/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/lib/CodeGen/BuiltinGCs.cpp
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1 | | //===- BuiltinGCs.cpp - Boilerplate for our built in GC types -------------===// |
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 contains the boilerplate required to define our various built in |
10 | | // gc lowering strategies. |
11 | | // |
12 | | //===----------------------------------------------------------------------===// |
13 | | |
14 | | #include "llvm/CodeGen/BuiltinGCs.h" |
15 | | #include "llvm/CodeGen/GCStrategy.h" |
16 | | #include "llvm/IR/DerivedTypes.h" |
17 | | #include "llvm/Support/Casting.h" |
18 | | |
19 | | using namespace llvm; |
20 | | |
21 | | namespace { |
22 | | |
23 | | /// An example GC which attempts to be compatibile with Erlang/OTP garbage |
24 | | /// collector. |
25 | | /// |
26 | | /// The frametable emitter is in ErlangGCPrinter.cpp. |
27 | | class ErlangGC : public GCStrategy { |
28 | | public: |
29 | 3 | ErlangGC() { |
30 | 3 | NeededSafePoints = true; |
31 | 3 | UsesMetadata = true; |
32 | 3 | } |
33 | | }; |
34 | | |
35 | | /// An example GC which attempts to be compatible with Objective Caml 3.10.0 |
36 | | /// |
37 | | /// The frametable emitter is in OcamlGCPrinter.cpp. |
38 | | class OcamlGC : public GCStrategy { |
39 | | public: |
40 | 3 | OcamlGC() { |
41 | 3 | NeededSafePoints = true; |
42 | 3 | UsesMetadata = true; |
43 | 3 | } |
44 | | }; |
45 | | |
46 | | /// A GC strategy for uncooperative targets. This implements lowering for the |
47 | | /// llvm.gc* intrinsics for targets that do not natively support them (which |
48 | | /// includes the C backend). Note that the code generated is not quite as |
49 | | /// efficient as algorithms which generate stack maps to identify roots. |
50 | | /// |
51 | | /// In order to support this particular transformation, all stack roots are |
52 | | /// coallocated in the stack. This allows a fully target-independent stack map |
53 | | /// while introducing only minor runtime overhead. |
54 | | class ShadowStackGC : public GCStrategy { |
55 | | public: |
56 | 2 | ShadowStackGC() {} |
57 | | }; |
58 | | |
59 | | /// A GCStrategy which serves as an example for the usage of a statepoint based |
60 | | /// lowering strategy. This GCStrategy is intended to suitable as a default |
61 | | /// implementation usable with any collector which can consume the standard |
62 | | /// stackmap format generated by statepoints, uses the default addrespace to |
63 | | /// distinguish between gc managed and non-gc managed pointers, and has |
64 | | /// reasonable relocation semantics. |
65 | | class StatepointGC : public GCStrategy { |
66 | | public: |
67 | 16 | StatepointGC() { |
68 | 16 | UseStatepoints = true; |
69 | 16 | // These options are all gc.root specific, we specify them so that the |
70 | 16 | // gc.root lowering code doesn't run. |
71 | 16 | NeededSafePoints = false; |
72 | 16 | UsesMetadata = false; |
73 | 16 | } |
74 | | |
75 | 0 | Optional<bool> isGCManagedPointer(const Type *Ty) const override { |
76 | 0 | // Method is only valid on pointer typed values. |
77 | 0 | const PointerType *PT = cast<PointerType>(Ty); |
78 | 0 | // For the sake of this example GC, we arbitrarily pick addrspace(1) as our |
79 | 0 | // GC managed heap. We know that a pointer into this heap needs to be |
80 | 0 | // updated and that no other pointer does. Note that addrspace(1) is used |
81 | 0 | // only as an example, it has no special meaning, and is not reserved for |
82 | 0 | // GC usage. |
83 | 0 | return (1 == PT->getAddressSpace()); |
84 | 0 | } |
85 | | }; |
86 | | |
87 | | /// A GCStrategy for the CoreCLR Runtime. The strategy is similar to |
88 | | /// Statepoint-example GC, but differs from it in certain aspects, such as: |
89 | | /// 1) Base-pointers need not be explicitly tracked and reported for |
90 | | /// interior pointers |
91 | | /// 2) Uses a different format for encoding stack-maps |
92 | | /// 3) Location of Safe-point polls: polls are only needed before loop-back |
93 | | /// edges and before tail-calls (not needed at function-entry) |
94 | | /// |
95 | | /// The above differences in behavior are to be implemented in upcoming |
96 | | /// checkins. |
97 | | class CoreCLRGC : public GCStrategy { |
98 | | public: |
99 | 2 | CoreCLRGC() { |
100 | 2 | UseStatepoints = true; |
101 | 2 | // These options are all gc.root specific, we specify them so that the |
102 | 2 | // gc.root lowering code doesn't run. |
103 | 2 | NeededSafePoints = false; |
104 | 2 | UsesMetadata = false; |
105 | 2 | } |
106 | | |
107 | 0 | Optional<bool> isGCManagedPointer(const Type *Ty) const override { |
108 | 0 | // Method is only valid on pointer typed values. |
109 | 0 | const PointerType *PT = cast<PointerType>(Ty); |
110 | 0 | // We pick addrspace(1) as our GC managed heap. |
111 | 0 | return (1 == PT->getAddressSpace()); |
112 | 0 | } |
113 | | }; |
114 | | |
115 | | } // end anonymous namespace |
116 | | |
117 | | // Register all the above so that they can be found at runtime. Note that |
118 | | // these static initializers are important since the registration list is |
119 | | // constructed from their storage. |
120 | | static GCRegistry::Add<ErlangGC> A("erlang", |
121 | | "erlang-compatible garbage collector"); |
122 | | static GCRegistry::Add<OcamlGC> B("ocaml", "ocaml 3.10-compatible GC"); |
123 | | static GCRegistry::Add<ShadowStackGC> |
124 | | C("shadow-stack", "Very portable GC for uncooperative code generators"); |
125 | | static GCRegistry::Add<StatepointGC> D("statepoint-example", |
126 | | "an example strategy for statepoint"); |
127 | | static GCRegistry::Add<CoreCLRGC> E("coreclr", "CoreCLR-compatible GC"); |
128 | | |
129 | | // Provide hook to ensure the containing library is fully loaded. |
130 | 0 | void llvm::linkAllBuiltinGCs() {} |