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//===- llvm/IR/Statepoint.h - gc.statepoint utilities -----------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file contains utility functions and a wrapper class analogous to
// CallSite for accessing the fields of gc.statepoint, gc.relocate,
// gc.result intrinsics; and some general utilities helpful when dealing with
// gc.statepoint.
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/MathExtras.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <vector>
namespace llvm {
/// The statepoint intrinsic accepts a set of flags as its third argument.
/// Valid values come out of this set.
enum class StatepointFlags {
None = 0,
GCTransition = 1, ///< Indicates that this statepoint is a transition from
///< GC-aware code to code that is not GC-aware.
/// Mark the deopt arguments associated with the statepoint as only being
/// "live-in". By default, deopt arguments are "live-through". "live-through"
/// requires that they the value be live on entry, on exit, and at any point
/// during the call. "live-in" only requires the value be available at the
/// start of the call. In particular, "live-in" values can be placed in
/// unused argument registers or other non-callee saved registers.
DeoptLiveIn = 2,
MaskAll = 3 ///< A bitmask that includes all valid flags.
class GCRelocateInst;
class GCResultInst;
bool isStatepoint(ImmutableCallSite CS);
bool isStatepoint(const Value *V);
bool isStatepoint(const Value &V);
bool isGCRelocate(ImmutableCallSite CS);
bool isGCRelocate(const Value *V);
bool isGCResult(ImmutableCallSite CS);
bool isGCResult(const Value *V);
/// Analogous to CallSiteBase, this provides most of the actual
/// functionality for Statepoint and ImmutableStatepoint. It is
/// templatized to allow easily specializing of const and non-const
/// concrete subtypes. This is structured analogous to CallSite
/// rather than the IntrinsicInst.h helpers since we need to support
/// invokable statepoints.
template <typename FunTy, typename InstructionTy, typename ValueTy,
typename CallSiteTy>
class StatepointBase {
CallSiteTy StatepointCS;
explicit StatepointBase(InstructionTy *I) {
if (isStatepoint(I)) {
StatepointCS = CallSiteTy(I);
assert(StatepointCS && "isStatepoint implies CallSite");
explicit StatepointBase(CallSiteTy CS) {
if (isStatepoint(CS))
StatepointCS = CS;
using arg_iterator = typename CallSiteTy::arg_iterator;
enum {
IDPos = 0,
NumPatchBytesPos = 1,
CalledFunctionPos = 2,
NumCallArgsPos = 3,
FlagsPos = 4,
CallArgsBeginPos = 5,
void *operator new(size_t, unsigned) = delete;
void *operator new(size_t s) = delete;
explicit operator bool() const {
// We do not assign non-statepoint CallSites to StatepointCS.
return (bool)StatepointCS;
/// Return the underlying CallSite.
CallSiteTy getCallSite() const {
assert(*this && "check validity first!");
return StatepointCS;
uint64_t getFlags() const {
return cast<ConstantInt>(getCallSite().getArgument(FlagsPos))
/// Return the ID associated with this statepoint.
uint64_t getID() const {
const Value *IDVal = getCallSite().getArgument(IDPos);
return cast<ConstantInt>(IDVal)->getZExtValue();
/// Return the number of patchable bytes associated with this statepoint.
uint32_t getNumPatchBytes() const {
const Value *NumPatchBytesVal = getCallSite().getArgument(NumPatchBytesPos);
uint64_t NumPatchBytes =
assert(isInt<32>(NumPatchBytes) && "should fit in 32 bits!");
return NumPatchBytes;
/// Return the value actually being called or invoked.
ValueTy *getCalledValue() const {
return getCallSite().getArgument(CalledFunctionPos);
InstructionTy *getInstruction() const {
return getCallSite().getInstruction();
/// Return the function being called if this is a direct call, otherwise
/// return null (if it's an indirect call).
FunTy *getCalledFunction() const {
return dyn_cast<Function>(getCalledValue());
/// Return the caller function for this statepoint.
FunTy *getCaller() const { return getCallSite().getCaller(); }
/// Determine if the statepoint cannot unwind.
bool doesNotThrow() const {
Function *F = getCalledFunction();
return getCallSite().doesNotThrow() || (F ? F->doesNotThrow() : false);
/// Return the type of the value returned by the call underlying the
/// statepoint.
Type *getActualReturnType() const {
auto *FTy = cast<FunctionType>(
return FTy->getReturnType();
/// Number of arguments to be passed to the actual callee.
int getNumCallArgs() const {
const Value *NumCallArgsVal = getCallSite().getArgument(NumCallArgsPos);
return cast<ConstantInt>(NumCallArgsVal)->getZExtValue();
size_t arg_size() const { return getNumCallArgs(); }
typename CallSiteTy::arg_iterator arg_begin() const {
assert(CallArgsBeginPos <= (int)getCallSite().arg_size());
return getCallSite().arg_begin() + CallArgsBeginPos;
typename CallSiteTy::arg_iterator arg_end() const {
auto I = arg_begin() + arg_size();
assert((getCallSite().arg_end() - I) >= 0);
return I;
ValueTy *getArgument(unsigned Index) {
assert(Index < arg_size() && "out of bounds!");
return *(arg_begin() + Index);
/// range adapter for call arguments
iterator_range<arg_iterator> call_args() const {
return make_range(arg_begin(), arg_end());
/// Return true if the call or the callee has the given attribute.
bool paramHasAttr(unsigned i, Attribute::AttrKind A) const {
Function *F = getCalledFunction();
return getCallSite().paramHasAttr(i + CallArgsBeginPos, A) ||
(F ? F->getAttributes().hasAttribute(i, A) : false);
/// Number of GC transition args.
int getNumTotalGCTransitionArgs() const {
const Value *NumGCTransitionArgs = *arg_end();
return cast<ConstantInt>(NumGCTransitionArgs)->getZExtValue();
typename CallSiteTy::arg_iterator gc_transition_args_begin() const {
auto I = arg_end() + 1;
assert((getCallSite().arg_end() - I) >= 0);
return I;
typename CallSiteTy::arg_iterator gc_transition_args_end() const {
auto I = gc_transition_args_begin() + getNumTotalGCTransitionArgs();
assert((getCallSite().arg_end() - I) >= 0);
return I;
/// range adapter for GC transition arguments
iterator_range<arg_iterator> gc_transition_args() const {
return make_range(gc_transition_args_begin(), gc_transition_args_end());
/// Number of additional arguments excluding those intended
/// for garbage collection.
int getNumTotalVMSArgs() const {
const Value *NumVMSArgs = *gc_transition_args_end();
return cast<ConstantInt>(NumVMSArgs)->getZExtValue();
typename CallSiteTy::arg_iterator deopt_begin() const {
auto I = gc_transition_args_end() + 1;
assert((getCallSite().arg_end() - I) >= 0);
return I;
typename CallSiteTy::arg_iterator deopt_end() const {
auto I = deopt_begin() + getNumTotalVMSArgs();
assert((getCallSite().arg_end() - I) >= 0);
return I;
/// range adapter for vm state arguments
iterator_range<arg_iterator> deopt_operands() const {
return make_range(deopt_begin(), deopt_end());
typename CallSiteTy::arg_iterator gc_args_begin() const {
return deopt_end();
typename CallSiteTy::arg_iterator gc_args_end() const {
return getCallSite().arg_end();
unsigned gcArgsStartIdx() const {
return gc_args_begin() - getInstruction()->op_begin();
/// range adapter for gc arguments
iterator_range<arg_iterator> gc_args() const {
return make_range(gc_args_begin(), gc_args_end());
/// Get list of all gc reloactes linked to this statepoint
/// May contain several relocations for the same base/derived pair.
/// For example this could happen due to relocations on unwinding
/// path of invoke.
std::vector<const GCRelocateInst *> getRelocates() const;
/// Get the experimental_gc_result call tied to this statepoint. Can be
/// nullptr if there isn't a gc_result tied to this statepoint. Guaranteed to
/// be a CallInst if non-null.
const GCResultInst *getGCResult() const {
for (auto *U : getInstruction()->users())
if (auto *GRI = dyn_cast<GCResultInst>(U))
return GRI;
return nullptr;
#ifndef NDEBUG
/// Asserts if this statepoint is malformed. Common cases for failure
/// include incorrect length prefixes for variable length sections or
/// illegal values for parameters.
void verify() {
assert(getNumCallArgs() >= 0 &&
"number of arguments to actually callee can't be negative");
// The internal asserts in the iterator accessors do the rest.
/// A specialization of it's base class for read only access
/// to a gc.statepoint.
class ImmutableStatepoint
: public StatepointBase<const Function, const Instruction, const Value,
ImmutableCallSite> {
using Base =
StatepointBase<const Function, const Instruction, const Value,
explicit ImmutableStatepoint(const Instruction *I) : Base(I) {}
explicit ImmutableStatepoint(ImmutableCallSite CS) : Base(CS) {}
/// A specialization of it's base class for read-write access
/// to a gc.statepoint.
class Statepoint
: public StatepointBase<Function, Instruction, Value, CallSite> {
using Base = StatepointBase<Function, Instruction, Value, CallSite>;
explicit Statepoint(Instruction *I) : Base(I) {}
explicit Statepoint(CallSite CS) : Base(CS) {}
/// Common base class for representing values projected from a statepoint.
/// Currently, the only projections available are gc.result and gc.relocate.
class GCProjectionInst : public IntrinsicInst {
static bool classof(const IntrinsicInst *I) {
return I->getIntrinsicID() == Intrinsic::experimental_gc_relocate ||
I->getIntrinsicID() == Intrinsic::experimental_gc_result;
static bool classof(const Value *V) {
return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
/// Return true if this relocate is tied to the invoke statepoint.
/// This includes relocates which are on the unwinding path.
bool isTiedToInvoke() const {
const Value *Token = getArgOperand(0);
return isa<LandingPadInst>(Token) || isa<InvokeInst>(Token);
/// The statepoint with which this gc.relocate is associated.
const Instruction *getStatepoint() const {
const Value *Token = getArgOperand(0);
// This takes care both of relocates for call statepoints and relocates
// on normal path of invoke statepoint.
if (!isa<LandingPadInst>(Token)) {
return cast<Instruction>(Token);
// This relocate is on exceptional path of an invoke statepoint
const BasicBlock *InvokeBB =
assert(InvokeBB && "safepoints should have unique landingpads");
assert(InvokeBB->getTerminator() &&
"safepoint block should be well formed");
return InvokeBB->getTerminator();
/// Represents calls to the gc.relocate intrinsic.
class GCRelocateInst : public GCProjectionInst {
static bool classof(const IntrinsicInst *I) {
return I->getIntrinsicID() == Intrinsic::experimental_gc_relocate;
static bool classof(const Value *V) {
return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
/// The index into the associate statepoint's argument list
/// which contains the base pointer of the pointer whose
/// relocation this gc.relocate describes.
unsigned getBasePtrIndex() const {
return cast<ConstantInt>(getArgOperand(1))->getZExtValue();
/// The index into the associate statepoint's argument list which
/// contains the pointer whose relocation this gc.relocate describes.
unsigned getDerivedPtrIndex() const {
return cast<ConstantInt>(getArgOperand(2))->getZExtValue();
Value *getBasePtr() const {
ImmutableCallSite CS(getStatepoint());
return *(CS.arg_begin() + getBasePtrIndex());
Value *getDerivedPtr() const {
ImmutableCallSite CS(getStatepoint());
return *(CS.arg_begin() + getDerivedPtrIndex());
/// Represents calls to the gc.result intrinsic.
class GCResultInst : public GCProjectionInst {
static bool classof(const IntrinsicInst *I) {
return I->getIntrinsicID() == Intrinsic::experimental_gc_result;
static bool classof(const Value *V) {
return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
template <typename FunTy, typename InstructionTy, typename ValueTy,
typename CallSiteTy>
std::vector<const GCRelocateInst *>
StatepointBase<FunTy, InstructionTy, ValueTy, CallSiteTy>::getRelocates()
const {
std::vector<const GCRelocateInst *> Result;
CallSiteTy StatepointCS = getCallSite();
// Search for relocated pointers. Note that working backwards from the
// gc_relocates ensures that we only get pairs which are actually relocated
// and used after the statepoint.
for (const User *U : getInstruction()->users())
if (auto *Relocate = dyn_cast<GCRelocateInst>(U))
if (!StatepointCS.isInvoke())
return Result;
// We need to scan thorough exceptional relocations if it is invoke statepoint
LandingPadInst *LandingPad =
// Search for gc relocates that are attached to this landingpad.
for (const User *LandingPadUser : LandingPad->users()) {
if (auto *Relocate = dyn_cast<GCRelocateInst>(LandingPadUser))
return Result;
/// Call sites that get wrapped by a gc.statepoint (currently only in
/// RewriteStatepointsForGC and potentially in other passes in the future) can
/// have attributes that describe properties of gc.statepoint call they will be
/// eventually be wrapped in. This struct is used represent such directives.
struct StatepointDirectives {
Optional<uint32_t> NumPatchBytes;
Optional<uint64_t> StatepointID;
static const uint64_t DefaultStatepointID = 0xABCDEF00;
static const uint64_t DeoptBundleStatepointID = 0xABCDEF0F;
/// Parse out statepoint directives from the function attributes present in \p
/// AS.
StatepointDirectives parseStatepointDirectivesFromAttrs(AttributeList AS);
/// Return \c true if the \p Attr is an attribute that is a statepoint
/// directive.
bool isStatepointDirectiveAttr(Attribute Attr);
} // end namespace llvm