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
};
}
+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);
}
}
+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?!");
+
+ Old = nullptr;
+ New = nullptr;
+
+ if (NewI)
+ OldI->replaceAllUsesWith(NewI);
+ OldI->eraseFromParent();
+ }
+};
+}
+
static void
makeStatepointExplicitImpl(const CallSite CS, /* to replace */
const SmallVectorImpl<Value *> &BasePtrs,
const SmallVectorImpl<Value *> &LiveVariables,
- PartiallyConstructedSafepointRecord &Result) {
+ PartiallyConstructedSafepointRecord &Result,
+ std::vector<DeferredReplacement> &Replacements) {
assert(BasePtrs.size() == LiveVariables.size());
- assert(isStatepoint(CS) &&
+ 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
Instruction *InsertBefore = CS.getInstruction();
IRBuilder<> Builder(InsertBefore);
- Statepoint OldSP(CS);
-
ArrayRef<Value *> GCArgs(LiveVariables);
- uint64_t StatepointID = OldSP.getID();
- uint32_t NumPatchBytes = OldSP.getNumPatchBytes();
- uint32_t Flags = OldSP.getFlags();
+ 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();
- ArrayRef<Use> CallArgs(OldSP.arg_begin(), OldSP.arg_end());
- ArrayRef<Use> DeoptArgs(OldSP.vm_state_begin(), OldSP.vm_state_end());
- ArrayRef<Use> TransitionArgs(OldSP.gc_transition_args_begin(),
- OldSP.gc_transition_args_end());
- Value *CallTarget = OldSP.getCalledValue();
+ 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;
}
assert(Token && "Should be set in one of the above branches!");
- // Take the name of the original value call if it had one.
- Token->takeName(CS.getInstruction());
+ 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->hasNUsesOrMore(2) &&
- "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;
// values. That's the callers responsibility.
static void
makeStatepointExplicit(DominatorTree &DT, const CallSite &CS,
- PartiallyConstructedSafepointRecord &Result) {
+ PartiallyConstructedSafepointRecord &Result,
+ std::vector<DeferredReplacement> &Replacements) {
const auto &LiveSet = Result.LiveSet;
const auto &PointerToBase = Result.PointerToBase;
StabilizeOrder(BaseVec, LiveVec);
// Do the actual rewriting and delete the old statepoint
- makeStatepointExplicitImpl(CS, BaseVec, LiveVec, Result);
- CS.getInstruction()->eraseFromParent();
+ makeStatepointExplicitImpl(CS, BaseVec, LiveVec, Result, Replacements);
}
// Helper function for the relocationViaAlloca.
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 deopt argument list are considered live through the safepoint (and
// thus makes sure they get relocated.)
for (CallSite CS : ToUpdate) {
- Statepoint StatepointCS(CS);
-
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);
}
for (size_t i = 0; i < Records.size(); i++)
rematerializeLiveValues(ToUpdate[i], Records[i], 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
// relocated. We have references to live variables that need to
// 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++)
- makeStatepointExplicit(DT, ToUpdate[i], Records[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();
+ }
+
// 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++) {
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.
DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
+ 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.
bool HasUnreachableStatepoint = false;
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
projects / oota-llvm.git / blobdiff