1 | //====- Internalize.h - Internalization API ---------------------*- C++ -*-===// |
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 pass loops over all of the functions and variables in the input module. |
10 | // If the function or variable does not need to be preserved according to the |
11 | // client supplied callback, it is marked as internal. |
12 | // |
13 | // This transformation would not be legal in a regular compilation, but it gets |
14 | // extra information from the linker about what is safe. |
15 | // |
16 | // For example: Internalizing a function with external linkage. Only if we are |
17 | // told it is only used from within this module, it is safe to do it. |
18 | // |
19 | //===----------------------------------------------------------------------===// |
20 | |
21 | #ifndef LLVM_TRANSFORMS_IPO_INTERNALIZE_H |
22 | #define LLVM_TRANSFORMS_IPO_INTERNALIZE_H |
23 | |
24 | #include "llvm/ADT/DenseMap.h" |
25 | #include "llvm/ADT/StringSet.h" |
26 | #include "llvm/IR/PassManager.h" |
27 | #include <functional> |
28 | |
29 | namespace llvm { |
30 | class Module; |
31 | |
32 | /// A pass that internalizes all functions and variables other than those that |
33 | /// must be preserved according to \c MustPreserveGV. |
34 | class InternalizePass : public PassInfoMixin<InternalizePass> { |
35 | struct ComdatInfo { |
36 | // The number of members. A comdat with one member which is not externally |
37 | // visible can be freely dropped. |
38 | size_t Size = 0; |
39 | // Whether the comdat has an externally visible member. |
40 | bool External = false; |
41 | }; |
42 | |
43 | bool IsWasm = false; |
44 | |
45 | /// Client supplied callback to control wheter a symbol must be preserved. |
46 | const std::function<bool(const GlobalValue &)> MustPreserveGV; |
47 | /// Set of symbols private to the compiler that this pass should not touch. |
48 | StringSet<> AlwaysPreserved; |
49 | |
50 | /// Return false if we're allowed to internalize this GV. |
51 | bool shouldPreserveGV(const GlobalValue &GV); |
52 | /// Internalize GV if it is possible to do so, i.e. it is not externally |
53 | /// visible and is not a member of an externally visible comdat. |
54 | bool maybeInternalize(GlobalValue &GV, |
55 | DenseMap<const Comdat *, ComdatInfo> &ComdatMap); |
56 | /// If GV is part of a comdat and is externally visible, keep track of its |
57 | /// comdat so that we don't internalize any of its members. |
58 | void checkComdat(GlobalValue &GV, |
59 | DenseMap<const Comdat *, ComdatInfo> &ComdatMap); |
60 | |
61 | public: |
62 | InternalizePass(); |
63 | InternalizePass(std::function<bool(const GlobalValue &)> MustPreserveGV) |
64 | : MustPreserveGV(std::move(MustPreserveGV)) {} |
65 | |
66 | /// Run the internalizer on \p TheModule, returns true if any changes was |
67 | /// made. |
68 | bool internalizeModule(Module &TheModule); |
69 | |
70 | PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM); |
71 | }; |
72 | |
73 | /// Helper function to internalize functions and variables in a Module. |
74 | inline bool |
75 | internalizeModule(Module &TheModule, |
76 | std::function<bool(const GlobalValue &)> MustPreserveGV) { |
77 | return InternalizePass(std::move(MustPreserveGV)) |
78 | .internalizeModule(TheModule); |
79 | } |
80 | } // end namespace llvm |
81 | |
82 | #endif // LLVM_TRANSFORMS_IPO_INTERNALIZE_H |
83 | |