BB->getTerminator()) - BB->getInstList().pop_back(); - new UnreachableInst(BB->getContext(), BB); - assert(succ_empty(BB) && "The successor list of BB isn't empty before " - "applying corresponding DTU updates."); - ++I; - } else { - I = F.getBasicBlockList().erase(I); - } - } - - if (DTU) { - DTU->applyUpdatesPermissive(Updates); - bool Deleted = false; - for (auto *BB : DeadBlockSet) { - if (DTU->isBBPendingDeletion(BB)) - --NumRemoved; - else - Deleted = true; - DTU->deleteBB(BB); - } - if (!Deleted) - return false; - } - return true; -} - -void llvm::combineMetadata(Instruction *K, const Instruction *J, - ArrayRef KnownIDs, bool DoesKMove) { - SmallVector, 4> Metadata; - K->dropUnknownNonDebugMetadata(KnownIDs); - K->getAllMetadataOtherThanDebugLoc(Metadata); - for (const auto &MD : Metadata) { - unsigned Kind = MD.first; - MDNode *JMD = J->getMetadata(Kind); - MDNode *KMD = MD.second; - - switch (Kind) { - default: - K->setMetadata(Kind, nullptr); // Remove unknown metadata - break; - case LLVMContext::MD_dbg: - llvm_unreachable("getAllMetadataOtherThanDebugLoc returned a MD_dbg"); - case LLVMContext::MD_tbaa: - K->setMetadata(Kind, MDNode::getMostGenericTBAA(JMD, KMD)); - break; - case LLVMContext::MD_alias_scope: - K->setMetadata(Kind, MDNode::getMostGenericAliasScope(JMD, KMD)); - break; - case LLVMContext::MD_noalias: - case LLVMContext::MD_mem_parallel_loop_access: - K->setMetadata(Kind, MDNode::intersect(JMD, KMD)); - break; - case LLVMContext::MD_access_group: - K->setMetadata(LLVMContext::MD_access_group, - intersectAccessGroups(K, J)); - break; - case LLVMContext::MD_range: - - // If K does move, use most generic range. Otherwise keep the range of - // K. - if (DoesKMove) - // FIXME: If K does move, we should drop the range info and nonnull. - // Currently this function is used with DoesKMove in passes - // doing hoisting/sinking and the current behavior of using the - // most generic range is correct in those cases. - K->setMetadata(Kind, MDNode::getMostGenericRange(JMD, KMD)); - break; - case LLVMContext::MD_fpmath: - K->setMetadata(Kind, MDNode::getMostGenericFPMath(JMD, KMD)); - break; - case LLVMContext::MD_invariant_load: - // Only set the !invariant.load if it is present in both instructions. - K->setMetadata(Kind, JMD); - break; - case LLVMContext::MD_nonnull: - // If K does move, keep nonull if it is present in both instructions. - if (DoesKMove) - K->setMetadata(Kind, JMD); - break; - case LLVMContext::MD_invariant_group: - // Preserve !invariant.group in K. - break; - case LLVMContext::MD_align: - K->setMetadata(Kind, - MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD)); - break; - case LLVMContext::MD_dereferenceable: - case LLVMContext::MD_dereferenceable_or_null: - K->setMetadata(Kind, - MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD)); - break; - } - } - // Set !invariant.group from J if J has it. If both instructions have it - // then we will just pick it from J - even when they are different. - // Also make sure that K is load or store - f.e. combining bitcast with load - // could produce bitcast with invariant.group metadata, which is invalid. - // FIXME: we should try to preserve both invariant.group md if they are - // different, but right now instruction can only have one invariant.group. - if (auto *JMD = J->getMetadata(LLVMContext::MD_invariant_group)) - if (isa(K) || isa(K)) - K->setMetadata(LLVMContext::MD_invariant_group, JMD); -} - -void llvm::combineMetadataForCSE(Instruction *K, const Instruction *J, - bool KDominatesJ) { - unsigned KnownIDs[] = { - LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope, - LLVMContext::MD_noalias, LLVMContext::MD_range, - LLVMContext::MD_invariant_load, LLVMContext::MD_nonnull, - LLVMContext::MD_invariant_group, LLVMContext::MD_align, - LLVMContext::MD_dereferenceable, - LLVMContext::MD_dereferenceable_or_null, - LLVMContext::MD_access_group}; - combineMetadata(K, J, KnownIDs, KDominatesJ); -} - -void llvm::patchReplacementInstruction(Instruction *I, Value *Repl) { - auto *ReplInst = dyn_cast(Repl); - if (!ReplInst) - return; - - // Patch the replacement so that it is not more restrictive than the value - // being replaced. - // Note that if 'I' is a load being replaced by some operation, - // for example, by an arithmetic operation, then andIRFlags() - // would just erase all math flags from the original arithmetic - // operation, which is clearly not wanted and not needed. - if (!isa(I)) - ReplInst->andIRFlags(I); - - // FIXME: If both the original and replacement value are part of the - // same control-flow region (meaning that the execution of one - // guarantees the execution of the other), then we can combine the - // noalias scopes here and do better than the general conservative - // answer used in combineMetadata(). - - // In general, GVN unifies expressions over different control-flow - // regions, and so we need a conservative combination of the noalias - // scopes. - static const unsigned KnownIDs[] = { - LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope, - LLVMContext::MD_noalias, LLVMContext::MD_range, - LLVMContext::MD_fpmath, LLVMContext::MD_invariant_load, - LLVMContext::MD_invariant_group, LLVMContext::MD_nonnull, - LLVMContext::MD_access_group}; - combineMetadata(ReplInst, I, KnownIDs, false); -} - -template -static unsigned replaceDominatedUsesWith(Value *From, Value *To, - const RootType &Root, - const DominatesFn &Dominates) { - assert(From->getType() == To->getType()); - - unsigned Count = 0; - for (Value::use_iterator UI = From->use_begin(), UE = From->use_end(); - UI != UE;) { - Use &U = *UI++; - if (!Dominates(Root, U)) - continue; - U.set(To); - LLVM_DEBUG(dbgs() << "Replace dominated use of '" << From->getName() - << "' as " << *To << " in " << *U << "\n"); - ++Count; - } - return Count; -} - -unsigned llvm::replaceNonLocalUsesWith(Instruction *From, Value *To) { - assert(From->getType() == To->getType()); - auto *BB = From->getParent(); - unsigned Count = 0; - - for (Value::use_iterator UI = From->use_begin(), UE = From->use_end(); - UI != UE;) { - Use &U = *UI++; - auto *I = cast(U.getUser()); - if (I->getParent() == BB) - continue; - U.set(To); - ++Count; - } - return Count; -} - -unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To, - DominatorTree &DT, - const BasicBlockEdge &Root) { - auto Dominates = [&DT](const BasicBlockEdge &Root, const Use &U) { - return DT.dominates(Root, U); - }; - return ::replaceDominatedUsesWith(From, To, Root, Dominates); -} - -unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To, - DominatorTree &DT, - const BasicBlock *BB) { - auto ProperlyDominates = [&DT](const BasicBlock *BB, const Use &U) { - auto *I = cast(U.getUser())->getParent(); - return DT.properlyDominates(BB, I); - }; - return ::replaceDominatedUsesWith(From, To, BB, ProperlyDominates); -} - -bool llvm::callsGCLeafFunction(const CallBase *Call, - const TargetLibraryInfo &TLI) { - // Check if the function is specifically marked as a gc leaf function. - if (Call->hasFnAttr("gc-leaf-function")) - return true; - if (const Function *F = Call->getCalledFunction()) { - if (F->hasFnAttribute("gc-leaf-function")) - return true; - - if (auto IID = F->getIntrinsicID()) - // Most LLVM intrinsics do not take safepoints. - return IID != Intrinsic::experimental_gc_statepoint && - IID != Intrinsic::experimental_deoptimize; - } - - // Lib calls can be materialized by some passes, and won't be - // marked as 'gc-leaf-function.' All available Libcalls are - // GC-leaf. - LibFunc LF; - if (TLI.getLibFunc(ImmutableCallSite(Call), LF)) { - return TLI.has(LF); - } - - return false; -} - -void llvm::copyNonnullMetadata(const LoadInst &OldLI, MDNode *N, - LoadInst &NewLI) { - auto *NewTy = NewLI.getType(); - - // This only directly applies if the new type is also a pointer. - if (NewTy->isPointerTy()) { - NewLI.setMetadata(LLVMContext::MD_nonnull, N); - return; - } - - // The only other translation we can do is to integral loads with !range - // metadata. - if (!NewTy->isIntegerTy()) - return; - - MDBuilder MDB(NewLI.getContext()); - const Value *Ptr = OldLI.getPointerOperand(); - auto *ITy = cast(NewTy); - auto *NullInt = ConstantExpr::getPtrToInt( - ConstantPointerNull::get(cast(Ptr->getType())), ITy); - auto *NonNullInt = ConstantExpr::getAdd(NullInt, ConstantInt::get(ITy, 1)); - NewLI.setMetadata(LLVMContext::MD_range, - MDB.createRange(NonNullInt, NullInt)); -} - -void llvm::copyRangeMetadata(const DataLayout &DL, const LoadInst &OldLI, - MDNode *N, LoadInst &NewLI) { - auto *NewTy = NewLI.getType(); - - // Give up unless it is converted to a pointer where there is a single very - // valuable mapping we can do reliably. - // FIXME: It would be nice to propagate this in more ways, but the type - // conversions make it hard. - if (!NewTy->isPointerTy()) - return; - - unsigned BitWidth = DL.getIndexTypeSizeInBits(NewTy); - if (!getConstantRangeFromMetadata(*N).contains(APInt(BitWidth, 0))) { - MDNode *NN = MDNode::get(OldLI.getContext(), None); - NewLI.setMetadata(LLVMContext::MD_nonnull, NN); - } -} - -void llvm::dropDebugUsers(Instruction &I) { - SmallVector DbgUsers; - findDbgUsers(DbgUsers, &I); - for (auto *DII : DbgUsers) - DII->eraseFromParent(); -} - -void llvm::hoistAllInstructionsInto(BasicBlock *DomBlock, Instruction *InsertPt, - BasicBlock *BB) { - // Since we are moving the instructions out of its basic block, we do not - // retain their original debug locations (DILocations) and debug intrinsic - // instructions. - // - // Doing so would degrade the debugging experience and adversely affect the - // accuracy of profiling information. - // - // Currently, when hoisting the instructions, we take the following actions: - // - Remove their debug intrinsic instructions. - // - Set their debug locations to the values from the insertion point. - // - // As per PR39141 (comment #8), the more fundamental reason why the dbg.values - // need to be deleted, is because there will not be any instructions with a - // DILocation in either branch left after performing the transformation. We - // can only insert a dbg.value after the two branches are joined again. - // - // See PR38762, PR39243 for more details. - // - // TODO: Extend llvm.dbg.value to take more than one SSA Value (PR39141) to - // encode predicated DIExpressions that yield different results on different - // code paths. - for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE;) { - Instruction *I = &*II; - I->dropUnknownNonDebugMetadata(); - if (I->isUsedByMetadata()) - dropDebugUsers(*I); - if (isa(I)) { - // Remove DbgInfo Intrinsics. - II = I->eraseFromParent(); - continue; - } - I->setDebugLoc(InsertPt->getDebugLoc()); - ++II; - } - DomBlock->getInstList().splice(InsertPt->getIterator(), BB->getInstList(), - BB->begin(), - BB->getTerminator()->getIterator()); -} - -namespace { - -/// A potential constituent of a bitreverse or bswap expression. See -/// collectBitParts for a fuller explanation. -struct BitPart { - BitPart(Value *P, unsigned BW) : Provider(P) { - Provenance.resize(BW); - } - - /// The Value that this is a bitreverse/bswap of. - Value *Provider; - - /// The "provenance" of each bit. Provenance[A] = B means that bit A - /// in Provider becomes bit B in the result of this expression. - SmallVector Provenance; // int8_t means max size is i128. - - enum { Unset = -1 }; -}; - -} // end anonymous namespace - -/// Analyze the specified subexpression and see if it is capable of providing -/// pieces of a bswap or bitreverse. The subexpression provides a potential -/// piece of a bswap or bitreverse if it can be proven that each non-zero bit in -/// the output of the expression came from a corresponding bit in some other -/// value. This function is recursive, and the end result is a mapping of -/// bitnumber to bitnumber. It is the caller's responsibility to validate that -/// the bitnumber to bitnumber mapping is correct for a bswap or bitreverse. -/// -/// For example, if the current subexpression if "(shl i32 %X, 24)" then we know -/// that the expression deposits the low byte of %X into the high byte of the -/// result and that all other bits are zero. This expression is accepted and a -/// BitPart is returned with Provider set to %X and Provenance[24-31] set to -/// [0-7]. -/// -/// To avoid revisiting values, the BitPart results are memoized into the -/// provided map. To avoid unnecessary copying of BitParts, BitParts are -/// constructed in-place in the \c BPS map. Because of this \c BPS needs to -/// store BitParts objects, not pointers. As we need the concept of a nullptr -/// BitParts (Value has been analyzed and the analysis failed), we an Optional -/// type instead to provide the same functionality. -/// -/// Because we pass around references into \c BPS, we must use a container that -/// does not invalidate internal references (std::map instead of DenseMap). -static const Optional & -collectBitParts(Value *V, bool MatchBSwaps, bool MatchBitReversals, - std::map> &BPS, int Depth) { - auto I = BPS.find(V); - if (I != BPS.end()) - return I->second; - - auto &Result = BPS[V] = None; - auto BitWidth = cast(V->getType())->getBitWidth(); - - // Prevent stack overflow by limiting the recursion depth - if (Depth == BitPartRecursionMaxDepth) { - LLVM_DEBUG(dbgs() << "collectBitParts max recursion depth reached.\n"); - return Result; - } - - if (Instruction *I = dyn_cast(V)) { - // If this is an or instruction, it may be an inner node of the bswap. - if (I->getOpcode() == Instruction::Or) { - auto &A = collectBitParts(I->getOperand(0), MatchBSwaps, - MatchBitReversals, BPS, Depth + 1); - auto &B = collectBitParts(I->getOperand(1), MatchBSwaps, - MatchBitReversals, BPS, Depth + 1); - if (!A || !B) - return Result; - - // Try and merge the two together. - if (!A->Provider || A->Provider != B->Provider) - return Result; - - Result = BitPart(A->Provider, BitWidth); - for (unsigned i = 0; i < A->Provenance.size(); ++i) { - if (A->Provenance[i] != BitPart::Unset && - B->Provenance[i] != BitPart::Unset && - A->Provenance[i] != B->Provenance[i]) - return Result = None; - - if (A->Provenance[i] == BitPart::Unset) - Result->Provenance[i] = B->Provenance[i]; - else - Result->Provenance[i] = A->Provenance[i]; - } - - return Result; - } - - // If this is a logical shift by a constant, recurse then shift the result. - if (I->isLogicalShift() && isa(I->getOperand(1))) { - unsigned BitShift = - cast(I->getOperand(1))->getLimitedValue(~0U); - // Ensure the shift amount is defined. - if (BitShift > BitWidth) - return Result; - - auto &Res = collectBitParts(I->getOperand(0), MatchBSwaps, - MatchBitReversals, BPS, Depth + 1); - if (!Res) - return Result; - Result = Res; - - // Perform the "shift" on BitProvenance. - auto &P = Result->Provenance; - if (I->getOpcode() == Instruction::Shl) { - P.erase(std::prev(P.end(), BitShift), P.end()); - P.insert(P.begin(), BitShift, BitPart::Unset); - } else { - P.erase(P.begin(), std::next(P.begin(), BitShift)); - P.insert(P.end(), BitShift, BitPart::Unset); - } - - return Result; - } - - // If this is a logical 'and' with a mask that clears bits, recurse then - // unset the appropriate bits. - if (I->getOpcode() == Instruction::And && - isa(I->getOperand(1))) { - APInt Bit(I->getType()->getPrimitiveSizeInBits(), 1); - const APInt &AndMask = cast(I->getOperand(1))->getValue(); - - // Check that the mask allows a multiple of 8 bits for a bswap, for an - // early exit. - unsigned NumMaskedBits = AndMask.countPopulation(); - if (!MatchBitReversals && NumMaskedBits % 8 != 0) - return Result; - - auto &Res = collectBitParts(I->getOperand(0), MatchBSwaps, - MatchBitReversals, BPS, Depth + 1); - if (!Res) - return Result; - Result = Res; - - for (unsigned i = 0; i < BitWidth; ++i, Bit <<= 1) - // If the AndMask is zero for this bit, clear the bit. - if ((AndMask & Bit) == 0) - Result->Provenance[i] = BitPart::Unset; - return Result; - } - - // If this is a zext instruction zero extend the result. - if (I->getOpcode() == Instruction::ZExt) { - auto &Res = collectBitParts(I->getOperand(0), MatchBSwaps, - MatchBitReversals, BPS, Depth + 1); - if (!Res) - return Result; - - Result = BitPart(Res->Provider, BitWidth); - auto NarrowBitWidth = - cast(cast(I)->getSrcTy())->getBitWidth(); - for (unsigned i = 0; i < NarrowBitWidth; ++i) - Result->Provenance[i] = Res->Provenance[i]; - for (unsigned i = NarrowBitWidth; i < BitWidth; ++i) - Result->Provenance[i] = BitPart::Unset; - return Result; - } - } - - // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be - // the input value to the bswap/bitreverse. - Result = BitPart(V, BitWidth); - for (unsigned i = 0; i < BitWidth; ++i) - Result->Provenance[i] = i; - return Result; -} - -static bool bitTransformIsCorrectForBSwap(unsigned From, unsigned To, - unsigned BitWidth) { - if (From % 8 != To % 8) - return false; - // Convert from bit indices to byte indices and check for a byte reversal. - From >>= 3; - To >>= 3; - BitWidth >>= 3; - return From == BitWidth - To - 1; -} - -static bool bitTransformIsCorrectForBitReverse(unsigned From, unsigned To, - unsigned BitWidth) { - return From == BitWidth - To - 1; -} - -bool llvm::recognizeBSwapOrBitReverseIdiom( - Instruction *I, bool MatchBSwaps, bool MatchBitReversals, - SmallVectorImpl &InsertedInsts) { - if (Operator::getOpcode(I) != Instruction::Or) - return false; - if (!MatchBSwaps && !MatchBitReversals) - return false; - IntegerType *ITy = dyn_cast(I->getType()); - if (!ITy || ITy->getBitWidth() > 128) - return false; // Can't do vectors or integers > 128 bits. - unsigned BW = ITy->getBitWidth(); - - unsigned DemandedBW = BW; - IntegerType *DemandedTy = ITy; - if (I->hasOneUse()) { - if (TruncInst *Trunc = dyn_cast(I->user_back())) { - DemandedTy = cast(Trunc->getType()); - DemandedBW = DemandedTy->getBitWidth(); - } - } - - // Try to find all the pieces corresponding to the bswap. - std::map> BPS; - auto Res = collectBitParts(I, MatchBSwaps, MatchBitReversals, BPS, 0); - if (!Res) - return false; - auto &BitProvenance = Res->Provenance; - - // Now, is the bit permutation correct for a bswap or a bitreverse? We can - // only byteswap values with an even number of bytes. - bool OKForBSwap = DemandedBW % 16 == 0, OKForBitReverse = true; - for (unsigned i = 0; i < DemandedBW; ++i) { - OKForBSwap &= - bitTransformIsCorrectForBSwap(BitProvenance[i], i, DemandedBW); - OKForBitReverse &= - bitTransformIsCorrectForBitReverse(BitProvenance[i], i, DemandedBW); - } - - Intrinsic::ID Intrin; - if (OKForBSwap && MatchBSwaps) - Intrin = Intrinsic::bswap; - else if (OKForBitReverse && MatchBitReversals) - Intrin = Intrinsic::bitreverse; - else - return false; - - if (ITy != DemandedTy) { - Function *F = Intrinsic::getDeclaration(I->getModule(), Intrin, DemandedTy); - Value *Provider = Res->Provider; - IntegerType *ProviderTy = cast(Provider->getType()); - // We may need to truncate the provider. - if (DemandedTy != ProviderTy) { - auto *Trunc = CastInst::Create(Instruction::Trunc, Provider, DemandedTy, - "trunc", I); - InsertedInsts.push_back(Trunc); - Provider = Trunc; - } - auto *CI = CallInst::Create(F, Provider, "rev", I); - InsertedInsts.push_back(CI); - auto *ExtInst = CastInst::Create(Instruction::ZExt, CI, ITy, "zext", I); - InsertedInsts.push_back(ExtInst); - return true; - } - - Function *F = Intrinsic::getDeclaration(I->getModule(), Intrin, ITy); - InsertedInsts.push_back(CallInst::Create(F, Res->Provider, "rev", I)); - return true; -} - -// CodeGen has special handling for some string functions that may replace -// them with target-specific intrinsics. Since that'd skip our interceptors -// in ASan/MSan/TSan/DFSan, and thus make us miss some memory accesses, -// we mark affected calls as NoBuiltin, which will disable optimization -// in CodeGen. -void llvm::maybeMarkSanitizerLibraryCallNoBuiltin( - CallInst *CI, const TargetLibraryInfo *TLI) { - Function *F = CI->getCalledFunction(); - LibFunc Func; - if (F && !F->hasLocalLinkage() && F->hasName() && - TLI->getLibFunc(F->getName(), Func) && TLI->hasOptimizedCodeGen(Func) && - !F->doesNotAccessMemory()) - CI->addAttribute(AttributeList::FunctionIndex, Attribute::NoBuiltin); -} - -bool llvm::canReplaceOperandWithVariable(const Instruction *I, unsigned OpIdx) { - // We can't have a PHI with a metadata type. - if (I->getOperand(OpIdx)->getType()->isMetadataTy()) - return false; - - // Early exit. - if (!isa(I->getOperand(OpIdx))) - return true; - - switch (I->getOpcode()) { - default: - return true; - case Instruction::Call: - case Instruction::Invoke: - // Can't handle inline asm. Skip it. - if (isa(ImmutableCallSite(I).getCalledValue())) - return false; - // Many arithmetic intrinsics have no issue taking a - // variable, however it's hard to distingish these from - // specials such as @llvm.frameaddress that require a constant. - if (isa(I)) - return false; - - // Constant bundle operands may need to retain their constant-ness for - // correctness. - if (ImmutableCallSite(I).isBundleOperand(OpIdx)) - return false; - return true; - case Instruction::ShuffleVector: - // Shufflevector masks are constant. - return OpIdx != 2; - case Instruction::Switch: - case Instruction::ExtractValue: - // All operands apart from the first are constant. - return OpIdx == 0; - case Instruction::InsertValue: - // All operands apart from the first and the second are constant. - return OpIdx < 2; - case Instruction::Alloca: - // Static allocas (constant size in the entry block) are handled by - // prologue/epilogue insertion so they're free anyway. We definitely don't - // want to make them non-constant. - return !cast(I)->isStaticAlloca(); - case Instruction::GetElementPtr: - if (OpIdx == 0) - return true; - gep_type_iterator It = gep_type_begin(I); - for (auto E = std::next(It, OpIdx); It != E; ++It) - if (It.isStruct()) - return false; - return true; - } -} - -using AllocaForValueMapTy = DenseMap; -AllocaInst *llvm::findAllocaForValue(Value *V, - AllocaForValueMapTy &AllocaForValue) { - if (AllocaInst *AI = dyn_cast(V)) - return AI; - // See if we've already calculated (or started to calculate) alloca for a - // given value. - AllocaForValueMapTy::iterator I = AllocaForValue.find(V); - if (I != AllocaForValue.end()) - return I->second; - // Store 0 while we're calculating alloca for value V to avoid - // infinite recursion if the value references itself. - AllocaForValue[V] = nullptr; - AllocaInst *Res = nullptr; - if (CastInst *CI = dyn_cast(V)) - Res = findAllocaForValue(CI->getOperand(0), AllocaForValue); - else if (PHINode *PN = dyn_cast(V)) { - for (Value *IncValue : PN->incoming_values()) { - // Allow self-referencing phi-nodes. - if (IncValue == PN) - continue; - AllocaInst *IncValueAI = findAllocaForValue(IncValue, AllocaForValue); - // AI for incoming values should exist and should all be equal. - if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res)) - return nullptr; - Res = IncValueAI; - } - } else if (GetElementPtrInst *EP = dyn_cast(V)) { - Res = findAllocaForValue(EP->getPointerOperand(), AllocaForValue); - } else { - LLVM_DEBUG(dbgs() << "Alloca search cancelled on unknown instruction: " - << *V << "\n"); - } - if (Res) - AllocaForValue[V] = Res; - return Res; -} -- cgit v1.2.3