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07fbc5c1c6
Note: This change ended up being slightly more controversial than expected. Chandler has tentatively okayed this for the moment, but I may be revisiting this in the near future after we settle some high level questions. Rather than have the GCStrategy object owned by the GCModuleInfo - which is an immutable analysis pass used mainly by gc.root - have it be owned by the LLVMContext. This simplifies the ownership logic (i.e. can you have two instances of the same strategy at once?), but more importantly, allows us to access the GCStrategy in the middle end optimizer. To this end, I add an accessor through Function which becomes the canonical way to get at a GCStrategy instance. In the near future, this will allows me to move some of the checks from http://reviews.llvm.org/D6808 into the Verifier itself, and to introduce optimization legality predicates for some of the recent additions to InstCombine. (These will follow as separate changes.) Differential Revision: http://reviews.llvm.org/D6811 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226311 91177308-0d34-0410-b5e6-96231b3b80d8
54 lines
1.8 KiB
C++
54 lines
1.8 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/IR/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 Value *V) const override {
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// Method is only valid on pointer typed values.
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PointerType *PT = cast<PointerType>(V->getType());
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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.
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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>
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X("statepoint-example", "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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