/// SplitLandingPadPreds - The landing pad needs to be extracted with the invoke
/// instruction. The critical edge breaker will refuse to break critical edges
/// to a landing pad. So do them here. After this method runs, all landing pads
/// should have only one predecessor.
void BlockExtractorPass::SplitLandingPadPreds(Function *F) {
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
InvokeInst *II = dyn_cast<InvokeInst>(I);
if (!II) continue;
BasicBlock *Parent = II->getParent();
BasicBlock *LPad = II->getUnwindDest();
// Look through the landing pad's predecessors. If one of them ends in an
// 'invoke', then we want to split the landing pad.
bool Split = false;
for (pred_iterator
PI = pred_begin(LPad), PE = pred_end(LPad); PI != PE; ++PI) {
BasicBlock *BB = *PI;
if (BB->isLandingPad() && BB != Parent &&
isa<InvokeInst>(Parent->getTerminator())) {
Split = true;
break;
}
}
if (!Split) continue;
SmallVector<BasicBlock*, 2> NewBBs;
SplitLandingPadPredecessors(LPad, Parent, ".1", ".2", NewBBs);
}
}
/// Extracts the landing pads to make sure all of them have only one
/// predecessor.
void BlockExtractor::splitLandingPadPreds(Function &F) {
for (BasicBlock &BB : F) {
for (Instruction &I : BB) {
if (!isa<InvokeInst>(&I))
continue;
InvokeInst *II = cast<InvokeInst>(&I);
BasicBlock *Parent = II->getParent();
BasicBlock *LPad = II->getUnwindDest();
// Look through the landing pad's predecessors. If one of them ends in an
// 'invoke', then we want to split the landing pad.
bool Split = false;
for (auto PredBB : predecessors(LPad)) {
if (PredBB->isLandingPad() && PredBB != Parent &&
isa<InvokeInst>(Parent->getTerminator())) {
Split = true;
break;
}
}
if (!Split)
continue;
SmallVector<BasicBlock *, 2> NewBBs;
SplitLandingPadPredecessors(LPad, Parent, ".1", ".2", NewBBs);
}
}
}
// visitInvokeInst - Converting the "invoke" instruction is fairly
// straight-forward. The old exception part is replaced by a query asking
// if this is a longjmp exception. If it is, then it goes to the longjmp
// exception blocks. Otherwise, control is passed the old exception.
void LowerSetJmp::visitInvokeInst(InvokeInst& II)
{
if (II.getCalledFunction())
if (!IsTransformableFunction(II.getCalledFunction()->getName()) ||
II.getCalledFunction()->isIntrinsic()) return;
BasicBlock* BB = II.getParent();
// If not reachable from a setjmp call, don't transform.
if (!DFSBlocks.count(BB)) return;
BasicBlock* ExceptBB = II.getUnwindDest();
Function* Func = BB->getParent();
BasicBlock* NewExceptBB = BasicBlock::Create("InvokeExcept", Func);
BasicBlock::InstListType& InstList = NewExceptBB->getInstList();
// If this is a longjmp exception, then branch to the preliminary BB of
// the longjmp exception handling. Otherwise, go to the old exception.
CallInst* IsLJExcept = CallInst::Create(IsLJException, "IsLJExcept");
InstList.push_back(IsLJExcept);
BranchInst::Create(PrelimBBMap[Func], ExceptBB, IsLJExcept, NewExceptBB);
II.setUnwindDest(NewExceptBB);
++InvokesTransformed;
}
/// Replaces the given call site (Call or Invoke) with a gc.statepoint
/// intrinsic with an empty deoptimization arguments list. This does
/// NOT do explicit relocation for GC support.
static Value *ReplaceWithStatepoint(const CallSite &CS /* to replace */) {
assert(CS.getInstruction()->getModule() && "must be set");
// TODO: technically, a pass is not allowed to get functions from within a
// function pass since it might trigger a new function addition. Refactor
// this logic out to the initialization of the pass. Doesn't appear to
// matter in practice.
// Then go ahead and use the builder do actually do the inserts. We insert
// immediately before the previous instruction under the assumption that all
// arguments will be available here. We can't insert afterwards since we may
// be replacing a terminator.
IRBuilder<> Builder(CS.getInstruction());
// Note: The gc args are not filled in at this time, that's handled by
// RewriteStatepointsForGC (which is currently under review).
// Create the statepoint given all the arguments
Instruction *Token = nullptr;
uint64_t ID;
uint32_t NumPatchBytes;
AttributeSet OriginalAttrs = CS.getAttributes();
Attribute AttrID =
OriginalAttrs.getAttribute(AttributeSet::FunctionIndex, "statepoint-id");
Attribute AttrNumPatchBytes = OriginalAttrs.getAttribute(
AttributeSet::FunctionIndex, "statepoint-num-patch-bytes");
AttrBuilder AttrsToRemove;
bool HasID = AttrID.isStringAttribute() &&
!AttrID.getValueAsString().getAsInteger(10, ID);
if (HasID)
AttrsToRemove.addAttribute("statepoint-id");
else
ID = 0xABCDEF00;
bool HasNumPatchBytes =
AttrNumPatchBytes.isStringAttribute() &&
!AttrNumPatchBytes.getValueAsString().getAsInteger(10, NumPatchBytes);
if (HasNumPatchBytes)
AttrsToRemove.addAttribute("statepoint-num-patch-bytes");
else
NumPatchBytes = 0;
OriginalAttrs = OriginalAttrs.removeAttributes(
CS.getInstruction()->getContext(), AttributeSet::FunctionIndex,
AttrsToRemove);
if (CS.isCall()) {
CallInst *ToReplace = cast<CallInst>(CS.getInstruction());
CallInst *Call = Builder.CreateGCStatepointCall(
ID, NumPatchBytes, CS.getCalledValue(),
makeArrayRef(CS.arg_begin(), CS.arg_end()), None, None,
"safepoint_token");
Call->setTailCall(ToReplace->isTailCall());
Call->setCallingConv(ToReplace->getCallingConv());
// In case if we can handle this set of attributes - set up function
// attributes directly on statepoint and return attributes later for
// gc_result intrinsic.
Call->setAttributes(OriginalAttrs.getFnAttributes());
Token = Call;
// Put the following gc_result and gc_relocate calls immediately after
// the old call (which we're about to delete).
assert(ToReplace->getNextNode() && "not a terminator, must have next");
Builder.SetInsertPoint(ToReplace->getNextNode());
Builder.SetCurrentDebugLocation(ToReplace->getNextNode()->getDebugLoc());
} else if (CS.isInvoke()) {
InvokeInst *ToReplace = cast<InvokeInst>(CS.getInstruction());
// Insert the new invoke into the old block. We'll remove the old one in a
// moment at which point this will become the new terminator for the
// original block.
Builder.SetInsertPoint(ToReplace->getParent());
InvokeInst *Invoke = Builder.CreateGCStatepointInvoke(
ID, NumPatchBytes, CS.getCalledValue(), ToReplace->getNormalDest(),
ToReplace->getUnwindDest(), makeArrayRef(CS.arg_begin(), CS.arg_end()),
None, None, "safepoint_token");
Invoke->setCallingConv(ToReplace->getCallingConv());
// In case if we can handle this set of attributes - set up function
// attributes directly on statepoint and return attributes later for
// gc_result intrinsic.
Invoke->setAttributes(OriginalAttrs.getFnAttributes());
Token = Invoke;
// We'll insert the gc.result into the normal block
BasicBlock *NormalDest = ToReplace->getNormalDest();
// Can not insert gc.result in case of phi nodes preset.
// Should have removed this cases prior to running this function
assert(!isa<PHINode>(NormalDest->begin()));
Instruction *IP = &*(NormalDest->getFirstInsertionPt());
Builder.SetInsertPoint(IP);
} else {
llvm_unreachable("unexpect type of CallSite");
}
assert(Token);
// Handle the return value of the original call - update all uses to use a
// gc_result hanging off the statepoint node we just inserted
// Only add the gc_result iff there is actually a used result
if (!CS.getType()->isVoidTy() && !CS.getInstruction()->use_empty()) {
std::string TakenName =
CS.getInstruction()->hasName() ? CS.getInstruction()->getName() : "";
CallInst *GCResult = Builder.CreateGCResult(Token, CS.getType(), TakenName);
GCResult->setAttributes(OriginalAttrs.getRetAttributes());
return GCResult;
} else {
// No return value for the call.
return nullptr;
}
}
/// Replaces the given call site (Call or Invoke) with a gc.statepoint
/// intrinsic with an empty deoptimization arguments list. This does
/// NOT do explicit relocation for GC support.
static Value *ReplaceWithStatepoint(const CallSite &CS, /* to replace */
Pass *P) {
BasicBlock *BB = CS.getInstruction()->getParent();
Function *F = BB->getParent();
Module *M = F->getParent();
assert(M && "must be set");
// TODO: technically, a pass is not allowed to get functions from within a
// function pass since it might trigger a new function addition. Refactor
// this logic out to the initialization of the pass. Doesn't appear to
// matter in practice.
// Fill in the one generic type'd argument (the function is also vararg)
std::vector<Type *> argTypes;
argTypes.push_back(CS.getCalledValue()->getType());
Function *gc_statepoint_decl = Intrinsic::getDeclaration(
M, Intrinsic::experimental_gc_statepoint, argTypes);
// Then go ahead and use the builder do actually do the inserts. We insert
// immediately before the previous instruction under the assumption that all
// arguments will be available here. We can't insert afterwards since we may
// be replacing a terminator.
Instruction *insertBefore = CS.getInstruction();
IRBuilder<> Builder(insertBefore);
// First, create the statepoint (with all live ptrs as arguments).
std::vector<llvm::Value *> args;
// target, #args, unused, args
Value *Target = CS.getCalledValue();
args.push_back(Target);
int callArgSize = CS.arg_size();
args.push_back(
ConstantInt::get(Type::getInt32Ty(M->getContext()), callArgSize));
// TODO: add a 'Needs GC-rewrite' later flag
args.push_back(ConstantInt::get(Type::getInt32Ty(M->getContext()), 0));
// Copy all the arguments of the original call
args.insert(args.end(), CS.arg_begin(), CS.arg_end());
// Create the statepoint given all the arguments
Instruction *token = nullptr;
AttributeSet return_attributes;
if (CS.isCall()) {
CallInst *toReplace = cast<CallInst>(CS.getInstruction());
CallInst *call =
Builder.CreateCall(gc_statepoint_decl, args, "safepoint_token");
call->setTailCall(toReplace->isTailCall());
call->setCallingConv(toReplace->getCallingConv());
// Before we have to worry about GC semantics, all attributes are legal
AttributeSet new_attrs = toReplace->getAttributes();
// In case if we can handle this set of sttributes - set up function attrs
// directly on statepoint and return attrs later for gc_result intrinsic.
call->setAttributes(new_attrs.getFnAttributes());
return_attributes = new_attrs.getRetAttributes();
// TODO: handle param attributes
token = call;
// Put the following gc_result and gc_relocate calls immediately after the
// the old call (which we're about to delete)
BasicBlock::iterator next(toReplace);
assert(BB->end() != next && "not a terminator, must have next");
next++;
Instruction *IP = &*(next);
Builder.SetInsertPoint(IP);
Builder.SetCurrentDebugLocation(IP->getDebugLoc());
} else if (CS.isInvoke()) {
InvokeInst *toReplace = cast<InvokeInst>(CS.getInstruction());
// Insert the new invoke into the old block. We'll remove the old one in a
// moment at which point this will become the new terminator for the
// original block.
InvokeInst *invoke = InvokeInst::Create(
gc_statepoint_decl, toReplace->getNormalDest(),
toReplace->getUnwindDest(), args, "", toReplace->getParent());
invoke->setCallingConv(toReplace->getCallingConv());
// Currently we will fail on parameter attributes and on certain
// function attributes.
AttributeSet new_attrs = toReplace->getAttributes();
// In case if we can handle this set of sttributes - set up function attrs
// directly on statepoint and return attrs later for gc_result intrinsic.
invoke->setAttributes(new_attrs.getFnAttributes());
return_attributes = new_attrs.getRetAttributes();
token = invoke;
// We'll insert the gc.result into the normal block
BasicBlock *normalDest = normalizeBBForInvokeSafepoint(
toReplace->getNormalDest(), invoke->getParent());
Instruction *IP = &*(normalDest->getFirstInsertionPt());
Builder.SetInsertPoint(IP);
} else {
llvm_unreachable("unexpect type of CallSite");
}
assert(token);
// Handle the return value of the original call - update all uses to use a
// gc_result hanging off the statepoint node we just inserted
// Only add the gc_result iff there is actually a used result
if (!CS.getType()->isVoidTy() && !CS.getInstruction()->use_empty()) {
Instruction *gc_result = nullptr;
std::vector<Type *> types; // one per 'any' type
types.push_back(CS.getType()); // result type
auto get_gc_result_id = [&](Type &Ty) {
if (Ty.isIntegerTy()) {
return Intrinsic::experimental_gc_result_int;
} else if (Ty.isFloatingPointTy()) {
return Intrinsic::experimental_gc_result_float;
} else if (Ty.isPointerTy()) {
return Intrinsic::experimental_gc_result_ptr;
} else {
llvm_unreachable("non java type encountered");
}
};
Intrinsic::ID Id = get_gc_result_id(*CS.getType());
Value *gc_result_func = Intrinsic::getDeclaration(M, Id, types);
std::vector<Value *> args;
args.push_back(token);
gc_result = Builder.CreateCall(
gc_result_func, args,
CS.getInstruction()->hasName() ? CS.getInstruction()->getName() : "");
cast<CallInst>(gc_result)->setAttributes(return_attributes);
return gc_result;
} else {
// No return value for the call.
return nullptr;
}
}
/// Replaces the given call site (Call or Invoke) with a gc.statepoint
/// intrinsic with an empty deoptimization arguments list. This does
/// NOT do explicit relocation for GC support.
static Value *ReplaceWithStatepoint(const CallSite &CS, /* to replace */
Pass *P) {
assert(CS.getInstruction()->getParent()->getParent()->getParent() &&
"must be set");
// TODO: technically, a pass is not allowed to get functions from within a
// function pass since it might trigger a new function addition. Refactor
// this logic out to the initialization of the pass. Doesn't appear to
// matter in practice.
// Then go ahead and use the builder do actually do the inserts. We insert
// immediately before the previous instruction under the assumption that all
// arguments will be available here. We can't insert afterwards since we may
// be replacing a terminator.
IRBuilder<> Builder(CS.getInstruction());
// Note: The gc args are not filled in at this time, that's handled by
// RewriteStatepointsForGC (which is currently under review).
// Create the statepoint given all the arguments
Instruction *Token = nullptr;
AttributeSet OriginalAttrs;
if (CS.isCall()) {
CallInst *ToReplace = cast<CallInst>(CS.getInstruction());
CallInst *Call = Builder.CreateGCStatepointCall(
CS.getCalledValue(), makeArrayRef(CS.arg_begin(), CS.arg_end()), None,
None, "safepoint_token");
Call->setTailCall(ToReplace->isTailCall());
Call->setCallingConv(ToReplace->getCallingConv());
// Before we have to worry about GC semantics, all attributes are legal
// TODO: handle param attributes
OriginalAttrs = ToReplace->getAttributes();
// In case if we can handle this set of attributes - set up function
// attributes directly on statepoint and return attributes later for
// gc_result intrinsic.
Call->setAttributes(OriginalAttrs.getFnAttributes());
Token = Call;
// Put the following gc_result and gc_relocate calls immediately after the
// the old call (which we're about to delete).
assert(ToReplace->getNextNode() && "not a terminator, must have next");
Builder.SetInsertPoint(ToReplace->getNextNode());
Builder.SetCurrentDebugLocation(ToReplace->getNextNode()->getDebugLoc());
} else if (CS.isInvoke()) {
InvokeInst *ToReplace = cast<InvokeInst>(CS.getInstruction());
// Insert the new invoke into the old block. We'll remove the old one in a
// moment at which point this will become the new terminator for the
// original block.
Builder.SetInsertPoint(ToReplace->getParent());
InvokeInst *Invoke = Builder.CreateGCStatepointInvoke(
CS.getCalledValue(), ToReplace->getNormalDest(),
ToReplace->getUnwindDest(), makeArrayRef(CS.arg_begin(), CS.arg_end()),
Builder.getInt32(0), None, "safepoint_token");
// Currently we will fail on parameter attributes and on certain
// function attributes.
OriginalAttrs = ToReplace->getAttributes();
// In case if we can handle this set of attributes - set up function
// attributes directly on statepoint and return attributes later for
// gc_result intrinsic.
Invoke->setAttributes(OriginalAttrs.getFnAttributes());
Token = Invoke;
// We'll insert the gc.result into the normal block
BasicBlock *NormalDest = normalizeBBForInvokeSafepoint(
ToReplace->getNormalDest(), Invoke->getParent());
Builder.SetInsertPoint(NormalDest->getFirstInsertionPt());
} else {
llvm_unreachable("unexpect type of CallSite");
}
assert(Token);
// Handle the return value of the original call - update all uses to use a
// gc_result hanging off the statepoint node we just inserted
// Only add the gc_result iff there is actually a used result
if (!CS.getType()->isVoidTy() && !CS.getInstruction()->use_empty()) {
std::string TakenName =
CS.getInstruction()->hasName() ? CS.getInstruction()->getName() : "";
CallInst *GCResult = Builder.CreateGCResult(Token, CS.getType(), TakenName);
GCResult->setAttributes(OriginalAttrs.getRetAttributes());
return GCResult;
} else {
// No return value for the call.
return nullptr;
}
}
/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge
/// we spill into a stack location, guaranteeing that there is nothing live
/// across the unwind edge. This process also splits all critical edges
/// coming out of invoke's.
/// FIXME: Move this function to a common utility file (Local.cpp?) so
/// both SjLj and LowerInvoke can use it.
void SjLjEHPass::
splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) {
// First step, split all critical edges from invoke instructions.
for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
InvokeInst *II = Invokes[i];
SplitCriticalEdge(II, 0, this);
// FIXME: New EH - This if-condition will be always true in the new scheme.
if (II->getUnwindDest()->isLandingPad()) {
SmallVector<BasicBlock*, 2> NewBBs;
SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(),
".1", ".2", this, NewBBs);
LPadSuccMap[II] = *succ_begin(NewBBs[0]);
} else {
SplitCriticalEdge(II, 1, this);
}
assert(!isa<PHINode>(II->getNormalDest()) &&
!isa<PHINode>(II->getUnwindDest()) &&
"Critical edge splitting left single entry phi nodes?");
}
Function *F = Invokes.back()->getParent()->getParent();
// To avoid having to handle incoming arguments specially, we lower each arg
// to a copy instruction in the entry block. This ensures that the argument
// value itself cannot be live across the entry block.
BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
while (isa<AllocaInst>(AfterAllocaInsertPt) &&
isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
++AfterAllocaInsertPt;
for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
AI != E; ++AI) {
Type *Ty = AI->getType();
// Aggregate types can't be cast, but are legal argument types, so we have
// to handle them differently. We use an extract/insert pair as a
// lightweight method to achieve the same goal.
if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) {
Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt);
Instruction *NI = InsertValueInst::Create(AI, EI, 0);
NI->insertAfter(EI);
AI->replaceAllUsesWith(NI);
// Set the operand of the instructions back to the AllocaInst.
EI->setOperand(0, AI);
NI->setOperand(0, AI);
} else {
// This is always a no-op cast because we're casting AI to AI->getType()
// so src and destination types are identical. BitCast is the only
// possibility.
CastInst *NC = new BitCastInst(
AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
AI->replaceAllUsesWith(NC);
// Set the operand of the cast instruction back to the AllocaInst.
// Normally it's forbidden to replace a CastInst's operand because it
// could cause the opcode to reflect an illegal conversion. However,
// we're replacing it here with the same value it was constructed with.
// We do this because the above replaceAllUsesWith() clobbered the
// operand, but we want this one to remain.
NC->setOperand(0, AI);
}
}
// Finally, scan the code looking for instructions with bad live ranges.
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
// Ignore obvious cases we don't have to handle. In particular, most
// instructions either have no uses or only have a single use inside the
// current block. Ignore them quickly.
Instruction *Inst = II;
if (Inst->use_empty()) continue;
if (Inst->hasOneUse() &&
cast<Instruction>(Inst->use_back())->getParent() == BB &&
!isa<PHINode>(Inst->use_back())) continue;
// If this is an alloca in the entry block, it's not a real register
// value.
if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
continue;
// Avoid iterator invalidation by copying users to a temporary vector.
SmallVector<Instruction*,16> Users;
for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
UI != E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
if (User->getParent() != BB || isa<PHINode>(User))
Users.push_back(User);
}
// Find all of the blocks that this value is live in.
std::set<BasicBlock*> LiveBBs;
LiveBBs.insert(Inst->getParent());
while (!Users.empty()) {
Instruction *U = Users.back();
Users.pop_back();
if (!isa<PHINode>(U)) {
MarkBlocksLiveIn(U->getParent(), LiveBBs);
} else {
// Uses for a PHI node occur in their predecessor block.
PHINode *PN = cast<PHINode>(U);
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == Inst)
MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
}
}
// Now that we know all of the blocks that this thing is live in, see if
// it includes any of the unwind locations.
bool NeedsSpill = false;
for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
NeedsSpill = true;
}
}
// If we decided we need a spill, do it.
// FIXME: Spilling this way is overkill, as it forces all uses of
// the value to be reloaded from the stack slot, even those that aren't
// in the unwind blocks. We should be more selective.
if (NeedsSpill) {
++NumSpilled;
DemoteRegToStack(*Inst, true);
}
}
}