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8a660bd822
Searching all of the existing gc.root implementations I'm aware of (all three of them), there was exactly one use of this mechanism, and that was to implement a performance improvement that should have been applied to the default lowering. Having this function is requiring a dependency on a CodeGen class (MachineFunction), in a class which is otherwise completely independent of CodeGen. I could solve this differently, but given that I see absolutely no value in preserving this mechanism, I going to just get rid of it. Note: Tis is the first time I'm intentionally breaking previously supported gc.root functionality. Given 3.6 has branched, I believe this is a good time to do this. Differential Revision: http://reviews.llvm.org/D7004 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226305 91177308-0d34-0410-b5e6-96231b3b80d8
54 lines
1.9 KiB
C++
54 lines
1.9 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 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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