//===- llvm/IR/Statepoint.h - gc.statepoint utilities -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains utility functions and a wrapper class analogous to
// CallBase for accessing the fields of gc.statepoint, gc.relocate,
// gc.result intrinsics; and some general utilities helpful when dealing with
// gc.statepoint.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_STATEPOINT_H
#define LLVM_IR_STATEPOINT_H
#include "llvm/ADT/iterator_range.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstrTypes.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 <optional>
#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.
};
// These two are defined in IntrinsicInst since they're part of the
// IntrinsicInst class hierarchy.
class GCRelocateInst;
/// Represents a gc.statepoint intrinsic call. This extends directly from
/// CallBase as the IntrinsicInst only supports calls and gc.statepoint is
/// invokable.
class GCStatepointInst : public CallBase {
public:
GCStatepointInst() = delete;
GCStatepointInst(const GCStatepointInst &) = delete;
GCStatepointInst &operator=(const GCStatepointInst &) = delete;
static bool classof(const CallBase *I) {
if (const Function *CF = I->getCalledFunction())
return CF->getIntrinsicID() == Intrinsic::experimental_gc_statepoint;
return false;
}
static bool classof(const Value *V) {
return isa<CallBase>(V) && classof(cast<CallBase>(V));
}
enum {
IDPos = 0,
NumPatchBytesPos = 1,
CalledFunctionPos = 2,
NumCallArgsPos = 3,
FlagsPos = 4,
CallArgsBeginPos = 5,
};
/// Return the ID associated with this statepoint.
uint64_t getID() const {
return cast<ConstantInt>(getArgOperand(IDPos))->getZExtValue();
}
/// Return the number of patchable bytes associated with this statepoint.
uint32_t getNumPatchBytes() const {
const Value *NumPatchBytesVal = getArgOperand(NumPatchBytesPos);
uint64_t NumPatchBytes =
cast<ConstantInt>(NumPatchBytesVal)->getZExtValue();
assert(isInt<32>(NumPatchBytes) && "should fit in 32 bits!");
return NumPatchBytes;
}
/// Number of arguments to be passed to the actual callee.
int getNumCallArgs() const {
return cast<ConstantInt>(getArgOperand(NumCallArgsPos))->getZExtValue();
}
uint64_t getFlags() const {
return cast<ConstantInt>(getArgOperand(FlagsPos))->getZExtValue();
}
/// Return the value actually being called or invoked.
Value *getActualCalledOperand() const {
return getArgOperand(CalledFunctionPos);
}
/// Returns the function called if this is a wrapping a direct call, and null
/// otherwise.
Function *getActualCalledFunction() const {
return dyn_cast_or_null<Function>(getActualCalledOperand());
}
/// Return the type of the value returned by the call underlying the
/// statepoint.
Type *getActualReturnType() const {
auto *FT = cast<FunctionType>(getParamElementType(CalledFunctionPos));
return FT->getReturnType();
}
/// Return the number of arguments to the underlying call.
size_t actual_arg_size() const { return getNumCallArgs(); }
/// Return an iterator to the begining of the arguments to the underlying call
const_op_iterator actual_arg_begin() const {
assert(CallArgsBeginPos <= (int)arg_size());
return arg_begin() + CallArgsBeginPos;
}
/// Return an end iterator of the arguments to the underlying call
const_op_iterator actual_arg_end() const {
auto I = actual_arg_begin() + actual_arg_size();
assert((arg_end() - I) == 2);
return I;
}
/// range adapter for actual call arguments
iterator_range<const_op_iterator> actual_args() const {
return make_range(actual_arg_begin(), actual_arg_end());
}
const_op_iterator gc_transition_args_begin() const {
if (auto Opt = getOperandBundle(LLVMContext::OB_gc_transition))
return Opt->Inputs.begin();
return arg_end();
}
const_op_iterator gc_transition_args_end() const {
if (auto Opt = getOperandBundle(LLVMContext::OB_gc_transition))
return Opt->Inputs.end();
return arg_end();
}
/// range adapter for GC transition arguments
iterator_range<const_op_iterator> gc_transition_args() const {
return make_range(gc_transition_args_begin(), gc_transition_args_end());
}
const_op_iterator deopt_begin() const {
if (auto Opt = getOperandBundle(LLVMContext::OB_deopt))
return Opt->Inputs.begin();
return arg_end();
}
const_op_iterator deopt_end() const {
if (auto Opt = getOperandBundle(LLVMContext::OB_deopt))
return Opt->Inputs.end();
return arg_end();
}
/// range adapter for vm state arguments
iterator_range<const_op_iterator> deopt_operands() const {
return make_range(deopt_begin(), deopt_end());
}
/// Returns an iterator to the begining of the argument range describing gc
/// values for the statepoint.
const_op_iterator gc_args_begin() const {
if (auto Opt = getOperandBundle(LLVMContext::OB_gc_live))
return Opt->Inputs.begin();
return arg_end();
}
/// Return an end iterator for the gc argument range
const_op_iterator gc_args_end() const {
if (auto Opt = getOperandBundle(LLVMContext::OB_gc_live))
return Opt->Inputs.end();
return arg_end();
}
/// range adapter for gc arguments
iterator_range<const_op_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.
inline std::vector<const GCRelocateInst *> getGCRelocates() const;
};
std::vector<const GCRelocateInst *> GCStatepointInst::getGCRelocates() const {
std::vector<const GCRelocateInst *> Result;
// 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 : users())
if (auto *Relocate = dyn_cast<GCRelocateInst>(U))
Result.push_back(Relocate);
auto *StatepointInvoke = dyn_cast<InvokeInst>(this);
if (!StatepointInvoke)
return Result;
// We need to scan thorough exceptional relocations if it is invoke statepoint
LandingPadInst *LandingPad = StatepointInvoke->getLandingPadInst();
// Search for gc relocates that are attached to this landingpad.
for (const User *LandingPadUser : LandingPad->users()) {
if (auto *Relocate = dyn_cast<GCRelocateInst>(LandingPadUser))
Result.push_back(Relocate);
}
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 {
std::optional<uint32_t> NumPatchBytes;
std::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
#endif // LLVM_IR_STATEPOINT_H