#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/ScopedHashTable.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/RecyclingAllocator.h"
-#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include <deque>
/// expected that a later pass of GVN will catch the interesting/hard cases.
class EarlyCSE {
public:
- Function &F;
- const DataLayout *DL;
const TargetLibraryInfo &TLI;
const TargetTransformInfo &TTI;
DominatorTree &DT;
/// current generation count. The current generation count is incremented
/// after every possibly writing memory operation, which ensures that we only
/// CSE loads with other loads that have no intervening store.
- typedef RecyclingAllocator<
- BumpPtrAllocator,
- ScopedHashTableVal<Value *, std::pair<Value *, unsigned>>>
+ struct LoadValue {
+ Value *Data;
+ unsigned Generation;
+ int MatchingId;
+ LoadValue() : Data(nullptr), Generation(0), MatchingId(-1) {}
+ LoadValue(Value *Data, unsigned Generation, unsigned MatchingId)
+ : Data(Data), Generation(Generation), MatchingId(MatchingId) {}
+ };
+ typedef RecyclingAllocator<BumpPtrAllocator,
+ ScopedHashTableVal<Value *, LoadValue>>
LoadMapAllocator;
- typedef ScopedHashTable<Value *, std::pair<Value *, unsigned>,
- DenseMapInfo<Value *>, LoadMapAllocator> LoadHTType;
+ typedef ScopedHashTable<Value *, LoadValue, DenseMapInfo<Value *>,
+ LoadMapAllocator> LoadHTType;
LoadHTType AvailableLoads;
/// \brief A scoped hash table of the current values of read-only call
unsigned CurrentGeneration;
/// \brief Set up the EarlyCSE runner for a particular function.
- EarlyCSE(Function &F, const DataLayout *DL, const TargetLibraryInfo &TLI,
- const TargetTransformInfo &TTI, DominatorTree &DT,
- AssumptionCache &AC)
- : F(F), DL(DL), TLI(TLI), TTI(TTI), DT(DT), AC(AC), CurrentGeneration(0) {
- }
+ EarlyCSE(const TargetLibraryInfo &TLI, const TargetTransformInfo &TTI,
+ DominatorTree &DT, AssumptionCache &AC)
+ : TLI(TLI), TTI(TTI), DT(DT), AC(AC), CurrentGeneration(0) {}
bool run();
Ptr = SI->getPointerOperand();
}
}
- bool isLoad() { return Load; }
- bool isStore() { return Store; }
- bool isVolatile() { return Vol; }
- bool isMatchingMemLoc(const ParseMemoryInst &Inst) {
+ bool isLoad() const { return Load; }
+ bool isStore() const { return Store; }
+ bool isVolatile() const { return Vol; }
+ bool isMatchingMemLoc(const ParseMemoryInst &Inst) const {
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; }
+ bool isValid() const { return Ptr != nullptr; }
+ int getMatchingId() const { return MatchingId; }
+ Value *getPtr() const { return Ptr; }
+ bool mayReadFromMemory() const { return MayReadFromMemory; }
+ bool mayWriteToMemory() const { return MayWriteToMemory; }
private:
bool Load;
if (!BB->getSinglePredecessor())
++CurrentGeneration;
+ // If this node has a single predecessor which ends in a conditional branch,
+ // we can infer the value of the branch condition given that we took this
+ // path. We need the single predeccesor to ensure there's not another path
+ // which reaches this block where the condition might hold a different
+ // value. Since we're adding this to the scoped hash table (like any other
+ // def), it will have been popped if we encounter a future merge block.
+ if (BasicBlock *Pred = BB->getSinglePredecessor())
+ if (auto *BI = dyn_cast<BranchInst>(Pred->getTerminator()))
+ if (BI->isConditional())
+ if (auto *CondInst = dyn_cast<Instruction>(BI->getCondition()))
+ if (SimpleValue::canHandle(CondInst)) {
+ assert(BI->getSuccessor(0) == BB || BI->getSuccessor(1) == BB);
+ auto *ConditionalConstant = (BI->getSuccessor(0) == BB) ?
+ ConstantInt::getTrue(BB->getContext()) :
+ ConstantInt::getFalse(BB->getContext());
+ AvailableValues.insert(CondInst, ConditionalConstant);
+ DEBUG(dbgs() << "EarlyCSE CVP: Add conditional value for '"
+ << CondInst->getName() << "' as " << *ConditionalConstant
+ << " in " << BB->getName() << "\n");
+ // Replace all dominated uses with the known value
+ replaceDominatedUsesWith(CondInst, ConditionalConstant, DT,
+ BasicBlockEdge(Pred, BB));
+ }
+
/// LastStore - Keep track of the last non-volatile store that we saw... for
/// 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
Instruction *LastStore = nullptr;
bool Changed = false;
+ const DataLayout &DL = BB->getModule()->getDataLayout();
// See if any instructions in the block can be eliminated. If so, do it. If
// not, add them to AvailableValues.
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
- Instruction *Inst = I++;
+ Instruction *Inst = &*I++;
// Dead instructions should just be removed.
if (isInstructionTriviallyDead(Inst, &TLI)) {
// 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(MemInst.getPtr());
- if (InVal.first != nullptr && InVal.second == CurrentGeneration) {
- Value *Op = getOrCreateResult(InVal.first, Inst->getType());
+ LoadValue InVal = AvailableLoads.lookup(MemInst.getPtr());
+ if (InVal.Data != nullptr && InVal.Generation == CurrentGeneration &&
+ InVal.MatchingId == MemInst.getMatchingId()) {
+ Value *Op = getOrCreateResult(InVal.Data, Inst->getType());
if (Op != nullptr) {
DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst
- << " to: " << *InVal.first << '\n');
+ << " to: " << *InVal.Data << '\n');
if (!Inst->use_empty())
Inst->replaceAllUsesWith(Op);
Inst->eraseFromParent();
}
// Otherwise, remember that we have this instruction.
- AvailableLoads.insert(MemInst.getPtr(), std::pair<Value *, unsigned>(
- Inst, CurrentGeneration));
+ AvailableLoads.insert(
+ MemInst.getPtr(),
+ LoadValue(Inst, CurrentGeneration, MemInst.getMatchingId()));
LastStore = nullptr;
continue;
}
continue;
}
+ // A release fence requires that all stores complete before it, but does
+ // not prevent the reordering of following loads 'before' the fence. As a
+ // result, we don't need to consider it as writing to memory and don't need
+ // to advance the generation. We do need to prevent DSE across the fence,
+ // but that's handled above.
+ if (FenceInst *FI = dyn_cast<FenceInst>(Inst))
+ if (FI->getOrdering() == Release) {
+ assert(Inst->mayReadFromMemory() && "relied on to prevent DSE above");
+ continue;
+ }
+
// Okay, this isn't something we can CSE at all. Check to see if it is
// something that could modify memory. If so, our available memory values
// cannot be used so bump the generation count.
// 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(MemInst.getPtr(), std::pair<Value *, unsigned>(
- Inst, CurrentGeneration));
+ AvailableLoads.insert(
+ MemInst.getPtr(),
+ LoadValue(Inst, CurrentGeneration, MemInst.getMatchingId()));
// Remember that this was the last store we saw for DSE.
if (!MemInst.isVolatile())
// gains over vector when the container becomes very large due to the
// specific access patterns. For more information see the mailing list
// discussion on this:
- // http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120116/135228.html
+ // http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20120116/135228.html
std::deque<StackNode *> nodesToProcess;
bool Changed = false;
PreservedAnalyses EarlyCSEPass::run(Function &F,
AnalysisManager<Function> *AM) {
- const DataLayout *DL = F.getParent()->getDataLayout();
-
auto &TLI = AM->getResult<TargetLibraryAnalysis>(F);
auto &TTI = AM->getResult<TargetIRAnalysis>(F);
auto &DT = AM->getResult<DominatorTreeAnalysis>(F);
auto &AC = AM->getResult<AssumptionAnalysis>(F);
- EarlyCSE CSE(F, DL, TLI, TTI, DT, AC);
+ EarlyCSE CSE(TLI, TTI, DT, AC);
if (!CSE.run())
return PreservedAnalyses::all();
if (skipOptnoneFunction(F))
return false;
- DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
- auto *DL = DLP ? &DLP->getDataLayout() : nullptr;
auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
- EarlyCSE CSE(F, DL, TLI, TTI, DT, AC);
+ EarlyCSE CSE(TLI, TTI, DT, AC);
return CSE.run();
}
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
+ AU.addPreserved<GlobalsAAWrapperPass>();
AU.setPreservesCFG();
}
};
projects / oota-llvm.git / blobdiff