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llvm-project/llvm/lib/Transforms/Utils/CloneFunction.cpp

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//===- CloneFunction.cpp - Clone a function into another function ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the CloneFunctionInto interface, which is used as the
// low-level function cloner. This is used by the CloneFunction and function
// inliner to do the dirty work of copying the body of a function around.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <map>
using namespace llvm;
/// See comments in Cloning.h.
BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
const Twine &NameSuffix, Function *F,
ClonedCodeInfo *CodeInfo,
DebugInfoFinder *DIFinder) {
DenseMap<const MDNode *, MDNode *> Cache;
BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
Module *TheModule = F ? F->getParent() : nullptr;
// Loop over all instructions, and copy them over.
for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
II != IE; ++II) {
if (DIFinder && TheModule) {
if (auto *DDI = dyn_cast<DbgDeclareInst>(II))
DIFinder->processDeclare(*TheModule, DDI);
else if (auto *DVI = dyn_cast<DbgValueInst>(II))
DIFinder->processValue(*TheModule, DVI);
if (auto DbgLoc = II->getDebugLoc())
DIFinder->processLocation(*TheModule, DbgLoc.get());
}
Instruction *NewInst = II->clone();
if (II->hasName())
NewInst->setName(II->getName()+NameSuffix);
NewBB->getInstList().push_back(NewInst);
VMap[&*II] = NewInst; // Add instruction map to value.
hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (isa<ConstantInt>(AI->getArraySize()))
hasStaticAllocas = true;
else
hasDynamicAllocas = true;
}
}
if (CodeInfo) {
CodeInfo->ContainsCalls |= hasCalls;
CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
BB != &BB->getParent()->getEntryBlock();
}
return NewBB;
}
// Clone OldFunc into NewFunc, transforming the old arguments into references to
// VMap values.
//
void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
ValueToValueMapTy &VMap,
bool ModuleLevelChanges,
SmallVectorImpl<ReturnInst*> &Returns,
const char *NameSuffix, ClonedCodeInfo *CodeInfo,
ValueMapTypeRemapper *TypeMapper,
ValueMaterializer *Materializer) {
assert(NameSuffix && "NameSuffix cannot be null!");
#ifndef NDEBUG
for (const Argument &I : OldFunc->args())
assert(VMap.count(&I) && "No mapping from source argument specified!");
#endif
// Copy all attributes other than those stored in the AttributeList. We need
// to remap the parameter indices of the AttributeList.
AttributeList NewAttrs = NewFunc->getAttributes();
NewFunc->copyAttributesFrom(OldFunc);
NewFunc->setAttributes(NewAttrs);
// Fix up the personality function that got copied over.
if (OldFunc->hasPersonalityFn())
NewFunc->setPersonalityFn(
MapValue(OldFunc->getPersonalityFn(), VMap,
ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
TypeMapper, Materializer));
SmallVector<AttributeSet, 4> NewArgAttrs(NewFunc->arg_size());
AttributeList OldAttrs = OldFunc->getAttributes();
// Clone any argument attributes that are present in the VMap.
for (const Argument &OldArg : OldFunc->args()) {
if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) {
NewArgAttrs[NewArg->getArgNo()] =
OldAttrs.getParamAttributes(OldArg.getArgNo());
}
}
NewFunc->setAttributes(
AttributeList::get(NewFunc->getContext(), OldAttrs.getFnAttributes(),
OldAttrs.getRetAttributes(), NewArgAttrs));
bool MustCloneSP =
OldFunc->getParent() && OldFunc->getParent() == NewFunc->getParent();
DISubprogram *SP = OldFunc->getSubprogram();
if (SP) {
assert(!MustCloneSP || ModuleLevelChanges);
// Add mappings for some DebugInfo nodes that we don't want duplicated
// even if they're distinct.
auto &MD = VMap.MD();
MD[SP->getUnit()].reset(SP->getUnit());
MD[SP->getType()].reset(SP->getType());
MD[SP->getFile()].reset(SP->getFile());
// If we're not cloning into the same module, no need to clone the
// subprogram
if (!MustCloneSP)
MD[SP].reset(SP);
}
SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
OldFunc->getAllMetadata(MDs);
for (auto MD : MDs) {
NewFunc->addMetadata(
MD.first,
*MapMetadata(MD.second, VMap,
ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
TypeMapper, Materializer));
}
// When we remap instructions, we want to avoid duplicating inlined
// DISubprograms, so record all subprograms we find as we duplicate
// instructions and then freeze them in the MD map.
// We also record information about dbg.value and dbg.declare to avoid
// duplicating the types.
DebugInfoFinder DIFinder;
// Loop over all of the basic blocks in the function, cloning them as
// appropriate. Note that we save BE this way in order to handle cloning of
// recursive functions into themselves.
//
for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
BI != BE; ++BI) {
const BasicBlock &BB = *BI;
// Create a new basic block and copy instructions into it!
BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo,
SP ? &DIFinder : nullptr);
// Add basic block mapping.
VMap[&BB] = CBB;
// It is only legal to clone a function if a block address within that
// function is never referenced outside of the function. Given that, we
// want to map block addresses from the old function to block addresses in
// the clone. (This is different from the generic ValueMapper
// implementation, which generates an invalid blockaddress when
// cloning a function.)
if (BB.hasAddressTaken()) {
Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
const_cast<BasicBlock*>(&BB));
VMap[OldBBAddr] = BlockAddress::get(NewFunc, CBB);
}
// Note return instructions for the caller.
if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
Returns.push_back(RI);
}
for (DISubprogram *ISP : DIFinder.subprograms()) {
if (ISP != SP) {
VMap.MD()[ISP].reset(ISP);
}
}
for (auto *Type : DIFinder.types()) {
VMap.MD()[Type].reset(Type);
}
// Loop over all of the instructions in the function, fixing up operand
// references as we go. This uses VMap to do all the hard work.
for (Function::iterator BB =
cast<BasicBlock>(VMap[&OldFunc->front()])->getIterator(),
BE = NewFunc->end();
BB != BE; ++BB)
// Loop over all instructions, fixing each one as we find it...
for (Instruction &II : *BB)
RemapInstruction(&II, VMap,
ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
TypeMapper, Materializer);
}
/// Return a copy of the specified function and add it to that function's
/// module. Also, any references specified in the VMap are changed to refer to
/// their mapped value instead of the original one. If any of the arguments to
/// the function are in the VMap, the arguments are deleted from the resultant
/// function. The VMap is updated to include mappings from all of the
/// instructions and basicblocks in the function from their old to new values.
///
Function *llvm::CloneFunction(Function *F, ValueToValueMapTy &VMap,
ClonedCodeInfo *CodeInfo) {
std::vector<Type*> ArgTypes;
// The user might be deleting arguments to the function by specifying them in
// the VMap. If so, we need to not add the arguments to the arg ty vector
//
for (const Argument &I : F->args())
if (VMap.count(&I) == 0) // Haven't mapped the argument to anything yet?
ArgTypes.push_back(I.getType());
// Create a new function type...
FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
ArgTypes, F->getFunctionType()->isVarArg());
// Create the new function...
Function *NewF =
Function::Create(FTy, F->getLinkage(), F->getName(), F->getParent());
// Loop over the arguments, copying the names of the mapped arguments over...
Function::arg_iterator DestI = NewF->arg_begin();
for (const Argument & I : F->args())
if (VMap.count(&I) == 0) { // Is this argument preserved?
DestI->setName(I.getName()); // Copy the name over...
VMap[&I] = &*DestI++; // Add mapping to VMap
}
SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
CloneFunctionInto(NewF, F, VMap, F->getSubprogram() != nullptr, Returns, "",
CodeInfo);
return NewF;
}
namespace {
/// This is a private class used to implement CloneAndPruneFunctionInto.
struct PruningFunctionCloner {
Function *NewFunc;
const Function *OldFunc;
ValueToValueMapTy &VMap;
bool ModuleLevelChanges;
const char *NameSuffix;
ClonedCodeInfo *CodeInfo;
public:
PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
ValueToValueMapTy &valueMap, bool moduleLevelChanges,
const char *nameSuffix, ClonedCodeInfo *codeInfo)
: NewFunc(newFunc), OldFunc(oldFunc), VMap(valueMap),
ModuleLevelChanges(moduleLevelChanges), NameSuffix(nameSuffix),
CodeInfo(codeInfo) {}
/// The specified block is found to be reachable, clone it and
/// anything that it can reach.
void CloneBlock(const BasicBlock *BB,
BasicBlock::const_iterator StartingInst,
std::vector<const BasicBlock*> &ToClone);
};
}
/// The specified block is found to be reachable, clone it and
/// anything that it can reach.
void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
BasicBlock::const_iterator StartingInst,
std::vector<const BasicBlock*> &ToClone){
WeakTrackingVH &BBEntry = VMap[BB];
// Have we already cloned this block?
if (BBEntry) return;
// Nope, clone it now.
BasicBlock *NewBB;
BBEntry = NewBB = BasicBlock::Create(BB->getContext());
if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
// It is only legal to clone a function if a block address within that
// function is never referenced outside of the function. Given that, we
// want to map block addresses from the old function to block addresses in
// the clone. (This is different from the generic ValueMapper
// implementation, which generates an invalid blockaddress when
// cloning a function.)
//
// Note that we don't need to fix the mapping for unreachable blocks;
// the default mapping there is safe.
if (BB->hasAddressTaken()) {
Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
const_cast<BasicBlock*>(BB));
VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
}
bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
// Loop over all instructions, and copy them over, DCE'ing as we go. This
// loop doesn't include the terminator.
for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end();
II != IE; ++II) {
Instruction *NewInst = II->clone();
// Eagerly remap operands to the newly cloned instruction, except for PHI
// nodes for which we defer processing until we update the CFG.
if (!isa<PHINode>(NewInst)) {
RemapInstruction(NewInst, VMap,
ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
// If we can simplify this instruction to some other value, simply add
// a mapping to that value rather than inserting a new instruction into
// the basic block.
if (Value *V =
SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) {
// On the off-chance that this simplifies to an instruction in the old
// function, map it back into the new function.
if (NewFunc != OldFunc)
if (Value *MappedV = VMap.lookup(V))
V = MappedV;
if (!NewInst->mayHaveSideEffects()) {
VMap[&*II] = V;
NewInst->deleteValue();
continue;
}
}
}
if (II->hasName())
NewInst->setName(II->getName()+NameSuffix);
VMap[&*II] = NewInst; // Add instruction map to value.
NewBB->getInstList().push_back(NewInst);
hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
if (CodeInfo)
if (auto CS = ImmutableCallSite(&*II))
if (CS.hasOperandBundles())
CodeInfo->OperandBundleCallSites.push_back(NewInst);
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (isa<ConstantInt>(AI->getArraySize()))
hasStaticAllocas = true;
else
hasDynamicAllocas = true;
}
}
// Finally, clone over the terminator.
const TerminatorInst *OldTI = BB->getTerminator();
bool TerminatorDone = false;
if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
if (BI->isConditional()) {
// If the condition was a known constant in the callee...
ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
// Or is a known constant in the caller...
if (!Cond) {
Value *V = VMap.lookup(BI->getCondition());
Cond = dyn_cast_or_null<ConstantInt>(V);
}
// Constant fold to uncond branch!
if (Cond) {
BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
VMap[OldTI] = BranchInst::Create(Dest, NewBB);
ToClone.push_back(Dest);
TerminatorDone = true;
}
}
} else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
// If switching on a value known constant in the caller.
ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
if (!Cond) { // Or known constant after constant prop in the callee...
Value *V = VMap.lookup(SI->getCondition());
Cond = dyn_cast_or_null<ConstantInt>(V);
}
if (Cond) { // Constant fold to uncond branch!
SwitchInst::ConstCaseHandle Case = *SI->findCaseValue(Cond);
BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
VMap[OldTI] = BranchInst::Create(Dest, NewBB);
ToClone.push_back(Dest);
TerminatorDone = true;
}
}
if (!TerminatorDone) {
Instruction *NewInst = OldTI->clone();
if (OldTI->hasName())
NewInst->setName(OldTI->getName()+NameSuffix);
NewBB->getInstList().push_back(NewInst);
VMap[OldTI] = NewInst; // Add instruction map to value.
if (CodeInfo)
if (auto CS = ImmutableCallSite(OldTI))
if (CS.hasOperandBundles())
CodeInfo->OperandBundleCallSites.push_back(NewInst);
// Recursively clone any reachable successor blocks.
const TerminatorInst *TI = BB->getTerminator();
for (const BasicBlock *Succ : TI->successors())
ToClone.push_back(Succ);
}
if (CodeInfo) {
CodeInfo->ContainsCalls |= hasCalls;
CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
BB != &BB->getParent()->front();
}
}
/// This works like CloneAndPruneFunctionInto, except that it does not clone the
/// entire function. Instead it starts at an instruction provided by the caller
/// and copies (and prunes) only the code reachable from that instruction.
void llvm::CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
const Instruction *StartingInst,
ValueToValueMapTy &VMap,
bool ModuleLevelChanges,
SmallVectorImpl<ReturnInst *> &Returns,
const char *NameSuffix,
ClonedCodeInfo *CodeInfo) {
assert(NameSuffix && "NameSuffix cannot be null!");
ValueMapTypeRemapper *TypeMapper = nullptr;
ValueMaterializer *Materializer = nullptr;
#ifndef NDEBUG
// If the cloning starts at the beginning of the function, verify that
// the function arguments are mapped.
if (!StartingInst)
for (const Argument &II : OldFunc->args())
assert(VMap.count(&II) && "No mapping from source argument specified!");
#endif
PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
NameSuffix, CodeInfo);
const BasicBlock *StartingBB;
if (StartingInst)
StartingBB = StartingInst->getParent();
else {
StartingBB = &OldFunc->getEntryBlock();
StartingInst = &StartingBB->front();
}
// Clone the entry block, and anything recursively reachable from it.
std::vector<const BasicBlock*> CloneWorklist;
PFC.CloneBlock(StartingBB, StartingInst->getIterator(), CloneWorklist);
while (!CloneWorklist.empty()) {
const BasicBlock *BB = CloneWorklist.back();
CloneWorklist.pop_back();
PFC.CloneBlock(BB, BB->begin(), CloneWorklist);
}
// Loop over all of the basic blocks in the old function. If the block was
// reachable, we have cloned it and the old block is now in the value map:
// insert it into the new function in the right order. If not, ignore it.
//
// Defer PHI resolution until rest of function is resolved.
SmallVector<const PHINode*, 16> PHIToResolve;
for (const BasicBlock &BI : *OldFunc) {
Value *V = VMap.lookup(&BI);
BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
if (!NewBB) continue; // Dead block.
// Add the new block to the new function.
NewFunc->getBasicBlockList().push_back(NewBB);
// Handle PHI nodes specially, as we have to remove references to dead
// blocks.
for (const PHINode &PN : BI.phis()) {
// PHI nodes may have been remapped to non-PHI nodes by the caller or
// during the cloning process.
if (isa<PHINode>(VMap[&PN]))
PHIToResolve.push_back(&PN);
else
break;
}
// Finally, remap the terminator instructions, as those can't be remapped
// until all BBs are mapped.
RemapInstruction(NewBB->getTerminator(), VMap,
ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
TypeMapper, Materializer);
}
// Defer PHI resolution until rest of function is resolved, PHI resolution
// requires the CFG to be up-to-date.
for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
const PHINode *OPN = PHIToResolve[phino];
unsigned NumPreds = OPN->getNumIncomingValues();
const BasicBlock *OldBB = OPN->getParent();
BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);
// Map operands for blocks that are live and remove operands for blocks
// that are dead.
for (; phino != PHIToResolve.size() &&
PHIToResolve[phino]->getParent() == OldBB; ++phino) {
OPN = PHIToResolve[phino];
PHINode *PN = cast<PHINode>(VMap[OPN]);
for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
Value *V = VMap.lookup(PN->getIncomingBlock(pred));
if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
Value *InVal = MapValue(PN->getIncomingValue(pred),
VMap,
ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
assert(InVal && "Unknown input value?");
PN->setIncomingValue(pred, InVal);
PN->setIncomingBlock(pred, MappedBlock);
} else {
PN->removeIncomingValue(pred, false);
--pred; // Revisit the next entry.
--e;
}
}
}
// The loop above has removed PHI entries for those blocks that are dead
// and has updated others. However, if a block is live (i.e. copied over)
// but its terminator has been changed to not go to this block, then our
// phi nodes will have invalid entries. Update the PHI nodes in this
// case.
PHINode *PN = cast<PHINode>(NewBB->begin());
NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
if (NumPreds != PN->getNumIncomingValues()) {
assert(NumPreds < PN->getNumIncomingValues());
// Count how many times each predecessor comes to this block.
std::map<BasicBlock*, unsigned> PredCount;
for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
PI != E; ++PI)
--PredCount[*PI];
// Figure out how many entries to remove from each PHI.
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
++PredCount[PN->getIncomingBlock(i)];
// At this point, the excess predecessor entries are positive in the
// map. Loop over all of the PHIs and remove excess predecessor
// entries.
BasicBlock::iterator I = NewBB->begin();
for (; (PN = dyn_cast<PHINode>(I)); ++I) {
for (const auto &PCI : PredCount) {
BasicBlock *Pred = PCI.first;
for (unsigned NumToRemove = PCI.second; NumToRemove; --NumToRemove)
PN->removeIncomingValue(Pred, false);
}
}
}
// If the loops above have made these phi nodes have 0 or 1 operand,
// replace them with undef or the input value. We must do this for
// correctness, because 0-operand phis are not valid.
PN = cast<PHINode>(NewBB->begin());
if (PN->getNumIncomingValues() == 0) {
BasicBlock::iterator I = NewBB->begin();
BasicBlock::const_iterator OldI = OldBB->begin();
while ((PN = dyn_cast<PHINode>(I++))) {
Value *NV = UndefValue::get(PN->getType());
PN->replaceAllUsesWith(NV);
assert(VMap[&*OldI] == PN && "VMap mismatch");
VMap[&*OldI] = NV;
PN->eraseFromParent();
++OldI;
}
}
}
// Make a second pass over the PHINodes now that all of them have been
// remapped into the new function, simplifying the PHINode and performing any
// recursive simplifications exposed. This will transparently update the
// WeakTrackingVH in the VMap. Notably, we rely on that so that if we coalesce
// two PHINodes, the iteration over the old PHIs remains valid, and the
// mapping will just map us to the new node (which may not even be a PHI
// node).
const DataLayout &DL = NewFunc->getParent()->getDataLayout();
SmallSetVector<const Value *, 8> Worklist;
for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
if (isa<PHINode>(VMap[PHIToResolve[Idx]]))
Worklist.insert(PHIToResolve[Idx]);
// Note that we must test the size on each iteration, the worklist can grow.
for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
const Value *OrigV = Worklist[Idx];
auto *I = dyn_cast_or_null<Instruction>(VMap.lookup(OrigV));
if (!I)
continue;
// Skip over non-intrinsic callsites, we don't want to remove any nodes from
// the CGSCC.
CallSite CS = CallSite(I);
if (CS && CS.getCalledFunction() && !CS.getCalledFunction()->isIntrinsic())
continue;
// See if this instruction simplifies.
Value *SimpleV = SimplifyInstruction(I, DL);
if (!SimpleV)
continue;
// Stash away all the uses of the old instruction so we can check them for
// recursive simplifications after a RAUW. This is cheaper than checking all
// uses of To on the recursive step in most cases.
for (const User *U : OrigV->users())
Worklist.insert(cast<Instruction>(U));
// Replace the instruction with its simplified value.
I->replaceAllUsesWith(SimpleV);
// If the original instruction had no side effects, remove it.
if (isInstructionTriviallyDead(I))
I->eraseFromParent();
else
VMap[OrigV] = I;
}
// Now that the inlined function body has been fully constructed, go through
// and zap unconditional fall-through branches. This happens all the time when
// specializing code: code specialization turns conditional branches into
// uncond branches, and this code folds them.
Function::iterator Begin = cast<BasicBlock>(VMap[StartingBB])->getIterator();
Function::iterator I = Begin;
while (I != NewFunc->end()) {
// Check if this block has become dead during inlining or other
// simplifications. Note that the first block will appear dead, as it has
// not yet been wired up properly.
if (I != Begin && (pred_begin(&*I) == pred_end(&*I) ||
I->getSinglePredecessor() == &*I)) {
BasicBlock *DeadBB = &*I++;
DeleteDeadBlock(DeadBB);
continue;
}
// We need to simplify conditional branches and switches with a constant
// operand. We try to prune these out when cloning, but if the
// simplification required looking through PHI nodes, those are only
// available after forming the full basic block. That may leave some here,
// and we still want to prune the dead code as early as possible.
ConstantFoldTerminator(&*I);
BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
if (!BI || BI->isConditional()) { ++I; continue; }
BasicBlock *Dest = BI->getSuccessor(0);
if (!Dest->getSinglePredecessor()) {
++I; continue;
}
// We shouldn't be able to get single-entry PHI nodes here, as instsimplify
// above should have zapped all of them..
assert(!isa<PHINode>(Dest->begin()));
// We know all single-entry PHI nodes in the inlined function have been
// removed, so we just need to splice the blocks.
BI->eraseFromParent();
// Make all PHI nodes that referred to Dest now refer to I as their source.
Dest->replaceAllUsesWith(&*I);
// Move all the instructions in the succ to the pred.
I->getInstList().splice(I->end(), Dest->getInstList());
// Remove the dest block.
Dest->eraseFromParent();
// Do not increment I, iteratively merge all things this block branches to.
}
// Make a final pass over the basic blocks from the old function to gather
// any return instructions which survived folding. We have to do this here
// because we can iteratively remove and merge returns above.
for (Function::iterator I = cast<BasicBlock>(VMap[StartingBB])->getIterator(),
E = NewFunc->end();
I != E; ++I)
if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator()))
Returns.push_back(RI);
}
/// This works exactly like CloneFunctionInto,
/// except that it does some simple constant prop and DCE on the fly. The
/// effect of this is to copy significantly less code in cases where (for
/// example) a function call with constant arguments is inlined, and those
/// constant arguments cause a significant amount of code in the callee to be
/// dead. Since this doesn't produce an exact copy of the input, it can't be
/// used for things like CloneFunction or CloneModule.
void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
ValueToValueMapTy &VMap,
bool ModuleLevelChanges,
SmallVectorImpl<ReturnInst*> &Returns,
const char *NameSuffix,
ClonedCodeInfo *CodeInfo,
Instruction *TheCall) {
CloneAndPruneIntoFromInst(NewFunc, OldFunc, &OldFunc->front().front(), VMap,
ModuleLevelChanges, Returns, NameSuffix, CodeInfo);
}
/// \brief Remaps instructions in \p Blocks using the mapping in \p VMap.
void llvm::remapInstructionsInBlocks(
const SmallVectorImpl<BasicBlock *> &Blocks, ValueToValueMapTy &VMap) {
// Rewrite the code to refer to itself.
for (auto *BB : Blocks)
for (auto &Inst : *BB)
RemapInstruction(&Inst, VMap,
RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
}
/// \brief Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
/// Blocks.
///
/// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
/// \p LoopDomBB. Insert the new blocks before block specified in \p Before.
Loop *llvm::cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
Loop *OrigLoop, ValueToValueMapTy &VMap,
const Twine &NameSuffix, LoopInfo *LI,
DominatorTree *DT,
SmallVectorImpl<BasicBlock *> &Blocks) {
assert(OrigLoop->getSubLoops().empty() &&
"Loop to be cloned cannot have inner loop");
Function *F = OrigLoop->getHeader()->getParent();
Loop *ParentLoop = OrigLoop->getParentLoop();
Loop *NewLoop = LI->AllocateLoop();
if (ParentLoop)
ParentLoop->addChildLoop(NewLoop);
else
LI->addTopLevelLoop(NewLoop);
BasicBlock *OrigPH = OrigLoop->getLoopPreheader();
assert(OrigPH && "No preheader");
BasicBlock *NewPH = CloneBasicBlock(OrigPH, VMap, NameSuffix, F);
// To rename the loop PHIs.
VMap[OrigPH] = NewPH;
Blocks.push_back(NewPH);
// Update LoopInfo.
if (ParentLoop)
ParentLoop->addBasicBlockToLoop(NewPH, *LI);
// Update DominatorTree.
DT->addNewBlock(NewPH, LoopDomBB);
for (BasicBlock *BB : OrigLoop->getBlocks()) {
BasicBlock *NewBB = CloneBasicBlock(BB, VMap, NameSuffix, F);
VMap[BB] = NewBB;
// Update LoopInfo.
NewLoop->addBasicBlockToLoop(NewBB, *LI);
// Add DominatorTree node. After seeing all blocks, update to correct IDom.
DT->addNewBlock(NewBB, NewPH);
Blocks.push_back(NewBB);
}
for (BasicBlock *BB : OrigLoop->getBlocks()) {
// Update DominatorTree.
BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock();
DT->changeImmediateDominator(cast<BasicBlock>(VMap[BB]),
cast<BasicBlock>(VMap[IDomBB]));
}
// Move them physically from the end of the block list.
F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
NewPH);
F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
NewLoop->getHeader()->getIterator(), F->end());
return NewLoop;
}
/// \brief Duplicate non-Phi instructions from the beginning of block up to
/// StopAt instruction into a split block between BB and its predecessor.
BasicBlock *
llvm::DuplicateInstructionsInSplitBetween(BasicBlock *BB, BasicBlock *PredBB,
Instruction *StopAt,
ValueToValueMapTy &ValueMapping) {
// We are going to have to map operands from the original BB block to the new
// copy of the block 'NewBB'. If there are PHI nodes in BB, evaluate them to
// account for entry from PredBB.
BasicBlock::iterator BI = BB->begin();
for (; PHINode *PN = dyn_cast<PHINode>(BI); ++BI)
ValueMapping[PN] = PN->getIncomingValueForBlock(PredBB);
BasicBlock *NewBB = SplitEdge(PredBB, BB);
NewBB->setName(PredBB->getName() + ".split");
Instruction *NewTerm = NewBB->getTerminator();
// Clone the non-phi instructions of BB into NewBB, keeping track of the
// mapping and using it to remap operands in the cloned instructions.
// Stop once we see the terminator too. This covers the case where BB's
// terminator gets replaced and StopAt == BB's terminator.
for (; StopAt != &*BI && BB->getTerminator() != &*BI; ++BI) {
Instruction *New = BI->clone();
New->setName(BI->getName());
New->insertBefore(NewTerm);
ValueMapping[&*BI] = New;
// Remap operands to patch up intra-block references.
for (unsigned i = 0, e = New->getNumOperands(); i != e; ++i)
if (Instruction *Inst = dyn_cast<Instruction>(New->getOperand(i))) {
auto I = ValueMapping.find(Inst);
if (I != ValueMapping.end())
New->setOperand(i, I->second);
}
}
return NewBB;
}
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