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e80a72c967
Reasons: 1) The existing form was a form of false generality. None of the implemented GCStrategies use anything other than a type. Its becoming more and more clear we're going to need some type of strong GC pointer in the type system and we shouldn't pretend otherwise at this point. 2) The API was awkward when applied to vectors-of-pointers. The old one could have been made to work, but calling isGCManagedPointer(Ty->getScalarType()) is much cleaner than the Value alternatives. 3) The rewriting implementation effectively assumes the type based predicate as well. We should be consistent. llvm-svn: 256312
56 lines
2.0 KiB
C++
56 lines
2.0 KiB
C++
//===-- StatepointDefaultGC.cpp - The default statepoint GC strategy ------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains a GCStrategy which serves as an example for the usage
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// of a statepoint based lowering strategy. This GCStrategy is intended to
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// suitable as a default implementation usable with any collector which can
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// consume the standard stackmap format generated by statepoints, uses the
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// default addrespace to distinguish between gc managed and non-gc managed
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// pointers, and has reasonable relocation semantics.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/GCStrategy.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Value.h"
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using namespace llvm;
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namespace {
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class StatepointGC : public GCStrategy {
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public:
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StatepointGC() {
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UseStatepoints = true;
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// These options are all gc.root specific, we specify them so that the
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// gc.root lowering code doesn't run.
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InitRoots = false;
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NeededSafePoints = 0;
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UsesMetadata = false;
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CustomRoots = false;
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}
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Optional<bool> isGCManagedPointer(const Type *Ty) const override {
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// Method is only valid on pointer typed values.
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const PointerType *PT = cast<PointerType>(Ty);
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// For the sake of this example GC, we arbitrarily pick addrspace(1) as our
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// GC managed heap. We know that a pointer into this heap needs to be
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// updated and that no other pointer does. Note that addrspace(1) is used
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// only as an example, it has no special meaning, and is not reserved for
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// GC usage.
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return (1 == PT->getAddressSpace());
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}
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};
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}
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static GCRegistry::Add<StatepointGC> X("statepoint-example",
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"an example strategy for statepoint");
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namespace llvm {
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void linkStatepointExampleGC() {}
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}
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