#include "llvm/Pass.h"
#include "llvm/Analysis/CFG.h"
+#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/MapVector.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Dominators.h"
using namespace llvm;
-// Print tracing output
-static cl::opt<bool> TraceLSP("trace-rewrite-statepoints", cl::Hidden,
- cl::init(false));
-
// Print the liveset found at the insert location
static cl::opt<bool> PrintLiveSet("spp-print-liveset", cl::Hidden,
cl::init(false));
cl::location(ClobberNonLive),
cl::Hidden);
+static cl::opt<bool> UseDeoptBundles("rs4gc-use-deopt-bundles", cl::Hidden,
+ cl::init(false));
+static cl::opt<bool>
+ AllowStatepointWithNoDeoptInfo("rs4gc-allow-statepoint-with-no-deopt-info",
+ cl::Hidden, cl::init(true));
+
namespace {
struct RewriteStatepointsForGC : public ModulePass {
static char ID; // Pass identification, replacement for typeid
Changed |= runOnFunction(F);
if (Changed) {
- // stripDereferenceabilityInfo asserts that shouldRewriteStatepointsIn
+ // stripNonValidAttributes asserts that shouldRewriteStatepointsIn
// returns true for at least one function in the module. Since at least
// one function changed, we know that the precondition is satisfied.
- stripDereferenceabilityInfo(M);
+ stripNonValidAttributes(M);
}
return Changed;
/// dereferenceability that are no longer valid/correct after
/// RewriteStatepointsForGC has run. This is because semantically, after
/// RewriteStatepointsForGC runs, all calls to gc.statepoint "free" the entire
- /// heap. stripDereferenceabilityInfo (conservatively) restores correctness
+ /// heap. stripNonValidAttributes (conservatively) restores correctness
/// by erasing all attributes in the module that externally imply
/// dereferenceability.
- ///
- void stripDereferenceabilityInfo(Module &M);
+ /// Similar reasoning also applies to the noalias attributes. gc.statepoint
+ /// can touch the entire heap including noalias objects.
+ void stripNonValidAttributes(Module &M);
- // Helpers for stripDereferenceabilityInfo
- void stripDereferenceabilityInfoFromBody(Function &F);
- void stripDereferenceabilityInfoFromPrototype(Function &F);
+ // Helpers for stripNonValidAttributes
+ void stripNonValidAttributesFromBody(Function &F);
+ void stripNonValidAttributesFromPrototype(Function &F);
};
} // namespace
// base relation will remain. Internally, we add a mixture of the two
// types, then update all the second type to the first type
typedef DenseMap<Value *, Value *> DefiningValueMapTy;
-typedef DenseSet<llvm::Value *> StatepointLiveSetTy;
-typedef DenseMap<Instruction *, Value *> RematerializedValueMapTy;
+typedef DenseSet<Value *> StatepointLiveSetTy;
+typedef DenseMap<AssertingVH<Instruction>, AssertingVH<Value>>
+ RematerializedValueMapTy;
struct PartiallyConstructedSafepointRecord {
- /// The set of values known to be live accross this safepoint
- StatepointLiveSetTy liveset;
+ /// The set of values known to be live across this safepoint
+ StatepointLiveSetTy LiveSet;
/// Mapping from live pointers to a base-defining-value
- DenseMap<llvm::Value *, llvm::Value *> PointerToBase;
+ DenseMap<Value *, Value *> PointerToBase;
/// The *new* gc.statepoint instruction itself. This produces the token
/// that normal path gc.relocates and the gc.result are tied to.
Instruction *UnwindToken;
/// Record live values we are rematerialized instead of relocating.
- /// They are not included into 'liveset' field.
+ /// They are not included into 'LiveSet' field.
/// Maps rematerialized copy to it's original value.
RematerializedValueMapTy RematerializedValues;
};
}
+static ArrayRef<Use> GetDeoptBundleOperands(ImmutableCallSite CS) {
+ assert(UseDeoptBundles && "Should not be called otherwise!");
+
+ Optional<OperandBundleUse> DeoptBundle = CS.getOperandBundle("deopt");
+
+ if (!DeoptBundle.hasValue()) {
+ assert(AllowStatepointWithNoDeoptInfo &&
+ "Found non-leaf call without deopt info!");
+ return None;
+ }
+
+ return DeoptBundle.getValue().Inputs;
+}
+
/// Compute the live-in set for every basic block in the function
static void computeLiveInValues(DominatorTree &DT, Function &F,
GCPtrLivenessData &Data);
// TODO: Once we can get to the GCStrategy, this becomes
// Optional<bool> isGCManagedPointer(const Value *V) const override {
-static bool isGCPointerType(const Type *T) {
- if (
const PointerType *PT = dyn_cast<PointerType>(T))
+static bool isGCPointerType(Type *T) {
+ if (
auto *PT = dyn_cast<PointerType>(T))
// For the sake of this example GC, we arbitrarily pick addrspace(1) as our
// GC managed heap. We know that a pointer into this heap needs to be
// updated and that no other pointer does.
if (ArrayType *AT = dyn_cast<ArrayType>(Ty))
return containsGCPtrType(AT->getElementType());
if (StructType *ST = dyn_cast<StructType>(Ty))
- return std::any_of(
- ST->subtypes().begin(), ST->subtypes().end(),
- [](Type *SubType) { return containsGCPtrType(SubType); });
+ return std::any_of(ST->subtypes().begin(), ST->subtypes().end(),
+ containsGCPtrType);
return false;
}
}
#endif
-static bool order_by_name(llvm::Value *a, llvm::Value *b) {
+static bool order_by_name(Value *a, Value *b) {
if (a->hasName() && b->hasName()) {
return -1 == a->getName().compare(b->getName());
} else if (a->hasName() && !b->hasName()) {
}
}
+// Return the name of the value suffixed with the provided value, or if the
+// value didn't have a name, the default value specified.
+static std::string suffixed_name_or(Value *V, StringRef Suffix,
+ StringRef DefaultName) {
+ return V->hasName() ? (V->getName() + Suffix).str() : DefaultName.str();
+}
+
// Conservatively identifies any definitions which might be live at the
// given instruction. The analysis is performed immediately before the
// given instruction. Values defined by that instruction are not considered
const CallSite &CS, PartiallyConstructedSafepointRecord &result) {
Instruction *inst = CS.getInstruction();
- StatepointLiveSetTy liveset;
- findLiveSetAtInst(inst, OriginalLivenessData, liveset);
+ StatepointLiveSetTy LiveSet;
+ findLiveSetAtInst(inst, OriginalLivenessData, LiveSet);
if (PrintLiveSet) {
// Note: This output is used by several of the test cases
- // The order of elemtns in a set is not stable, put them in a vec and sort
+ // The order of elements in a set is not stable, put them in a vec and sort
// by name
- SmallVector<Value *, 64> temp;
- temp.insert(temp.end(), liveset.begin(), liveset.end());
- std::sort(temp.begin(), temp.end(), order_by_name);
+ SmallVector<Value *, 64> Temp;
+ Temp.insert(Temp.end(), LiveSet.begin(), LiveSet.end());
+ std::sort(Temp.begin(), Temp.end(), order_by_name);
errs() << "Live Variables:\n";
- for (Value *V : temp) {
- errs() << " " << V->getName(); // no newline
- V->dump();
- }
+ for (Value *V : Temp)
+ dbgs() << " " << V->getName() << " " << *V << "\n";
}
if (PrintLiveSetSize) {
errs() << "Safepoint For: " << CS.getCalledValue()->getName() << "\n";
- errs() << "Number live values: " << liveset.size() << "\n";
+ errs() << "Number live values: " << LiveSet.size() << "\n";
+ }
+ result.LiveSet = LiveSet;
+}
+
+static bool isKnownBaseResult(Value *V);
+namespace {
+/// A single base defining value - An immediate base defining value for an
+/// instruction 'Def' is an input to 'Def' whose base is also a base of 'Def'.
+/// For instructions which have multiple pointer [vector] inputs or that
+/// transition between vector and scalar types, there is no immediate base
+/// defining value. The 'base defining value' for 'Def' is the transitive
+/// closure of this relation stopping at the first instruction which has no
+/// immediate base defining value. The b.d.v. might itself be a base pointer,
+/// but it can also be an arbitrary derived pointer.
+struct BaseDefiningValueResult {
+ /// Contains the value which is the base defining value.
+ Value * const BDV;
+ /// True if the base defining value is also known to be an actual base
+ /// pointer.
+ const bool IsKnownBase;
+ BaseDefiningValueResult(Value *BDV, bool IsKnownBase)
+ : BDV(BDV), IsKnownBase(IsKnownBase) {
+#ifndef NDEBUG
+ // Check consistency between new and old means of checking whether a BDV is
+ // a base.
+ bool MustBeBase = isKnownBaseResult(BDV);
+ assert(!MustBeBase || MustBeBase == IsKnownBase);
+#endif
}
- result.liveset = liveset;
+};
}
-static Value *findBaseDefiningValue(Value *I);
+static BaseDefiningValueResult findBaseDefiningValue(Value *I);
/// Return a base defining value for the 'Index' element of the given vector
/// instruction 'I'. If Index is null, returns a BDV for the entire vector
/// vector returned is a BDV (and possibly a base) of the entire vector 'I'.
/// If the later, the return pointer is a BDV (or possibly a base) for the
/// particular element in 'I'.
-static std::pair<Value *, bool>
-findBaseDefiningValueOfVector(Value *I, Value *Index = nullptr) {
+static BaseDefiningValueResult
+findBaseDefiningValueOfVector(Value *I) {
assert(I->getType()->isVectorTy() &&
cast<VectorType>(I->getType())->getElementType()->isPointerTy() &&
"Illegal to ask for the base pointer of a non-pointer type");
if (isa<Argument>(I))
// An incoming argument to the function is a base pointer
- return std::make_pair(I, true);
+ return BaseDefiningValueResult(I, true);
// We shouldn't see the address of a global as a vector value?
assert(!isa<GlobalVariable>(I) &&
if (isa<UndefValue>(I))
// utterly meaningless, but useful for dealing with partially optimized
// code.
- return std::make_pair(I, true);
+ return BaseDefiningValueResult(I, true);
// Due to inheritance, this must be _after_ the global variable and undef
// checks
assert(!isa<GlobalVariable>(I) && !isa<UndefValue>(I) &&
"order of checks wrong!");
assert(Con->isNullValue() && "null is the only case which makes sense");
- return std::make_pair(Con, true);
+ return BaseDefiningValueResult(Con, true);
}
if (isa<LoadInst>(I))
- return std::make_pair(I, true);
-
- // For an insert element, we might be able to look through it if we know
- // something about the indexes.
- if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(I)) {
- if (Index) {
- Value *InsertIndex = IEI->getOperand(2);
- // This index is inserting the value, look for its BDV
- if (InsertIndex == Index)
- return std::make_pair(findBaseDefiningValue(IEI->getOperand(1)), false);
- // Both constant, and can't be equal per above. This insert is definitely
- // not relevant, look back at the rest of the vector and keep trying.
- if (isa<ConstantInt>(Index) && isa<ConstantInt>(InsertIndex))
- return findBaseDefiningValueOfVector(IEI->getOperand(0), Index);
- }
-
+ return BaseDefiningValueResult(I, true);
+
+ if (isa<InsertElementInst>(I))
// We don't know whether this vector contains entirely base pointers or
// not. To be conservatively correct, we treat it as a BDV and will
// duplicate code as needed to construct a parallel vector of bases.
- return std::make_pair(IEI, false);
- }
+ return BaseDefiningValueResult(I, false);
if (isa<ShuffleVectorInst>(I))
// We don't know whether this vector contains entirely base pointers or
// duplicate code as needed to construct a parallel vector of bases.
// TODO: There a number of local optimizations which could be applied here
// for particular sufflevector patterns.
- return std::make_pair(I, false);
+ return BaseDefiningValueResult(I, false);
// A PHI or Select is a base defining value. The outer findBasePointer
// algorithm is responsible for constructing a base value for this BDV.
assert((isa<SelectInst>(I) || isa<PHINode>(I)) &&
"unknown vector instruction - no base found for vector element");
- return std::make_pair(I, false);
+ return BaseDefiningValueResult(I, false);
}
-static bool isKnownBaseResult(Value *V);
-
/// Helper function for findBasePointer - Will return a value which either a)
-/// defines the base pointer for the input or b) blocks the simple search
-/// (i.e. a PHI or Select of two derived pointers)
-static Value *findBaseDefiningValue(Value *I) {
+/// defines the base pointer for the input, b) blocks the simple search
+/// (i.e. a PHI or Select of two derived pointers), or c) involves a change
+/// from pointer to vector type or back.
+static BaseDefiningValueResult findBaseDefiningValue(Value *I) {
if (I->getType()->isVectorTy())
- return findBaseDefiningValueOfVector(I).first;
+ return findBaseDefiningValueOfVector(I);
assert(I->getType()->isPointerTy() &&
"Illegal to ask for the base pointer of a non-pointer type");
- // This case is a bit of a hack - it only handles extracts from vectors which
- // trivially contain only base pointers or cases where we can directly match
- // the index of the original extract element to an insertion into the vector.
- // See note inside the function for how to improve this.
- if (auto *EEI = dyn_cast<ExtractElementInst>(I)) {
- Value *VectorOperand = EEI->getVectorOperand();
- Value *Index = EEI->getIndexOperand();
- std::pair<Value *, bool> pair =
- findBaseDefiningValueOfVector(VectorOperand, Index);
- Value *VectorBase = pair.first;
- if (VectorBase->getType()->isPointerTy())
- // We found a BDV for this specific element with the vector. This is an
- // optimization, but in practice it covers most of the useful cases
- // created via scalarization.
- return VectorBase;
- else {
- assert(VectorBase->getType()->isVectorTy());
- if (pair.second)
- // If the entire vector returned is known to be entirely base pointers,
- // then the extractelement is valid base for this value.
- return EEI;
- else {
- // Otherwise, we have an instruction which potentially produces a
- // derived pointer and we need findBasePointers to clone code for us
- // such that we can create an instruction which produces the
- // accompanying base pointer.
- // Note: This code is currently rather incomplete. We don't currently
- // support the general form of shufflevector of insertelement.
- // Conceptually, these are just 'base defining values' of the same
- // variety as phi or select instructions. We need to update the
- // findBasePointers algorithm to insert new 'base-only' versions of the
- // original instructions. This is relative straight forward to do, but
- // the case which would motivate the work hasn't shown up in real
- // workloads yet.
- assert((isa<PHINode>(VectorBase) || isa<SelectInst>(VectorBase)) &&
- "need to extend findBasePointers for generic vector"
- "instruction cases");
- return VectorBase;
- }
- }
- }
-
if (isa<Argument>(I))
// An incoming argument to the function is a base pointer
// We should have never reached here if this argument isn't an gc value
- return I;
+ return BaseDefiningValueResult(I, true);
if (isa<GlobalVariable>(I))
// base case
- return I;
+ return BaseDefiningValueResult(I, true);
// inlining could possibly introduce phi node that contains
// undef if callee has multiple returns
if (isa<UndefValue>(I))
// utterly meaningless, but useful for dealing with
// partially optimized code.
- return I;
+ return BaseDefiningValueResult(I, true);
// Due to inheritance, this must be _after_ the global variable and undef
// checks
- if (Constant *Con = dyn_cast<Constant>(I)) {
+ if (isa<Constant>(I)) {
assert(!isa<GlobalVariable>(I) && !isa<UndefValue>(I) &&
"order of checks wrong!");
// Note: Finding a constant base for something marked for relocation
// off a potentially null value and have proven it null. We also use
// null pointers in dead paths of relocation phis (which we might later
// want to find a base pointer for).
- assert(isa<ConstantPointerNull>(Con) &&
+ assert(isa<ConstantPointerNull>(I) &&
"null is the only case which makes sense");
- return Con;
+ return BaseDefiningValueResult(I, true);
}
if (CastInst *CI = dyn_cast<CastInst>(I)) {
}
if (isa<LoadInst>(I))
- return I; // The value loaded is an gc base itself
+ // The value loaded is an gc base itself
+ return BaseDefiningValueResult(I, true);
+
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I))
// The base of this GEP is the base
// pointers. This should probably be generalized via attributes to support
// both source language and internal functions.
if (isa<CallInst>(I) || isa<InvokeInst>(I))
- return I;
+ return BaseDefiningValueResult(I, true);
// I have absolutely no idea how to implement this part yet. It's not
- // neccessarily hard, I just haven't really looked at it yet.
+ // necessarily hard, I just haven't really looked at it yet.
assert(!isa<LandingPadInst>(I) && "Landing Pad is unimplemented");
if (isa<AtomicCmpXchgInst>(I))
// A CAS is effectively a atomic store and load combined under a
// predicate. From the perspective of base pointers, we just treat it
// like a load.
- return I;
+ return BaseDefiningValueResult(I, true);
assert(!isa<AtomicRMWInst>(I) && "Xchg handled above, all others are "
"binary ops which don't apply to pointers");
// stack, but in either case, this is simply a field load. As a result,
// this is a defining definition of the base just like a load is.
if (isa<ExtractValueInst>(I))
- return I;
+ return BaseDefiningValueResult(I, true);
// We should never see an insert vector since that would require we be
// tracing back a struct value not a pointer value.
assert(!isa<InsertValueInst>(I) &&
"Base pointer for a struct is meaningless");
+ // An extractelement produces a base result exactly when it's input does.
+ // We may need to insert a parallel instruction to extract the appropriate
+ // element out of the base vector corresponding to the input. Given this,
+ // it's analogous to the phi and select case even though it's not a merge.
+ if (isa<ExtractElementInst>(I))
+ // Note: There a lot of obvious peephole cases here. This are deliberately
+ // handled after the main base pointer inference algorithm to make writing
+ // test cases to exercise that code easier.
+ return BaseDefiningValueResult(I, false);
+
// The last two cases here don't return a base pointer. Instead, they
- // return a value which dynamically selects from amoung several base
+ // return a value which dynamically selects from among several base
// derived pointers (each with it's own base potentially). It's the job of
// the caller to resolve these.
assert((isa<SelectInst>(I) || isa<PHINode>(I)) &&
"missing instruction case in findBaseDefiningValing");
- return I;
+ return BaseDefiningValueResult(I, false);
}
/// Returns the base defining value for this value.
static Value *findBaseDefiningValueCached(Value *I, DefiningValueMapTy &Cache) {
Value *&Cached = Cache[I];
if (!Cached) {
- Cached = findBaseDefiningValue(I);
+ Cached = findBaseDefiningValue(I).BDV;
+ DEBUG(dbgs() << "fBDV-cached: " << I->getName() << " -> "
+ << Cached->getName() << "\n");
}
assert(Cache[I] != nullptr);
-
- if (TraceLSP) {
- dbgs() << "fBDV-cached: " << I->getName() << " -> " << Cached->getName()
- << "\n";
- }
return Cached;
}
/// Given the result of a call to findBaseDefiningValue, or findBaseOrBDV,
/// is it known to be a base pointer? Or do we need to continue searching.
static bool isKnownBaseResult(Value *V) {
- if (!isa<PHINode>(V) && !isa<SelectInst>(V)) {
+ if (!isa<PHINode>(V) && !isa<SelectInst>(V) &&
+ !isa<ExtractElementInst>(V) && !isa<InsertElementInst>(V) &&
+ !isa<ShuffleVectorInst>(V)) {
// no recursion possible
return true;
}
return false;
}
-// TODO: find a better name for this
namespace {
-class PhiState {
+/// Models the state of a single base defining value in the findBasePointer
+/// algorithm for determining where a new instruction is needed to propagate
+/// the base of this BDV.
+class BDVState {
public:
enum Status { Unknown, Base, Conflict };
- PhiState(Status s, Value *b = nullptr) : status(s), base(b) {
+ BDVState(Status s, Value *b = nullptr) : status(s), base(b) {
assert(status != Base || b);
}
- PhiState(Value *b) : status(Base), base(b) {}
- PhiState() : status(Unknown), base(nullptr) {}
+ explicit BDVState(Value *b) : status(Base), base(b) {}
+ BDVState() : status(Unknown), base(nullptr) {}
Status getStatus() const { return status; }
Value *getBase() const { return base; }
bool isUnknown() const { return getStatus() == Unknown; }
bool isConflict() const { return getStatus() == Conflict; }
- bool operator==(const PhiState &other) const {
+ bool operator==(const BDVState &other) const {
return base == other.base && status == other.status;
}
- bool operator!=(const PhiState &other) const { return !(*this == other); }
+ bool operator!=(const BDVState &other) const { return !(*this == other); }
- void dump() {
- errs() << status << " (" << base << " - "
- << (base ? base->getName() : "nullptr") << "): ";
+ LLVM_DUMP_METHOD
+ void dump() const { print(dbgs()); dbgs() << '\n'; }
+
+ void print(raw_ostream &OS) const {
+ switch (status) {
+ case Unknown:
+ OS << "U";
+ break;
+ case Base:
+ OS << "B";
+ break;
+ case Conflict:
+ OS << "C";
+ break;
+ };
+ OS << " (" << base << " - "
+ << (base ? base->getName() : "nullptr") << "): ";
}
private:
Status status;
- Value *base; // non null only if status == base
+ AssertingVH<Value> base; // non null only if status == base
};
+}
-typedef DenseMap<Value *, PhiState> ConflictStateMapTy;
-// Values of type PhiState form a lattice, and this is a helper
+#ifndef NDEBUG
+static raw_ostream &operator<<(raw_ostream &OS, const BDVState &State) {
+ State.print(OS);
+ return OS;
+}
+#endif
+
+namespace {
+// Values of type BDVState form a lattice, and this is a helper
// class that implementes the meet operation. The meat of the meet
-// operation is implemented in MeetPhiStates::pureMeet
-class MeetPhiStates {
+// operation is implemented in MeetBDVStates::pureMeet
+class MeetBDVStates {
public:
- // phiStates is a mapping from PHINodes and SelectInst's to PhiStates.
- explicit MeetPhiStates(const ConflictStateMapTy &phiStates)
- : phiStates(phiStates) {}
-
- // Destructively meet the current result with the base V. V can
- // either be a merge instruction (SelectInst / PHINode), in which
- // case its status is looked up in the phiStates map; or a regular
- // SSA value, in which case it is assumed to be a base.
- void meetWith(Value *V) {
- PhiState otherState = getStateForBDV(V);
- assert((MeetPhiStates::pureMeet(otherState, currentResult) ==
- MeetPhiStates::pureMeet(currentResult, otherState)) &&
- "math is wrong: meet does not commute!");
- currentResult = MeetPhiStates::pureMeet(otherState, currentResult);
+ /// Initializes the currentResult to the TOP state so that if can be met with
+ /// any other state to produce that state.
+ MeetBDVStates() {}
+
+ // Destructively meet the current result with the given BDVState
+ void meetWith(BDVState otherState) {
+ currentResult = meet(otherState, currentResult);
}
- PhiState getResult() const { return currentResult; }
+ BDVState getResult() const { return currentResult; }
private:
- const ConflictStateMapTy &phiStates;
- PhiState currentResult;
-
- /// Return a phi state for a base defining value. We'll generate a new
- /// base state for known bases and expect to find a cached state otherwise
- PhiState getStateForBDV(Value *baseValue) {
- if (isKnownBaseResult(baseValue)) {
- return PhiState(baseValue);
- } else {
- return lookupFromMap(baseValue);
- }
- }
+ BDVState currentResult;
- PhiState lookupFromMap(Value *V) {
- auto I = phiStates.find(V);
- assert(I != phiStates.end() && "lookup failed!");
- return I->second;
+ /// Perform a meet operation on two elements of the BDVState lattice.
+ static BDVState meet(BDVState LHS, BDVState RHS) {
+ assert((pureMeet(LHS, RHS) == pureMeet(RHS, LHS)) &&
+ "math is wrong: meet does not commute!");
+ BDVState Result = pureMeet(LHS, RHS);
+ DEBUG(dbgs() << "meet of " << LHS << " with " << RHS
+ << " produced " << Result << "\n");
+ return Result;
}
- static PhiState pureMeet(const PhiState &stateA, const PhiState &stateB) {
+ static BDVState pureMeet(const BDVState &stateA, const BDVState &stateB) {
switch (stateA.getStatus()) {
- case PhiState::Unknown:
+ case BDVState::Unknown:
return stateB;
- case PhiState::Base:
+ case BDVState::Base:
assert(stateA.getBase() && "can't be null");
if (stateB.isUnknown())
return stateA;
assert(stateA == stateB && "equality broken!");
return stateA;
}
- return PhiState(PhiState::Conflict);
+ return BDVState(BDVState::Conflict);
}
assert(stateB.isConflict() && "only three states!");
- return PhiState(PhiState::Conflict);
+ return BDVState(BDVState::Conflict);
- case PhiState::Conflict:
+ case BDVState::Conflict:
return stateA;
}
llvm_unreachable("only three states!");
}
};
}
+
+
/// For a given value or instruction, figure out what base ptr it's derived
/// from. For gc objects, this is simply itself. On success, returns a value
/// which is the base pointer. (This is reliable and can be used for
//
// Note: A simpler form of this would be to add the conflict form of all
// PHIs without running the optimistic algorithm. This would be
- // analougous to pessimistic data flow and would likely lead to an
+ // analogous to pessimistic data flow and would likely lead to an
// overall worse solution.
- ConflictStateMapTy states;
- states[def] = PhiState();
- // Recursively fill in all phis & selects reachable from the initial one
- // for which we don't already know a definite base value for
- // TODO: This should be rewritten with a worklist
- bool done = false;
- while (!done) {
- done = true;
- // Since we're adding elements to 'states' as we run, we can't keep
- // iterators into the set.
- SmallVector<Value *, 16> Keys;
- Keys.reserve(states.size());
- for (auto Pair : states) {
- Value *V = Pair.first;
- Keys.push_back(V);
- }
- for (Value *v : Keys) {
- assert(!isKnownBaseResult(v) && "why did it get added?");
- if (PHINode *phi = dyn_cast<PHINode>(v)) {
- assert(phi->getNumIncomingValues() > 0 &&
- "zero input phis are illegal");
- for (Value *InVal : phi->incoming_values()) {
- Value *local = findBaseOrBDV(InVal, cache);
- if (!isKnownBaseResult(local) && states.find(local) == states.end()) {
- states[local] = PhiState();
- done = false;
- }
- }
- } else if (SelectInst *sel = dyn_cast<SelectInst>(v)) {
- Value *local = findBaseOrBDV(sel->getTrueValue(), cache);
- if (!isKnownBaseResult(local) && states.find(local) == states.end()) {
- states[local] = PhiState();
- done = false;
- }
- local = findBaseOrBDV(sel->getFalseValue(), cache);
- if (!isKnownBaseResult(local) && states.find(local) == states.end()) {
- states[local] = PhiState();
- done = false;
- }
+#ifndef NDEBUG
+ auto isExpectedBDVType = [](Value *BDV) {
+ return isa<PHINode>(BDV) || isa<SelectInst>(BDV) ||
+ isa<ExtractElementInst>(BDV) || isa<InsertElementInst>(BDV);
+ };
+#endif
+
+ // Once populated, will contain a mapping from each potentially non-base BDV
+ // to a lattice value (described above) which corresponds to that BDV.
+ // We use the order of insertion (DFS over the def/use graph) to provide a
+ // stable deterministic ordering for visiting DenseMaps (which are unordered)
+ // below. This is important for deterministic compilation.
+ MapVector<Value *, BDVState> States;
+
+ // Recursively fill in all base defining values reachable from the initial
+ // one for which we don't already know a definite base value for
+ /* scope */ {
+ SmallVector<Value*, 16> Worklist;
+ Worklist.push_back(def);
+ States.insert(std::make_pair(def, BDVState()));
+ while (!Worklist.empty()) {
+ Value *Current = Worklist.pop_back_val();
+ assert(!isKnownBaseResult(Current) && "why did it get added?");
+
+ auto visitIncomingValue = [&](Value *InVal) {
+ Value *Base = findBaseOrBDV(InVal, cache);
+ if (isKnownBaseResult(Base))
+ // Known bases won't need new instructions introduced and can be
+ // ignored safely
+ return;
+ assert(isExpectedBDVType(Base) && "the only non-base values "
+ "we see should be base defining values");
+ if (States.insert(std::make_pair(Base, BDVState())).second)
+ Worklist.push_back(Base);
+ };
+ if (PHINode *Phi = dyn_cast<PHINode>(Current)) {
+ for (Value *InVal : Phi->incoming_values())
+ visitIncomingValue(InVal);
+ } else if (SelectInst *Sel = dyn_cast<SelectInst>(Current)) {
+ visitIncomingValue(Sel->getTrueValue());
+ visitIncomingValue(Sel->getFalseValue());
+ } else if (auto *EE = dyn_cast<ExtractElementInst>(Current)) {
+ visitIncomingValue(EE->getVectorOperand());
+ } else if (auto *IE = dyn_cast<InsertElementInst>(Current)) {
+ visitIncomingValue(IE->getOperand(0)); // vector operand
+ visitIncomingValue(IE->getOperand(1)); // scalar operand
+ } else {
+ // There is one known class of instructions we know we don't handle.
+ assert(isa<ShuffleVectorInst>(Current));
+ llvm_unreachable("unimplemented instruction case");
}
}
}
- if (TraceLSP) {
- errs() << "States after initialization:\n";
- for (auto Pair : states) {
- Instruction *v = cast<Instruction>(Pair.first);
- PhiState state = Pair.second;
- state.dump();
- v->dump();
- }
+#ifndef NDEBUG
+ DEBUG(dbgs() << "States after initialization:\n");
+ for (auto Pair : States) {
+ DEBUG(dbgs() << " " << Pair.second << " for " << *Pair.first << "\n");
}
+#endif
- // TODO: come back and revisit the state transitions around inputs which
- // have reached conflict state. The current version seems too conservative.
+ // Return a phi state for a base defining value. We'll generate a new
+ // base state for known bases and expect to find a cached state otherwise.
+ auto getStateForBDV = [&](Value *baseValue) {
+ if (isKnownBaseResult(baseValue))
+ return BDVState(baseValue);
+ auto I = States.find(baseValue);
+ assert(I != States.end() && "lookup failed!");
+ return I->second;
+ };
bool progress = true;
while (progress) {
#ifndef NDEBUG
- size_t oldSize = states.size();
+ const size_t oldSize = States.size();
#endif
progress = false;
- // We're only changing keys in this loop, thus safe to keep iterators
- for (auto Pair : states) {
- MeetPhiStates calculateMeet(states);
- Value *v = Pair.first;
- assert(!isKnownBaseResult(v) && "why did it get added?");
- if (SelectInst *select = dyn_cast<SelectInst>(v)) {
- calculateMeet.meetWith(findBaseOrBDV(select->getTrueValue(), cache));
- calculateMeet.meetWith(findBaseOrBDV(select->getFalseValue(), cache));
- } else
- for (Value *Val : cast<PHINode>(v)->incoming_values())
- calculateMeet.meetWith(findBaseOrBDV(Val, cache));
-
- PhiState oldState = states[v];
- PhiState newState = calculateMeet.getResult();
+ // We're only changing values in this loop, thus safe to keep iterators.
+ // Since this is computing a fixed point, the order of visit does not
+ // effect the result. TODO: We could use a worklist here and make this run
+ // much faster.
+ for (auto Pair : States) {
+ Value *BDV = Pair.first;
+ assert(!isKnownBaseResult(BDV) && "why did it get added?");
+
+ // Given an input value for the current instruction, return a BDVState
+ // instance which represents the BDV of that value.
+ auto getStateForInput = [&](Value *V) mutable {
+ Value *BDV = findBaseOrBDV(V, cache);
+ return getStateForBDV(BDV);
+ };
+
+ MeetBDVStates calculateMeet;
+ if (SelectInst *select = dyn_cast<SelectInst>(BDV)) {
+ calculateMeet.meetWith(getStateForInput(select->getTrueValue()));
+ calculateMeet.meetWith(getStateForInput(select->getFalseValue()));
+ } else if (PHINode *Phi = dyn_cast<PHINode>(BDV)) {
+ for (Value *Val : Phi->incoming_values())
+ calculateMeet.meetWith(getStateForInput(Val));
+ } else if (auto *EE = dyn_cast<ExtractElementInst>(BDV)) {
+ // The 'meet' for an extractelement is slightly trivial, but it's still
+ // useful in that it drives us to conflict if our input is.
+ calculateMeet.meetWith(getStateForInput(EE->getVectorOperand()));
+ } else {
+ // Given there's a inherent type mismatch between the operands, will
+ // *always* produce Conflict.
+ auto *IE = cast<InsertElementInst>(BDV);
+ calculateMeet.meetWith(getStateForInput(IE->getOperand(0)));
+ calculateMeet.meetWith(getStateForInput(IE->getOperand(1)));
+ }
+
+ BDVState oldState = States[BDV];
+ BDVState newState = calculateMeet.getResult();
if (oldState != newState) {
progress = true;
- states[v] = newState;
+ States[BDV] = newState;
}
}
- assert(oldSize <= states.size());
- assert(oldSize == states.size() || progress);
+ assert(oldSize == States.size() &&
+ "fixed point shouldn't be adding any new nodes to state");
}
- if (TraceLSP) {
- errs() << "States after meet iteration:\n";
- for (auto Pair : states) {
- Instruction *v = cast<Instruction>(Pair.first);
- PhiState state = Pair.second;
- state.dump();
- v->dump();
- }
+#ifndef NDEBUG
+ DEBUG(dbgs() << "States after meet iteration:\n");
+ for (auto Pair : States) {
+ DEBUG(dbgs() << " " << Pair.second << " for " << *Pair.first << "\n");
}
-
+#endif
+
// Insert Phis for all conflicts
- // We want to keep naming deterministic in the loop that follows, so
- // sort the keys before iteration. This is useful in allowing us to
- // write stable tests. Note that there is no invalidation issue here.
- SmallVector<Value *, 16> Keys;
- Keys.reserve(states.size());
- for (auto Pair : states) {
- Value *V = Pair.first;
- Keys.push_back(V);
- }
- std::sort(Keys.begin(), Keys.end(), order_by_name);
// TODO: adjust naming patterns to avoid this order of iteration dependency
- for (Value *V : Keys) {
- Instruction *I = cast<Instruction>(V);
- PhiState State = states[I];
+ for (auto Pair : States) {
+ Instruction *I = cast<Instruction>(Pair.first);
+ BDVState State = Pair.second;
assert(!isKnownBaseResult(I) && "why did it get added?");
assert(!State.isUnknown() && "Optimistic algorithm didn't complete!");
+
+ // extractelement instructions are a bit special in that we may need to
+ // insert an extract even when we know an exact base for the instruction.
+ // The problem is that we need to convert from a vector base to a scalar
+ // base for the particular indice we're interested in.
+ if (State.isBase() && isa<ExtractElementInst>(I) &&
+ isa<VectorType>(State.getBase()->getType())) {
+ auto *EE = cast<ExtractElementInst>(I);
+ // TODO: In many cases, the new instruction is just EE itself. We should
+ // exploit this, but can't do it here since it would break the invariant
+ // about the BDV not being known to be a base.
+ auto *BaseInst = ExtractElementInst::Create(State.getBase(),
+ EE->getIndexOperand(),
+ "base_ee", EE);
+ BaseInst->setMetadata("is_base_value", MDNode::get(I->getContext(), {}));
+ States[I] = BDVState(BDVState::Base, BaseInst);
+ }
+
+ // Since we're joining a vector and scalar base, they can never be the
+ // same. As a result, we should always see insert element having reached
+ // the conflict state.
+ if (isa<InsertElementInst>(I)) {
+ assert(State.isConflict());
+ }
+
if (!State.isConflict())
continue;
BasicBlock *BB = I->getParent();
int NumPreds = std::distance(pred_begin(BB), pred_end(BB));
assert(NumPreds > 0 && "how did we reach here");
- return PHINode::Create(I->getType(), NumPreds, "base_phi", I);
+ std::string Name = suffixed_name_or(I, ".base", "base_phi");
+ return PHINode::Create(I->getType(), NumPreds, Name, I);
+ } else if (SelectInst *Sel = dyn_cast<SelectInst>(I)) {
+ // The undef will be replaced later
+ UndefValue *Undef = UndefValue::get(Sel->getType());
+ std::string Name = suffixed_name_or(I, ".base", "base_select");
+ return SelectInst::Create(Sel->getCondition(), Undef,
+ Undef, Name, Sel);
+ } else if (auto *EE = dyn_cast<ExtractElementInst>(I)) {
+ UndefValue *Undef = UndefValue::get(EE->getVectorOperand()->getType());
+ std::string Name = suffixed_name_or(I, ".base", "base_ee");
+ return ExtractElementInst::Create(Undef, EE->getIndexOperand(), Name,
+ EE);
+ } else {
+ auto *IE = cast<InsertElementInst>(I);
+ UndefValue *VecUndef = UndefValue::get(IE->getOperand(0)->getType());
+ UndefValue *ScalarUndef = UndefValue::get(IE->getOperand(1)->getType());
+ std::string Name = suffixed_name_or(I, ".base", "base_ie");
+ return InsertElementInst::Create(VecUndef, ScalarUndef,
+ IE->getOperand(2), Name, IE);
}
- SelectInst *Sel = cast<SelectInst>(I);
- // The undef will be replaced later
- UndefValue *Undef = UndefValue::get(Sel->getType());
- return SelectInst::Create(Sel->getCondition(), Undef,
- Undef, "base_select", Sel);
+
};
Instruction *BaseInst = MakeBaseInstPlaceholder(I);
// Add metadata marking this as a base value
BaseInst->setMetadata("is_base_value", MDNode::get(I->getContext(), {}));
- states[I] = PhiState(PhiState::Conflict, BaseInst);
- }
+ States[I] = BDVState(BDVState::Conflict, BaseInst);
+ }
+
+ // Returns a instruction which produces the base pointer for a given
+ // instruction. The instruction is assumed to be an input to one of the BDVs
+ // seen in the inference algorithm above. As such, we must either already
+ // know it's base defining value is a base, or have inserted a new
+ // instruction to propagate the base of it's BDV and have entered that newly
+ // introduced instruction into the state table. In either case, we are
+ // assured to be able to determine an instruction which produces it's base
+ // pointer.
+ auto getBaseForInput = [&](Value *Input, Instruction *InsertPt) {
+ Value *BDV = findBaseOrBDV(Input, cache);
+ Value *Base = nullptr;
+ if (isKnownBaseResult(BDV)) {
+ Base = BDV;
+ } else {
+ // Either conflict or base.
+ assert(States.count(BDV));
+ Base = States[BDV].getBase();
+ }
+ assert(Base && "can't be null");
+ // The cast is needed since base traversal may strip away bitcasts
+ if (Base->getType() != Input->getType() &&
+ InsertPt) {
+ Base = new BitCastInst(Base, Input->getType(), "cast",
+ InsertPt);
+ }
+ return Base;
+ };
- // Fixup all the inputs of the new PHIs
- for (auto Pair : states) {
- Instruction *v = cast<Instruction>(Pair.first);
- PhiState state = Pair.second;
+ // Fixup all the inputs of the new PHIs. Visit order needs to be
+ // deterministic and predictable because we're naming newly created
+ // instructions.
+ for (auto Pair : States) {
+ Instruction *BDV = cast<Instruction>(Pair.first);
+ BDVState State = Pair.second;
- assert(!isKnownBaseResult(v) && "why did it get added?");
- assert(!state.isUnknown() && "Optimistic algorithm didn't complete!");
- if (!state.isConflict())
+ assert(!isKnownBaseResult(BDV) && "why did it get added?");
+ assert(!State.isUnknown() && "Optimistic algorithm didn't complete!");
+ if (!State.isConflict())
continue;
- if (PHINode *basephi = dyn_cast<PHINode>(state.getBase())) {
- PHINode *phi = cast<PHINode>(v);
+ if (PHINode *basephi = dyn_cast<PHINode>(State.getBase())) {
+ PHINode *phi = cast<PHINode>(BDV);
unsigned NumPHIValues = phi->getNumIncomingValues();
for (unsigned i = 0; i < NumPHIValues; i++) {
Value *InVal = phi->getIncomingValue(i);
if (blockIndex != -1) {
Value *oldBase = basephi->getIncomingValue(blockIndex);
basephi->addIncoming(oldBase, InBB);
+
#ifndef NDEBUG
- Value *base = findBaseOrBDV(InVal, cache);
- if (!isKnownBaseResult(base)) {
- // Either conflict or base.
- assert(states.count(base));
- base = states[base].getBase();
- assert(base != nullptr && "unknown PhiState!");
- }
-
- // In essense this assert states: the only way two
+ Value *Base = getBaseForInput(InVal, nullptr);
+ // In essence this assert states: the only way two
// values incoming from the same basic block may be
// different is by being different bitcasts of the same
// value. A cleanup that remains TODO is changing
// findBaseOrBDV to return an llvm::Value of the correct
// type (and still remain pure). This will remove the
// need to add bitcasts.
- assert(base->stripPointerCasts() == oldBase->stripPointerCasts() &&
+ assert(Base->stripPointerCasts() == oldBase->stripPointerCasts() &&
"sanity -- findBaseOrBDV should be pure!");
#endif
continue;
}
- // Find either the defining value for the PHI or the normal base for
- // a non-phi node
- Value *base = findBaseOrBDV(InVal, cache);
- if (!isKnownBaseResult(base)) {
- // Either conflict or base.
- assert(states.count(base));
- base = states[base].getBase();
- assert(base != nullptr && "unknown PhiState!");
- }
- assert(base && "can't be null");
- // Must use original input BB since base may not be Instruction
- // The cast is needed since base traversal may strip away bitcasts
- if (base->getType() != basephi->getType()) {
- base = new BitCastInst(base, basephi->getType(), "cast",
- InBB->getTerminator());
- }
- basephi->addIncoming(base, InBB);
+ // Find the instruction which produces the base for each input. We may
+ // need to insert a bitcast in the incoming block.
+ // TODO: Need to split critical edges if insertion is needed
+ Value *Base = getBaseForInput(InVal, InBB->getTerminator());
+ basephi->addIncoming(Base, InBB);
}
assert(basephi->getNumIncomingValues() == NumPHIValues);
- } else {
- SelectInst *basesel = cast<SelectInst>(state.getBase());
- SelectInst *sel = cast<SelectInst>(v);
+ } else if (SelectInst *BaseSel = dyn_cast<SelectInst>(State.getBase())) {
+ SelectInst *Sel = cast<SelectInst>(BDV);
// Operand 1 & 2 are true, false path respectively. TODO: refactor to
// something more safe and less hacky.
for (int i = 1; i <= 2; i++) {
- Value *InVal = sel->getOperand(i);
- // Find either the defining value for the PHI or the normal base for
- // a non-phi node
- Value *base = findBaseOrBDV(InVal, cache);
- if (!isKnownBaseResult(base)) {
- // Either conflict or base.
- assert(states.count(base));
- base = states[base].getBase();
- assert(base != nullptr && "unknown PhiState!");
- }
- assert(base && "can't be null");
- // Must use original input BB since base may not be Instruction
- // The cast is needed since base traversal may strip away bitcasts
- if (base->getType() != basesel->getType()) {
- base = new BitCastInst(base, basesel->getType(), "cast", basesel);
- }
- basesel->setOperand(i, base);
+ Value *InVal = Sel->getOperand(i);
+ // Find the instruction which produces the base for each input. We may
+ // need to insert a bitcast.
+ Value *Base = getBaseForInput(InVal, BaseSel);
+ BaseSel->setOperand(i, Base);
+ }
+ } else if (auto *BaseEE = dyn_cast<ExtractElementInst>(State.getBase())) {
+ Value *InVal = cast<ExtractElementInst>(BDV)->getVectorOperand();
+ // Find the instruction which produces the base for each input. We may
+ // need to insert a bitcast.
+ Value *Base = getBaseForInput(InVal, BaseEE);
+ BaseEE->setOperand(0, Base);
+ } else {
+ auto *BaseIE = cast<InsertElementInst>(State.getBase());
+ auto *BdvIE = cast<InsertElementInst>(BDV);
+ auto UpdateOperand = [&](int OperandIdx) {
+ Value *InVal = BdvIE->getOperand(OperandIdx);
+ Value *Base = getBaseForInput(InVal, BaseIE);
+ BaseIE->setOperand(OperandIdx, Base);
+ };
+ UpdateOperand(0); // vector operand
+ UpdateOperand(1); // scalar operand
+ }
+
+ }
+
+ // Now that we're done with the algorithm, see if we can optimize the
+ // results slightly by reducing the number of new instructions needed.
+ // Arguably, this should be integrated into the algorithm above, but
+ // doing as a post process step is easier to reason about for the moment.
+ DenseMap<Value *, Value *> ReverseMap;
+ SmallPtrSet<Instruction *, 16> NewInsts;
+ SmallSetVector<AssertingVH<Instruction>, 16> Worklist;
+ // Note: We need to visit the states in a deterministic order. We uses the
+ // Keys we sorted above for this purpose. Note that we are papering over a
+ // bigger problem with the algorithm above - it's visit order is not
+ // deterministic. A larger change is needed to fix this.
+ for (auto Pair : States) {
+ auto *BDV = Pair.first;
+ auto State = Pair.second;
+ Value *Base = State.getBase();
+ assert(BDV && Base);
+ assert(!isKnownBaseResult(BDV) && "why did it get added?");
+ assert(isKnownBaseResult(Base) &&
+ "must be something we 'know' is a base pointer");
+ if (!State.isConflict())
+ continue;
+
+ ReverseMap[Base] = BDV;
+ if (auto *BaseI = dyn_cast<Instruction>(Base)) {
+ NewInsts.insert(BaseI);
+ Worklist.insert(BaseI);
+ }
+ }
+ auto ReplaceBaseInstWith = [&](Value *BDV, Instruction *BaseI,
+ Value *Replacement) {
+ // Add users which are new instructions (excluding self references)
+ for (User *U : BaseI->users())
+ if (auto *UI = dyn_cast<Instruction>(U))
+ if (NewInsts.count(UI) && UI != BaseI)
+ Worklist.insert(UI);
+ // Then do the actual replacement
+ NewInsts.erase(BaseI);
+ ReverseMap.erase(BaseI);
+ BaseI->replaceAllUsesWith(Replacement);
+ assert(States.count(BDV));
+ assert(States[BDV].isConflict() && States[BDV].getBase() == BaseI);
+ States[BDV] = BDVState(BDVState::Conflict, Replacement);
+ BaseI->eraseFromParent();
+ };
+ const DataLayout &DL = cast<Instruction>(def)->getModule()->getDataLayout();
+ while (!Worklist.empty()) {
+ Instruction *BaseI = Worklist.pop_back_val();
+ assert(NewInsts.count(BaseI));
+ Value *Bdv = ReverseMap[BaseI];
+ if (auto *BdvI = dyn_cast<Instruction>(Bdv))
+ if (BaseI->isIdenticalTo(BdvI)) {
+ DEBUG(dbgs() << "Identical Base: " << *BaseI << "\n");
+ ReplaceBaseInstWith(Bdv, BaseI, Bdv);
+ continue;
}
+ if (Value *V = SimplifyInstruction(BaseI, DL)) {
+ DEBUG(dbgs() << "Base " << *BaseI << " simplified to " << *V << "\n");
+ ReplaceBaseInstWith(Bdv, BaseI, V);
+ continue;
}
}
// Cache all of our results so we can cheaply reuse them
// NOTE: This is actually two caches: one of the base defining value
// relation and one of the base pointer relation! FIXME
- for (auto item : states) {
- Value *v = item.first;
- Value *base = item.second.getBase();
- assert(v && base);
- assert(!isKnownBaseResult(v) && "why did it get added?");
-
- if (TraceLSP) {
- std::string fromstr =
- cache.count(v) ? (cache[v]->hasName() ? cache[v]->getName() : "")
- : "none";
- errs() << "Updating base value cache"
- << " for: " << (v->hasName() ? v->getName() : "")
- << " from: " << fromstr
- << " to: " << (base->hasName() ? base->getName() : "") << "\n";
- }
-
- assert(isKnownBaseResult(base) &&
- "must be something we 'know' is a base pointer");
- if (cache.count(v)) {
+ for (auto Pair : States) {
+ auto *BDV = Pair.first;
+ Value *base = Pair.second.getBase();
+ assert(BDV && base);
+
+ std::string fromstr = cache.count(BDV) ? cache[BDV]->getName() : "none";
+ DEBUG(dbgs() << "Updating base value cache"
+ << " for: " << BDV->getName()
+ << " from: " << fromstr
+ << " to: " << base->getName() << "\n");
+
+ if (cache.count(BDV)) {
// Once we transition from the BDV relation being store in the cache to
// the base relation being stored, it must be stable
- assert((!isKnownBaseResult(cache[v]) || cache[v] == base) &&
+ assert((!isKnownBaseResult(cache[BDV]) || cache[BDV] == base) &&
"base relation should be stable");
}
- cache[v] = base;
+ cache[BDV] = base;
}
assert(cache.find(def) != cache.end());
return cache[def];
// pointer was a base pointer.
static void
findBasePointers(const StatepointLiveSetTy &live,
- DenseMap<llvm::Value *, llvm::Value *> &PointerToBase,
+ DenseMap<Value *, Value *> &PointerToBase,
DominatorTree *DT, DefiningValueMapTy &DVCache) {
// For the naming of values inserted to be deterministic - which makes for
// much cleaner and more stable tests - we need to assign an order to the
// If you see this trip and like to live really dangerously, the code should
// be correct, just with idioms the verifier can't handle. You can try
- // disabling the verifier at your own substaintial risk.
+ // disabling the verifier at your own substantial risk.
assert(!isa<ConstantPointerNull>(base) &&
"the relocation code needs adjustment to handle the relocation of "
"a null pointer constant without causing false positives in the "
static void findBasePointers(DominatorTree &DT, DefiningValueMapTy &DVCache,
const CallSite &CS,
PartiallyConstructedSafepointRecord &result) {
- DenseMap<llvm::Value *, llvm::Value *> PointerToBase;
- findBasePointers(result.liveset, PointerToBase, &DT, DVCache);
+ DenseMap<Value *, Value *> PointerToBase;
+ findBasePointers(result.LiveSet, PointerToBase, &DT, DVCache);
if (PrintBasePointers) {
// Note: Need to print these in a stable order since this is checked in
PartiallyConstructedSafepointRecord &result);
static void recomputeLiveInValues(
- Function &F, DominatorTree &DT, Pass *P, ArrayRef<CallSite> toUpdate,
+ Function &F, DominatorTree &DT, ArrayRef<CallSite> toUpdate,
MutableArrayRef<struct PartiallyConstructedSafepointRecord> records) {
// TODO-PERF: reuse the original liveness, then simply run the dataflow
- // again. The old values are still live and will help it stablize quickly.
+ // again. The old values are still live and will help it stabilize quickly.
GCPtrLivenessData RevisedLivenessData;
computeLiveInValues(DT, F, RevisedLivenessData);
for (size_t i = 0; i < records.size(); i++) {
}
}
-// When inserting gc.relocate calls, we need to ensure there are no uses
-// of the original value between the gc.statepoint and the gc.relocate call.
-// One case which can arise is a phi node starting one of the successor blocks.
-// We also need to be able to insert the gc.relocates only on the path which
-// goes through the statepoint. We might need to split an edge to make this
-// possible.
+// When inserting gc.relocate and gc.result calls, we need to ensure there are
+// no uses of the original value / return value between the gc.statepoint and
+// the gc.relocate / gc.result call. One case which can arise is a phi node
+// starting one of the successor blocks. We also need to be able to insert the
+// gc.relocates only on the path which goes through the statepoint. We might
+// need to split an edge to make this possible.
static BasicBlock *
normalizeForInvokeSafepoint(BasicBlock *BB, BasicBlock *InvokeParent,
DominatorTree &DT) {
BasicBlock *Ret = BB;
- if (!BB->getUniquePredecessor()) {
+ if (!BB->getUniquePredecessor())
Ret = SplitBlockPredecessors(BB, InvokeParent, "", &DT);
- }
- // Now that 'ret' has unique predecessor we can safely remove all phi nodes
+ // Now that 'Ret' has unique predecessor we can safely remove all phi nodes
// from it
FoldSingleEntryPHINodes(Ret);
- assert(!isa<PHINode>(Ret->begin()));
+ assert(!isa<PHINode>(Ret->begin()) &&
+ "All PHI nodes should have been removed!");
- // At this point, we can safely insert a gc.relocate as the first instruction
- // in Ret if needed.
+ // At this point, we can safely insert a gc.relocate or gc.result as the first
+ // instruction in Ret if needed.
return Ret;
}
-static int find_index(ArrayRef<Value *> livevec, Value *val) {
- auto itr = std::find(livevec.begin(), livevec.end(), val);
- assert(livevec.end() != itr);
- size_t index = std::distance(livevec.begin(), itr);
- assert(index < livevec.size());
- return index;
-}
-
-// Create new attribute set containing only attributes which can be transfered
+// Create new attribute set containing only attributes which can be transferred
// from original call to the safepoint.
static AttributeSet legalizeCallAttributes(AttributeSet AS) {
- AttributeSet ret;
+ AttributeSet Ret;
for (unsigned Slot = 0; Slot < AS.getNumSlots(); Slot++) {
- unsigned index = AS.getSlotIndex(Slot);
+ unsigned Index = AS.getSlotIndex(Slot);
- if (index == AttributeSet::ReturnIndex ||
- index == AttributeSet::FunctionIndex) {
+ if (Index == AttributeSet::ReturnIndex ||
+ Index == AttributeSet::FunctionIndex) {
- for (auto it = AS.begin(Slot), it_end = AS.end(Slot); it != it_end;
- ++it) {
- Attribute attr = *it;
+ for (Attribute Attr : make_range(AS.begin(Slot), AS.end(Slot))) {
// Do not allow certain attributes - just skip them
// Safepoint can not be read only or read none.
- if (attr.hasAttribute(Attribute::ReadNone) ||
- attr.hasAttribute(Attribute::ReadOnly))
+ if (Attr.hasAttribute(Attribute::ReadNone) ||
+ Attr.hasAttribute(Attribute::ReadOnly))
+ continue;
+
+ // These attributes control the generation of the gc.statepoint call /
+ // invoke itself; and once the gc.statepoint is in place, they're of no
+ // use.
+ if (Attr.hasAttribute("statepoint-num-patch-bytes") ||
+ Attr.hasAttribute("statepoint-id"))
continue;
- ret = ret.addAttributes(
- AS.getContext(), index,
- AttributeSet::get(AS.getContext(), index, AttrBuilder(attr)));
+ Ret = Ret.addAttributes(
+ AS.getContext(), Index,
+ AttributeSet::get(AS.getContext(), Index, AttrBuilder(Attr)));
}
}
// Just skip parameter attributes for now
}
- return ret;
+ return Ret;
}
/// Helper function to place all gc relocates necessary for the given
/// statepointToken - statepoint instruction to which relocates should be
/// bound.
/// Builder - Llvm IR builder to be used to construct new calls.
-static void CreateGCRelocates(ArrayRef<llvm::Value *> LiveVariables,
+static void CreateGCRelocates(ArrayRef<Value *> LiveVariables,
const int LiveStart,
- ArrayRef<llvm::Value *> BasePtrs,
+ ArrayRef<Value *> BasePtrs,
Instruction *StatepointToken,
IRBuilder<> Builder) {
if (LiveVariables.empty())
return;
-
+
+ auto FindIndex = [](ArrayRef<Value *> LiveVec, Value *Val) {
+ auto ValIt = std::find(LiveVec.begin(), LiveVec.end(), Val);
+ assert(ValIt != LiveVec.end() && "Val not found in LiveVec!");
+ size_t Index = std::distance(LiveVec.begin(), ValIt);
+ assert(Index < LiveVec.size() && "Bug in std::find?");
+ return Index;
+ };
+
// All gc_relocate are set to i8 addrspace(1)* type. We originally generated
// unique declarations for each pointer type, but this proved problematic
// because the intrinsic mangling code is incomplete and fragile. Since
for (unsigned i = 0; i < LiveVariables.size(); i++) {
// Generate the gc.relocate call and save the result
Value *BaseIdx =
- Builder.getInt32(LiveStart + find_index(LiveVariables, BasePtrs[i]));
- Value *LiveIdx =
- Builder.getInt32(LiveStart + find_index(LiveVariables, LiveVariables[i]));
+ Builder.getInt32(LiveStart + FindIndex(LiveVariables, BasePtrs[i]));
+ Value *LiveIdx = Builder.getInt32(LiveStart + i);
// only specify a debug name if we can give a useful one
CallInst *Reloc = Builder.CreateCall(
GCRelocateDecl, {StatepointToken, BaseIdx, LiveIdx},
- LiveVariables[i]->hasName() ? LiveVariables[i]->getName() + ".relocated"
- : "");
+ suffixed_name_or(LiveVariables[i], ".relocated", ""));
// Trick CodeGen into thinking there are lots of free registers at this
// fake call.
Reloc->setCallingConv(CallingConv::Cold);
}
}
-static void
-makeStatepointExplicitImpl(const CallSite &CS, /* to replace */
- const SmallVectorImpl<llvm::Value *> &basePtrs,
- const SmallVectorImpl<llvm::Value *> &liveVariables,
- Pass *P,
- PartiallyConstructedSafepointRecord &result) {
- assert(basePtrs.size() == liveVariables.size());
- assert(isStatepoint(CS) &&
- "This method expects to be rewriting a statepoint");
+namespace {
+
+/// This struct is used to defer RAUWs and `eraseFromParent` s. Using this
+/// avoids having to worry about keeping around dangling pointers to Values.
+class DeferredReplacement {
+ AssertingVH<Instruction> Old;
+ AssertingVH<Instruction> New;
+
+public:
+ explicit DeferredReplacement(Instruction *Old, Instruction *New) :
+ Old(Old), New(New) {
+ assert(Old != New && "Not allowed!");
+ }
+
+ /// Does the task represented by this instance.
+ void doReplacement() {
+ Instruction *OldI = Old;
+ Instruction *NewI = New;
+
+ assert(OldI != NewI && "Disallowed at construction?!");
- BasicBlock *BB = CS.getInstruction()->getParent();
- assert(BB);
- Function *F = BB->getParent();
- assert(F && "must be set");
- Module *M = F->getParent();
- (void)M;
- assert(M && "must be set");
+ Old = nullptr;
+ New = nullptr;
+
+ if (NewI)
+ OldI->replaceAllUsesWith(NewI);
+ OldI->eraseFromParent();
+ }
+};
+}
- // We're not changing the function signature of the statepoint since the gc
- // arguments go into the var args section.
- Function *gc_statepoint_decl = CS.getCalledFunction();
+static void
+makeStatepointExplicitImpl(const CallSite CS, /* to replace */
+ const SmallVectorImpl<Value *> &BasePtrs,
+ const SmallVectorImpl<Value *> &LiveVariables,
+ PartiallyConstructedSafepointRecord &Result,
+ std::vector<DeferredReplacement> &Replacements) {
+ assert(BasePtrs.size() == LiveVariables.size());
+ assert((UseDeoptBundles || isStatepoint(CS)) &&
+ "This method expects to be rewriting a statepoint");
// 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);
- // Copy all of the arguments from the original statepoint - this includes the
- // target, call args, and deopt args
- SmallVector<llvm::Value *, 64> args;
- args.insert(args.end(), CS.arg_begin(), CS.arg_end());
- // TODO: Clear the 'needs rewrite' flag
-
- // add all the pointers to be relocated (gc arguments)
- // Capture the start of the live variable list for use in the gc_relocates
- const int live_start = args.size();
- args.insert(args.end(), liveVariables.begin(), liveVariables.end());
+ Instruction *InsertBefore = CS.getInstruction();
+ IRBuilder<> Builder(InsertBefore);
+
+ ArrayRef<Value *> GCArgs(LiveVariables);
+ uint64_t StatepointID = 0xABCDEF00;
+ uint32_t NumPatchBytes = 0;
+ uint32_t Flags = uint32_t(StatepointFlags::None);
+
+ ArrayRef<Use> CallArgs;
+ ArrayRef<Use> DeoptArgs;
+ ArrayRef<Use> TransitionArgs;
+
+ Value *CallTarget = nullptr;
+
+ if (UseDeoptBundles) {
+ CallArgs = {CS.arg_begin(), CS.arg_end()};
+ DeoptArgs = GetDeoptBundleOperands(CS);
+ // TODO: we don't fill in TransitionArgs or Flags in this branch, but we
+ // could have an operand bundle for that too.
+ AttributeSet OriginalAttrs = CS.getAttributes();
+
+ Attribute AttrID = OriginalAttrs.getAttribute(AttributeSet::FunctionIndex,
+ "statepoint-id");
+ if (AttrID.isStringAttribute())
+ AttrID.getValueAsString().getAsInteger(10, StatepointID);
+
+ Attribute AttrNumPatchBytes = OriginalAttrs.getAttribute(
+ AttributeSet::FunctionIndex, "statepoint-num-patch-bytes");
+ if (AttrNumPatchBytes.isStringAttribute())
+ AttrNumPatchBytes.getValueAsString().getAsInteger(10, NumPatchBytes);
+
+ CallTarget = CS.getCalledValue();
+ } else {
+ // This branch will be gone soon, and we will soon only support the
+ // UseDeoptBundles == true configuration.
+ Statepoint OldSP(CS);
+ StatepointID = OldSP.getID();
+ NumPatchBytes = OldSP.getNumPatchBytes();
+ Flags = OldSP.getFlags();
+
+ CallArgs = {OldSP.arg_begin(), OldSP.arg_end()};
+ DeoptArgs = {OldSP.vm_state_begin(), OldSP.vm_state_end()};
+ TransitionArgs = {OldSP.gc_transition_args_begin(),
+ OldSP.gc_transition_args_end()};
+ CallTarget = OldSP.getCalledValue();
+ }
// Create the statepoint given all the arguments
- Instruction *token = nullptr;
- AttributeSet return_attributes;
+ Instruction *Token = nullptr;
+ AttributeSet ReturnAttrs;
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());
+ CallInst *ToReplace = cast<CallInst>(CS.getInstruction());
+ CallInst *Call = Builder.CreateGCStatepointCall(
+ StatepointID, NumPatchBytes, CallTarget, Flags, CallArgs,
+ TransitionArgs, DeoptArgs, GCArgs, "safepoint_token");
+
+ Call->setTailCall(ToReplace->isTailCall());
+ Call->setCallingConv(ToReplace->getCallingConv());
// Currently we will fail on parameter attributes and on certain
// function attributes.
- AttributeSet new_attrs = legalizeCallAttributes(toReplace->getAttributes());
- // In case if we can handle this set of sttributes - set up function attrs
+ AttributeSet NewAttrs = legalizeCallAttributes(ToReplace->getAttributes());
+ // In case if we can handle this set of attributes - 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();
+ Call->setAttributes(NewAttrs.getFnAttributes());
+ ReturnAttrs = NewAttrs.getRetAttributes();
- token = call;
+ 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());
-
+ assert(ToReplace->getNextNode() && "Not a terminator, must have next!");
+ Builder.SetInsertPoint(ToReplace->getNextNode());
+ Builder.SetCurrentDebugLocation(ToReplace->getNextNode()->getDebugLoc());
} else {
- InvokeInst *toReplace = cast<InvokeInst>(CS.getInstruction());
+ 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());
+ InvokeInst *Invoke = Builder.CreateGCStatepointInvoke(
+ StatepointID, NumPatchBytes, CallTarget, ToReplace->getNormalDest(),
+ ToReplace->getUnwindDest(), Flags, CallArgs, TransitionArgs, DeoptArgs,
+ GCArgs, "statepoint_token");
+
+ Invoke->setCallingConv(ToReplace->getCallingConv());
// Currently we will fail on parameter attributes and on certain
// function attributes.
- AttributeSet new_attrs = legalizeCallAttributes(toReplace->getAttributes());
- // In case if we can handle this set of sttributes - set up function attrs
+ AttributeSet NewAttrs = legalizeCallAttributes(ToReplace->getAttributes());
+ // In case if we can handle this set of attributes - 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();
+ Invoke->setAttributes(NewAttrs.getFnAttributes());
+ ReturnAttrs = NewAttrs.getRetAttributes();
- token = invoke;
+ Token = Invoke;
// Generate gc relocates in exceptional path
- BasicBlock *unwindBlock = toReplace->getUnwindDest();
- assert(!isa<PHINode>(unwindBlock->begin()) &&
- unwindBlock->getUniquePredecessor() &&
+ BasicBlock *UnwindBlock = ToReplace->getUnwindDest();
+ assert(!isa<PHINode>(UnwindBlock->begin()) &&
+ UnwindBlock->getUniquePredecessor() &&
"can't safely insert in this block!");
- Instruction *IP = &*(unwindBlock->getFirstInsertionPt());
- Builder.SetInsertPoint(IP);
- Builder.SetCurrentDebugLocation(toReplace->getDebugLoc());
+ Builder.SetInsertPoint(&*UnwindBlock->getFirstInsertionPt());
+ Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
// Extract second element from landingpad return value. We will attach
// exceptional gc relocates to it.
- const unsigned idx = 1;
- Instruction *exceptional_token =
+ Instruction *ExceptionalToken =
cast<Instruction>(Builder.CreateExtractValue(
- unwindBlock->getLandingPadInst(), idx, "relocate_token"));
- result.UnwindToken = exceptional_token;
+ UnwindBlock->getLandingPadInst(), 1, "relocate_token"));
+ Result.UnwindToken = ExceptionalToken;
- CreateGCRelocates(liveVariables, live_start, basePtrs,
- exceptional_token, Builder);
+ const unsigned LiveStartIdx = Statepoint(Token).gcArgsStartIdx();
+ CreateGCRelocates(LiveVariables, LiveStartIdx, BasePtrs, ExceptionalToken,
+ Builder);
// Generate gc relocates and returns for normal block
- BasicBlock *normalDest = toReplace->getNormalDest();
- assert(!isa<PHINode>(normalDest->begin()) &&
- normalDest->getUniquePredecessor() &&
+ BasicBlock *NormalDest = ToReplace->getNormalDest();
+ assert(!isa<PHINode>(NormalDest->begin()) &&
+ NormalDest->getUniquePredecessor() &&
"can't safely insert in this block!");
- IP = &*(normalDest->getFirstInsertionPt());
- Builder.SetInsertPoint(IP);
+ Builder.SetInsertPoint(&*NormalDest->getFirstInsertionPt());
// gc relocates will be generated later as if it were regular call
// statepoint
}
- assert(token);
-
- // Take the name of the original value call if it had one.
- token->takeName(CS.getInstruction());
+ assert(Token && "Should be set in one of the above branches!");
+
+ if (UseDeoptBundles) {
+ Token->setName("statepoint_token");
+ if (!CS.getType()->isVoidTy() && !CS.getInstruction()->use_empty()) {
+ StringRef Name =
+ CS.getInstruction()->hasName() ? CS.getInstruction()->getName() : "";
+ CallInst *GCResult = Builder.CreateGCResult(Token, CS.getType(), Name);
+ GCResult->setAttributes(CS.getAttributes().getRetAttributes());
+
+ // We cannot RAUW or delete CS.getInstruction() because it could be in the
+ // live set of some other safepoint, in which case that safepoint's
+ // PartiallyConstructedSafepointRecord will hold a raw pointer to this
+ // llvm::Instruction. Instead, we defer the replacement and deletion to
+ // after the live sets have been made explicit in the IR, and we no longer
+ // have raw pointers to worry about.
+ Replacements.emplace_back(CS.getInstruction(), GCResult);
+ } else {
+ Replacements.emplace_back(CS.getInstruction(), nullptr);
+ }
+ } else {
+ assert(!CS.getInstruction()->hasNUsesOrMore(2) &&
+ "only valid use before rewrite is gc.result");
+ assert(!CS.getInstruction()->hasOneUse() ||
+ isGCResult(cast<Instruction>(*CS.getInstruction()->user_begin())));
-// The GCResult is already inserted, we just need to find it
-#ifndef NDEBUG
- Instruction *toReplace = CS.getInstruction();
- assert((toReplace->hasNUses(0) || toReplace->hasNUses(1)) &&
- "only valid use before rewrite is gc.result");
- assert(!toReplace->hasOneUse() ||
- isGCResult(cast<Instruction>(*toReplace->user_begin())));
-#endif
+ // Take the name of the original statepoint token if there was one.
+ Token->takeName(CS.getInstruction());
- // Update the gc.result of the original statepoint (if any) to use the newly
- // inserted statepoint. This is safe to do here since the token can't be
- // considered a live reference.
- CS.getInstruction()->replaceAllUsesWith(token);
+ // Update the gc.result of the original statepoint (if any) to use the newly
+ // inserted statepoint. This is safe to do here since the token can't be
+ // considered a live reference.
+ CS.getInstruction()->replaceAllUsesWith(Token);
+ CS.getInstruction()->eraseFromParent();
+ }
- result.StatepointToken = token;
+ Result.StatepointToken = Token;
// Second, create a gc.relocate for every live variable
- CreateGCRelocates(liveVariables, live_start, basePtrs, token, Builder);
+ const unsigned LiveStartIdx = Statepoint(Token).gcArgsStartIdx();
+ CreateGCRelocates(LiveVariables, LiveStartIdx, BasePtrs, Token, Builder);
}
namespace {
-struct name_ordering {
- Value *base;
- Value *derived;
- bool operator()(name_ordering const &a, name_ordering const &b) {
- return -1 == a.derived->getName().compare(b.derived->getName());
+struct NameOrdering {
+ Value *Base;
+ Value *Derived;
+
+ bool operator()(NameOrdering const &a, NameOrdering const &b) {
+ return -1 == a.Derived->getName().compare(b.Derived->getName());
}
};
}
-static void stablize_order(SmallVectorImpl<Value *> &basevec,
- SmallVectorImpl<Value *> &livevec) {
- assert(basevec.size() == livevec.size());
-
- SmallVector<name_ordering, 64> temp;
- for (size_t i = 0; i < basevec.size(); i++) {
- name_ordering v;
- v.base = basevec[i];
- v.derived = livevec[i];
- temp.push_back(v);
- }
- std::sort(temp.begin(), temp.end(), name_ordering());
- for (size_t i = 0; i < basevec.size(); i++) {
- basevec[i] = temp[i].base;
- livevec[i] = temp[i].derived;
+
+static void StabilizeOrder(SmallVectorImpl<Value *> &BaseVec,
+ SmallVectorImpl<Value *> &LiveVec) {
+ assert(BaseVec.size() == LiveVec.size());
+
+ SmallVector<NameOrdering, 64> Temp;
+ for (size_t i = 0; i < BaseVec.size(); i++) {
+ NameOrdering v;
+ v.Base = BaseVec[i];
+ v.Derived = LiveVec[i];
+ Temp.push_back(v);
+ }
+
+ std::sort(Temp.begin(), Temp.end(), NameOrdering());
+ for (size_t i = 0; i < BaseVec.size(); i++) {
+ BaseVec[i] = Temp[i].Base;
+ LiveVec[i] = Temp[i].Derived;
}
}
// WARNING: Does not do any fixup to adjust users of the original live
// values. That's the callers responsibility.
static void
-makeStatepointExplicit(DominatorTree &DT, const CallSite &CS, Pass *P,
- PartiallyConstructedSafepointRecord &result) {
- auto liveset = result.liveset;
- auto PointerToBase = result.PointerToBase;
+makeStatepointExplicit(DominatorTree &DT, const CallSite &CS,
+ PartiallyConstructedSafepointRecord &Result,
+ std::vector<DeferredReplacement> &Replacements) {
+ const auto &LiveSet = Result.LiveSet;
+ const auto &PointerToBase = Result.PointerToBase;
// Convert to vector for efficient cross referencing.
- SmallVector<Value *, 64> basevec, livevec;
- livevec.reserve(liveset.size());
- basevec.reserve(liveset.size());
- for (Value *L : liveset) {
- livevec.push_back(L);
+ SmallVector<Value *, 64> BaseVec, LiveVec;
+ LiveVec.reserve(LiveSet.size());
+ BaseVec.reserve(LiveSet.size());
+ for (Value *L : LiveSet) {
+ LiveVec.push_back(L);
assert(PointerToBase.count(L));
- Value *base = PointerToBase[L];
- basevec.push_back(base);
+ Value *Base = PointerToBase.find(L)->second;
+ BaseVec.push_back(Base);
}
- assert(livevec.size() == basevec.size());
+ assert(LiveVec.size() == BaseVec.size());
// To make the output IR slightly more stable (for use in diffs), ensure a
// fixed order of the values in the safepoint (by sorting the value name).
// The order is otherwise meaningless.
- stablize_order(basevec, livevec);
+ StabilizeOrder(BaseVec, LiveVec);
// Do the actual rewriting and delete the old statepoint
- makeStatepointExplicitImpl(CS, basevec, livevec, P, result);
- CS.getInstruction()->eraseFromParent();
+ makeStatepointExplicitImpl(CS, BaseVec, LiveVec, Result, Replacements);
}
// Helper function for the relocationViaAlloca.
-// It receives iterator to the statepoint gc relocates and emits store to the
-// assigned
-// location (via allocaMap) for the each one of them.
-// Add visited values into the visitedLiveValues set we will later use them
-// for sanity check.
+//
+// It receives iterator to the statepoint gc relocates and emits a store to the
+// assigned location (via allocaMap) for the each one of them. It adds the
+// visited values into the visitedLiveValues set, which we will later use them
+// for sanity checking.
static void
insertRelocationStores(iterator_range<Value::user_iterator> GCRelocs,
DenseMap<Value *, Value *> &AllocaMap,
Value *Alloca = AllocaMap[OriginalValue];
// Emit store into the related alloca
- // All gc_relocate are i8 addrspace(1)* typed, and it must be bitcasted to
+ // All gc_relocates are i8 addrspace(1)* typed, and it must be bitcasted to
// the correct type according to alloca.
- assert(RelocatedValue->getNextNode() && "Should always have one since it's not a terminator");
+ assert(RelocatedValue->getNextNode() &&
+ "Should always have one since it's not a terminator");
IRBuilder<> Builder(RelocatedValue->getNextNode());
Value *CastedRelocatedValue =
- Builder.CreateBitCast(RelocatedValue, cast<AllocaInst>(Alloca)->getAllocatedType(),
- RelocatedValue->hasName() ? RelocatedValue->getName() + ".casted" : "");
+ Builder.CreateBitCast(RelocatedValue,
+ cast<AllocaInst>(Alloca)->getAllocatedType(),
+ suffixed_name_or(RelocatedValue, ".casted", ""));
StoreInst *Store = new StoreInst(CastedRelocatedValue, Alloca);
Store->insertAfter(cast<Instruction>(CastedRelocatedValue));
}
}
-/// do all the relocation update via allocas and mem2reg
+/// Do all the relocation update via allocas and mem2reg
static void relocationViaAlloca(
Function &F, DominatorTree &DT, ArrayRef<Value *> Live,
- ArrayRef<struct PartiallyConstructedSafepointRecord> Records) {
+ ArrayRef<PartiallyConstructedSafepointRecord> Records) {
#ifndef NDEBUG
// record initial number of (static) allocas; we'll check we have the same
// number when we get done.
PromotableAllocas.push_back(Alloca);
};
- // emit alloca for each live gc pointer
- for (unsigned i = 0; i < Live.size(); i++) {
- emitAllocaFor(Live[i]);
- }
-
- // emit allocas for rematerialized values
- for (size_t i = 0; i < Records.size(); i++) {
- const struct PartiallyConstructedSafepointRecord &Info = Records[i];
+ // Emit alloca for each live gc pointer
+ for (Value *V : Live)
+ emitAllocaFor(V);
+ // Emit allocas for rematerialized values
+ for (const auto &Info : Records)
for (auto RematerializedValuePair : Info.RematerializedValues) {
Value *OriginalValue = RematerializedValuePair.second;
if (AllocaMap.count(OriginalValue) != 0)
emitAllocaFor(OriginalValue);
++NumRematerializedValues;
}
- }
// The next two loops are part of the same conceptual operation. We need to
// insert a store to the alloca after the original def and at each
// redefinition. We need to insert a load before each use. These are split
// into distinct loops for performance reasons.
- // update gc pointer after each statepoint
- // either store a relocated value or null (if no relocated value found for
- // this gc pointer and it is not a gc_result)
- // this must happen before we update the statepoint with load of alloca
- // otherwise we lose the link between statepoint and old def
- for (size_t i = 0; i < Records.size(); i++) {
- const struct PartiallyConstructedSafepointRecord &Info = Records[i];
+ // Update gc pointer after each statepoint: either store a relocated value or
+ // null (if no relocated value was found for this gc pointer and it is not a
+ // gc_result). This must happen before we update the statepoint with load of
+ // alloca otherwise we lose the link between statepoint and old def.
+ for (const auto &Info : Records) {
Value *Statepoint = Info.StatepointToken;
// This will be used for consistency check
VisitedLiveValues);
if (ClobberNonLive) {
- // As a debuging aid, pretend that an unrelocated pointer becomes null at
+ // As a debugging aid, pretend that an unrelocated pointer becomes null at
// the gc.statepoint. This will turn some subtle GC problems into
// slightly easier to debug SEGVs. Note that on large IR files with
// lots of gc.statepoints this is extremely costly both memory and time
// Insert the clobbering stores. These may get intermixed with the
// gc.results and gc.relocates, but that's fine.
if (auto II = dyn_cast<InvokeInst>(Statepoint)) {
- InsertClobbersAt(II->getNormalDest()->getFirstInsertionPt());
- InsertClobbersAt(II->getUnwindDest()->getFirstInsertionPt());
+ InsertClobbersAt(&*II->getNormalDest()->getFirstInsertionPt());
+ InsertClobbersAt(&*II->getUnwindDest()->getFirstInsertionPt());
} else {
- BasicBlock::iterator Next(cast<CallInst>(Statepoint));
- Next++;
- InsertClobbersAt(Next);
+ InsertClobbersAt(cast<Instruction>(Statepoint)->getNextNode());
}
}
}
- // update use with load allocas and add store for gc_relocated
+
+ // Update use with load allocas and add store for gc_relocated.
for (auto Pair : AllocaMap) {
Value *Def = Pair.first;
Value *Alloca = Pair.second;
- // we pre-record the uses of allocas so that we dont have to worry about
- // later update
- // that change the user information.
+ // We pre-record the uses of allocas so that we dont have to worry about
+ // later update that changes the user information..
+
SmallVector<Instruction *, 20> Uses;
// PERF: trade a linear scan for repeated reallocation
Uses.reserve(std::distance(Def->user_begin(), Def->user_end()));
}
}
- // emit store for the initial gc value
- // store must be inserted after load, otherwise store will be in alloca's
- // use list and an extra load will be inserted before it
+ // Emit store for the initial gc value. Store must be inserted after load,
+ // otherwise store will be in alloca's use list and an extra load will be
+ // inserted before it.
StoreInst *Store = new StoreInst(Def, Alloca);
if (Instruction *Inst = dyn_cast<Instruction>(Def)) {
if (InvokeInst *Invoke = dyn_cast<InvokeInst>(Inst)) {
assert(PromotableAllocas.size() == Live.size() + NumRematerializedValues &&
"we must have the same allocas with lives");
if (!PromotableAllocas.empty()) {
- // apply mem2reg to promote alloca to SSA
+ // Apply mem2reg to promote alloca to SSA
PromoteMemToReg(PromotableAllocas, DT);
}
#ifndef NDEBUG
- for (auto I = F.getEntryBlock().begin(), E = F.getEntryBlock().end(); I != E;
- I++)
- if (isa<AllocaInst>(*I))
+ for (auto &I : F.getEntryBlock())
+ if (isa<AllocaInst>(I))
InitialAllocaNum--;
assert(InitialAllocaNum == 0 && "We must not introduce any extra allocas");
#endif
// No values to hold live, might as well not insert the empty holder
return;
- Module *M = CS.getInstruction()->getParent()->getParent()->getParent();
+ Module *M = CS.getInstruction()->getModule();
// Use a dummy vararg function to actually hold the values live
Function *Func = cast<Function>(M->getOrInsertFunction(
"__tmp_use", FunctionType::get(Type::getVoidTy(M->getContext()), true)));
if (CS.isCall()) {
// For call safepoints insert dummy calls right after safepoint
- BasicBlock::iterator Next(CS.getInstruction());
- Next++;
- Holders.push_back(CallInst::Create(Func, Values, "", Next));
+ Holders.push_back(CallInst::Create(Func, Values, "",
+ &*++CS.getInstruction()->getIterator()));
return;
}
// For invoke safepooints insert dummy calls both in normal and
// exceptional destination blocks
auto *II = cast<InvokeInst>(CS.getInstruction());
Holders.push_back(CallInst::Create(
- Func, Values, "", II->getNormalDest()->getFirstInsertionPt()));
+ Func, Values, "", &*II->getNormalDest()->getFirstInsertionPt()));
Holders.push_back(CallInst::Create(
- Func, Values, "", II->getUnwindDest()->getFirstInsertionPt()));
+ Func, Values, "", &*II->getUnwindDest()->getFirstInsertionPt()));
}
static void findLiveReferences(
- Function &F, DominatorTree &DT, Pass *P, ArrayRef<CallSite> toUpdate,
+ Function &F, DominatorTree &DT, ArrayRef<CallSite> toUpdate,
MutableArrayRef<struct PartiallyConstructedSafepointRecord> records) {
GCPtrLivenessData OriginalLivenessData;
computeLiveInValues(DT, F, OriginalLivenessData);
}
}
-/// Remove any vector of pointers from the liveset by scalarizing them over the
-/// statepoint instruction. Adds the scalarized pieces to the liveset. It
-/// would be preferrable to include the vector in the statepoint itself, but
+/// Remove any vector of pointers from the live set by scalarizing them over the
+/// statepoint instruction. Adds the scalarized pieces to the live set. It
+/// would be preferable to include the vector in the statepoint itself, but
/// the lowering code currently does not handle that. Extending it would be
/// slightly non-trivial since it requires a format change. Given how rare
-/// such cases are (for the moment?) scalarizing is an acceptable comprimise.
+/// such cases are (for the moment?) scalarizing is an acceptable compromise.
static void splitVectorValues(Instruction *StatepointInst,
StatepointLiveSetTy &LiveSet,
DenseMap<Value *, Value *>& PointerToBase,
// Helper function for the "rematerializeLiveValues". It walks use chain
// starting from the "CurrentValue" until it meets "BaseValue". Only "simple"
// values are visited (currently it is GEP's and casts). Returns true if it
-// sucessfully reached "BaseValue" and false otherwise.
+// successfully reached "BaseValue" and false otherwise.
// Fills "ChainToBase" array with all visited values. "BaseValue" is not
// recorded.
static bool findRematerializableChainToBasePointer(
return Cost;
}
-// From the statepoint liveset pick values that are cheaper to recompute then to
-// relocate. Remove this values from the liveset, rematerialize them after
+// From the statepoint live set pick values that are cheaper to recompute then
+// to relocate. Remove this values from the live set, rematerialize them after
// statepoint and record them in "Info" structure. Note that similar to
// relocated values we don't do any user adjustments here.
static void rematerializeLiveValues(CallSite CS,
// We can not di this in following loop due to iterator invalidation.
SmallVector<Value *, 32> LiveValuesToBeDeleted;
- for (Value *LiveValue: Info.liveset) {
+ for (Value *LiveValue: Info.LiveSet) {
// For each live pointer find it's defining chain
SmallVector<Instruction *, 3> ChainToBase;
assert(Info.PointerToBase.count(LiveValue));
InvokeInst *Invoke = cast<InvokeInst>(CS.getInstruction());
Instruction *NormalInsertBefore =
- Invoke->getNormalDest()->getFirstInsertionPt();
+ &*Invoke->getNormalDest()->getFirstInsertionPt();
Instruction *UnwindInsertBefore =
- Invoke->getUnwindDest()->getFirstInsertionPt();
+ &*Invoke->getUnwindDest()->getFirstInsertionPt();
Instruction *NormalRematerializedValue =
rematerializeChain(NormalInsertBefore);
// Remove rematerializaed values from the live set
for (auto LiveValue: LiveValuesToBeDeleted) {
- Info.liveset.erase(LiveValue);
+ Info.LiveSet.erase(LiveValue);
}
}
-static bool insertParsePoints(Function &F, DominatorTree &DT, Pass *P,
- SmallVectorImpl<CallSite> &toUpdate) {
+static bool insertParsePoints(Function &F, DominatorTree &DT,
+ TargetTransformInfo &TTI,
+ SmallVectorImpl<CallSite> &ToUpdate) {
#ifndef NDEBUG
// sanity check the input
- std::set<CallSite> uniqued;
- uniqued.insert(toUpdate.begin(), toUpdate.end());
- assert(uniqued.size() == toUpdate.size() && "no duplicates please!");
+ std::set<CallSite> Uniqued;
+ Uniqued.insert(ToUpdate.begin(), ToUpdate.end());
+ assert(Uniqued.size() == ToUpdate.size() && "no duplicates please!");
- for (size_t i = 0; i < toUpdate.size(); i++) {
- CallSite &CS = toUpdate[i];
+ for (CallSite CS : ToUpdate) {
assert(CS.getInstruction()->getParent()->getParent() == &F);
- assert(isStatepoint(CS) && "expected to already be a deopt statepoint");
+ assert((UseDeoptBundles || isStatepoint(CS)) &&
+ "expected to already be a deopt statepoint");
}
#endif
// the top of the successor blocks. See the comment on
// normalForInvokeSafepoint on exactly what is needed. Note that this step
// may restructure the CFG.
- for (CallSite CS : toUpdate) {
+ for (CallSite CS : ToUpdate) {
if (!CS.isInvoke())
continue;
- InvokeInst *invoke = cast<InvokeInst>(CS.getInstruction());
- normalizeForInvokeSafepoint(invoke->getNormalDest(), invoke->getParent(),
- DT);
- normalizeForInvokeSafepoint(invoke->getUnwindDest(), invoke->getParent(),
- DT);
+ auto *II = cast<InvokeInst>(CS.getInstruction());
+ normalizeForInvokeSafepoint(II->getNormalDest(), II->getParent(), DT);
+ normalizeForInvokeSafepoint(II->getUnwindDest(), II->getParent(), DT);
}
// A list of dummy calls added to the IR to keep various values obviously
// live in the IR. We'll remove all of these when done.
- SmallVector<CallInst *, 64> holders;
+ SmallVector<CallInst *, 64> Holders;
// Insert a dummy call with all of the arguments to the vm_state we'll need
// for the actual safepoint insertion. This ensures reference arguments in
// the deopt argument list are considered live through the safepoint (and
// thus makes sure they get relocated.)
- for (size_t i = 0; i < toUpdate.size(); i++) {
- CallSite &CS = toUpdate[i];
- Statepoint StatepointCS(CS);
-
+ for (CallSite CS : ToUpdate) {
SmallVector<Value *, 64> DeoptValues;
- for (Use &U : StatepointCS.vm_state_args()) {
- Value *Arg = cast<Value>(&U);
+
+ iterator_range<const Use *> DeoptStateRange =
+ UseDeoptBundles
+ ? iterator_range<const Use *>(GetDeoptBundleOperands(CS))
+ : iterator_range<const Use *>(Statepoint(CS).vm_state_args());
+
+ for (Value *Arg : DeoptStateRange) {
assert(!isUnhandledGCPointerType(Arg->getType()) &&
"support for FCA unimplemented");
if (isHandledGCPointerType(Arg->getType()))
DeoptValues.push_back(Arg);
}
- insertUseHolderAfter(CS, DeoptValues, holders);
- }
- SmallVector<struct PartiallyConstructedSafepointRecord, 64> records;
- records.reserve(toUpdate.size());
- for (size_t i = 0; i < toUpdate.size(); i++) {
- struct PartiallyConstructedSafepointRecord info;
- records.push_back(info);
+ insertUseHolderAfter(CS, DeoptValues, Holders);
}
- assert(records.size() == toUpdate.size());
- // A) Identify all gc pointers which are staticly live at the given call
+ SmallVector<PartiallyConstructedSafepointRecord, 64> Records(ToUpdate.size());
+
+ // A) Identify all gc pointers which are statically live at the given call
// site.
- findLiveReferences(F, DT, P, toUpdate, records);
+ findLiveReferences(F, DT, ToUpdate, Records);
// B) Find the base pointers for each live pointer
/* scope for caching */ {
// large numbers of duplicate base_phis.
DefiningValueMapTy DVCache;
- for (size_t i = 0; i < records.size(); i++) {
- struct PartiallyConstructedSafepointRecord &info = records[i];
- CallSite &CS = toUpdate[i];
- findBasePointers(DT, DVCache, CS, info);
+ for (size_t i = 0; i < Records.size(); i++) {
+ PartiallyConstructedSafepointRecord &info = Records[i];
+ findBasePointers(DT, DVCache, ToUpdate[i], info);
}
} // end of cache scope
// the base pointers which were identified for that safepoint. We'll then
// ask liveness for _every_ base inserted to see what is now live. Then we
// remove the dummy calls.
- holders.reserve(holders.size() + records.size());
- for (size_t i = 0; i < records.size(); i++) {
- struct PartiallyConstructedSafepointRecord &info = records[i];
- CallSite &CS = toUpdate[i];
+ Holders.reserve(Holders.size() + Records.size());
+ for (size_t i = 0; i < Records.size(); i++) {
+ PartiallyConstructedSafepointRecord &Info = Records[i];
SmallVector<Value *, 128> Bases;
- for (auto Pair : info.PointerToBase) {
+ for (auto Pair : Info.PointerToBase)
Bases.push_back(Pair.second);
- }
- insertUseHolderAfter(CS, Bases, holders);
+
+ insertUseHolderAfter(ToUpdate[i], Bases, Holders);
}
// By selecting base pointers, we've effectively inserted new uses. Thus, we
// need to rerun liveness. We may *also* have inserted new defs, but that's
// not the key issue.
- recomputeLiveInValues(F, DT, P, toUpdate, records);
+ recomputeLiveInValues(F, DT, ToUpdate, Records);
if (PrintBasePointers) {
- for (size_t i = 0; i < records.size(); i++) {
- struct PartiallyConstructedSafepointRecord &info = records[i];
+ for (auto &Info : Records) {
errs() << "Base Pairs: (w/Relocation)\n";
- for (auto Pair : info.PointerToBase) {
+ for (auto Pair : Info.PointerToBase)
errs() << " derived %" << Pair.first->getName() << " base %"
<< Pair.second->getName() << "\n";
- }
}
}
- for (size_t i = 0; i < holders.size(); i++) {
- holders[i]->eraseFromParent();
- holders[i] = nullptr;
- }
- holders.clear();
+
+ for (CallInst *CI : Holders)
+ CI->eraseFromParent();
+
+ Holders.clear();
// Do a limited scalarization of any live at safepoint vector values which
// contain pointers. This enables this pass to run after vectorization at
// the cost of some possible performance loss. TODO: it would be nice to
// natively support vectors all the way through the backend so we don't need
// to scalarize here.
- for (size_t i = 0; i < records.size(); i++) {
- struct PartiallyConstructedSafepointRecord &info = records[i];
- Instruction *statepoint = toUpdate[i].getInstruction();
- splitVectorValues(cast<Instruction>(statepoint), info.liveset,
- info.PointerToBase, DT);
+ for (size_t i = 0; i < Records.size(); i++) {
+ PartiallyConstructedSafepointRecord &Info = Records[i];
+ Instruction *Statepoint = ToUpdate[i].getInstruction();
+ splitVectorValues(cast<Instruction>(Statepoint), Info.LiveSet,
+ Info.PointerToBase, DT);
}
// In order to reduce live set of statepoint we might choose to rematerialize
- // some values instead of relocating them. This is purelly an optimization and
+ // some values instead of relocating them. This is purely an optimization and
// does not influence correctness.
- TargetTransformInfo &TTI =
- P->getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
+ for (size_t i = 0; i < Records.size(); i++)
+ rematerializeLiveValues(ToUpdate[i], Records[i], TTI);
- for (size_t i = 0; i < records.size(); i++) {
- struct PartiallyConstructedSafepointRecord &info = records[i];
- CallSite &CS = toUpdate[i];
-
- rematerializeLiveValues(CS, info, TTI);
- }
+ // We need this to safely RAUW and delete call or invoke return values that
+ // may themselves be live over a statepoint. For details, please see usage in
+ // makeStatepointExplicitImpl.
+ std::vector<DeferredReplacement> Replacements;
// Now run through and replace the existing statepoints with new ones with
// the live variables listed. We do not yet update uses of the values being
// survive to the last iteration of this loop. (By construction, the
// previous statepoint can not be a live variable, thus we can and remove
// the old statepoint calls as we go.)
- for (size_t i = 0; i < records.size(); i++) {
- struct PartiallyConstructedSafepointRecord &info = records[i];
- CallSite &CS = toUpdate[i];
- makeStatepointExplicit(DT, CS, P, info);
+ for (size_t i = 0; i < Records.size(); i++)
+ makeStatepointExplicit(DT, ToUpdate[i], Records[i], Replacements);
+
+ ToUpdate.clear(); // prevent accident use of invalid CallSites
+
+ for (auto &PR : Replacements)
+ PR.doReplacement();
+
+ Replacements.clear();
+
+ for (auto &Info : Records) {
+ // These live sets may contain state Value pointers, since we replaced calls
+ // with operand bundles with calls wrapped in gc.statepoint, and some of
+ // those calls may have been def'ing live gc pointers. Clear these out to
+ // avoid accidentally using them.
+ //
+ // TODO: We should create a separate data structure that does not contain
+ // these live sets, and migrate to using that data structure from this point
+ // onward.
+ Info.LiveSet.clear();
+ Info.PointerToBase.clear();
}
- toUpdate.clear(); // prevent accident use of invalid CallSites
// Do all the fixups of the original live variables to their relocated selves
- SmallVector<Value *, 128> live;
- for (size_t i = 0; i < records.size(); i++) {
- struct PartiallyConstructedSafepointRecord &info = records[i];
+ SmallVector<Value *, 128> Live;
+ for (size_t i = 0; i < Records.size(); i++) {
+ PartiallyConstructedSafepointRecord &Info = Records[i];
+
// We can't simply save the live set from the original insertion. One of
// the live values might be the result of a call which needs a safepoint.
// That Value* no longer exists and we need to use the new gc_result.
- // Thankfully, the liveset is embedded in the statepoint (and updated), so
+ // Thankfully, the live set is embedded in the statepoint (and updated), so
// we just grab that.
- Statepoint statepoint(info.StatepointToken);
- live.insert(live.end(), statepoint.gc_args_begin(),
- statepoint.gc_args_end());
+ Statepoint Statepoint(Info.StatepointToken);
+ Live.insert(Live.end(), Statepoint.gc_args_begin(),
+ Statepoint.gc_args_end());
#ifndef NDEBUG
// Do some basic sanity checks on our liveness results before performing
// relocation. Relocation can and will turn mistakes in liveness results
// into non-sensical code which is must harder to debug.
// TODO: It would be nice to test consistency as well
- assert(DT.isReachableFromEntry(info.StatepointToken->getParent()) &&
+ assert(DT.isReachableFromEntry(Info.StatepointToken->getParent()) &&
"statepoint must be reachable or liveness is meaningless");
- for (Value *V : statepoint.gc_args()) {
+ for (Value *V : Statepoint.gc_args()) {
if (!isa<Instruction>(V))
// Non-instruction values trivial dominate all possible uses
continue;
- auto LiveInst = cast<Instruction>(V);
+ auto *LiveInst = cast<Instruction>(V);
assert(DT.isReachableFromEntry(LiveInst->getParent()) &&
"unreachable values should never be live");
- assert(DT.dominates(LiveInst, info.StatepointToken) &&
+ assert(DT.dominates(LiveInst, Info.StatepointToken) &&
"basic SSA liveness expectation violated by liveness analysis");
}
#endif
}
- unique_unsorted(live);
+ unique_unsorted(Live);
#ifndef NDEBUG
// sanity check
- for (auto ptr : live) {
- assert(isGCPointerType(ptr->getType()) && "must be a gc pointer type");
- }
+ for (auto *Ptr : Live)
+ assert(isGCPointerType(Ptr->getType()) && "must be a gc pointer type");
#endif
- relocationViaAlloca(F, DT, live, records);
- return !records.empty();
+ relocationViaAlloca(F, DT, Live, Records);
+ return !Records.empty();
}
// Handles both return values and arguments for Functions and CallSites.
template <typename AttrHolder>
-static void RemoveDerefAttrAtIndex(LLVMContext &Ctx, AttrHolder &AH,
- unsigned Index) {
+static void RemoveNonValidAttrAtIndex(LLVMContext &Ctx, AttrHolder &AH,
+ unsigned Index) {
AttrBuilder R;
if (AH.getDereferenceableBytes(Index))
R.addAttribute(Attribute::get(Ctx, Attribute::Dereferenceable,
if (AH.getDereferenceableOrNullBytes(Index))
R.addAttribute(Attribute::get(Ctx, Attribute::DereferenceableOrNull,
AH.getDereferenceableOrNullBytes(Index)));
+ if (AH.doesNotAlias(Index))
+ R.addAttribute(Attribute::NoAlias);
if (!R.empty())
AH.setAttributes(AH.getAttributes().removeAttributes(
}
void
-RewriteStatepointsForGC::stripDereferenceabilityInfoFromPrototype(Function &F) {
+RewriteStatepointsForGC::stripNonValidAttributesFromPrototype(Function &F) {
LLVMContext &Ctx = F.getContext();
for (Argument &A : F.args())
if (isa<PointerType>(A.getType()))
- RemoveDerefAttrAtIndex(Ctx, F, A.getArgNo() + 1);
+ RemoveNonValidAttrAtIndex(Ctx, F, A.getArgNo() + 1);
if (isa<PointerType>(F.getReturnType()))
- RemoveDerefAttrAtIndex(Ctx, F, AttributeSet::ReturnIndex);
+ RemoveNonValidAttrAtIndex(Ctx, F, AttributeSet::ReturnIndex);
}
-void RewriteStatepointsForGC::stripDereferenceabilityInfoFromBody(Function &F) {
+void RewriteStatepointsForGC::stripNonValidAttributesFromBody(Function &F) {
if (F.empty())
return;
LLVMContext &Ctx = F.getContext();
MDBuilder Builder(Ctx);
- for (Instruction &I : inst_range(F)) {
+ for (Instruction &I : instructions(F)) {
if (const MDNode *MD = I.getMetadata(LLVMContext::MD_tbaa)) {
assert(MD->getNumOperands() < 5 && "unrecognized metadata shape!");
bool IsImmutableTBAA =
if (CallSite CS = CallSite(&I)) {
for (int i = 0, e = CS.arg_size(); i != e; i++)
if (isa<PointerType>(CS.getArgument(i)->getType()))
- RemoveDerefAttrAtIndex(Ctx, CS, i + 1);
+ RemoveNonValidAttrAtIndex(Ctx, CS, i + 1);
if (isa<PointerType>(CS.getType()))
- RemoveDerefAttrAtIndex(Ctx, CS, AttributeSet::ReturnIndex);
+ RemoveNonValidAttrAtIndex(Ctx, CS, AttributeSet::ReturnIndex);
}
}
}
return false;
}
-void RewriteStatepointsForGC::stripDereferenceabilityInfo(Module &M) {
+void RewriteStatepointsForGC::stripNonValidAttributes(Module &M) {
#ifndef NDEBUG
assert(std::any_of(M.begin(), M.end(), shouldRewriteStatepointsIn) &&
"precondition!");
#endif
for (Function &F : M)
- stripDereferenceabilityInfoFromPrototype(F);
+ stripNonValidAttributesFromPrototype(F);
for (Function &F : M)
- stripDereferenceabilityInfoFromBody(F);
+ stripNonValidAttributesFromBody(F);
}
bool RewriteStatepointsForGC::runOnFunction(Function &F) {
return false;
DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
+ TargetTransformInfo &TTI =
+ getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
+
+ auto NeedsRewrite = [](Instruction &I) {
+ if (UseDeoptBundles) {
+ if (ImmutableCallSite CS = ImmutableCallSite(&I))
+ return !callsGCLeafFunction(CS);
+ return false;
+ }
+
+ return isStatepoint(I);
+ };
// Gather all the statepoints which need rewritten. Be careful to only
// consider those in reachable code since we need to ask dominance queries
// when rewriting. We'll delete the unreachable ones in a moment.
SmallVector<CallSite, 64> ParsePointNeeded;
bool HasUnreachableStatepoint = false;
- for (Instruction &I : inst_range(F)) {
+ for (Instruction &I : instructions(F)) {
// TODO: only the ones with the flag set!
- if (isStatepoint(I)) {
+ if (NeedsRewrite(I)) {
if (DT.isReachableFromEntry(I.getParent()))
ParsePointNeeded.push_back(CallSite(&I));
else
FoldSingleEntryPHINodes(&BB);
}
- MadeChange |= insertParsePoints(F, DT, this, ParsePointNeeded);
+ // Before we start introducing relocations, we want to tweak the IR a bit to
+ // avoid unfortunate code generation effects. The main example is that we
+ // want to try to make sure the comparison feeding a branch is after any
+ // safepoints. Otherwise, we end up with a comparison of pre-relocation
+ // values feeding a branch after relocation. This is semantically correct,
+ // but results in extra register pressure since both the pre-relocation and
+ // post-relocation copies must be available in registers. For code without
+ // relocations this is handled elsewhere, but teaching the scheduler to
+ // reverse the transform we're about to do would be slightly complex.
+ // Note: This may extend the live range of the inputs to the icmp and thus
+ // increase the liveset of any statepoint we move over. This is profitable
+ // as long as all statepoints are in rare blocks. If we had in-register
+ // lowering for live values this would be a much safer transform.
+ auto getConditionInst = [](TerminatorInst *TI) -> Instruction* {
+ if (auto *BI = dyn_cast<BranchInst>(TI))
+ if (BI->isConditional())
+ return dyn_cast<Instruction>(BI->getCondition());
+ // TODO: Extend this to handle switches
+ return nullptr;
+ };
+ for (BasicBlock &BB : F) {
+ TerminatorInst *TI = BB.getTerminator();
+ if (auto *Cond = getConditionInst(TI))
+ // TODO: Handle more than just ICmps here. We should be able to move
+ // most instructions without side effects or memory access.
+ if (isa<ICmpInst>(Cond) && Cond->hasOneUse()) {
+ MadeChange = true;
+ Cond->moveBefore(TI);
+ }
+ }
+
+ MadeChange |= insertParsePoints(F, DT, TTI, ParsePointNeeded);
return MadeChange;
}
"support for FCA unimplemented");
if (isHandledGCPointerType(V->getType()) && !isa<Constant>(V)) {
// The choice to exclude all things constant here is slightly subtle.
- // There are two idependent reasons:
+ // There are two independent reasons:
// - We assume that things which are constant (from LLVM's definition)
// do not move at runtime. For example, the address of a global
// variable is fixed, even though it's contents may not be.
} // while( !worklist.empty() )
#ifndef NDEBUG
- // Sanity check our ouput against SSA properties. This helps catch any
+ // Sanity check our output against SSA properties. This helps catch any
// missing kills during the above iteration.
for (BasicBlock &BB : F) {
checkBasicSSA(DT, Data, BB);
// call result is not live (normal), nor are it's arguments
// (unless they're used again later). This adjustment is
// specifically what we need to relocate
- BasicBlock::reverse_iterator rend(Inst);
+ BasicBlock::reverse_iterator rend(Inst->getIterator());
computeLiveInValues(BB->rbegin(), rend, LiveOut);
LiveOut.erase(Inst);
Out.insert(LiveOut.begin(), LiveOut.end());
assert(Updated.count(KVPair.first) && "record for non-live value");
#endif
- Info.liveset = Updated;
+ Info.LiveSet = Updated;
}
projects / oota-llvm.git / blobdiff