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 18 using namespace llvm; 19 20 LLVM_INSTANTIATE_REGISTRY(GCRegistry) 21 22 GCStrategy::GCStrategy() = default; 23 24 std::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 const std::string error = 45 std::string("unsupported GC: ") + Name.str() + 46 " (did you remember to link and initialize the library?)"; 47 report_fatal_error(Twine(error)); 48 } else 49 report_fatal_error(Twine(std::string("unsupported GC: ") + Name.str())); 50 } 51