#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
public:
const DataLayout *DL;
const TargetLibraryInfo *TLI;
+ const TargetTransformInfo *TTI;
DominatorTree *DT;
AssumptionCache *AC;
typedef RecyclingAllocator<
bool Processed;
};
+ /// \brief Wrapper class to handle memory instructions, including loads,
+ /// stores and intrinsic loads and stores defined by the target.
+ class ParseMemoryInst {
+ public:
+ ParseMemoryInst(Instruction *Inst, const TargetTransformInfo *TTI)
+ : Load(false), Store(false), Vol(false), MayReadFromMemory(false),
+ MayWriteToMemory(false), MatchingId(-1), Ptr(nullptr) {
+ MayReadFromMemory = Inst->mayReadFromMemory();
+ MayWriteToMemory = Inst->mayWriteToMemory();
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
+ MemIntrinsicInfo Info;
+ if (!TTI->getTgtMemIntrinsic(II, Info))
+ return;
+ if (Info.NumMemRefs == 1) {
+ Store = Info.WriteMem;
+ Load = Info.ReadMem;
+ MatchingId = Info.MatchingId;
+ MayReadFromMemory = Info.ReadMem;
+ MayWriteToMemory = Info.WriteMem;
+ Vol = Info.Vol;
+ Ptr = Info.PtrVal;
+ }
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ Load = true;
+ Vol = !LI->isSimple();
+ Ptr = LI->getPointerOperand();
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ Store = true;
+ Vol = !SI->isSimple();
+ Ptr = SI->getPointerOperand();
+ }
+ }
+ bool isLoad() { return Load; }
+ bool isStore() { return Store; }
+ bool isVolatile() { return Vol; }
+ bool isMatchingMemLoc(const ParseMemoryInst &Inst) {
+ return Ptr == Inst.Ptr && MatchingId == Inst.MatchingId;
+ }
+ bool isValid() { return Ptr != nullptr; }
+ int getMatchingId() { return MatchingId; }
+ Value *getPtr() { return Ptr; }
+ bool mayReadFromMemory() { return MayReadFromMemory; }
+ bool mayWriteToMemory() { return MayWriteToMemory; }
+
+ private:
+ bool Load;
+ bool Store;
+ bool Vol;
+ bool MayReadFromMemory;
+ bool MayWriteToMemory;
+ // For regular (non-intrinsic) loads/stores, this is set to -1. For
+ // intrinsic loads/stores, the id is retrieved from the corresponding
+ // field in the MemIntrinsicInfo structure. That field contains
+ // non-negative values only.
+ int MatchingId;
+ Value *Ptr;
+ };
+
bool processNode(DomTreeNode *Node);
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
+ AU.addRequired<TargetTransformInfo>();
AU.setPreservesCFG();
}
+
+ Value *getOrCreateResult(Value *Inst, Type *ExpectedType) const {
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
+ return LI;
+ else if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
+ return SI->getValueOperand();
+ assert(isa<IntrinsicInst>(Inst) && "Instruction not supported");
+ return TTI->getOrCreateResultFromMemIntrinsic(cast<IntrinsicInst>(Inst),
+ ExpectedType);
+ }
};
}
/// as long as there in no instruction that reads memory. If we see a store
/// to the same location, we delete the dead store. This zaps trivial dead
/// stores which can occur in bitfield code among other things.
- StoreInst *LastStore = nullptr;
+ Instruction *LastStore = nullptr;
bool Changed = false;
continue;
}
+ ParseMemoryInst MemInst(Inst, TTI);
// If this is a non-volatile load, process it.
- if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ if (MemInst.isValid() && MemInst.isLoad()) {
// Ignore volatile loads.
- if (!LI->isSimple()) {
+ if (MemInst.isVolatile()) {
LastStore = nullptr;
continue;
}
// If we have an available version of this load, and if it is the right
// generation, replace this instruction.
std::pair<Value *, unsigned> InVal =
- AvailableLoads->lookup(Inst->getOperand(0));
+ AvailableLoads->lookup(MemInst.getPtr());
if (InVal.first != nullptr && InVal.second == CurrentGeneration) {
- DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst
- << " to: " << *InVal.first << '\n');
- if (!Inst->use_empty())
- Inst->replaceAllUsesWith(InVal.first);
- Inst->eraseFromParent();
- Changed = true;
- ++NumCSELoad;
- continue;
+ Value *Op = getOrCreateResult(InVal.first, Inst->getType());
+ if (Op != nullptr) {
+ DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst
+ << " to: " << *InVal.first << '\n');
+ if (!Inst->use_empty())
+ Inst->replaceAllUsesWith(Op);
+ Inst->eraseFromParent();
+ Changed = true;
+ ++NumCSELoad;
+ continue;
+ }
}
// Otherwise, remember that we have this instruction.
- AvailableLoads->insert(Inst->getOperand(0), std::pair<Value *, unsigned>(
- Inst, CurrentGeneration));
+ AvailableLoads->insert(MemInst.getPtr(), std::pair<Value *, unsigned>(
+ Inst, CurrentGeneration));
LastStore = nullptr;
continue;
}
// If this instruction may read from memory, forget LastStore.
- if (Inst->mayReadFromMemory())
+ // Load/store intrinsics will indicate both a read and a write to
+ // memory. The target may override this (e.g. so that a store intrinsic
+ // does not read from memory, and thus will be treated the same as a
+ // regular store for commoning purposes).
+ if (Inst->mayReadFromMemory() &&
+ !(MemInst.isValid() && !MemInst.mayReadFromMemory()))
LastStore = nullptr;
// If this is a read-only call, process it.
if (Inst->mayWriteToMemory()) {
++CurrentGeneration;
- if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ if (MemInst.isValid() && MemInst.isStore()) {
// We do a trivial form of DSE if there are two stores to the same
// location with no intervening loads. Delete the earlier store.
- if (LastStore &&
- LastStore->getPointerOperand() == SI->getPointerOperand()) {
- DEBUG(dbgs() << "EarlyCSE DEAD STORE: " << *LastStore
- << " due to: " << *Inst << '\n');
- LastStore->eraseFromParent();
- Changed = true;
- ++NumDSE;
- LastStore = nullptr;
+ if (LastStore) {
+ ParseMemoryInst LastStoreMemInst(LastStore, TTI);
+ if (LastStoreMemInst.isMatchingMemLoc(MemInst)) {
+ DEBUG(dbgs() << "EarlyCSE DEAD STORE: " << *LastStore
+ << " due to: " << *Inst << '\n');
+ LastStore->eraseFromParent();
+ Changed = true;
+ ++NumDSE;
+ LastStore = nullptr;
+ }
// fallthrough - we can exploit information about this store
}
// version of the pointer. It is safe to forward from volatile stores
// to non-volatile loads, so we don't have to check for volatility of
// the store.
- AvailableLoads->insert(SI->getPointerOperand(),
- std::pair<Value *, unsigned>(
- SI->getValueOperand(), CurrentGeneration));
+ AvailableLoads->insert(MemInst.getPtr(), std::pair<Value *, unsigned>(
+ Inst, CurrentGeneration));
// Remember that this was the last store we saw for DSE.
- if (SI->isSimple())
- LastStore = SI;
+ if (!MemInst.isVolatile())
+ LastStore = Inst;
}
}
}
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
DL = DLP ? &DLP->getDataLayout() : nullptr;
TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ TTI = &getAnalysis<TargetTransformInfo>();
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
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