/Users/buildslave/jenkins/sharedspace/clang-stage2-coverage-R@2/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp
Line | Count | Source |
1 | | //===-- ElimAvailExtern.cpp - DCE unreachable internal functions |
2 | | //----------------===// |
3 | | // |
4 | | // The LLVM Compiler Infrastructure |
5 | | // |
6 | | // This file is distributed under the University of Illinois Open Source |
7 | | // License. See LICENSE.TXT for details. |
8 | | // |
9 | | //===----------------------------------------------------------------------===// |
10 | | // |
11 | | // This transform is designed to eliminate available external global |
12 | | // definitions from the program, turning them into declarations. |
13 | | // |
14 | | //===----------------------------------------------------------------------===// |
15 | | |
16 | | #include "llvm/Transforms/IPO/ElimAvailExtern.h" |
17 | | #include "llvm/ADT/Statistic.h" |
18 | | #include "llvm/IR/Constants.h" |
19 | | #include "llvm/IR/Module.h" |
20 | | #include "llvm/Pass.h" |
21 | | #include "llvm/Transforms/IPO.h" |
22 | | #include "llvm/Transforms/Utils/GlobalStatus.h" |
23 | | using namespace llvm; |
24 | | |
25 | | #define DEBUG_TYPE "elim-avail-extern" |
26 | | |
27 | | STATISTIC(NumFunctions, "Number of functions removed"); |
28 | | STATISTIC(NumVariables, "Number of global variables removed"); |
29 | | |
30 | 17.3k | static bool eliminateAvailableExternally(Module &M) { |
31 | 17.3k | bool Changed = false; |
32 | 17.3k | |
33 | 17.3k | // Drop initializers of available externally global variables. |
34 | 773k | for (GlobalVariable &GV : M.globals()) { |
35 | 773k | if (!GV.hasAvailableExternallyLinkage()) |
36 | 773k | continue; |
37 | 117 | if (117 GV.hasInitializer()117 ) { |
38 | 117 | Constant *Init = GV.getInitializer(); |
39 | 117 | GV.setInitializer(nullptr); |
40 | 117 | if (isSafeToDestroyConstant(Init)) |
41 | 116 | Init->destroyConstant(); |
42 | 117 | } |
43 | 773k | GV.removeDeadConstantUsers(); |
44 | 773k | GV.setLinkage(GlobalValue::ExternalLinkage); |
45 | 773k | NumVariables++; |
46 | 773k | Changed = true; |
47 | 773k | } |
48 | 17.3k | |
49 | 17.3k | // Drop the bodies of available externally functions. |
50 | 673k | for (Function &F : M) { |
51 | 673k | if (!F.hasAvailableExternallyLinkage()) |
52 | 673k | continue; |
53 | 79 | if (79 !F.isDeclaration()79 ) |
54 | 79 | // This will set the linkage to external |
55 | 79 | F.deleteBody(); |
56 | 673k | F.removeDeadConstantUsers(); |
57 | 673k | NumFunctions++; |
58 | 673k | Changed = true; |
59 | 673k | } |
60 | 17.3k | |
61 | 17.3k | return Changed; |
62 | 17.3k | } |
63 | | |
64 | | PreservedAnalyses |
65 | 48 | EliminateAvailableExternallyPass::run(Module &M, ModuleAnalysisManager &) { |
66 | 48 | if (!eliminateAvailableExternally(M)) |
67 | 47 | return PreservedAnalyses::all(); |
68 | 1 | return PreservedAnalyses::none(); |
69 | 1 | } |
70 | | |
71 | | namespace { |
72 | | struct EliminateAvailableExternallyLegacyPass : public ModulePass { |
73 | | static char ID; // Pass identification, replacement for typeid |
74 | 17.3k | EliminateAvailableExternallyLegacyPass() : ModulePass(ID) { |
75 | 17.3k | initializeEliminateAvailableExternallyLegacyPassPass( |
76 | 17.3k | *PassRegistry::getPassRegistry()); |
77 | 17.3k | } |
78 | | |
79 | | // run - Do the EliminateAvailableExternally pass on the specified module, |
80 | | // optionally updating the specified callgraph to reflect the changes. |
81 | | // |
82 | 17.3k | bool runOnModule(Module &M) { |
83 | 17.3k | if (skipModule(M)) |
84 | 10 | return false; |
85 | 17.3k | return eliminateAvailableExternally(M); |
86 | 17.3k | } |
87 | | }; |
88 | | } |
89 | | |
90 | | char EliminateAvailableExternallyLegacyPass::ID = 0; |
91 | | INITIALIZE_PASS(EliminateAvailableExternallyLegacyPass, "elim-avail-extern", |
92 | | "Eliminate Available Externally Globals", false, false) |
93 | | |
94 | 17.3k | ModulePass *llvm::createEliminateAvailableExternallyPass() { |
95 | 17.3k | return new EliminateAvailableExternallyLegacyPass(); |
96 | 17.3k | } |