Devang Patel | 76c8563 | 2011-10-17 17:17:43 +0000 | [diff] [blame] | 1 | //===-- GlobalMerge.cpp - Internal globals merging -----------------------===// |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // This pass merges globals with internal linkage into one. This way all the |
| 10 | // globals which were merged into a biggest one can be addressed using offsets |
| 11 | // from the same base pointer (no need for separate base pointer for each of the |
| 12 | // global). Such a transformation can significantly reduce the register pressure |
| 13 | // when many globals are involved. |
| 14 | // |
Nadav Rotem | 465834c | 2012-07-24 10:51:42 +0000 | [diff] [blame] | 15 | // For example, consider the code which touches several global variables at |
Eric Christopher | bf86fd3 | 2010-09-28 04:18:29 +0000 | [diff] [blame] | 16 | // once: |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 17 | // |
| 18 | // static int foo[N], bar[N], baz[N]; |
| 19 | // |
| 20 | // for (i = 0; i < N; ++i) { |
| 21 | // foo[i] = bar[i] * baz[i]; |
| 22 | // } |
| 23 | // |
| 24 | // On ARM the addresses of 3 arrays should be kept in the registers, thus |
| 25 | // this code has quite large register pressure (loop body): |
| 26 | // |
| 27 | // ldr r1, [r5], #4 |
| 28 | // ldr r2, [r6], #4 |
| 29 | // mul r1, r2, r1 |
| 30 | // str r1, [r0], #4 |
| 31 | // |
| 32 | // Pass converts the code to something like: |
| 33 | // |
| 34 | // static struct { |
| 35 | // int foo[N]; |
| 36 | // int bar[N]; |
| 37 | // int baz[N]; |
| 38 | // } merged; |
| 39 | // |
| 40 | // for (i = 0; i < N; ++i) { |
| 41 | // merged.foo[i] = merged.bar[i] * merged.baz[i]; |
| 42 | // } |
| 43 | // |
| 44 | // and in ARM code this becomes: |
| 45 | // |
| 46 | // ldr r0, [r5, #40] |
| 47 | // ldr r1, [r5, #80] |
| 48 | // mul r0, r1, r0 |
| 49 | // str r0, [r5], #4 |
| 50 | // |
| 51 | // note that we saved 2 registers here almostly "for free". |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 52 | // |
| 53 | // However, merging globals can have tradeoffs: |
| 54 | // - it confuses debuggers, tools, and users |
| 55 | // - it makes linker optimizations less useful (order files, LOHs, ...) |
| 56 | // - it forces usage of indexed addressing (which isn't necessarily "free") |
| 57 | // - it can increase register pressure when the uses are disparate enough. |
| 58 | // |
| 59 | // We use heuristics to discover the best global grouping we can (cf cl::opts). |
Eric Christopher | bf86fd3 | 2010-09-28 04:18:29 +0000 | [diff] [blame] | 60 | // ===---------------------------------------------------------------------===// |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 61 | |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 62 | #include "llvm/ADT/DenseMap.h" |
| 63 | #include "llvm/ADT/SmallBitVector.h" |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 64 | #include "llvm/ADT/SmallPtrSet.h" |
Chandler Carruth | ed0881b | 2012-12-03 16:50:05 +0000 | [diff] [blame] | 65 | #include "llvm/ADT/Statistic.h" |
Chandler Carruth | d990388 | 2015-01-14 11:23:27 +0000 | [diff] [blame] | 66 | #include "llvm/CodeGen/Passes.h" |
Chandler Carruth | 9fb823b | 2013-01-02 11:36:10 +0000 | [diff] [blame] | 67 | #include "llvm/IR/Attributes.h" |
| 68 | #include "llvm/IR/Constants.h" |
| 69 | #include "llvm/IR/DataLayout.h" |
| 70 | #include "llvm/IR/DerivedTypes.h" |
| 71 | #include "llvm/IR/Function.h" |
| 72 | #include "llvm/IR/GlobalVariable.h" |
| 73 | #include "llvm/IR/Instructions.h" |
| 74 | #include "llvm/IR/Intrinsics.h" |
| 75 | #include "llvm/IR/Module.h" |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 76 | #include "llvm/Pass.h" |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 77 | #include "llvm/Support/CommandLine.h" |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 78 | #include "llvm/Support/Debug.h" |
| 79 | #include "llvm/Support/raw_ostream.h" |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 80 | #include "llvm/Target/TargetLowering.h" |
Bob Wilson | 881b45c | 2010-11-17 21:25:39 +0000 | [diff] [blame] | 81 | #include "llvm/Target/TargetLoweringObjectFile.h" |
Eric Christopher | d913448 | 2014-08-04 21:25:23 +0000 | [diff] [blame] | 82 | #include "llvm/Target/TargetSubtargetInfo.h" |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 83 | #include <algorithm> |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 84 | using namespace llvm; |
| 85 | |
Chandler Carruth | 964daaa | 2014-04-22 02:55:47 +0000 | [diff] [blame] | 86 | #define DEBUG_TYPE "global-merge" |
| 87 | |
Ahmed Bougacha | b96444e | 2015-04-11 00:06:36 +0000 | [diff] [blame] | 88 | // FIXME: This is only useful as a last-resort way to disable the pass. |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 89 | static cl::opt<bool> |
Jiangning Liu | 3e5b855 | 2014-06-11 06:35:26 +0000 | [diff] [blame] | 90 | EnableGlobalMerge("enable-global-merge", cl::Hidden, |
Ahmed Bougacha | b96444e | 2015-04-11 00:06:36 +0000 | [diff] [blame] | 91 | cl::desc("Enable the global merge pass"), |
Tim Northover | f804c17 | 2014-02-18 11:17:29 +0000 | [diff] [blame] | 92 | cl::init(true)); |
| 93 | |
Peter Collingbourne | fe12d0e | 2016-05-19 04:38:56 +0000 | [diff] [blame] | 94 | static cl::opt<unsigned> |
| 95 | GlobalMergeMaxOffset("global-merge-max-offset", cl::Hidden, |
| 96 | cl::desc("Set maximum offset for global merge pass"), |
| 97 | cl::init(0)); |
| 98 | |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 99 | static cl::opt<bool> GlobalMergeGroupByUse( |
| 100 | "global-merge-group-by-use", cl::Hidden, |
| 101 | cl::desc("Improve global merge pass to look at uses"), cl::init(true)); |
| 102 | |
| 103 | static cl::opt<bool> GlobalMergeIgnoreSingleUse( |
| 104 | "global-merge-ignore-single-use", cl::Hidden, |
| 105 | cl::desc("Improve global merge pass to ignore globals only used alone"), |
| 106 | cl::init(true)); |
| 107 | |
Tim Northover | f804c17 | 2014-02-18 11:17:29 +0000 | [diff] [blame] | 108 | static cl::opt<bool> |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 109 | EnableGlobalMergeOnConst("global-merge-on-const", cl::Hidden, |
Jakub Staszak | 6b36db0 | 2013-07-22 21:11:30 +0000 | [diff] [blame] | 110 | cl::desc("Enable global merge pass on constants"), |
| 111 | cl::init(false)); |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 112 | |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 113 | // FIXME: this could be a transitional option, and we probably need to remove |
| 114 | // it if only we are sure this optimization could always benefit all targets. |
John Brawn | 8b95424 | 2015-08-03 12:08:41 +0000 | [diff] [blame] | 115 | static cl::opt<cl::boolOrDefault> |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 116 | EnableGlobalMergeOnExternal("global-merge-on-external", cl::Hidden, |
John Brawn | 8b95424 | 2015-08-03 12:08:41 +0000 | [diff] [blame] | 117 | cl::desc("Enable global merge pass on external linkage")); |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 118 | |
Eric Christopher | ed47b22 | 2015-02-23 19:28:45 +0000 | [diff] [blame] | 119 | STATISTIC(NumMerged, "Number of globals merged"); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 120 | namespace { |
Devang Patel | 76c8563 | 2011-10-17 17:17:43 +0000 | [diff] [blame] | 121 | class GlobalMerge : public FunctionPass { |
Bill Wendling | 7a639ea | 2013-06-19 21:07:11 +0000 | [diff] [blame] | 122 | const TargetMachine *TM; |
Eric Christopher | ed47b22 | 2015-02-23 19:28:45 +0000 | [diff] [blame] | 123 | // FIXME: Infer the maximum possible offset depending on the actual users |
| 124 | // (these max offsets are different for the users inside Thumb or ARM |
| 125 | // functions), see the code that passes in the offset in the ARM backend |
| 126 | // for more information. |
| 127 | unsigned MaxOffset; |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 128 | |
Ahmed Bougacha | 8207641 | 2015-06-04 20:39:23 +0000 | [diff] [blame] | 129 | /// Whether we should try to optimize for size only. |
| 130 | /// Currently, this applies a dead simple heuristic: only consider globals |
| 131 | /// used in minsize functions for merging. |
| 132 | /// FIXME: This could learn about optsize, and be used in the cost model. |
| 133 | bool OnlyOptimizeForSize; |
| 134 | |
John Brawn | 8b95424 | 2015-08-03 12:08:41 +0000 | [diff] [blame] | 135 | /// Whether we should merge global variables that have external linkage. |
| 136 | bool MergeExternalGlobals; |
| 137 | |
Peter Collingbourne | fe12d0e | 2016-05-19 04:38:56 +0000 | [diff] [blame] | 138 | bool IsMachO; |
| 139 | |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 140 | bool doMerge(SmallVectorImpl<GlobalVariable*> &Globals, |
Silviu Baranga | a055aab | 2013-01-07 12:31:25 +0000 | [diff] [blame] | 141 | Module &M, bool isConst, unsigned AddrSpace) const; |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 142 | /// \brief Merge everything in \p Globals for which the corresponding bit |
| 143 | /// in \p GlobalSet is set. |
David Blaikie | 47bf5c0 | 2015-08-21 22:19:06 +0000 | [diff] [blame] | 144 | bool doMerge(const SmallVectorImpl<GlobalVariable *> &Globals, |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 145 | const BitVector &GlobalSet, Module &M, bool isConst, |
| 146 | unsigned AddrSpace) const; |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 147 | |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 148 | /// \brief Check if the given variable has been identified as must keep |
| 149 | /// \pre setMustKeepGlobalVariables must have been called on the Module that |
| 150 | /// contains GV |
| 151 | bool isMustKeepGlobalVariable(const GlobalVariable *GV) const { |
| 152 | return MustKeepGlobalVariables.count(GV); |
| 153 | } |
| 154 | |
| 155 | /// Collect every variables marked as "used" or used in a landing pad |
| 156 | /// instruction for this Module. |
| 157 | void setMustKeepGlobalVariables(Module &M); |
| 158 | |
| 159 | /// Collect every variables marked as "used" |
| 160 | void collectUsedGlobalVariables(Module &M); |
| 161 | |
Quentin Colombet | 2393cb9 | 2013-03-19 21:46:49 +0000 | [diff] [blame] | 162 | /// Keep track of the GlobalVariable that must not be merged away |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 163 | SmallPtrSet<const GlobalVariable *, 16> MustKeepGlobalVariables; |
| 164 | |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 165 | public: |
| 166 | static char ID; // Pass identification, replacement for typeid. |
Peter Collingbourne | fe12d0e | 2016-05-19 04:38:56 +0000 | [diff] [blame] | 167 | explicit GlobalMerge() |
| 168 | : FunctionPass(ID), TM(nullptr), MaxOffset(GlobalMergeMaxOffset), |
| 169 | OnlyOptimizeForSize(false), MergeExternalGlobals(false) { |
| 170 | initializeGlobalMergePass(*PassRegistry::getPassRegistry()); |
| 171 | } |
| 172 | |
| 173 | explicit GlobalMerge(const TargetMachine *TM, unsigned MaximalOffset, |
| 174 | bool OnlyOptimizeForSize, bool MergeExternalGlobals) |
Mehdi Amini | f6727b0 | 2015-07-07 18:49:25 +0000 | [diff] [blame] | 175 | : FunctionPass(ID), TM(TM), MaxOffset(MaximalOffset), |
John Brawn | 8b95424 | 2015-08-03 12:08:41 +0000 | [diff] [blame] | 176 | OnlyOptimizeForSize(OnlyOptimizeForSize), |
| 177 | MergeExternalGlobals(MergeExternalGlobals) { |
Devang Patel | 76c8563 | 2011-10-17 17:17:43 +0000 | [diff] [blame] | 178 | initializeGlobalMergePass(*PassRegistry::getPassRegistry()); |
| 179 | } |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 180 | |
Craig Topper | 3e4c697 | 2014-03-05 09:10:37 +0000 | [diff] [blame] | 181 | bool doInitialization(Module &M) override; |
| 182 | bool runOnFunction(Function &F) override; |
| 183 | bool doFinalization(Module &M) override; |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 184 | |
Mehdi Amini | 117296c | 2016-10-01 02:56:57 +0000 | [diff] [blame] | 185 | StringRef getPassName() const override { return "Merge internal globals"; } |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 186 | |
Craig Topper | 3e4c697 | 2014-03-05 09:10:37 +0000 | [diff] [blame] | 187 | void getAnalysisUsage(AnalysisUsage &AU) const override { |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 188 | AU.setPreservesCFG(); |
| 189 | FunctionPass::getAnalysisUsage(AU); |
| 190 | } |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 191 | }; |
| 192 | } // end anonymous namespace |
| 193 | |
Devang Patel | 76c8563 | 2011-10-17 17:17:43 +0000 | [diff] [blame] | 194 | char GlobalMerge::ID = 0; |
Eric Christopher | ed47b22 | 2015-02-23 19:28:45 +0000 | [diff] [blame] | 195 | INITIALIZE_PASS_BEGIN(GlobalMerge, "global-merge", "Merge global variables", |
| 196 | false, false) |
| 197 | INITIALIZE_PASS_END(GlobalMerge, "global-merge", "Merge global variables", |
| 198 | false, false) |
Devang Patel | 76c8563 | 2011-10-17 17:17:43 +0000 | [diff] [blame] | 199 | |
| 200 | bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals, |
Silviu Baranga | a055aab | 2013-01-07 12:31:25 +0000 | [diff] [blame] | 201 | Module &M, bool isConst, unsigned AddrSpace) const { |
Mehdi Amini | f6727b0 | 2015-07-07 18:49:25 +0000 | [diff] [blame] | 202 | auto &DL = M.getDataLayout(); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 203 | // FIXME: Find better heuristics |
David Blaikie | 9ed57a9 | 2015-08-21 22:00:44 +0000 | [diff] [blame] | 204 | std::stable_sort(Globals.begin(), Globals.end(), |
| 205 | [&DL](const GlobalVariable *GV1, const GlobalVariable *GV2) { |
| 206 | return DL.getTypeAllocSize(GV1->getValueType()) < |
| 207 | DL.getTypeAllocSize(GV2->getValueType()); |
| 208 | }); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 209 | |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 210 | // If we want to just blindly group all globals together, do so. |
| 211 | if (!GlobalMergeGroupByUse) { |
| 212 | BitVector AllGlobals(Globals.size()); |
| 213 | AllGlobals.set(); |
| 214 | return doMerge(Globals, AllGlobals, M, isConst, AddrSpace); |
| 215 | } |
| 216 | |
| 217 | // If we want to be smarter, look at all uses of each global, to try to |
| 218 | // discover all sets of globals used together, and how many times each of |
Benjamin Kramer | df005cb | 2015-08-08 18:27:36 +0000 | [diff] [blame] | 219 | // these sets occurred. |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 220 | // |
| 221 | // Keep this reasonably efficient, by having an append-only list of all sets |
| 222 | // discovered so far (UsedGlobalSet), and mapping each "together-ness" unit of |
| 223 | // code (currently, a Function) to the set of globals seen so far that are |
| 224 | // used together in that unit (GlobalUsesByFunction). |
| 225 | // |
| 226 | // When we look at the Nth global, we now that any new set is either: |
| 227 | // - the singleton set {N}, containing this global only, or |
| 228 | // - the union of {N} and a previously-discovered set, containing some |
| 229 | // combination of the previous N-1 globals. |
| 230 | // Using that knowledge, when looking at the Nth global, we can keep: |
| 231 | // - a reference to the singleton set {N} (CurGVOnlySetIdx) |
| 232 | // - a list mapping each previous set to its union with {N} (EncounteredUGS), |
| 233 | // if it actually occurs. |
| 234 | |
| 235 | // We keep track of the sets of globals used together "close enough". |
| 236 | struct UsedGlobalSet { |
| 237 | UsedGlobalSet(size_t Size) : Globals(Size), UsageCount(1) {} |
| 238 | BitVector Globals; |
| 239 | unsigned UsageCount; |
| 240 | }; |
| 241 | |
| 242 | // Each set is unique in UsedGlobalSets. |
| 243 | std::vector<UsedGlobalSet> UsedGlobalSets; |
| 244 | |
| 245 | // Avoid repeating the create-global-set pattern. |
| 246 | auto CreateGlobalSet = [&]() -> UsedGlobalSet & { |
| 247 | UsedGlobalSets.emplace_back(Globals.size()); |
| 248 | return UsedGlobalSets.back(); |
| 249 | }; |
| 250 | |
| 251 | // The first set is the empty set. |
| 252 | CreateGlobalSet().UsageCount = 0; |
| 253 | |
| 254 | // We define "close enough" to be "in the same function". |
| 255 | // FIXME: Grouping uses by function is way too aggressive, so we should have |
| 256 | // a better metric for distance between uses. |
| 257 | // The obvious alternative would be to group by BasicBlock, but that's in |
| 258 | // turn too conservative.. |
| 259 | // Anything in between wouldn't be trivial to compute, so just stick with |
| 260 | // per-function grouping. |
| 261 | |
| 262 | // The value type is an index into UsedGlobalSets. |
| 263 | // The default (0) conveniently points to the empty set. |
| 264 | DenseMap<Function *, size_t /*UsedGlobalSetIdx*/> GlobalUsesByFunction; |
| 265 | |
| 266 | // Now, look at each merge-eligible global in turn. |
| 267 | |
| 268 | // Keep track of the sets we already encountered to which we added the |
| 269 | // current global. |
| 270 | // Each element matches the same-index element in UsedGlobalSets. |
| 271 | // This lets us efficiently tell whether a set has already been expanded to |
| 272 | // include the current global. |
| 273 | std::vector<size_t> EncounteredUGS; |
| 274 | |
| 275 | for (size_t GI = 0, GE = Globals.size(); GI != GE; ++GI) { |
| 276 | GlobalVariable *GV = Globals[GI]; |
| 277 | |
| 278 | // Reset the encountered sets for this global... |
| 279 | std::fill(EncounteredUGS.begin(), EncounteredUGS.end(), 0); |
| 280 | // ...and grow it in case we created new sets for the previous global. |
| 281 | EncounteredUGS.resize(UsedGlobalSets.size()); |
| 282 | |
| 283 | // We might need to create a set that only consists of the current global. |
| 284 | // Keep track of its index into UsedGlobalSets. |
| 285 | size_t CurGVOnlySetIdx = 0; |
| 286 | |
| 287 | // For each global, look at all its Uses. |
| 288 | for (auto &U : GV->uses()) { |
| 289 | // This Use might be a ConstantExpr. We're interested in Instruction |
| 290 | // users, so look through ConstantExpr... |
| 291 | Use *UI, *UE; |
| 292 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U.getUser())) { |
Oliver Stannard | 8379e29 | 2015-06-08 16:55:31 +0000 | [diff] [blame] | 293 | if (CE->use_empty()) |
| 294 | continue; |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 295 | UI = &*CE->use_begin(); |
| 296 | UE = nullptr; |
| 297 | } else if (isa<Instruction>(U.getUser())) { |
| 298 | UI = &U; |
| 299 | UE = UI->getNext(); |
| 300 | } else { |
| 301 | continue; |
| 302 | } |
| 303 | |
| 304 | // ...to iterate on all the instruction users of the global. |
| 305 | // Note that we iterate on Uses and not on Users to be able to getNext(). |
| 306 | for (; UI != UE; UI = UI->getNext()) { |
| 307 | Instruction *I = dyn_cast<Instruction>(UI->getUser()); |
| 308 | if (!I) |
| 309 | continue; |
| 310 | |
| 311 | Function *ParentFn = I->getParent()->getParent(); |
Ahmed Bougacha | 8207641 | 2015-06-04 20:39:23 +0000 | [diff] [blame] | 312 | |
| 313 | // If we're only optimizing for size, ignore non-minsize functions. |
Sanjay Patel | 1cd6d88 | 2015-08-18 16:44:23 +0000 | [diff] [blame] | 314 | if (OnlyOptimizeForSize && !ParentFn->optForMinSize()) |
Ahmed Bougacha | 8207641 | 2015-06-04 20:39:23 +0000 | [diff] [blame] | 315 | continue; |
| 316 | |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 317 | size_t UGSIdx = GlobalUsesByFunction[ParentFn]; |
| 318 | |
| 319 | // If this is the first global the basic block uses, map it to the set |
| 320 | // consisting of this global only. |
| 321 | if (!UGSIdx) { |
| 322 | // If that set doesn't exist yet, create it. |
| 323 | if (!CurGVOnlySetIdx) { |
| 324 | CurGVOnlySetIdx = UsedGlobalSets.size(); |
| 325 | CreateGlobalSet().Globals.set(GI); |
| 326 | } else { |
| 327 | ++UsedGlobalSets[CurGVOnlySetIdx].UsageCount; |
| 328 | } |
| 329 | |
| 330 | GlobalUsesByFunction[ParentFn] = CurGVOnlySetIdx; |
| 331 | continue; |
| 332 | } |
| 333 | |
| 334 | // If we already encountered this BB, just increment the counter. |
| 335 | if (UsedGlobalSets[UGSIdx].Globals.test(GI)) { |
| 336 | ++UsedGlobalSets[UGSIdx].UsageCount; |
| 337 | continue; |
| 338 | } |
| 339 | |
| 340 | // If not, the previous set wasn't actually used in this function. |
| 341 | --UsedGlobalSets[UGSIdx].UsageCount; |
| 342 | |
| 343 | // If we already expanded the previous set to include this global, just |
| 344 | // reuse that expanded set. |
| 345 | if (size_t ExpandedIdx = EncounteredUGS[UGSIdx]) { |
| 346 | ++UsedGlobalSets[ExpandedIdx].UsageCount; |
| 347 | GlobalUsesByFunction[ParentFn] = ExpandedIdx; |
| 348 | continue; |
| 349 | } |
| 350 | |
| 351 | // If not, create a new set consisting of the union of the previous set |
| 352 | // and this global. Mark it as encountered, so we can reuse it later. |
| 353 | GlobalUsesByFunction[ParentFn] = EncounteredUGS[UGSIdx] = |
| 354 | UsedGlobalSets.size(); |
| 355 | |
| 356 | UsedGlobalSet &NewUGS = CreateGlobalSet(); |
| 357 | NewUGS.Globals.set(GI); |
| 358 | NewUGS.Globals |= UsedGlobalSets[UGSIdx].Globals; |
| 359 | } |
| 360 | } |
| 361 | } |
| 362 | |
| 363 | // Now we found a bunch of sets of globals used together. We accumulated |
| 364 | // the number of times we encountered the sets (i.e., the number of blocks |
| 365 | // that use that exact set of globals). |
| 366 | // |
| 367 | // Multiply that by the size of the set to give us a crude profitability |
| 368 | // metric. |
| 369 | std::sort(UsedGlobalSets.begin(), UsedGlobalSets.end(), |
| 370 | [](const UsedGlobalSet &UGS1, const UsedGlobalSet &UGS2) { |
| 371 | return UGS1.Globals.count() * UGS1.UsageCount < |
| 372 | UGS2.Globals.count() * UGS2.UsageCount; |
| 373 | }); |
| 374 | |
| 375 | // We can choose to merge all globals together, but ignore globals never used |
| 376 | // with another global. This catches the obviously non-profitable cases of |
| 377 | // having a single global, but is aggressive enough for any other case. |
| 378 | if (GlobalMergeIgnoreSingleUse) { |
| 379 | BitVector AllGlobals(Globals.size()); |
| 380 | for (size_t i = 0, e = UsedGlobalSets.size(); i != e; ++i) { |
| 381 | const UsedGlobalSet &UGS = UsedGlobalSets[e - i - 1]; |
| 382 | if (UGS.UsageCount == 0) |
| 383 | continue; |
| 384 | if (UGS.Globals.count() > 1) |
| 385 | AllGlobals |= UGS.Globals; |
| 386 | } |
| 387 | return doMerge(Globals, AllGlobals, M, isConst, AddrSpace); |
| 388 | } |
| 389 | |
| 390 | // Starting from the sets with the best (=biggest) profitability, find a |
| 391 | // good combination. |
| 392 | // The ideal (and expensive) solution can only be found by trying all |
| 393 | // combinations, looking for the one with the best profitability. |
| 394 | // Don't be smart about it, and just pick the first compatible combination, |
| 395 | // starting with the sets with the best profitability. |
| 396 | BitVector PickedGlobals(Globals.size()); |
| 397 | bool Changed = false; |
| 398 | |
| 399 | for (size_t i = 0, e = UsedGlobalSets.size(); i != e; ++i) { |
| 400 | const UsedGlobalSet &UGS = UsedGlobalSets[e - i - 1]; |
| 401 | if (UGS.UsageCount == 0) |
| 402 | continue; |
| 403 | if (PickedGlobals.anyCommon(UGS.Globals)) |
| 404 | continue; |
| 405 | PickedGlobals |= UGS.Globals; |
| 406 | // If the set only contains one global, there's no point in merging. |
| 407 | // Ignore the global for inclusion in other sets though, so keep it in |
| 408 | // PickedGlobals. |
| 409 | if (UGS.Globals.count() < 2) |
| 410 | continue; |
| 411 | Changed |= doMerge(Globals, UGS.Globals, M, isConst, AddrSpace); |
| 412 | } |
| 413 | |
| 414 | return Changed; |
| 415 | } |
| 416 | |
David Blaikie | 47bf5c0 | 2015-08-21 22:19:06 +0000 | [diff] [blame] | 417 | bool GlobalMerge::doMerge(const SmallVectorImpl<GlobalVariable *> &Globals, |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 418 | const BitVector &GlobalSet, Module &M, bool isConst, |
| 419 | unsigned AddrSpace) const { |
David Blaikie | 47bf5c0 | 2015-08-21 22:19:06 +0000 | [diff] [blame] | 420 | assert(Globals.size() > 1); |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 421 | |
Chris Lattner | 229907c | 2011-07-18 04:54:35 +0000 | [diff] [blame] | 422 | Type *Int32Ty = Type::getInt32Ty(M.getContext()); |
Mehdi Amini | f6727b0 | 2015-07-07 18:49:25 +0000 | [diff] [blame] | 423 | auto &DL = M.getDataLayout(); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 424 | |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 425 | DEBUG(dbgs() << " Trying to merge set, starts with #" |
| 426 | << GlobalSet.find_first() << "\n"); |
| 427 | |
| 428 | ssize_t i = GlobalSet.find_first(); |
| 429 | while (i != -1) { |
| 430 | ssize_t j = 0; |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 431 | uint64_t MergedSize = 0; |
Jay Foad | b804a2b | 2011-07-12 14:06:48 +0000 | [diff] [blame] | 432 | std::vector<Type*> Tys; |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 433 | std::vector<Constant*> Inits; |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 434 | |
Adrian Prantl | 554fd99 | 2016-11-11 17:50:09 +0000 | [diff] [blame] | 435 | bool HasExternal = false; |
Adrian Prantl | 622bddb | 2016-11-11 22:09:25 +0000 | [diff] [blame] | 436 | StringRef FirstExternalName; |
Ahmed Bougacha | 279e3ee | 2015-04-18 01:21:58 +0000 | [diff] [blame] | 437 | for (j = i; j != -1; j = GlobalSet.find_next(j)) { |
David Blaikie | 9ed57a9 | 2015-08-21 22:00:44 +0000 | [diff] [blame] | 438 | Type *Ty = Globals[j]->getValueType(); |
Mehdi Amini | f6727b0 | 2015-07-07 18:49:25 +0000 | [diff] [blame] | 439 | MergedSize += DL.getTypeAllocSize(Ty); |
Bob Wilson | 4c8ab19 | 2010-11-17 21:25:36 +0000 | [diff] [blame] | 440 | if (MergedSize > MaxOffset) { |
| 441 | break; |
| 442 | } |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 443 | Tys.push_back(Ty); |
| 444 | Inits.push_back(Globals[j]->getInitializer()); |
Adrian Prantl | 554fd99 | 2016-11-11 17:50:09 +0000 | [diff] [blame] | 445 | |
| 446 | if (Globals[j]->hasExternalLinkage() && !HasExternal) { |
| 447 | HasExternal = true; |
Adrian Prantl | 622bddb | 2016-11-11 22:09:25 +0000 | [diff] [blame] | 448 | FirstExternalName = Globals[j]->getName(); |
Adrian Prantl | 554fd99 | 2016-11-11 17:50:09 +0000 | [diff] [blame] | 449 | } |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 450 | } |
| 451 | |
Adrian Prantl | 554fd99 | 2016-11-11 17:50:09 +0000 | [diff] [blame] | 452 | // If merged variables doesn't have external linkage, we needn't to expose |
| 453 | // the symbol after merging. |
| 454 | GlobalValue::LinkageTypes Linkage = HasExternal |
| 455 | ? GlobalValue::ExternalLinkage |
| 456 | : GlobalValue::InternalLinkage; |
Chris Lattner | e40007a | 2010-09-05 21:18:45 +0000 | [diff] [blame] | 457 | StructType *MergedTy = StructType::get(M.getContext(), Tys); |
| 458 | Constant *MergedInit = ConstantStruct::get(MergedTy, Inits); |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 459 | |
Adrian Prantl | 6cb849e | 2016-11-11 21:48:09 +0000 | [diff] [blame] | 460 | // On Darwin external linkage needs to be preserved, otherwise |
| 461 | // dsymutil cannot preserve the debug info for the merged |
| 462 | // variables. If they have external linkage, use the symbol name |
| 463 | // of the first variable merged as the suffix of global symbol |
| 464 | // name. This avoids a link-time naming conflict for the |
| 465 | // _MergedGlobals symbols. |
Adrian Prantl | 554fd99 | 2016-11-11 17:50:09 +0000 | [diff] [blame] | 466 | Twine MergedName = |
| 467 | (IsMachO && HasExternal) |
Adrian Prantl | 622bddb | 2016-11-11 22:09:25 +0000 | [diff] [blame] | 468 | ? "_MergedGlobals_" + FirstExternalName |
Adrian Prantl | 554fd99 | 2016-11-11 17:50:09 +0000 | [diff] [blame] | 469 | : "_MergedGlobals"; |
| 470 | auto MergedLinkage = IsMachO ? Linkage : GlobalValue::PrivateLinkage; |
| 471 | auto *MergedGV = new GlobalVariable( |
| 472 | M, MergedTy, isConst, MergedLinkage, MergedInit, MergedName, nullptr, |
| 473 | GlobalVariable::NotThreadLocal, AddrSpace); |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 474 | |
Peter Collingbourne | d4135bb | 2016-09-13 01:12:59 +0000 | [diff] [blame] | 475 | const StructLayout *MergedLayout = DL.getStructLayout(MergedTy); |
| 476 | |
David Blaikie | 6614d8d | 2015-09-14 20:29:26 +0000 | [diff] [blame] | 477 | for (ssize_t k = i, idx = 0; k != j; k = GlobalSet.find_next(k), ++idx) { |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 478 | GlobalValue::LinkageTypes Linkage = Globals[k]->getLinkage(); |
| 479 | std::string Name = Globals[k]->getName(); |
| 480 | |
Peter Collingbourne | d4135bb | 2016-09-13 01:12:59 +0000 | [diff] [blame] | 481 | // Copy metadata while adjusting any debug info metadata by the original |
| 482 | // global's offset within the merged global. |
| 483 | MergedGV->copyMetadata(Globals[k], MergedLayout->getElementOffset(idx)); |
| 484 | |
Chris Lattner | e40007a | 2010-09-05 21:18:45 +0000 | [diff] [blame] | 485 | Constant *Idx[2] = { |
| 486 | ConstantInt::get(Int32Ty, 0), |
David Blaikie | 6614d8d | 2015-09-14 20:29:26 +0000 | [diff] [blame] | 487 | ConstantInt::get(Int32Ty, idx), |
Chris Lattner | e40007a | 2010-09-05 21:18:45 +0000 | [diff] [blame] | 488 | }; |
David Blaikie | 4a2e73b | 2015-04-02 18:55:32 +0000 | [diff] [blame] | 489 | Constant *GEP = |
| 490 | ConstantExpr::getInBoundsGetElementPtr(MergedTy, MergedGV, Idx); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 491 | Globals[k]->replaceAllUsesWith(GEP); |
| 492 | Globals[k]->eraseFromParent(); |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 493 | |
John Brawn | 0bef27d | 2015-08-12 13:36:48 +0000 | [diff] [blame] | 494 | // When the linkage is not internal we must emit an alias for the original |
| 495 | // variable name as it may be accessed from another object. On non-Mach-O |
| 496 | // we can also emit an alias for internal linkage as it's safe to do so. |
| 497 | // It's not safe on Mach-O as the alias (and thus the portion of the |
| 498 | // MergedGlobals variable) may be dead stripped at link time. |
Peter Collingbourne | fe12d0e | 2016-05-19 04:38:56 +0000 | [diff] [blame] | 499 | if (Linkage != GlobalValue::InternalLinkage || !IsMachO) { |
David Blaikie | 6614d8d | 2015-09-14 20:29:26 +0000 | [diff] [blame] | 500 | GlobalAlias::create(Tys[idx], AddrSpace, Linkage, Name, GEP, &M); |
John Brawn | 0bef27d | 2015-08-12 13:36:48 +0000 | [diff] [blame] | 501 | } |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 502 | |
Devang Patel | 76c8563 | 2011-10-17 17:17:43 +0000 | [diff] [blame] | 503 | NumMerged++; |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 504 | } |
| 505 | i = j; |
| 506 | } |
| 507 | |
| 508 | return true; |
| 509 | } |
| 510 | |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 511 | void GlobalMerge::collectUsedGlobalVariables(Module &M) { |
| 512 | // Extract global variables from llvm.used array |
| 513 | const GlobalVariable *GV = M.getGlobalVariable("llvm.used"); |
| 514 | if (!GV || !GV->hasInitializer()) return; |
| 515 | |
| 516 | // Should be an array of 'i8*'. |
Rafael Espindola | 74f2e46 | 2013-04-22 14:58:02 +0000 | [diff] [blame] | 517 | const ConstantArray *InitList = cast<ConstantArray>(GV->getInitializer()); |
| 518 | |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 519 | for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) |
| 520 | if (const GlobalVariable *G = |
| 521 | dyn_cast<GlobalVariable>(InitList->getOperand(i)->stripPointerCasts())) |
| 522 | MustKeepGlobalVariables.insert(G); |
| 523 | } |
| 524 | |
| 525 | void GlobalMerge::setMustKeepGlobalVariables(Module &M) { |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 526 | collectUsedGlobalVariables(M); |
| 527 | |
Reid Kleckner | f8d1d12 | 2016-10-19 19:56:22 +0000 | [diff] [blame] | 528 | for (Function &F : M) { |
| 529 | for (BasicBlock &BB : F) { |
| 530 | Instruction *Pad = BB.getFirstNonPHI(); |
| 531 | if (!Pad->isEHPad()) |
| 532 | continue; |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 533 | |
Reid Kleckner | f8d1d12 | 2016-10-19 19:56:22 +0000 | [diff] [blame] | 534 | // Keep globals used by landingpads and catchpads. |
| 535 | for (const Use &U : Pad->operands()) { |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 536 | if (const GlobalVariable *GV = |
Reid Kleckner | f8d1d12 | 2016-10-19 19:56:22 +0000 | [diff] [blame] | 537 | dyn_cast<GlobalVariable>(U->stripPointerCasts())) |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 538 | MustKeepGlobalVariables.insert(GV); |
Reid Kleckner | f8d1d12 | 2016-10-19 19:56:22 +0000 | [diff] [blame] | 539 | } |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 540 | } |
| 541 | } |
| 542 | } |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 543 | |
Devang Patel | 76c8563 | 2011-10-17 17:17:43 +0000 | [diff] [blame] | 544 | bool GlobalMerge::doInitialization(Module &M) { |
Tim Northover | f804c17 | 2014-02-18 11:17:29 +0000 | [diff] [blame] | 545 | if (!EnableGlobalMerge) |
| 546 | return false; |
| 547 | |
Peter Collingbourne | fe12d0e | 2016-05-19 04:38:56 +0000 | [diff] [blame] | 548 | IsMachO = Triple(M.getTargetTriple()).isOSBinFormatMachO(); |
| 549 | |
Mehdi Amini | f6727b0 | 2015-07-07 18:49:25 +0000 | [diff] [blame] | 550 | auto &DL = M.getDataLayout(); |
Silviu Baranga | a055aab | 2013-01-07 12:31:25 +0000 | [diff] [blame] | 551 | DenseMap<unsigned, SmallVector<GlobalVariable*, 16> > Globals, ConstGlobals, |
| 552 | BSSGlobals; |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 553 | bool Changed = false; |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 554 | setMustKeepGlobalVariables(M); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 555 | |
| 556 | // Grab all non-const globals. |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 557 | for (auto &GV : M.globals()) { |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 558 | // Merge is safe for "normal" internal or external globals only |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 559 | if (GV.isDeclaration() || GV.isThreadLocal() || GV.hasSection()) |
Jiangning Liu | b2ae37f | 2014-06-11 06:44:53 +0000 | [diff] [blame] | 560 | continue; |
| 561 | |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 562 | if (!(MergeExternalGlobals && GV.hasExternalLinkage()) && |
| 563 | !GV.hasInternalLinkage()) |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 564 | continue; |
| 565 | |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 566 | PointerType *PT = dyn_cast<PointerType>(GV.getType()); |
Silviu Baranga | a055aab | 2013-01-07 12:31:25 +0000 | [diff] [blame] | 567 | assert(PT && "Global variable is not a pointer!"); |
| 568 | |
| 569 | unsigned AddressSpace = PT->getAddressSpace(); |
| 570 | |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 571 | // Ignore fancy-aligned globals for now. |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 572 | unsigned Alignment = DL.getPreferredAlignment(&GV); |
| 573 | Type *Ty = GV.getValueType(); |
Mehdi Amini | f6727b0 | 2015-07-07 18:49:25 +0000 | [diff] [blame] | 574 | if (Alignment > DL.getABITypeAlignment(Ty)) |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 575 | continue; |
| 576 | |
Anton Korobeynikov | 6bcea06 | 2010-07-26 18:45:39 +0000 | [diff] [blame] | 577 | // Ignore all 'special' globals. |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 578 | if (GV.getName().startswith("llvm.") || |
| 579 | GV.getName().startswith(".llvm.")) |
Anton Korobeynikov | 6bcea06 | 2010-07-26 18:45:39 +0000 | [diff] [blame] | 580 | continue; |
| 581 | |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 582 | // Ignore all "required" globals: |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 583 | if (isMustKeepGlobalVariable(&GV)) |
Quentin Colombet | 8fc3409 | 2013-03-18 22:30:07 +0000 | [diff] [blame] | 584 | continue; |
| 585 | |
Mehdi Amini | f6727b0 | 2015-07-07 18:49:25 +0000 | [diff] [blame] | 586 | if (DL.getTypeAllocSize(Ty) < MaxOffset) { |
Peter Collingbourne | fe12d0e | 2016-05-19 04:38:56 +0000 | [diff] [blame] | 587 | if (TM && |
| 588 | TargetLoweringObjectFile::getKindForGlobal(&GV, *TM).isBSSLocal()) |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 589 | BSSGlobals[AddressSpace].push_back(&GV); |
| 590 | else if (GV.isConstant()) |
| 591 | ConstGlobals[AddressSpace].push_back(&GV); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 592 | else |
Duncan P. N. Exon Smith | 530d040 | 2015-10-09 18:57:47 +0000 | [diff] [blame] | 593 | Globals[AddressSpace].push_back(&GV); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 594 | } |
| 595 | } |
| 596 | |
David Blaikie | 47bf5c0 | 2015-08-21 22:19:06 +0000 | [diff] [blame] | 597 | for (auto &P : Globals) |
| 598 | if (P.second.size() > 1) |
| 599 | Changed |= doMerge(P.second, M, false, P.first); |
Silviu Baranga | a055aab | 2013-01-07 12:31:25 +0000 | [diff] [blame] | 600 | |
David Blaikie | 47bf5c0 | 2015-08-21 22:19:06 +0000 | [diff] [blame] | 601 | for (auto &P : BSSGlobals) |
| 602 | if (P.second.size() > 1) |
| 603 | Changed |= doMerge(P.second, M, false, P.first); |
Bob Wilson | 881b45c | 2010-11-17 21:25:39 +0000 | [diff] [blame] | 604 | |
David Blaikie | d486000 | 2015-08-25 17:01:36 +0000 | [diff] [blame] | 605 | if (EnableGlobalMergeOnConst) |
| 606 | for (auto &P : ConstGlobals) |
| 607 | if (P.second.size() > 1) |
| 608 | Changed |= doMerge(P.second, M, true, P.first); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 609 | |
| 610 | return Changed; |
| 611 | } |
| 612 | |
Devang Patel | 76c8563 | 2011-10-17 17:17:43 +0000 | [diff] [blame] | 613 | bool GlobalMerge::runOnFunction(Function &F) { |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 614 | return false; |
| 615 | } |
| 616 | |
Quentin Colombet | 2393cb9 | 2013-03-19 21:46:49 +0000 | [diff] [blame] | 617 | bool GlobalMerge::doFinalization(Module &M) { |
| 618 | MustKeepGlobalVariables.clear(); |
| 619 | return false; |
| 620 | } |
| 621 | |
Ahmed Bougacha | 8207641 | 2015-06-04 20:39:23 +0000 | [diff] [blame] | 622 | Pass *llvm::createGlobalMergePass(const TargetMachine *TM, unsigned Offset, |
John Brawn | 8b95424 | 2015-08-03 12:08:41 +0000 | [diff] [blame] | 623 | bool OnlyOptimizeForSize, |
| 624 | bool MergeExternalByDefault) { |
| 625 | bool MergeExternal = (EnableGlobalMergeOnExternal == cl::BOU_UNSET) ? |
| 626 | MergeExternalByDefault : (EnableGlobalMergeOnExternal == cl::BOU_TRUE); |
| 627 | return new GlobalMerge(TM, Offset, OnlyOptimizeForSize, MergeExternal); |
Anton Korobeynikov | 19edda0 | 2010-07-24 21:52:08 +0000 | [diff] [blame] | 628 | } |