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//===-- StatepointDefaultGC.cpp - The default statepoint GC strategy ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a GCStrategy which serves as an example for the usage
// of a statepoint based lowering strategy. This GCStrategy is intended to
// suitable as a default implementation usable with any collector which can
// consume the standard stackmap format generated by statepoints, uses the
// default addrespace to distinguish between gc managed and non-gc managed
// pointers, and has reasonable relocation semantics.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GCStrategy.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Value.h"
using namespace llvm;
namespace {
class StatepointGC : public GCStrategy {
public:
StatepointGC() {
UseStatepoints = true;
// These options are all gc.root specific, we specify them so that the
// gc.root lowering code doesn't run.
InitRoots = false;
NeededSafePoints = 0;
UsesMetadata = false;
CustomRoots = false;
}
Optional<bool> isGCManagedPointer(const Value *V) const override {
// Method is only valid on pointer typed values.
PointerType *PT = cast<PointerType>(V->getType());
// 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. Note that addrspace(1) is used
// only as an example, it has no special meaning, and is not reserved for
// GC usage.
return (1 == PT->getAddressSpace());
}
};
}
static GCRegistry::Add<StatepointGC> X("statepoint-example",
"an example strategy for statepoint");
namespace llvm {
void linkStatepointExampleGC() {}
}
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