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comparison lib/Transforms/IPO/ConstantMerge.cpp @ 121:803732b1fca8

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LLVM 5.0
author kono
date Fri, 27 Oct 2017 17:07:41 +0900
parents 1172e4bd9c6f
children c2174574ed3a
comparison
equal deleted inserted replaced
120:1172e4bd9c6f 121:803732b1fca8
17 // 17 //
18 //===----------------------------------------------------------------------===// 18 //===----------------------------------------------------------------------===//
19 19
20 #include "llvm/Transforms/IPO/ConstantMerge.h" 20 #include "llvm/Transforms/IPO/ConstantMerge.h"
21 #include "llvm/ADT/DenseMap.h" 21 #include "llvm/ADT/DenseMap.h"
22 #include "llvm/ADT/PointerIntPair.h"
23 #include "llvm/ADT/SmallPtrSet.h" 22 #include "llvm/ADT/SmallPtrSet.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/Statistic.h" 24 #include "llvm/ADT/Statistic.h"
25 #include "llvm/IR/Constants.h" 25 #include "llvm/IR/Constants.h"
26 #include "llvm/IR/DataLayout.h" 26 #include "llvm/IR/DataLayout.h"
27 #include "llvm/IR/DerivedTypes.h" 27 #include "llvm/IR/DerivedTypes.h"
28 #include "llvm/IR/GlobalValue.h"
29 #include "llvm/IR/GlobalVariable.h"
30 #include "llvm/IR/LLVMContext.h"
28 #include "llvm/IR/Module.h" 31 #include "llvm/IR/Module.h"
29 #include "llvm/IR/Operator.h"
30 #include "llvm/Pass.h" 32 #include "llvm/Pass.h"
33 #include "llvm/Support/Casting.h"
31 #include "llvm/Transforms/IPO.h" 34 #include "llvm/Transforms/IPO.h"
35 #include <algorithm>
36 #include <cassert>
37 #include <utility>
38
32 using namespace llvm; 39 using namespace llvm;
33 40
34 #define DEBUG_TYPE "constmerge" 41 #define DEBUG_TYPE "constmerge"
35 42
36 STATISTIC(NumMerged, "Number of global constants merged"); 43 STATISTIC(NumMerged, "Number of global constants merged");
58 return false; 65 return false;
59 66
60 return A.hasGlobalUnnamedAddr(); 67 return A.hasGlobalUnnamedAddr();
61 } 68 }
62 69
70 static bool hasMetadataOtherThanDebugLoc(const GlobalVariable *GV) {
71 SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
72 GV->getAllMetadata(MDs);
73 for (const auto &V : MDs)
74 if (V.first != LLVMContext::MD_dbg)
75 return true;
76 return false;
77 }
78
79 static void copyDebugLocMetadata(const GlobalVariable *From,
80 GlobalVariable *To) {
81 SmallVector<DIGlobalVariableExpression *, 1> MDs;
82 From->getDebugInfo(MDs);
83 for (auto MD : MDs)
84 To->addDebugInfo(MD);
85 }
86
63 static unsigned getAlignment(GlobalVariable *GV) { 87 static unsigned getAlignment(GlobalVariable *GV) {
64 unsigned Align = GV->getAlignment(); 88 unsigned Align = GV->getAlignment();
65 if (Align) 89 if (Align)
66 return Align; 90 return Align;
67 return GV->getParent()->getDataLayout().getPreferredAlignment(GV); 91 return GV->getParent()->getDataLayout().getPreferredAlignment(GV);
83 107
84 // Iterate constant merging while we are still making progress. Merging two 108 // Iterate constant merging while we are still making progress. Merging two
85 // constants together may allow us to merge other constants together if the 109 // constants together may allow us to merge other constants together if the
86 // second level constants have initializers which point to the globals that 110 // second level constants have initializers which point to the globals that
87 // were just merged. 111 // were just merged.
88 while (1) { 112 while (true) {
89
90 // First: Find the canonical constants others will be merged with. 113 // First: Find the canonical constants others will be merged with.
91 for (Module::global_iterator GVI = M.global_begin(), E = M.global_end(); 114 for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
92 GVI != E; ) { 115 GVI != E; ) {
93 GlobalVariable *GV = &*GVI++; 116 GlobalVariable *GV = &*GVI++;
94 117
109 // This transformation is legal for weak ODR globals in the sense it 132 // This transformation is legal for weak ODR globals in the sense it
110 // doesn't change semantics, but we really don't want to perform it 133 // doesn't change semantics, but we really don't want to perform it
111 // anyway; it's likely to pessimize code generation, and some tools 134 // anyway; it's likely to pessimize code generation, and some tools
112 // (like the Darwin linker in cases involving CFString) don't expect it. 135 // (like the Darwin linker in cases involving CFString) don't expect it.
113 if (GV->isWeakForLinker()) 136 if (GV->isWeakForLinker())
137 continue;
138
139 // Don't touch globals with metadata other then !dbg.
140 if (hasMetadataOtherThanDebugLoc(GV))
114 continue; 141 continue;
115 142
116 Constant *Init = GV->getInitializer(); 143 Constant *Init = GV->getInitializer();
117 144
118 // Check to see if the initializer is already known. 145 // Check to see if the initializer is already known.
151 178
152 if (!Slot || Slot == GV) 179 if (!Slot || Slot == GV)
153 continue; 180 continue;
154 181
155 if (!Slot->hasGlobalUnnamedAddr() && !GV->hasGlobalUnnamedAddr()) 182 if (!Slot->hasGlobalUnnamedAddr() && !GV->hasGlobalUnnamedAddr())
183 continue;
184
185 if (hasMetadataOtherThanDebugLoc(GV))
156 continue; 186 continue;
157 187
158 if (!GV->hasGlobalUnnamedAddr()) 188 if (!GV->hasGlobalUnnamedAddr())
159 Slot->setUnnamedAddr(GlobalValue::UnnamedAddr::None); 189 Slot->setUnnamedAddr(GlobalValue::UnnamedAddr::None);
160 190
176 Replacements[i].second->setAlignment( 206 Replacements[i].second->setAlignment(
177 std::max(getAlignment(Replacements[i].first), 207 std::max(getAlignment(Replacements[i].first),
178 getAlignment(Replacements[i].second))); 208 getAlignment(Replacements[i].second)));
179 } 209 }
180 210
211 copyDebugLocMetadata(Replacements[i].first, Replacements[i].second);
212
181 // Eliminate any uses of the dead global. 213 // Eliminate any uses of the dead global.
182 Replacements[i].first->replaceAllUsesWith(Replacements[i].second); 214 Replacements[i].first->replaceAllUsesWith(Replacements[i].second);
183 215
184 // Delete the global value from the module. 216 // Delete the global value from the module.
185 assert(Replacements[i].first->hasLocalLinkage() && 217 assert(Replacements[i].first->hasLocalLinkage() &&
197 return PreservedAnalyses::all(); 229 return PreservedAnalyses::all();
198 return PreservedAnalyses::none(); 230 return PreservedAnalyses::none();
199 } 231 }
200 232
201 namespace { 233 namespace {
234
202 struct ConstantMergeLegacyPass : public ModulePass { 235 struct ConstantMergeLegacyPass : public ModulePass {
203 static char ID; // Pass identification, replacement for typeid 236 static char ID; // Pass identification, replacement for typeid
237
204 ConstantMergeLegacyPass() : ModulePass(ID) { 238 ConstantMergeLegacyPass() : ModulePass(ID) {
205 initializeConstantMergeLegacyPassPass(*PassRegistry::getPassRegistry()); 239 initializeConstantMergeLegacyPassPass(*PassRegistry::getPassRegistry());
206 } 240 }
207 241
208 // For this pass, process all of the globals in the module, eliminating 242 // For this pass, process all of the globals in the module, eliminating
209 // duplicate constants. 243 // duplicate constants.
210 bool runOnModule(Module &M) { 244 bool runOnModule(Module &M) override {
211 if (skipModule(M)) 245 if (skipModule(M))
212 return false; 246 return false;
213 return mergeConstants(M); 247 return mergeConstants(M);
214 } 248 }
215 }; 249 };
216 } 250
251 } // end anonymous namespace
217 252
218 char ConstantMergeLegacyPass::ID = 0; 253 char ConstantMergeLegacyPass::ID = 0;
254
219 INITIALIZE_PASS(ConstantMergeLegacyPass, "constmerge", 255 INITIALIZE_PASS(ConstantMergeLegacyPass, "constmerge",
220 "Merge Duplicate Global Constants", false, false) 256 "Merge Duplicate Global Constants", false, false)
221 257
222 ModulePass *llvm::createConstantMergePass() { 258 ModulePass *llvm::createConstantMergePass() {
223 return new ConstantMergeLegacyPass(); 259 return new ConstantMergeLegacyPass();