LLVM  10.0.0svn
Internalize.h
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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/DenseSet.h"
25 #include "llvm/ADT/StringSet.h"
26 #include "llvm/IR/GlobalValue.h"
27 #include "llvm/IR/PassManager.h"
28 #include <functional>
29 
30 namespace llvm {
31 class Module;
32 class CallGraph;
33 
34 /// A pass that internalizes all functions and variables other than those that
35 /// must be preserved according to \c MustPreserveGV.
36 class InternalizePass : public PassInfoMixin<InternalizePass> {
37  /// Client supplied callback to control wheter a symbol must be preserved.
38  const std::function<bool(const GlobalValue &)> MustPreserveGV;
39  /// Set of symbols private to the compiler that this pass should not touch.
40  StringSet<> AlwaysPreserved;
41 
42  /// Return false if we're allowed to internalize this GV.
43  bool shouldPreserveGV(const GlobalValue &GV);
44  /// Internalize GV if it is possible to do so, i.e. it is not externally
45  /// visible and is not a member of an externally visible comdat.
46  bool maybeInternalize(GlobalValue &GV,
47  const DenseSet<const Comdat *> &ExternalComdats);
48  /// If GV is part of a comdat and is externally visible, keep track of its
49  /// comdat so that we don't internalize any of its members.
50  void checkComdatVisibility(GlobalValue &GV,
51  DenseSet<const Comdat *> &ExternalComdats);
52 
53 public:
55  InternalizePass(std::function<bool(const GlobalValue &)> MustPreserveGV)
56  : MustPreserveGV(std::move(MustPreserveGV)) {}
57 
58  /// Run the internalizer on \p TheModule, returns true if any changes was
59  /// made.
60  ///
61  /// If the CallGraph \p CG is supplied, it will be updated when
62  /// internalizing a function (by removing any edge from the "external node")
63  bool internalizeModule(Module &TheModule, CallGraph *CG = nullptr);
64 
66 };
67 
68 /// Helper function to internalize functions and variables in a Module.
69 inline bool
71  std::function<bool(const GlobalValue &)> MustPreserveGV,
72  CallGraph *CG = nullptr) {
73  return InternalizePass(std::move(MustPreserveGV))
74  .internalizeModule(TheModule, CG);
75 }
76 } // end namespace llvm
77 
78 #endif // LLVM_TRANSFORMS_IPO_INTERNALIZE_H
InternalizePass(std::function< bool(const GlobalValue &)> MustPreserveGV)
Definition: Internalize.h:55
This class represents lattice values for constants.
Definition: AllocatorList.h:23
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:65
PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM)
Implements a dense probed hash-table based set.
Definition: DenseSet.h:249
Definition: BitVector.h:937
A pass that internalizes all functions and variables other than those that must be preserved accordin...
Definition: Internalize.h:36
A CRTP mix-in to automatically provide informational APIs needed for passes.
Definition: PassManager.h:372
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
The basic data container for the call graph of a Module of IR.
Definition: CallGraph.h:73
bool internalizeModule(Module &TheModule, CallGraph *CG=nullptr)
Run the internalizer on TheModule, returns true if any changes was made.
StringSet - A wrapper for StringMap that provides set-like functionality.
Definition: StringSet.h:27
print Print MemDeps of function
A container for analyses that lazily runs them and caches their results.
This header defines various interfaces for pass management in LLVM.