| File: | llvm/lib/Transforms/Scalar/ConstantHoisting.cpp |
| Warning: | line 341, column 25 Called C++ object pointer is null |
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| 1 | //===- ConstantHoisting.cpp - Prepare code for expensive constants --------===// | |||
| 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 identifies expensive constants to hoist and coalesces them to | |||
| 10 | // better prepare it for SelectionDAG-based code generation. This works around | |||
| 11 | // the limitations of the basic-block-at-a-time approach. | |||
| 12 | // | |||
| 13 | // First it scans all instructions for integer constants and calculates its | |||
| 14 | // cost. If the constant can be folded into the instruction (the cost is | |||
| 15 | // TCC_Free) or the cost is just a simple operation (TCC_BASIC), then we don't | |||
| 16 | // consider it expensive and leave it alone. This is the default behavior and | |||
| 17 | // the default implementation of getIntImmCostInst will always return TCC_Free. | |||
| 18 | // | |||
| 19 | // If the cost is more than TCC_BASIC, then the integer constant can't be folded | |||
| 20 | // into the instruction and it might be beneficial to hoist the constant. | |||
| 21 | // Similar constants are coalesced to reduce register pressure and | |||
| 22 | // materialization code. | |||
| 23 | // | |||
| 24 | // When a constant is hoisted, it is also hidden behind a bitcast to force it to | |||
| 25 | // be live-out of the basic block. Otherwise the constant would be just | |||
| 26 | // duplicated and each basic block would have its own copy in the SelectionDAG. | |||
| 27 | // The SelectionDAG recognizes such constants as opaque and doesn't perform | |||
| 28 | // certain transformations on them, which would create a new expensive constant. | |||
| 29 | // | |||
| 30 | // This optimization is only applied to integer constants in instructions and | |||
| 31 | // simple (this means not nested) constant cast expressions. For example: | |||
| 32 | // %0 = load i64* inttoptr (i64 big_constant to i64*) | |||
| 33 | //===----------------------------------------------------------------------===// | |||
| 34 | ||||
| 35 | #include "llvm/Transforms/Scalar/ConstantHoisting.h" | |||
| 36 | #include "llvm/ADT/APInt.h" | |||
| 37 | #include "llvm/ADT/DenseMap.h" | |||
| 38 | #include "llvm/ADT/None.h" | |||
| 39 | #include "llvm/ADT/Optional.h" | |||
| 40 | #include "llvm/ADT/SmallPtrSet.h" | |||
| 41 | #include "llvm/ADT/SmallVector.h" | |||
| 42 | #include "llvm/ADT/Statistic.h" | |||
| 43 | #include "llvm/Analysis/BlockFrequencyInfo.h" | |||
| 44 | #include "llvm/Analysis/ProfileSummaryInfo.h" | |||
| 45 | #include "llvm/Analysis/TargetTransformInfo.h" | |||
| 46 | #include "llvm/IR/BasicBlock.h" | |||
| 47 | #include "llvm/IR/Constants.h" | |||
| 48 | #include "llvm/IR/DebugInfoMetadata.h" | |||
| 49 | #include "llvm/IR/Dominators.h" | |||
| 50 | #include "llvm/IR/Function.h" | |||
| 51 | #include "llvm/IR/InstrTypes.h" | |||
| 52 | #include "llvm/IR/Instruction.h" | |||
| 53 | #include "llvm/IR/Instructions.h" | |||
| 54 | #include "llvm/IR/IntrinsicInst.h" | |||
| 55 | #include "llvm/IR/Value.h" | |||
| 56 | #include "llvm/InitializePasses.h" | |||
| 57 | #include "llvm/Pass.h" | |||
| 58 | #include "llvm/Support/BlockFrequency.h" | |||
| 59 | #include "llvm/Support/Casting.h" | |||
| 60 | #include "llvm/Support/CommandLine.h" | |||
| 61 | #include "llvm/Support/Debug.h" | |||
| 62 | #include "llvm/Support/raw_ostream.h" | |||
| 63 | #include "llvm/Transforms/Scalar.h" | |||
| 64 | #include "llvm/Transforms/Utils/Local.h" | |||
| 65 | #include "llvm/Transforms/Utils/SizeOpts.h" | |||
| 66 | #include <algorithm> | |||
| 67 | #include <cassert> | |||
| 68 | #include <cstdint> | |||
| 69 | #include <iterator> | |||
| 70 | #include <tuple> | |||
| 71 | #include <utility> | |||
| 72 | ||||
| 73 | using namespace llvm; | |||
| 74 | using namespace consthoist; | |||
| 75 | ||||
| 76 | #define DEBUG_TYPE"consthoist" "consthoist" | |||
| 77 | ||||
| 78 | STATISTIC(NumConstantsHoisted, "Number of constants hoisted")static llvm::Statistic NumConstantsHoisted = {"consthoist", "NumConstantsHoisted" , "Number of constants hoisted"}; | |||
| 79 | STATISTIC(NumConstantsRebased, "Number of constants rebased")static llvm::Statistic NumConstantsRebased = {"consthoist", "NumConstantsRebased" , "Number of constants rebased"}; | |||
| 80 | ||||
| 81 | static cl::opt<bool> ConstHoistWithBlockFrequency( | |||
| 82 | "consthoist-with-block-frequency", cl::init(true), cl::Hidden, | |||
| 83 | cl::desc("Enable the use of the block frequency analysis to reduce the " | |||
| 84 | "chance to execute const materialization more frequently than " | |||
| 85 | "without hoisting.")); | |||
| 86 | ||||
| 87 | static cl::opt<bool> ConstHoistGEP( | |||
| 88 | "consthoist-gep", cl::init(false), cl::Hidden, | |||
| 89 | cl::desc("Try hoisting constant gep expressions")); | |||
| 90 | ||||
| 91 | static cl::opt<unsigned> | |||
| 92 | MinNumOfDependentToRebase("consthoist-min-num-to-rebase", | |||
| 93 | cl::desc("Do not rebase if number of dependent constants of a Base is less " | |||
| 94 | "than this number."), | |||
| 95 | cl::init(0), cl::Hidden); | |||
| 96 | ||||
| 97 | namespace { | |||
| 98 | ||||
| 99 | /// The constant hoisting pass. | |||
| 100 | class ConstantHoistingLegacyPass : public FunctionPass { | |||
| 101 | public: | |||
| 102 | static char ID; // Pass identification, replacement for typeid | |||
| 103 | ||||
| 104 | ConstantHoistingLegacyPass() : FunctionPass(ID) { | |||
| 105 | initializeConstantHoistingLegacyPassPass(*PassRegistry::getPassRegistry()); | |||
| 106 | } | |||
| 107 | ||||
| 108 | bool runOnFunction(Function &Fn) override; | |||
| 109 | ||||
| 110 | StringRef getPassName() const override { return "Constant Hoisting"; } | |||
| 111 | ||||
| 112 | void getAnalysisUsage(AnalysisUsage &AU) const override { | |||
| 113 | AU.setPreservesCFG(); | |||
| 114 | if (ConstHoistWithBlockFrequency) | |||
| 115 | AU.addRequired<BlockFrequencyInfoWrapperPass>(); | |||
| 116 | AU.addRequired<DominatorTreeWrapperPass>(); | |||
| 117 | AU.addRequired<ProfileSummaryInfoWrapperPass>(); | |||
| 118 | AU.addRequired<TargetTransformInfoWrapperPass>(); | |||
| 119 | } | |||
| 120 | ||||
| 121 | private: | |||
| 122 | ConstantHoistingPass Impl; | |||
| 123 | }; | |||
| 124 | ||||
| 125 | } // end anonymous namespace | |||
| 126 | ||||
| 127 | char ConstantHoistingLegacyPass::ID = 0; | |||
| 128 | ||||
| 129 | INITIALIZE_PASS_BEGIN(ConstantHoistingLegacyPass, "consthoist",static void *initializeConstantHoistingLegacyPassPassOnce(PassRegistry &Registry) { | |||
| 130 | "Constant Hoisting", false, false)static void *initializeConstantHoistingLegacyPassPassOnce(PassRegistry &Registry) { | |||
| 131 | INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)initializeBlockFrequencyInfoWrapperPassPass(Registry); | |||
| 132 | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry); | |||
| 133 | INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry); | |||
| 134 | INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry); | |||
| 135 | INITIALIZE_PASS_END(ConstantHoistingLegacyPass, "consthoist",PassInfo *PI = new PassInfo( "Constant Hoisting", "consthoist" , &ConstantHoistingLegacyPass::ID, PassInfo::NormalCtor_t (callDefaultCtor<ConstantHoistingLegacyPass>), false, false ); Registry.registerPass(*PI, true); return PI; } static llvm ::once_flag InitializeConstantHoistingLegacyPassPassFlag; void llvm::initializeConstantHoistingLegacyPassPass(PassRegistry & Registry) { llvm::call_once(InitializeConstantHoistingLegacyPassPassFlag , initializeConstantHoistingLegacyPassPassOnce, std::ref(Registry )); } | |||
| 136 | "Constant Hoisting", false, false)PassInfo *PI = new PassInfo( "Constant Hoisting", "consthoist" , &ConstantHoistingLegacyPass::ID, PassInfo::NormalCtor_t (callDefaultCtor<ConstantHoistingLegacyPass>), false, false ); Registry.registerPass(*PI, true); return PI; } static llvm ::once_flag InitializeConstantHoistingLegacyPassPassFlag; void llvm::initializeConstantHoistingLegacyPassPass(PassRegistry & Registry) { llvm::call_once(InitializeConstantHoistingLegacyPassPassFlag , initializeConstantHoistingLegacyPassPassOnce, std::ref(Registry )); } | |||
| 137 | ||||
| 138 | FunctionPass *llvm::createConstantHoistingPass() { | |||
| 139 | return new ConstantHoistingLegacyPass(); | |||
| 140 | } | |||
| 141 | ||||
| 142 | /// Perform the constant hoisting optimization for the given function. | |||
| 143 | bool ConstantHoistingLegacyPass::runOnFunction(Function &Fn) { | |||
| 144 | if (skipFunction(Fn)) | |||
| 145 | return false; | |||
| 146 | ||||
| 147 | LLVM_DEBUG(dbgs() << "********** Begin Constant Hoisting **********\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "********** Begin Constant Hoisting **********\n" ; } } while (false); | |||
| 148 | LLVM_DEBUG(dbgs() << "********** Function: " << Fn.getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "********** Function: " << Fn.getName() << '\n'; } } while (false); | |||
| 149 | ||||
| 150 | bool MadeChange = | |||
| 151 | Impl.runImpl(Fn, getAnalysis<TargetTransformInfoWrapperPass>().getTTI(Fn), | |||
| 152 | getAnalysis<DominatorTreeWrapperPass>().getDomTree(), | |||
| 153 | ConstHoistWithBlockFrequency | |||
| 154 | ? &getAnalysis<BlockFrequencyInfoWrapperPass>().getBFI() | |||
| 155 | : nullptr, | |||
| 156 | Fn.getEntryBlock(), | |||
| 157 | &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI()); | |||
| 158 | ||||
| 159 | if (MadeChange) { | |||
| 160 | LLVM_DEBUG(dbgs() << "********** Function after Constant Hoisting: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "********** Function after Constant Hoisting: " << Fn.getName() << '\n'; } } while (false) | |||
| 161 | << Fn.getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "********** Function after Constant Hoisting: " << Fn.getName() << '\n'; } } while (false); | |||
| 162 | LLVM_DEBUG(dbgs() << Fn)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << Fn; } } while (false); | |||
| 163 | } | |||
| 164 | LLVM_DEBUG(dbgs() << "********** End Constant Hoisting **********\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "********** End Constant Hoisting **********\n" ; } } while (false); | |||
| 165 | ||||
| 166 | return MadeChange; | |||
| 167 | } | |||
| 168 | ||||
| 169 | /// Find the constant materialization insertion point. | |||
| 170 | Instruction *ConstantHoistingPass::findMatInsertPt(Instruction *Inst, | |||
| 171 | unsigned Idx) const { | |||
| 172 | // If the operand is a cast instruction, then we have to materialize the | |||
| 173 | // constant before the cast instruction. | |||
| 174 | if (Idx != ~0U) { | |||
| 175 | Value *Opnd = Inst->getOperand(Idx); | |||
| 176 | if (auto CastInst = dyn_cast<Instruction>(Opnd)) | |||
| 177 | if (CastInst->isCast()) | |||
| 178 | return CastInst; | |||
| 179 | } | |||
| 180 | ||||
| 181 | // The simple and common case. This also includes constant expressions. | |||
| 182 | if (!isa<PHINode>(Inst) && !Inst->isEHPad()) | |||
| 183 | return Inst; | |||
| 184 | ||||
| 185 | // We can't insert directly before a phi node or an eh pad. Insert before | |||
| 186 | // the terminator of the incoming or dominating block. | |||
| 187 | assert(Entry != Inst->getParent() && "PHI or landing pad in entry block!")((Entry != Inst->getParent() && "PHI or landing pad in entry block!" ) ? static_cast<void> (0) : __assert_fail ("Entry != Inst->getParent() && \"PHI or landing pad in entry block!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 187, __PRETTY_FUNCTION__)); | |||
| 188 | if (Idx != ~0U && isa<PHINode>(Inst)) | |||
| 189 | return cast<PHINode>(Inst)->getIncomingBlock(Idx)->getTerminator(); | |||
| 190 | ||||
| 191 | // This must be an EH pad. Iterate over immediate dominators until we find a | |||
| 192 | // non-EH pad. We need to skip over catchswitch blocks, which are both EH pads | |||
| 193 | // and terminators. | |||
| 194 | auto IDom = DT->getNode(Inst->getParent())->getIDom(); | |||
| 195 | while (IDom->getBlock()->isEHPad()) { | |||
| 196 | assert(Entry != IDom->getBlock() && "eh pad in entry block")((Entry != IDom->getBlock() && "eh pad in entry block" ) ? static_cast<void> (0) : __assert_fail ("Entry != IDom->getBlock() && \"eh pad in entry block\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 196, __PRETTY_FUNCTION__)); | |||
| 197 | IDom = IDom->getIDom(); | |||
| 198 | } | |||
| 199 | ||||
| 200 | return IDom->getBlock()->getTerminator(); | |||
| 201 | } | |||
| 202 | ||||
| 203 | /// Given \p BBs as input, find another set of BBs which collectively | |||
| 204 | /// dominates \p BBs and have the minimal sum of frequencies. Return the BB | |||
| 205 | /// set found in \p BBs. | |||
| 206 | static void findBestInsertionSet(DominatorTree &DT, BlockFrequencyInfo &BFI, | |||
| 207 | BasicBlock *Entry, | |||
| 208 | SetVector<BasicBlock *> &BBs) { | |||
| 209 | assert(!BBs.count(Entry) && "Assume Entry is not in BBs")((!BBs.count(Entry) && "Assume Entry is not in BBs") ? static_cast<void> (0) : __assert_fail ("!BBs.count(Entry) && \"Assume Entry is not in BBs\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 209, __PRETTY_FUNCTION__)); | |||
| 210 | // Nodes on the current path to the root. | |||
| 211 | SmallPtrSet<BasicBlock *, 8> Path; | |||
| 212 | // Candidates includes any block 'BB' in set 'BBs' that is not strictly | |||
| 213 | // dominated by any other blocks in set 'BBs', and all nodes in the path | |||
| 214 | // in the dominator tree from Entry to 'BB'. | |||
| 215 | SmallPtrSet<BasicBlock *, 16> Candidates; | |||
| 216 | for (auto BB : BBs) { | |||
| 217 | // Ignore unreachable basic blocks. | |||
| 218 | if (!DT.isReachableFromEntry(BB)) | |||
| 219 | continue; | |||
| 220 | Path.clear(); | |||
| 221 | // Walk up the dominator tree until Entry or another BB in BBs | |||
| 222 | // is reached. Insert the nodes on the way to the Path. | |||
| 223 | BasicBlock *Node = BB; | |||
| 224 | // The "Path" is a candidate path to be added into Candidates set. | |||
| 225 | bool isCandidate = false; | |||
| 226 | do { | |||
| 227 | Path.insert(Node); | |||
| 228 | if (Node == Entry || Candidates.count(Node)) { | |||
| 229 | isCandidate = true; | |||
| 230 | break; | |||
| 231 | } | |||
| 232 | assert(DT.getNode(Node)->getIDom() &&((DT.getNode(Node)->getIDom() && "Entry doens't dominate current Node" ) ? static_cast<void> (0) : __assert_fail ("DT.getNode(Node)->getIDom() && \"Entry doens't dominate current Node\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 233, __PRETTY_FUNCTION__)) | |||
| 233 | "Entry doens't dominate current Node")((DT.getNode(Node)->getIDom() && "Entry doens't dominate current Node" ) ? static_cast<void> (0) : __assert_fail ("DT.getNode(Node)->getIDom() && \"Entry doens't dominate current Node\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 233, __PRETTY_FUNCTION__)); | |||
| 234 | Node = DT.getNode(Node)->getIDom()->getBlock(); | |||
| 235 | } while (!BBs.count(Node)); | |||
| 236 | ||||
| 237 | // If isCandidate is false, Node is another Block in BBs dominating | |||
| 238 | // current 'BB'. Drop the nodes on the Path. | |||
| 239 | if (!isCandidate) | |||
| 240 | continue; | |||
| 241 | ||||
| 242 | // Add nodes on the Path into Candidates. | |||
| 243 | Candidates.insert(Path.begin(), Path.end()); | |||
| 244 | } | |||
| 245 | ||||
| 246 | // Sort the nodes in Candidates in top-down order and save the nodes | |||
| 247 | // in Orders. | |||
| 248 | unsigned Idx = 0; | |||
| 249 | SmallVector<BasicBlock *, 16> Orders; | |||
| 250 | Orders.push_back(Entry); | |||
| 251 | while (Idx != Orders.size()) { | |||
| 252 | BasicBlock *Node = Orders[Idx++]; | |||
| 253 | for (auto ChildDomNode : DT.getNode(Node)->children()) { | |||
| 254 | if (Candidates.count(ChildDomNode->getBlock())) | |||
| 255 | Orders.push_back(ChildDomNode->getBlock()); | |||
| 256 | } | |||
| 257 | } | |||
| 258 | ||||
| 259 | // Visit Orders in bottom-up order. | |||
| 260 | using InsertPtsCostPair = | |||
| 261 | std::pair<SetVector<BasicBlock *>, BlockFrequency>; | |||
| 262 | ||||
| 263 | // InsertPtsMap is a map from a BB to the best insertion points for the | |||
| 264 | // subtree of BB (subtree not including the BB itself). | |||
| 265 | DenseMap<BasicBlock *, InsertPtsCostPair> InsertPtsMap; | |||
| 266 | InsertPtsMap.reserve(Orders.size() + 1); | |||
| 267 | for (auto RIt = Orders.rbegin(); RIt != Orders.rend(); RIt++) { | |||
| 268 | BasicBlock *Node = *RIt; | |||
| 269 | bool NodeInBBs = BBs.count(Node); | |||
| 270 | auto &InsertPts = InsertPtsMap[Node].first; | |||
| 271 | BlockFrequency &InsertPtsFreq = InsertPtsMap[Node].second; | |||
| 272 | ||||
| 273 | // Return the optimal insert points in BBs. | |||
| 274 | if (Node == Entry) { | |||
| 275 | BBs.clear(); | |||
| 276 | if (InsertPtsFreq > BFI.getBlockFreq(Node) || | |||
| 277 | (InsertPtsFreq == BFI.getBlockFreq(Node) && InsertPts.size() > 1)) | |||
| 278 | BBs.insert(Entry); | |||
| 279 | else | |||
| 280 | BBs.insert(InsertPts.begin(), InsertPts.end()); | |||
| 281 | break; | |||
| 282 | } | |||
| 283 | ||||
| 284 | BasicBlock *Parent = DT.getNode(Node)->getIDom()->getBlock(); | |||
| 285 | // Initially, ParentInsertPts is empty and ParentPtsFreq is 0. Every child | |||
| 286 | // will update its parent's ParentInsertPts and ParentPtsFreq. | |||
| 287 | auto &ParentInsertPts = InsertPtsMap[Parent].first; | |||
| 288 | BlockFrequency &ParentPtsFreq = InsertPtsMap[Parent].second; | |||
| 289 | // Choose to insert in Node or in subtree of Node. | |||
| 290 | // Don't hoist to EHPad because we may not find a proper place to insert | |||
| 291 | // in EHPad. | |||
| 292 | // If the total frequency of InsertPts is the same as the frequency of the | |||
| 293 | // target Node, and InsertPts contains more than one nodes, choose hoisting | |||
| 294 | // to reduce code size. | |||
| 295 | if (NodeInBBs || | |||
| 296 | (!Node->isEHPad() && | |||
| 297 | (InsertPtsFreq > BFI.getBlockFreq(Node) || | |||
| 298 | (InsertPtsFreq == BFI.getBlockFreq(Node) && InsertPts.size() > 1)))) { | |||
| 299 | ParentInsertPts.insert(Node); | |||
| 300 | ParentPtsFreq += BFI.getBlockFreq(Node); | |||
| 301 | } else { | |||
| 302 | ParentInsertPts.insert(InsertPts.begin(), InsertPts.end()); | |||
| 303 | ParentPtsFreq += InsertPtsFreq; | |||
| 304 | } | |||
| 305 | } | |||
| 306 | } | |||
| 307 | ||||
| 308 | /// Find an insertion point that dominates all uses. | |||
| 309 | SetVector<Instruction *> ConstantHoistingPass::findConstantInsertionPoint( | |||
| 310 | const ConstantInfo &ConstInfo) const { | |||
| 311 | assert(!ConstInfo.RebasedConstants.empty() && "Invalid constant info entry.")((!ConstInfo.RebasedConstants.empty() && "Invalid constant info entry." ) ? static_cast<void> (0) : __assert_fail ("!ConstInfo.RebasedConstants.empty() && \"Invalid constant info entry.\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 311, __PRETTY_FUNCTION__)); | |||
| 312 | // Collect all basic blocks. | |||
| 313 | SetVector<BasicBlock *> BBs; | |||
| 314 | SetVector<Instruction *> InsertPts; | |||
| 315 | for (auto const &RCI : ConstInfo.RebasedConstants) | |||
| 316 | for (auto const &U : RCI.Uses) | |||
| 317 | BBs.insert(findMatInsertPt(U.Inst, U.OpndIdx)->getParent()); | |||
| 318 | ||||
| 319 | if (BBs.count(Entry)) { | |||
| 320 | InsertPts.insert(&Entry->front()); | |||
| 321 | return InsertPts; | |||
| 322 | } | |||
| 323 | ||||
| 324 | if (BFI) { | |||
| 325 | findBestInsertionSet(*DT, *BFI, Entry, BBs); | |||
| 326 | for (auto BB : BBs) { | |||
| 327 | BasicBlock::iterator InsertPt = BB->begin(); | |||
| 328 | for (; isa<PHINode>(InsertPt) || InsertPt->isEHPad(); ++InsertPt) | |||
| 329 | ; | |||
| 330 | InsertPts.insert(&*InsertPt); | |||
| 331 | } | |||
| 332 | return InsertPts; | |||
| 333 | } | |||
| 334 | ||||
| 335 | while (BBs.size() >= 2) { | |||
| 336 | BasicBlock *BB, *BB1, *BB2; | |||
| 337 | BB1 = BBs.pop_back_val(); | |||
| 338 | BB2 = BBs.pop_back_val(); | |||
| 339 | BB = DT->findNearestCommonDominator(BB1, BB2); | |||
| 340 | if (BB == Entry) { | |||
| 341 | InsertPts.insert(&Entry->front()); | |||
| ||||
| 342 | return InsertPts; | |||
| 343 | } | |||
| 344 | BBs.insert(BB); | |||
| 345 | } | |||
| 346 | assert((BBs.size() == 1) && "Expected only one element.")(((BBs.size() == 1) && "Expected only one element.") ? static_cast<void> (0) : __assert_fail ("(BBs.size() == 1) && \"Expected only one element.\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 346, __PRETTY_FUNCTION__)); | |||
| 347 | Instruction &FirstInst = (*BBs.begin())->front(); | |||
| 348 | InsertPts.insert(findMatInsertPt(&FirstInst)); | |||
| 349 | return InsertPts; | |||
| 350 | } | |||
| 351 | ||||
| 352 | /// Record constant integer ConstInt for instruction Inst at operand | |||
| 353 | /// index Idx. | |||
| 354 | /// | |||
| 355 | /// The operand at index Idx is not necessarily the constant integer itself. It | |||
| 356 | /// could also be a cast instruction or a constant expression that uses the | |||
| 357 | /// constant integer. | |||
| 358 | void ConstantHoistingPass::collectConstantCandidates( | |||
| 359 | ConstCandMapType &ConstCandMap, Instruction *Inst, unsigned Idx, | |||
| 360 | ConstantInt *ConstInt) { | |||
| 361 | unsigned Cost; | |||
| 362 | // Ask the target about the cost of materializing the constant for the given | |||
| 363 | // instruction and operand index. | |||
| 364 | if (auto IntrInst = dyn_cast<IntrinsicInst>(Inst)) | |||
| 365 | Cost = TTI->getIntImmCostIntrin(IntrInst->getIntrinsicID(), Idx, | |||
| 366 | ConstInt->getValue(), ConstInt->getType(), | |||
| 367 | TargetTransformInfo::TCK_SizeAndLatency); | |||
| 368 | else | |||
| 369 | Cost = TTI->getIntImmCostInst( | |||
| 370 | Inst->getOpcode(), Idx, ConstInt->getValue(), ConstInt->getType(), | |||
| 371 | TargetTransformInfo::TCK_SizeAndLatency, Inst); | |||
| 372 | ||||
| 373 | // Ignore cheap integer constants. | |||
| 374 | if (Cost > TargetTransformInfo::TCC_Basic) { | |||
| 375 | ConstCandMapType::iterator Itr; | |||
| 376 | bool Inserted; | |||
| 377 | ConstPtrUnionType Cand = ConstInt; | |||
| 378 | std::tie(Itr, Inserted) = ConstCandMap.insert(std::make_pair(Cand, 0)); | |||
| 379 | if (Inserted) { | |||
| 380 | ConstIntCandVec.push_back(ConstantCandidate(ConstInt)); | |||
| 381 | Itr->second = ConstIntCandVec.size() - 1; | |||
| 382 | } | |||
| 383 | ConstIntCandVec[Itr->second].addUser(Inst, Idx, Cost); | |||
| 384 | LLVM_DEBUG(if (isa<ConstantInt>(Inst->getOperand(Idx))) dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { if (isa<ConstantInt>(Inst->getOperand (Idx))) dbgs() << "Collect constant " << *ConstInt << " from " << *Inst << " with cost " << Cost << '\n'; else dbgs() << "Collect constant " << *ConstInt << " indirectly from " << *Inst << " via " << *Inst->getOperand(Idx) << " with cost " << Cost << '\n';; } } while (false ) | |||
| 385 | << "Collect constant " << *ConstInt << " from " << *Instdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { if (isa<ConstantInt>(Inst->getOperand (Idx))) dbgs() << "Collect constant " << *ConstInt << " from " << *Inst << " with cost " << Cost << '\n'; else dbgs() << "Collect constant " << *ConstInt << " indirectly from " << *Inst << " via " << *Inst->getOperand(Idx) << " with cost " << Cost << '\n';; } } while (false ) | |||
| 386 | << " with cost " << Cost << '\n';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { if (isa<ConstantInt>(Inst->getOperand (Idx))) dbgs() << "Collect constant " << *ConstInt << " from " << *Inst << " with cost " << Cost << '\n'; else dbgs() << "Collect constant " << *ConstInt << " indirectly from " << *Inst << " via " << *Inst->getOperand(Idx) << " with cost " << Cost << '\n';; } } while (false ) | |||
| 387 | else dbgs() << "Collect constant " << *ConstIntdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { if (isa<ConstantInt>(Inst->getOperand (Idx))) dbgs() << "Collect constant " << *ConstInt << " from " << *Inst << " with cost " << Cost << '\n'; else dbgs() << "Collect constant " << *ConstInt << " indirectly from " << *Inst << " via " << *Inst->getOperand(Idx) << " with cost " << Cost << '\n';; } } while (false ) | |||
| 388 | << " indirectly from " << *Inst << " via "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { if (isa<ConstantInt>(Inst->getOperand (Idx))) dbgs() << "Collect constant " << *ConstInt << " from " << *Inst << " with cost " << Cost << '\n'; else dbgs() << "Collect constant " << *ConstInt << " indirectly from " << *Inst << " via " << *Inst->getOperand(Idx) << " with cost " << Cost << '\n';; } } while (false ) | |||
| 389 | << *Inst->getOperand(Idx) << " with cost " << Costdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { if (isa<ConstantInt>(Inst->getOperand (Idx))) dbgs() << "Collect constant " << *ConstInt << " from " << *Inst << " with cost " << Cost << '\n'; else dbgs() << "Collect constant " << *ConstInt << " indirectly from " << *Inst << " via " << *Inst->getOperand(Idx) << " with cost " << Cost << '\n';; } } while (false ) | |||
| 390 | << '\n';)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { if (isa<ConstantInt>(Inst->getOperand (Idx))) dbgs() << "Collect constant " << *ConstInt << " from " << *Inst << " with cost " << Cost << '\n'; else dbgs() << "Collect constant " << *ConstInt << " indirectly from " << *Inst << " via " << *Inst->getOperand(Idx) << " with cost " << Cost << '\n';; } } while (false ); | |||
| 391 | } | |||
| 392 | } | |||
| 393 | ||||
| 394 | /// Record constant GEP expression for instruction Inst at operand index Idx. | |||
| 395 | void ConstantHoistingPass::collectConstantCandidates( | |||
| 396 | ConstCandMapType &ConstCandMap, Instruction *Inst, unsigned Idx, | |||
| 397 | ConstantExpr *ConstExpr) { | |||
| 398 | // TODO: Handle vector GEPs | |||
| 399 | if (ConstExpr->getType()->isVectorTy()) | |||
| 400 | return; | |||
| 401 | ||||
| 402 | GlobalVariable *BaseGV = dyn_cast<GlobalVariable>(ConstExpr->getOperand(0)); | |||
| 403 | if (!BaseGV) | |||
| 404 | return; | |||
| 405 | ||||
| 406 | // Get offset from the base GV. | |||
| 407 | PointerType *GVPtrTy = cast<PointerType>(BaseGV->getType()); | |||
| 408 | IntegerType *PtrIntTy = DL->getIntPtrType(*Ctx, GVPtrTy->getAddressSpace()); | |||
| 409 | APInt Offset(DL->getTypeSizeInBits(PtrIntTy), /*val*/0, /*isSigned*/true); | |||
| 410 | auto *GEPO = cast<GEPOperator>(ConstExpr); | |||
| 411 | if (!GEPO->accumulateConstantOffset(*DL, Offset)) | |||
| 412 | return; | |||
| 413 | ||||
| 414 | if (!Offset.isIntN(32)) | |||
| 415 | return; | |||
| 416 | ||||
| 417 | // A constant GEP expression that has a GlobalVariable as base pointer is | |||
| 418 | // usually lowered to a load from constant pool. Such operation is unlikely | |||
| 419 | // to be cheaper than compute it by <Base + Offset>, which can be lowered to | |||
| 420 | // an ADD instruction or folded into Load/Store instruction. | |||
| 421 | int Cost = | |||
| 422 | TTI->getIntImmCostInst(Instruction::Add, 1, Offset, PtrIntTy, | |||
| 423 | TargetTransformInfo::TCK_SizeAndLatency, Inst); | |||
| 424 | ConstCandVecType &ExprCandVec = ConstGEPCandMap[BaseGV]; | |||
| 425 | ConstCandMapType::iterator Itr; | |||
| 426 | bool Inserted; | |||
| 427 | ConstPtrUnionType Cand = ConstExpr; | |||
| 428 | std::tie(Itr, Inserted) = ConstCandMap.insert(std::make_pair(Cand, 0)); | |||
| 429 | if (Inserted) { | |||
| 430 | ExprCandVec.push_back(ConstantCandidate( | |||
| 431 | ConstantInt::get(Type::getInt32Ty(*Ctx), Offset.getLimitedValue()), | |||
| 432 | ConstExpr)); | |||
| 433 | Itr->second = ExprCandVec.size() - 1; | |||
| 434 | } | |||
| 435 | ExprCandVec[Itr->second].addUser(Inst, Idx, Cost); | |||
| 436 | } | |||
| 437 | ||||
| 438 | /// Check the operand for instruction Inst at index Idx. | |||
| 439 | void ConstantHoistingPass::collectConstantCandidates( | |||
| 440 | ConstCandMapType &ConstCandMap, Instruction *Inst, unsigned Idx) { | |||
| 441 | Value *Opnd = Inst->getOperand(Idx); | |||
| 442 | ||||
| 443 | // Visit constant integers. | |||
| 444 | if (auto ConstInt = dyn_cast<ConstantInt>(Opnd)) { | |||
| 445 | collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt); | |||
| 446 | return; | |||
| 447 | } | |||
| 448 | ||||
| 449 | // Visit cast instructions that have constant integers. | |||
| 450 | if (auto CastInst = dyn_cast<Instruction>(Opnd)) { | |||
| 451 | // Only visit cast instructions, which have been skipped. All other | |||
| 452 | // instructions should have already been visited. | |||
| 453 | if (!CastInst->isCast()) | |||
| 454 | return; | |||
| 455 | ||||
| 456 | if (auto *ConstInt = dyn_cast<ConstantInt>(CastInst->getOperand(0))) { | |||
| 457 | // Pretend the constant is directly used by the instruction and ignore | |||
| 458 | // the cast instruction. | |||
| 459 | collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt); | |||
| 460 | return; | |||
| 461 | } | |||
| 462 | } | |||
| 463 | ||||
| 464 | // Visit constant expressions that have constant integers. | |||
| 465 | if (auto ConstExpr = dyn_cast<ConstantExpr>(Opnd)) { | |||
| 466 | // Handle constant gep expressions. | |||
| 467 | if (ConstHoistGEP && ConstExpr->isGEPWithNoNotionalOverIndexing()) | |||
| 468 | collectConstantCandidates(ConstCandMap, Inst, Idx, ConstExpr); | |||
| 469 | ||||
| 470 | // Only visit constant cast expressions. | |||
| 471 | if (!ConstExpr->isCast()) | |||
| 472 | return; | |||
| 473 | ||||
| 474 | if (auto ConstInt = dyn_cast<ConstantInt>(ConstExpr->getOperand(0))) { | |||
| 475 | // Pretend the constant is directly used by the instruction and ignore | |||
| 476 | // the constant expression. | |||
| 477 | collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt); | |||
| 478 | return; | |||
| 479 | } | |||
| 480 | } | |||
| 481 | } | |||
| 482 | ||||
| 483 | /// Scan the instruction for expensive integer constants and record them | |||
| 484 | /// in the constant candidate vector. | |||
| 485 | void ConstantHoistingPass::collectConstantCandidates( | |||
| 486 | ConstCandMapType &ConstCandMap, Instruction *Inst) { | |||
| 487 | // Skip all cast instructions. They are visited indirectly later on. | |||
| 488 | if (Inst->isCast()) | |||
| 489 | return; | |||
| 490 | ||||
| 491 | // Scan all operands. | |||
| 492 | for (unsigned Idx = 0, E = Inst->getNumOperands(); Idx != E; ++Idx) { | |||
| 493 | // The cost of materializing the constants (defined in | |||
| 494 | // `TargetTransformInfo::getIntImmCostInst`) for instructions which only | |||
| 495 | // take constant variables is lower than `TargetTransformInfo::TCC_Basic`. | |||
| 496 | // So it's safe for us to collect constant candidates from all | |||
| 497 | // IntrinsicInsts. | |||
| 498 | if (canReplaceOperandWithVariable(Inst, Idx)) { | |||
| 499 | collectConstantCandidates(ConstCandMap, Inst, Idx); | |||
| 500 | } | |||
| 501 | } // end of for all operands | |||
| 502 | } | |||
| 503 | ||||
| 504 | /// Collect all integer constants in the function that cannot be folded | |||
| 505 | /// into an instruction itself. | |||
| 506 | void ConstantHoistingPass::collectConstantCandidates(Function &Fn) { | |||
| 507 | ConstCandMapType ConstCandMap; | |||
| 508 | for (BasicBlock &BB : Fn) { | |||
| 509 | // Ignore unreachable basic blocks. | |||
| 510 | if (!DT->isReachableFromEntry(&BB)) | |||
| 511 | continue; | |||
| 512 | for (Instruction &Inst : BB) | |||
| 513 | collectConstantCandidates(ConstCandMap, &Inst); | |||
| 514 | } | |||
| 515 | } | |||
| 516 | ||||
| 517 | // This helper function is necessary to deal with values that have different | |||
| 518 | // bit widths (APInt Operator- does not like that). If the value cannot be | |||
| 519 | // represented in uint64 we return an "empty" APInt. This is then interpreted | |||
| 520 | // as the value is not in range. | |||
| 521 | static Optional<APInt> calculateOffsetDiff(const APInt &V1, const APInt &V2) { | |||
| 522 | Optional<APInt> Res = None; | |||
| 523 | unsigned BW = V1.getBitWidth() > V2.getBitWidth() ? | |||
| 524 | V1.getBitWidth() : V2.getBitWidth(); | |||
| 525 | uint64_t LimVal1 = V1.getLimitedValue(); | |||
| 526 | uint64_t LimVal2 = V2.getLimitedValue(); | |||
| 527 | ||||
| 528 | if (LimVal1 == ~0ULL || LimVal2 == ~0ULL) | |||
| 529 | return Res; | |||
| 530 | ||||
| 531 | uint64_t Diff = LimVal1 - LimVal2; | |||
| 532 | return APInt(BW, Diff, true); | |||
| 533 | } | |||
| 534 | ||||
| 535 | // From a list of constants, one needs to picked as the base and the other | |||
| 536 | // constants will be transformed into an offset from that base constant. The | |||
| 537 | // question is which we can pick best? For example, consider these constants | |||
| 538 | // and their number of uses: | |||
| 539 | // | |||
| 540 | // Constants| 2 | 4 | 12 | 42 | | |||
| 541 | // NumUses | 3 | 2 | 8 | 7 | | |||
| 542 | // | |||
| 543 | // Selecting constant 12 because it has the most uses will generate negative | |||
| 544 | // offsets for constants 2 and 4 (i.e. -10 and -8 respectively). If negative | |||
| 545 | // offsets lead to less optimal code generation, then there might be better | |||
| 546 | // solutions. Suppose immediates in the range of 0..35 are most optimally | |||
| 547 | // supported by the architecture, then selecting constant 2 is most optimal | |||
| 548 | // because this will generate offsets: 0, 2, 10, 40. Offsets 0, 2 and 10 are in | |||
| 549 | // range 0..35, and thus 3 + 2 + 8 = 13 uses are in range. Selecting 12 would | |||
| 550 | // have only 8 uses in range, so choosing 2 as a base is more optimal. Thus, in | |||
| 551 | // selecting the base constant the range of the offsets is a very important | |||
| 552 | // factor too that we take into account here. This algorithm calculates a total | |||
| 553 | // costs for selecting a constant as the base and substract the costs if | |||
| 554 | // immediates are out of range. It has quadratic complexity, so we call this | |||
| 555 | // function only when we're optimising for size and there are less than 100 | |||
| 556 | // constants, we fall back to the straightforward algorithm otherwise | |||
| 557 | // which does not do all the offset calculations. | |||
| 558 | unsigned | |||
| 559 | ConstantHoistingPass::maximizeConstantsInRange(ConstCandVecType::iterator S, | |||
| 560 | ConstCandVecType::iterator E, | |||
| 561 | ConstCandVecType::iterator &MaxCostItr) { | |||
| 562 | unsigned NumUses = 0; | |||
| 563 | ||||
| 564 | bool OptForSize = Entry->getParent()->hasOptSize() || | |||
| 565 | llvm::shouldOptimizeForSize(Entry->getParent(), PSI, BFI, | |||
| 566 | PGSOQueryType::IRPass); | |||
| 567 | if (!OptForSize || std::distance(S,E) > 100) { | |||
| 568 | for (auto ConstCand = S; ConstCand != E; ++ConstCand) { | |||
| 569 | NumUses += ConstCand->Uses.size(); | |||
| 570 | if (ConstCand->CumulativeCost > MaxCostItr->CumulativeCost) | |||
| 571 | MaxCostItr = ConstCand; | |||
| 572 | } | |||
| 573 | return NumUses; | |||
| 574 | } | |||
| 575 | ||||
| 576 | LLVM_DEBUG(dbgs() << "== Maximize constants in range ==\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "== Maximize constants in range ==\n" ; } } while (false); | |||
| 577 | int MaxCost = -1; | |||
| 578 | for (auto ConstCand = S; ConstCand != E; ++ConstCand) { | |||
| 579 | auto Value = ConstCand->ConstInt->getValue(); | |||
| 580 | Type *Ty = ConstCand->ConstInt->getType(); | |||
| 581 | int Cost = 0; | |||
| 582 | NumUses += ConstCand->Uses.size(); | |||
| 583 | LLVM_DEBUG(dbgs() << "= Constant: " << ConstCand->ConstInt->getValue()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "= Constant: " << ConstCand ->ConstInt->getValue() << "\n"; } } while (false) | |||
| 584 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "= Constant: " << ConstCand ->ConstInt->getValue() << "\n"; } } while (false); | |||
| 585 | ||||
| 586 | for (auto User : ConstCand->Uses) { | |||
| 587 | unsigned Opcode = User.Inst->getOpcode(); | |||
| 588 | unsigned OpndIdx = User.OpndIdx; | |||
| 589 | Cost += TTI->getIntImmCostInst(Opcode, OpndIdx, Value, Ty, | |||
| 590 | TargetTransformInfo::TCK_SizeAndLatency); | |||
| 591 | LLVM_DEBUG(dbgs() << "Cost: " << Cost << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Cost: " << Cost << "\n"; } } while (false); | |||
| 592 | ||||
| 593 | for (auto C2 = S; C2 != E; ++C2) { | |||
| 594 | Optional<APInt> Diff = calculateOffsetDiff( | |||
| 595 | C2->ConstInt->getValue(), | |||
| 596 | ConstCand->ConstInt->getValue()); | |||
| 597 | if (Diff) { | |||
| 598 | const int ImmCosts = | |||
| 599 | TTI->getIntImmCodeSizeCost(Opcode, OpndIdx, Diff.getValue(), Ty); | |||
| 600 | Cost -= ImmCosts; | |||
| 601 | LLVM_DEBUG(dbgs() << "Offset " << Diff.getValue() << " "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Offset " << Diff.getValue () << " " << "has penalty: " << ImmCosts << "\n" << "Adjusted cost: " << Cost << "\n"; } } while (false) | |||
| 602 | << "has penalty: " << ImmCosts << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Offset " << Diff.getValue () << " " << "has penalty: " << ImmCosts << "\n" << "Adjusted cost: " << Cost << "\n"; } } while (false) | |||
| 603 | << "Adjusted cost: " << Cost << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Offset " << Diff.getValue () << " " << "has penalty: " << ImmCosts << "\n" << "Adjusted cost: " << Cost << "\n"; } } while (false); | |||
| 604 | } | |||
| 605 | } | |||
| 606 | } | |||
| 607 | LLVM_DEBUG(dbgs() << "Cumulative cost: " << Cost << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Cumulative cost: " << Cost << "\n"; } } while (false); | |||
| 608 | if (Cost > MaxCost) { | |||
| 609 | MaxCost = Cost; | |||
| 610 | MaxCostItr = ConstCand; | |||
| 611 | LLVM_DEBUG(dbgs() << "New candidate: " << MaxCostItr->ConstInt->getValue()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "New candidate: " << MaxCostItr ->ConstInt->getValue() << "\n"; } } while (false) | |||
| 612 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "New candidate: " << MaxCostItr ->ConstInt->getValue() << "\n"; } } while (false); | |||
| 613 | } | |||
| 614 | } | |||
| 615 | return NumUses; | |||
| 616 | } | |||
| 617 | ||||
| 618 | /// Find the base constant within the given range and rebase all other | |||
| 619 | /// constants with respect to the base constant. | |||
| 620 | void ConstantHoistingPass::findAndMakeBaseConstant( | |||
| 621 | ConstCandVecType::iterator S, ConstCandVecType::iterator E, | |||
| 622 | SmallVectorImpl<consthoist::ConstantInfo> &ConstInfoVec) { | |||
| 623 | auto MaxCostItr = S; | |||
| 624 | unsigned NumUses = maximizeConstantsInRange(S, E, MaxCostItr); | |||
| 625 | ||||
| 626 | // Don't hoist constants that have only one use. | |||
| 627 | if (NumUses <= 1) | |||
| 628 | return; | |||
| 629 | ||||
| 630 | ConstantInt *ConstInt = MaxCostItr->ConstInt; | |||
| 631 | ConstantExpr *ConstExpr = MaxCostItr->ConstExpr; | |||
| 632 | ConstantInfo ConstInfo; | |||
| 633 | ConstInfo.BaseInt = ConstInt; | |||
| 634 | ConstInfo.BaseExpr = ConstExpr; | |||
| 635 | Type *Ty = ConstInt->getType(); | |||
| 636 | ||||
| 637 | // Rebase the constants with respect to the base constant. | |||
| 638 | for (auto ConstCand = S; ConstCand != E; ++ConstCand) { | |||
| 639 | APInt Diff = ConstCand->ConstInt->getValue() - ConstInt->getValue(); | |||
| 640 | Constant *Offset = Diff == 0 ? nullptr : ConstantInt::get(Ty, Diff); | |||
| 641 | Type *ConstTy = | |||
| 642 | ConstCand->ConstExpr ? ConstCand->ConstExpr->getType() : nullptr; | |||
| 643 | ConstInfo.RebasedConstants.push_back( | |||
| 644 | RebasedConstantInfo(std::move(ConstCand->Uses), Offset, ConstTy)); | |||
| 645 | } | |||
| 646 | ConstInfoVec.push_back(std::move(ConstInfo)); | |||
| 647 | } | |||
| 648 | ||||
| 649 | /// Finds and combines constant candidates that can be easily | |||
| 650 | /// rematerialized with an add from a common base constant. | |||
| 651 | void ConstantHoistingPass::findBaseConstants(GlobalVariable *BaseGV) { | |||
| 652 | // If BaseGV is nullptr, find base among candidate constant integers; | |||
| 653 | // Otherwise find base among constant GEPs that share the same BaseGV. | |||
| 654 | ConstCandVecType &ConstCandVec = BaseGV ? | |||
| 655 | ConstGEPCandMap[BaseGV] : ConstIntCandVec; | |||
| 656 | ConstInfoVecType &ConstInfoVec = BaseGV ? | |||
| 657 | ConstGEPInfoMap[BaseGV] : ConstIntInfoVec; | |||
| 658 | ||||
| 659 | // Sort the constants by value and type. This invalidates the mapping! | |||
| 660 | llvm::stable_sort(ConstCandVec, [](const ConstantCandidate &LHS, | |||
| 661 | const ConstantCandidate &RHS) { | |||
| 662 | if (LHS.ConstInt->getType() != RHS.ConstInt->getType()) | |||
| 663 | return LHS.ConstInt->getType()->getBitWidth() < | |||
| 664 | RHS.ConstInt->getType()->getBitWidth(); | |||
| 665 | return LHS.ConstInt->getValue().ult(RHS.ConstInt->getValue()); | |||
| 666 | }); | |||
| 667 | ||||
| 668 | // Simple linear scan through the sorted constant candidate vector for viable | |||
| 669 | // merge candidates. | |||
| 670 | auto MinValItr = ConstCandVec.begin(); | |||
| 671 | for (auto CC = std::next(ConstCandVec.begin()), E = ConstCandVec.end(); | |||
| 672 | CC != E; ++CC) { | |||
| 673 | if (MinValItr->ConstInt->getType() == CC->ConstInt->getType()) { | |||
| 674 | Type *MemUseValTy = nullptr; | |||
| 675 | for (auto &U : CC->Uses) { | |||
| 676 | auto *UI = U.Inst; | |||
| 677 | if (LoadInst *LI = dyn_cast<LoadInst>(UI)) { | |||
| 678 | MemUseValTy = LI->getType(); | |||
| 679 | break; | |||
| 680 | } else if (StoreInst *SI = dyn_cast<StoreInst>(UI)) { | |||
| 681 | // Make sure the constant is used as pointer operand of the StoreInst. | |||
| 682 | if (SI->getPointerOperand() == SI->getOperand(U.OpndIdx)) { | |||
| 683 | MemUseValTy = SI->getValueOperand()->getType(); | |||
| 684 | break; | |||
| 685 | } | |||
| 686 | } | |||
| 687 | } | |||
| 688 | ||||
| 689 | // Check if the constant is in range of an add with immediate. | |||
| 690 | APInt Diff = CC->ConstInt->getValue() - MinValItr->ConstInt->getValue(); | |||
| 691 | if ((Diff.getBitWidth() <= 64) && | |||
| 692 | TTI->isLegalAddImmediate(Diff.getSExtValue()) && | |||
| 693 | // Check if Diff can be used as offset in addressing mode of the user | |||
| 694 | // memory instruction. | |||
| 695 | (!MemUseValTy || TTI->isLegalAddressingMode(MemUseValTy, | |||
| 696 | /*BaseGV*/nullptr, /*BaseOffset*/Diff.getSExtValue(), | |||
| 697 | /*HasBaseReg*/true, /*Scale*/0))) | |||
| 698 | continue; | |||
| 699 | } | |||
| 700 | // We either have now a different constant type or the constant is not in | |||
| 701 | // range of an add with immediate anymore. | |||
| 702 | findAndMakeBaseConstant(MinValItr, CC, ConstInfoVec); | |||
| 703 | // Start a new base constant search. | |||
| 704 | MinValItr = CC; | |||
| 705 | } | |||
| 706 | // Finalize the last base constant search. | |||
| 707 | findAndMakeBaseConstant(MinValItr, ConstCandVec.end(), ConstInfoVec); | |||
| 708 | } | |||
| 709 | ||||
| 710 | /// Updates the operand at Idx in instruction Inst with the result of | |||
| 711 | /// instruction Mat. If the instruction is a PHI node then special | |||
| 712 | /// handling for duplicate values form the same incoming basic block is | |||
| 713 | /// required. | |||
| 714 | /// \return The update will always succeed, but the return value indicated if | |||
| 715 | /// Mat was used for the update or not. | |||
| 716 | static bool updateOperand(Instruction *Inst, unsigned Idx, Instruction *Mat) { | |||
| 717 | if (auto PHI = dyn_cast<PHINode>(Inst)) { | |||
| 718 | // Check if any previous operand of the PHI node has the same incoming basic | |||
| 719 | // block. This is a very odd case that happens when the incoming basic block | |||
| 720 | // has a switch statement. In this case use the same value as the previous | |||
| 721 | // operand(s), otherwise we will fail verification due to different values. | |||
| 722 | // The values are actually the same, but the variable names are different | |||
| 723 | // and the verifier doesn't like that. | |||
| 724 | BasicBlock *IncomingBB = PHI->getIncomingBlock(Idx); | |||
| 725 | for (unsigned i = 0; i < Idx; ++i) { | |||
| 726 | if (PHI->getIncomingBlock(i) == IncomingBB) { | |||
| 727 | Value *IncomingVal = PHI->getIncomingValue(i); | |||
| 728 | Inst->setOperand(Idx, IncomingVal); | |||
| 729 | return false; | |||
| 730 | } | |||
| 731 | } | |||
| 732 | } | |||
| 733 | ||||
| 734 | Inst->setOperand(Idx, Mat); | |||
| 735 | return true; | |||
| 736 | } | |||
| 737 | ||||
| 738 | /// Emit materialization code for all rebased constants and update their | |||
| 739 | /// users. | |||
| 740 | void ConstantHoistingPass::emitBaseConstants(Instruction *Base, | |||
| 741 | Constant *Offset, | |||
| 742 | Type *Ty, | |||
| 743 | const ConstantUser &ConstUser) { | |||
| 744 | Instruction *Mat = Base; | |||
| 745 | ||||
| 746 | // The same offset can be dereferenced to different types in nested struct. | |||
| 747 | if (!Offset && Ty && Ty != Base->getType()) | |||
| 748 | Offset = ConstantInt::get(Type::getInt32Ty(*Ctx), 0); | |||
| 749 | ||||
| 750 | if (Offset) { | |||
| 751 | Instruction *InsertionPt = findMatInsertPt(ConstUser.Inst, | |||
| 752 | ConstUser.OpndIdx); | |||
| 753 | if (Ty) { | |||
| 754 | // Constant being rebased is a ConstantExpr. | |||
| 755 | PointerType *Int8PtrTy = Type::getInt8PtrTy(*Ctx, | |||
| 756 | cast<PointerType>(Ty)->getAddressSpace()); | |||
| 757 | Base = new BitCastInst(Base, Int8PtrTy, "base_bitcast", InsertionPt); | |||
| 758 | Mat = GetElementPtrInst::Create(Int8PtrTy->getElementType(), Base, | |||
| 759 | Offset, "mat_gep", InsertionPt); | |||
| 760 | Mat = new BitCastInst(Mat, Ty, "mat_bitcast", InsertionPt); | |||
| 761 | } else | |||
| 762 | // Constant being rebased is a ConstantInt. | |||
| 763 | Mat = BinaryOperator::Create(Instruction::Add, Base, Offset, | |||
| 764 | "const_mat", InsertionPt); | |||
| 765 | ||||
| 766 | LLVM_DEBUG(dbgs() << "Materialize constant (" << *Base->getOperand(0)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Materialize constant (" << *Base->getOperand(0) << " + " << *Offset << ") in BB " << Mat->getParent()->getName() << '\n' << *Mat << '\n'; } } while (false) | |||
| 767 | << " + " << *Offset << ") in BB "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Materialize constant (" << *Base->getOperand(0) << " + " << *Offset << ") in BB " << Mat->getParent()->getName() << '\n' << *Mat << '\n'; } } while (false) | |||
| 768 | << Mat->getParent()->getName() << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Materialize constant (" << *Base->getOperand(0) << " + " << *Offset << ") in BB " << Mat->getParent()->getName() << '\n' << *Mat << '\n'; } } while (false) | |||
| 769 | << *Mat << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Materialize constant (" << *Base->getOperand(0) << " + " << *Offset << ") in BB " << Mat->getParent()->getName() << '\n' << *Mat << '\n'; } } while (false); | |||
| 770 | Mat->setDebugLoc(ConstUser.Inst->getDebugLoc()); | |||
| 771 | } | |||
| 772 | Value *Opnd = ConstUser.Inst->getOperand(ConstUser.OpndIdx); | |||
| 773 | ||||
| 774 | // Visit constant integer. | |||
| 775 | if (isa<ConstantInt>(Opnd)) { | |||
| 776 | LLVM_DEBUG(dbgs() << "Update: " << *ConstUser.Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Update: " << *ConstUser .Inst << '\n'; } } while (false); | |||
| 777 | if (!updateOperand(ConstUser.Inst, ConstUser.OpndIdx, Mat) && Offset) | |||
| 778 | Mat->eraseFromParent(); | |||
| 779 | LLVM_DEBUG(dbgs() << "To : " << *ConstUser.Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "To : " << *ConstUser .Inst << '\n'; } } while (false); | |||
| 780 | return; | |||
| 781 | } | |||
| 782 | ||||
| 783 | // Visit cast instruction. | |||
| 784 | if (auto CastInst = dyn_cast<Instruction>(Opnd)) { | |||
| 785 | assert(CastInst->isCast() && "Expected an cast instruction!")((CastInst->isCast() && "Expected an cast instruction!" ) ? static_cast<void> (0) : __assert_fail ("CastInst->isCast() && \"Expected an cast instruction!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 785, __PRETTY_FUNCTION__)); | |||
| 786 | // Check if we already have visited this cast instruction before to avoid | |||
| 787 | // unnecessary cloning. | |||
| 788 | Instruction *&ClonedCastInst = ClonedCastMap[CastInst]; | |||
| 789 | if (!ClonedCastInst) { | |||
| 790 | ClonedCastInst = CastInst->clone(); | |||
| 791 | ClonedCastInst->setOperand(0, Mat); | |||
| 792 | ClonedCastInst->insertAfter(CastInst); | |||
| 793 | // Use the same debug location as the original cast instruction. | |||
| 794 | ClonedCastInst->setDebugLoc(CastInst->getDebugLoc()); | |||
| 795 | LLVM_DEBUG(dbgs() << "Clone instruction: " << *CastInst << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Clone instruction: " << *CastInst << '\n' << "To : " << *ClonedCastInst << '\n'; } } while (false) | |||
| 796 | << "To : " << *ClonedCastInst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Clone instruction: " << *CastInst << '\n' << "To : " << *ClonedCastInst << '\n'; } } while (false); | |||
| 797 | } | |||
| 798 | ||||
| 799 | LLVM_DEBUG(dbgs() << "Update: " << *ConstUser.Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Update: " << *ConstUser .Inst << '\n'; } } while (false); | |||
| 800 | updateOperand(ConstUser.Inst, ConstUser.OpndIdx, ClonedCastInst); | |||
| 801 | LLVM_DEBUG(dbgs() << "To : " << *ConstUser.Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "To : " << *ConstUser .Inst << '\n'; } } while (false); | |||
| 802 | return; | |||
| 803 | } | |||
| 804 | ||||
| 805 | // Visit constant expression. | |||
| 806 | if (auto ConstExpr = dyn_cast<ConstantExpr>(Opnd)) { | |||
| 807 | if (ConstExpr->isGEPWithNoNotionalOverIndexing()) { | |||
| 808 | // Operand is a ConstantGEP, replace it. | |||
| 809 | updateOperand(ConstUser.Inst, ConstUser.OpndIdx, Mat); | |||
| 810 | return; | |||
| 811 | } | |||
| 812 | ||||
| 813 | // Aside from constant GEPs, only constant cast expressions are collected. | |||
| 814 | assert(ConstExpr->isCast() && "ConstExpr should be a cast")((ConstExpr->isCast() && "ConstExpr should be a cast" ) ? static_cast<void> (0) : __assert_fail ("ConstExpr->isCast() && \"ConstExpr should be a cast\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 814, __PRETTY_FUNCTION__)); | |||
| 815 | Instruction *ConstExprInst = ConstExpr->getAsInstruction(); | |||
| 816 | ConstExprInst->setOperand(0, Mat); | |||
| 817 | ConstExprInst->insertBefore(findMatInsertPt(ConstUser.Inst, | |||
| 818 | ConstUser.OpndIdx)); | |||
| 819 | ||||
| 820 | // Use the same debug location as the instruction we are about to update. | |||
| 821 | ConstExprInst->setDebugLoc(ConstUser.Inst->getDebugLoc()); | |||
| 822 | ||||
| 823 | LLVM_DEBUG(dbgs() << "Create instruction: " << *ConstExprInst << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Create instruction: " << *ConstExprInst << '\n' << "From : " << *ConstExpr << '\n'; } } while (false) | |||
| 824 | << "From : " << *ConstExpr << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Create instruction: " << *ConstExprInst << '\n' << "From : " << *ConstExpr << '\n'; } } while (false); | |||
| 825 | LLVM_DEBUG(dbgs() << "Update: " << *ConstUser.Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Update: " << *ConstUser .Inst << '\n'; } } while (false); | |||
| 826 | if (!updateOperand(ConstUser.Inst, ConstUser.OpndIdx, ConstExprInst)) { | |||
| 827 | ConstExprInst->eraseFromParent(); | |||
| 828 | if (Offset) | |||
| 829 | Mat->eraseFromParent(); | |||
| 830 | } | |||
| 831 | LLVM_DEBUG(dbgs() << "To : " << *ConstUser.Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "To : " << *ConstUser .Inst << '\n'; } } while (false); | |||
| 832 | return; | |||
| 833 | } | |||
| 834 | } | |||
| 835 | ||||
| 836 | /// Hoist and hide the base constant behind a bitcast and emit | |||
| 837 | /// materialization code for derived constants. | |||
| 838 | bool ConstantHoistingPass::emitBaseConstants(GlobalVariable *BaseGV) { | |||
| 839 | bool MadeChange = false; | |||
| 840 | SmallVectorImpl<consthoist::ConstantInfo> &ConstInfoVec = | |||
| 841 | BaseGV
| |||
| 842 | for (auto const &ConstInfo : ConstInfoVec) { | |||
| 843 | SetVector<Instruction *> IPSet = findConstantInsertionPoint(ConstInfo); | |||
| 844 | // We can have an empty set if the function contains unreachable blocks. | |||
| 845 | if (IPSet.empty()) | |||
| 846 | continue; | |||
| 847 | ||||
| 848 | unsigned UsesNum = 0; | |||
| 849 | unsigned ReBasesNum = 0; | |||
| 850 | unsigned NotRebasedNum = 0; | |||
| 851 | for (Instruction *IP : IPSet) { | |||
| 852 | // First, collect constants depending on this IP of the base. | |||
| 853 | unsigned Uses = 0; | |||
| 854 | using RebasedUse = std::tuple<Constant *, Type *, ConstantUser>; | |||
| 855 | SmallVector<RebasedUse, 4> ToBeRebased; | |||
| 856 | for (auto const &RCI : ConstInfo.RebasedConstants) { | |||
| 857 | for (auto const &U : RCI.Uses) { | |||
| 858 | Uses++; | |||
| 859 | BasicBlock *OrigMatInsertBB = | |||
| 860 | findMatInsertPt(U.Inst, U.OpndIdx)->getParent(); | |||
| 861 | // If Base constant is to be inserted in multiple places, | |||
| 862 | // generate rebase for U using the Base dominating U. | |||
| 863 | if (IPSet.size() == 1 || | |||
| 864 | DT->dominates(IP->getParent(), OrigMatInsertBB)) | |||
| 865 | ToBeRebased.push_back(RebasedUse(RCI.Offset, RCI.Ty, U)); | |||
| 866 | } | |||
| 867 | } | |||
| 868 | UsesNum = Uses; | |||
| 869 | ||||
| 870 | // If only few constants depend on this IP of base, skip rebasing, | |||
| 871 | // assuming the base and the rebased have the same materialization cost. | |||
| 872 | if (ToBeRebased.size() < MinNumOfDependentToRebase) { | |||
| 873 | NotRebasedNum += ToBeRebased.size(); | |||
| 874 | continue; | |||
| 875 | } | |||
| 876 | ||||
| 877 | // Emit an instance of the base at this IP. | |||
| 878 | Instruction *Base = nullptr; | |||
| 879 | // Hoist and hide the base constant behind a bitcast. | |||
| 880 | if (ConstInfo.BaseExpr) { | |||
| 881 | assert(BaseGV && "A base constant expression must have an base GV")((BaseGV && "A base constant expression must have an base GV" ) ? static_cast<void> (0) : __assert_fail ("BaseGV && \"A base constant expression must have an base GV\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 881, __PRETTY_FUNCTION__)); | |||
| 882 | Type *Ty = ConstInfo.BaseExpr->getType(); | |||
| 883 | Base = new BitCastInst(ConstInfo.BaseExpr, Ty, "const", IP); | |||
| 884 | } else { | |||
| 885 | IntegerType *Ty = ConstInfo.BaseInt->getType(); | |||
| 886 | Base = new BitCastInst(ConstInfo.BaseInt, Ty, "const", IP); | |||
| 887 | } | |||
| 888 | ||||
| 889 | Base->setDebugLoc(IP->getDebugLoc()); | |||
| 890 | ||||
| 891 | LLVM_DEBUG(dbgs() << "Hoist constant (" << *ConstInfo.BaseIntdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Hoist constant (" << *ConstInfo.BaseInt << ") to BB " << IP->getParent ()->getName() << '\n' << *Base << '\n'; } } while (false) | |||
| 892 | << ") to BB " << IP->getParent()->getName() << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Hoist constant (" << *ConstInfo.BaseInt << ") to BB " << IP->getParent ()->getName() << '\n' << *Base << '\n'; } } while (false) | |||
| 893 | << *Base << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("consthoist")) { dbgs() << "Hoist constant (" << *ConstInfo.BaseInt << ") to BB " << IP->getParent ()->getName() << '\n' << *Base << '\n'; } } while (false); | |||
| 894 | ||||
| 895 | // Emit materialization code for rebased constants depending on this IP. | |||
| 896 | for (auto const &R : ToBeRebased) { | |||
| 897 | Constant *Off = std::get<0>(R); | |||
| 898 | Type *Ty = std::get<1>(R); | |||
| 899 | ConstantUser U = std::get<2>(R); | |||
| 900 | emitBaseConstants(Base, Off, Ty, U); | |||
| 901 | ReBasesNum++; | |||
| 902 | // Use the same debug location as the last user of the constant. | |||
| 903 | Base->setDebugLoc(DILocation::getMergedLocation( | |||
| 904 | Base->getDebugLoc(), U.Inst->getDebugLoc())); | |||
| 905 | } | |||
| 906 | assert(!Base->use_empty() && "The use list is empty!?")((!Base->use_empty() && "The use list is empty!?") ? static_cast<void> (0) : __assert_fail ("!Base->use_empty() && \"The use list is empty!?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 906, __PRETTY_FUNCTION__)); | |||
| 907 | assert(isa<Instruction>(Base->user_back()) &&((isa<Instruction>(Base->user_back()) && "All uses should be instructions." ) ? static_cast<void> (0) : __assert_fail ("isa<Instruction>(Base->user_back()) && \"All uses should be instructions.\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 908, __PRETTY_FUNCTION__)) | |||
| 908 | "All uses should be instructions.")((isa<Instruction>(Base->user_back()) && "All uses should be instructions." ) ? static_cast<void> (0) : __assert_fail ("isa<Instruction>(Base->user_back()) && \"All uses should be instructions.\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 908, __PRETTY_FUNCTION__)); | |||
| 909 | } | |||
| 910 | (void)UsesNum; | |||
| 911 | (void)ReBasesNum; | |||
| 912 | (void)NotRebasedNum; | |||
| 913 | // Expect all uses are rebased after rebase is done. | |||
| 914 | assert(UsesNum == (ReBasesNum + NotRebasedNum) &&((UsesNum == (ReBasesNum + NotRebasedNum) && "Not all uses are rebased" ) ? static_cast<void> (0) : __assert_fail ("UsesNum == (ReBasesNum + NotRebasedNum) && \"Not all uses are rebased\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 915, __PRETTY_FUNCTION__)) | |||
| 915 | "Not all uses are rebased")((UsesNum == (ReBasesNum + NotRebasedNum) && "Not all uses are rebased" ) ? static_cast<void> (0) : __assert_fail ("UsesNum == (ReBasesNum + NotRebasedNum) && \"Not all uses are rebased\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp" , 915, __PRETTY_FUNCTION__)); | |||
| 916 | ||||
| 917 | NumConstantsHoisted++; | |||
| 918 | ||||
| 919 | // Base constant is also included in ConstInfo.RebasedConstants, so | |||
| 920 | // deduct 1 from ConstInfo.RebasedConstants.size(). | |||
| 921 | NumConstantsRebased += ConstInfo.RebasedConstants.size() - 1; | |||
| 922 | ||||
| 923 | MadeChange = true; | |||
| 924 | } | |||
| 925 | return MadeChange; | |||
| 926 | } | |||
| 927 | ||||
| 928 | /// Check all cast instructions we made a copy of and remove them if they | |||
| 929 | /// have no more users. | |||
| 930 | void ConstantHoistingPass::deleteDeadCastInst() const { | |||
| 931 | for (auto const &I : ClonedCastMap) | |||
| 932 | if (I.first->use_empty()) | |||
| 933 | I.first->eraseFromParent(); | |||
| 934 | } | |||
| 935 | ||||
| 936 | /// Optimize expensive integer constants in the given function. | |||
| 937 | bool ConstantHoistingPass::runImpl(Function &Fn, TargetTransformInfo &TTI, | |||
| 938 | DominatorTree &DT, BlockFrequencyInfo *BFI, | |||
| 939 | BasicBlock &Entry, ProfileSummaryInfo *PSI) { | |||
| 940 | this->TTI = &TTI; | |||
| 941 | this->DT = &DT; | |||
| 942 | this->BFI = BFI; | |||
| 943 | this->DL = &Fn.getParent()->getDataLayout(); | |||
| 944 | this->Ctx = &Fn.getContext(); | |||
| 945 | this->Entry = &Entry; | |||
| 946 | this->PSI = PSI; | |||
| 947 | // Collect all constant candidates. | |||
| 948 | collectConstantCandidates(Fn); | |||
| 949 | ||||
| 950 | // Combine constants that can be easily materialized with an add from a common | |||
| 951 | // base constant. | |||
| 952 | if (!ConstIntCandVec.empty()) | |||
| 953 | findBaseConstants(nullptr); | |||
| 954 | for (const auto &MapEntry : ConstGEPCandMap) | |||
| 955 | if (!MapEntry.second.empty()) | |||
| 956 | findBaseConstants(MapEntry.first); | |||
| 957 | ||||
| 958 | // Finally hoist the base constant and emit materialization code for dependent | |||
| 959 | // constants. | |||
| 960 | bool MadeChange = false; | |||
| 961 | if (!ConstIntInfoVec.empty()) | |||
| 962 | MadeChange = emitBaseConstants(nullptr); | |||
| 963 | for (const auto &MapEntry : ConstGEPInfoMap) | |||
| 964 | if (!MapEntry.second.empty()) | |||
| 965 | MadeChange |= emitBaseConstants(MapEntry.first); | |||
| 966 | ||||
| 967 | ||||
| 968 | // Cleanup dead instructions. | |||
| 969 | deleteDeadCastInst(); | |||
| 970 | ||||
| 971 | cleanup(); | |||
| 972 | ||||
| 973 | return MadeChange; | |||
| 974 | } | |||
| 975 | ||||
| 976 | PreservedAnalyses ConstantHoistingPass::run(Function &F, | |||
| 977 | FunctionAnalysisManager &AM) { | |||
| 978 | auto &DT = AM.getResult<DominatorTreeAnalysis>(F); | |||
| 979 | auto &TTI = AM.getResult<TargetIRAnalysis>(F); | |||
| 980 | auto BFI = ConstHoistWithBlockFrequency | |||
| ||||
| 981 | ? &AM.getResult<BlockFrequencyAnalysis>(F) | |||
| 982 | : nullptr; | |||
| 983 | auto &MAMProxy = AM.getResult<ModuleAnalysisManagerFunctionProxy>(F); | |||
| 984 | auto *PSI = MAMProxy.getCachedResult<ProfileSummaryAnalysis>(*F.getParent()); | |||
| 985 | if (!runImpl(F, TTI, DT, BFI, F.getEntryBlock(), PSI)) | |||
| 986 | return PreservedAnalyses::all(); | |||
| 987 | ||||
| 988 | PreservedAnalyses PA; | |||
| 989 | PA.preserveSet<CFGAnalyses>(); | |||
| 990 | return PA; | |||
| 991 | } |