1//===- GCStrategy.cpp - Garbage Collector Description ---------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the policy object GCStrategy which describes the
10// behavior of a given garbage collector.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/IR/GCStrategy.h"
15#include "llvm/ADT/Twine.h"
16#include "llvm/IR/BuiltinGCs.h"
17
18using namespace llvm;
19
20LLVM_INSTANTIATE_REGISTRY(GCRegistry)
21
22GCStrategy::GCStrategy() = default;
23
24std::unique_ptr<GCStrategy> llvm::getGCStrategy(const StringRef Name) {
25 for (auto &S : GCRegistry::entries())
26 if (S.getName() == Name)
27 return S.instantiate();
28
29 // We need to link all the builtin GCs when LLVM is used as a static library.
30 // The linker will quite happily remove the static constructors that register
31 // the builtin GCs if we don't use a function from that object. This function
32 // does nothing but we need to make sure it is (or at least could be, even
33 // with all optimisations enabled) called *somewhere*, and this is a good
34 // place to do that: if the GC strategies are being used then this function
35 // obviously can't be removed by the linker, and here it won't affect
36 // performance, since there's about to be a fatal error anyway.
37 llvm::linkAllBuiltinGCs();
38
39 if (GCRegistry::begin() == GCRegistry::end()) {
40 // In normal operation, the registry should not be empty. There should
41 // be the builtin GCs if nothing else. The most likely scenario here is
42 // that we got here without running the initializers used by the Registry
43 // itself and it's registration mechanism.
44 report_fatal_error(
45 reason: "unsupported GC: " + Name +
46 " (did you remember to link and initialize the library?)");
47 } else
48 report_fatal_error(reason: Twine("unsupported GC: ") + Name);
49}
50