//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "early-cse"
-#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Scalar/EarlyCSE.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/ScopedHashTable.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/Dominators.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/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/PatternMatch.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/RecyclingAllocator.h"
-#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include <deque>
using namespace llvm;
+using namespace llvm::PatternMatch;
+
+#define DEBUG_TYPE "early-cse"
STATISTIC(NumSimplify, "Number of instructions simplified or DCE'd");
STATISTIC(NumCSE, "Number of instructions CSE'd");
STATISTIC(NumCSECall, "Number of call instructions CSE'd");
STATISTIC(NumDSE, "Number of trivial dead stores removed");
-static unsigned getHash(const void *V) {
- return DenseMapInfo<const void*>::getHashValue(V);
-}
-
//===----------------------------------------------------------------------===//
// SimpleValue
//===----------------------------------------------------------------------===//
namespace {
- /// SimpleValue - Instances of this struct represent available values in the
- /// scoped hash table.
- struct SimpleValue {
- Instruction *Inst;
+/// \brief Struct representing the available values in the scoped hash table.
+struct SimpleValue {
+ Instruction *Inst;
- SimpleValue(Instruction *I) : Inst(I) {
- assert((isSentinel() || canHandle(I)) && "Inst can't be handled!");
- }
+ SimpleValue(Instruction *I) : Inst(I) {
+ assert((isSentinel() || canHandle(I)) && "Inst can't be handled!");
+ }
- bool isSentinel() const {
- return Inst == DenseMapInfo<Instruction*>::getEmptyKey() ||
- Inst == DenseMapInfo<Instruction*>::getTombstoneKey();
- }
+ bool isSentinel() const {
+ return Inst == DenseMapInfo<Instruction *>::getEmptyKey() ||
+ Inst == DenseMapInfo<Instruction *>::getTombstoneKey();
+ }
- static bool canHandle(Instruction *Inst) {
- // This can only handle non-void readnone functions.
- if (CallInst *CI = dyn_cast<CallInst>(Inst))
- return CI->doesNotAccessMemory() && !CI->getType()->isVoidTy();
- return isa<CastInst>(Inst) || isa<BinaryOperator>(Inst) ||
- isa<GetElementPtrInst>(Inst) || isa<CmpInst>(Inst) ||
- isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
- isa<InsertElementInst>(Inst) || isa<ShuffleVectorInst>(Inst) ||
- isa<ExtractValueInst>(Inst) || isa<InsertValueInst>(Inst);
- }
- };
+ static bool canHandle(Instruction *Inst) {
+ // This can only handle non-void readnone functions.
+ if (CallInst *CI = dyn_cast<CallInst>(Inst))
+ return CI->doesNotAccessMemory() && !CI->getType()->isVoidTy();
+ return isa<CastInst>(Inst) || isa<BinaryOperator>(Inst) ||
+ isa<GetElementPtrInst>(Inst) || isa<CmpInst>(Inst) ||
+ isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
+ isa<InsertElementInst>(Inst) || isa<ShuffleVectorInst>(Inst) ||
+ isa<ExtractValueInst>(Inst) || isa<InsertValueInst>(Inst);
+ }
+};
}
namespace llvm {
-// SimpleValue is POD.
-template<> struct isPodLike<SimpleValue> {
- static const bool value = true;
-};
-
-template<> struct DenseMapInfo<SimpleValue> {
+template <> struct DenseMapInfo<SimpleValue> {
static inline SimpleValue getEmptyKey() {
- return DenseMapInfo<Instruction*>::getEmptyKey();
+ return DenseMapInfo<Instruction *>::getEmptyKey();
}
static inline SimpleValue getTombstoneKey() {
- return DenseMapInfo<Instruction*>::getTombstoneKey();
+ return DenseMapInfo<Instruction *>::getTombstoneKey();
}
static unsigned getHashValue(SimpleValue Val);
static bool isEqual(SimpleValue LHS, SimpleValue RHS);
unsigned DenseMapInfo<SimpleValue>::getHashValue(SimpleValue Val) {
Instruction *Inst = Val.Inst;
// Hash in all of the operands as pointers.
- if (BinaryOperator* BinOp = dyn_cast<BinaryOperator>(Inst)) {
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst)) {
Value *LHS = BinOp->getOperand(0);
Value *RHS = BinOp->getOperand(1);
if (BinOp->isCommutative() && BinOp->getOperand(0) > BinOp->getOperand(1))
if (isa<OverflowingBinaryOperator>(BinOp)) {
// Hash the overflow behavior
unsigned Overflow =
- BinOp->hasNoSignedWrap() * OverflowingBinaryOperator::NoSignedWrap |
- BinOp->hasNoUnsignedWrap() * OverflowingBinaryOperator::NoUnsignedWrap;
+ BinOp->hasNoSignedWrap() * OverflowingBinaryOperator::NoSignedWrap |
+ BinOp->hasNoUnsignedWrap() *
+ OverflowingBinaryOperator::NoUnsignedWrap;
return hash_combine(BinOp->getOpcode(), Overflow, LHS, RHS);
}
assert((isa<CallInst>(Inst) || isa<BinaryOperator>(Inst) ||
isa<GetElementPtrInst>(Inst) || isa<SelectInst>(Inst) ||
isa<ExtractElementInst>(Inst) || isa<InsertElementInst>(Inst) ||
- isa<ShuffleVectorInst>(Inst)) && "Invalid/unknown instruction");
+ isa<ShuffleVectorInst>(Inst)) &&
+ "Invalid/unknown instruction");
// Mix in the opcode.
- return hash_combine(Inst->getOpcode(),
- hash_combine_range(Inst->value_op_begin(),
- Inst->value_op_end()));
+ return hash_combine(
+ Inst->getOpcode(),
+ hash_combine_range(Inst->value_op_begin(), Inst->value_op_end()));
}
bool DenseMapInfo<SimpleValue>::isEqual(SimpleValue LHS, SimpleValue RHS) {
if (LHS.isSentinel() || RHS.isSentinel())
return LHSI == RHSI;
- if (LHSI->getOpcode() != RHSI->getOpcode()) return false;
- if (LHSI->isIdenticalTo(RHSI)) return true;
+ if (LHSI->getOpcode() != RHSI->getOpcode())
+ return false;
+ if (LHSI->isIdenticalTo(RHSI))
+ return true;
// If we're not strictly identical, we still might be a commutable instruction
if (BinaryOperator *LHSBinOp = dyn_cast<BinaryOperator>(LHSI)) {
if (!LHSBinOp->isCommutative())
return false;
- assert(isa<BinaryOperator>(RHSI)
- && "same opcode, but different instruction type?");
+ assert(isa<BinaryOperator>(RHSI) &&
+ "same opcode, but different instruction type?");
BinaryOperator *RHSBinOp = cast<BinaryOperator>(RHSI);
// Check overflow attributes
if (isa<OverflowingBinaryOperator>(LHSBinOp)) {
- assert(isa<OverflowingBinaryOperator>(RHSBinOp)
- && "same opcode, but different operator type?");
+ assert(isa<OverflowingBinaryOperator>(RHSBinOp) &&
+ "same opcode, but different operator type?");
if (LHSBinOp->hasNoUnsignedWrap() != RHSBinOp->hasNoUnsignedWrap() ||
LHSBinOp->hasNoSignedWrap() != RHSBinOp->hasNoSignedWrap())
return false;
// Commuted equality
return LHSBinOp->getOperand(0) == RHSBinOp->getOperand(1) &&
- LHSBinOp->getOperand(1) == RHSBinOp->getOperand(0);
+ LHSBinOp->getOperand(1) == RHSBinOp->getOperand(0);
}
if (CmpInst *LHSCmp = dyn_cast<CmpInst>(LHSI)) {
- assert(isa<CmpInst>(RHSI)
- && "same opcode, but different instruction type?");
+ assert(isa<CmpInst>(RHSI) &&
+ "same opcode, but different instruction type?");
CmpInst *RHSCmp = cast<CmpInst>(RHSI);
// Commuted equality
return LHSCmp->getOperand(0) == RHSCmp->getOperand(1) &&
- LHSCmp->getOperand(1) == RHSCmp->getOperand(0) &&
- LHSCmp->getSwappedPredicate() == RHSCmp->getPredicate();
+ LHSCmp->getOperand(1) == RHSCmp->getOperand(0) &&
+ LHSCmp->getSwappedPredicate() == RHSCmp->getPredicate();
}
return false;
//===----------------------------------------------------------------------===//
namespace {
- /// CallValue - Instances of this struct represent available call values in
- /// the scoped hash table.
- struct CallValue {
- Instruction *Inst;
+/// \brief Struct representing the available call values in the scoped hash
+/// table.
+struct CallValue {
+ Instruction *Inst;
- CallValue(Instruction *I) : Inst(I) {
- assert((isSentinel() || canHandle(I)) && "Inst can't be handled!");
- }
+ CallValue(Instruction *I) : Inst(I) {
+ assert((isSentinel() || canHandle(I)) && "Inst can't be handled!");
+ }
- bool isSentinel() const {
- return Inst == DenseMapInfo<Instruction*>::getEmptyKey() ||
- Inst == DenseMapInfo<Instruction*>::getTombstoneKey();
- }
+ bool isSentinel() const {
+ return Inst == DenseMapInfo<Instruction *>::getEmptyKey() ||
+ Inst == DenseMapInfo<Instruction *>::getTombstoneKey();
+ }
- static bool canHandle(Instruction *Inst) {
- // Don't value number anything that returns void.
- if (Inst->getType()->isVoidTy())
- return false;
+ static bool canHandle(Instruction *Inst) {
+ // Don't value number anything that returns void.
+ if (Inst->getType()->isVoidTy())
+ return false;
- CallInst *CI = dyn_cast<CallInst>(Inst);
- if (CI == 0 || !CI->onlyReadsMemory())
- return false;
- return true;
- }
- };
+ CallInst *CI = dyn_cast<CallInst>(Inst);
+ if (!CI || !CI->onlyReadsMemory())
+ return false;
+ return true;
+ }
+};
}
namespace llvm {
- // CallValue is POD.
- template<> struct isPodLike<CallValue> {
- static const bool value = true;
- };
-
- template<> struct DenseMapInfo<CallValue> {
- static inline CallValue getEmptyKey() {
- return DenseMapInfo<Instruction*>::getEmptyKey();
- }
- static inline CallValue getTombstoneKey() {
- return DenseMapInfo<Instruction*>::getTombstoneKey();
- }
- static unsigned getHashValue(CallValue Val);
- static bool isEqual(CallValue LHS, CallValue RHS);
- };
+template <> struct DenseMapInfo<CallValue> {
+ static inline CallValue getEmptyKey() {
+ return DenseMapInfo<Instruction *>::getEmptyKey();
+ }
+ static inline CallValue getTombstoneKey() {
+ return DenseMapInfo<Instruction *>::getTombstoneKey();
+ }
+ static unsigned getHashValue(CallValue Val);
+ static bool isEqual(CallValue LHS, CallValue RHS);
+};
}
+
unsigned DenseMapInfo<CallValue>::getHashValue(CallValue Val) {
Instruction *Inst = Val.Inst;
- // Hash in all of the operands as pointers.
- unsigned Res = 0;
- for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i) {
- assert(!Inst->getOperand(i)->getType()->isMetadataTy() &&
- "Cannot value number calls with metadata operands");
- Res ^= getHash(Inst->getOperand(i)) << (i & 0xF);
- }
-
- // Mix in the opcode.
- return (Res << 1) ^ Inst->getOpcode();
+ // Hash all of the operands as pointers and mix in the opcode.
+ return hash_combine(
+ Inst->getOpcode(),
+ hash_combine_range(Inst->value_op_begin(), Inst->value_op_end()));
}
bool DenseMapInfo<CallValue>::isEqual(CallValue LHS, CallValue RHS) {
return LHSI->isIdenticalTo(RHSI);
}
-
//===----------------------------------------------------------------------===//
-// EarlyCSE pass.
+// EarlyCSE implementation
//===----------------------------------------------------------------------===//
namespace {
-
-/// EarlyCSE - This pass does a simple depth-first walk over the dominator
-/// tree, eliminating trivially redundant instructions and using instsimplify
-/// to canonicalize things as it goes. It is intended to be fast and catch
-/// obvious cases so that instcombine and other passes are more effective. It
-/// is expected that a later pass of GVN will catch the interesting/hard
-/// cases.
-class EarlyCSE : public FunctionPass {
+/// \brief A simple and fast domtree-based CSE pass.
+///
+/// This pass does a simple depth-first walk over the dominator tree,
+/// eliminating trivially redundant instructions and using instsimplify to
+/// canonicalize things as it goes. It is intended to be fast and catch obvious
+/// cases so that instcombine and other passes are more effective. It is
+/// expected that a later pass of GVN will catch the interesting/hard cases.
+class EarlyCSE {
public:
- const DataLayout *TD;
- const TargetLibraryInfo *TLI;
- DominatorTree *DT;
- typedef RecyclingAllocator<BumpPtrAllocator,
- ScopedHashTableVal<SimpleValue, Value*> > AllocatorTy;
- typedef ScopedHashTable<SimpleValue, Value*, DenseMapInfo<SimpleValue>,
+ const TargetLibraryInfo &TLI;
+ const TargetTransformInfo &TTI;
+ DominatorTree &DT;
+ AssumptionCache &AC;
+ typedef RecyclingAllocator<
+ BumpPtrAllocator, ScopedHashTableVal<SimpleValue, Value *>> AllocatorTy;
+ typedef ScopedHashTable<SimpleValue, Value *, DenseMapInfo<SimpleValue>,
AllocatorTy> ScopedHTType;
- /// AvailableValues - This scoped hash table contains the current values of
- /// all of our simple scalar expressions. As we walk down the domtree, we
- /// look to see if instructions are in this: if so, we replace them with what
- /// we find, otherwise we insert them so that dominated values can succeed in
- /// their lookup.
- ScopedHTType *AvailableValues;
-
- /// AvailableLoads - This scoped hash table contains the current values
- /// of loads. This allows us to get efficient access to dominating loads when
+ /// \brief A scoped hash table of the current values of all of our simple
+ /// scalar expressions.
+ ///
+ /// As we walk down the domtree, we look to see if instructions are in this:
+ /// if so, we replace them with what we find, otherwise we insert them so
+ /// that dominated values can succeed in their lookup.
+ ScopedHTType AvailableValues;
+
+ /// A scoped hash table of the current values of previously encounted memory
+ /// locations.
+ ///
+ /// This allows us to get efficient access to dominating loads or stores when
/// we have a fully redundant load. In addition to the most recent load, we
/// keep track of a generation count of the read, which is compared against
- /// the 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.
+ /// the 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. Ordering
+ /// events (such as fences or atomic instructions) increment the generation
+ /// count as well; essentially, we model these as writes to all possible
+ /// locations. Note that atomic and/or volatile loads and stores can be
+ /// present the table; it is the responsibility of the consumer to inspect
+ /// the atomicity/volatility if needed.
+ struct LoadValue {
+ Value *Data;
+ unsigned Generation;
+ int MatchingId;
+ bool IsAtomic;
+ LoadValue()
+ : Data(nullptr), Generation(0), MatchingId(-1), IsAtomic(false) {}
+ LoadValue(Value *Data, unsigned Generation, unsigned MatchingId,
+ bool IsAtomic)
+ : Data(Data), Generation(Generation), MatchingId(MatchingId),
+ IsAtomic(IsAtomic) {}
+ };
typedef RecyclingAllocator<BumpPtrAllocator,
- ScopedHashTableVal<Value*, std::pair<Value*, unsigned> > > LoadMapAllocator;
- typedef ScopedHashTable<Value*, std::pair<Value*, unsigned>,
- DenseMapInfo<Value*>, LoadMapAllocator> LoadHTType;
- LoadHTType *AvailableLoads;
-
- /// AvailableCalls - This scoped hash table contains the current values
- /// of read-only call values. It uses the same generation count as loads.
- typedef ScopedHashTable<CallValue, std::pair<Value*, unsigned> > CallHTType;
- CallHTType *AvailableCalls;
-
- /// CurrentGeneration - This is the current generation of the memory value.
+ ScopedHashTableVal<Value *, LoadValue>>
+ LoadMapAllocator;
+ typedef ScopedHashTable<Value *, LoadValue, DenseMapInfo<Value *>,
+ LoadMapAllocator> LoadHTType;
+ LoadHTType AvailableLoads;
+
+ /// \brief A scoped hash table of the current values of read-only call
+ /// values.
+ ///
+ /// It uses the same generation count as loads.
+ typedef ScopedHashTable<CallValue, std::pair<Value *, unsigned>> CallHTType;
+ CallHTType AvailableCalls;
+
+ /// \brief This is the current generation of the memory value.
unsigned CurrentGeneration;
- static char ID;
- explicit EarlyCSE() : FunctionPass(ID) {
- initializeEarlyCSEPass(*PassRegistry::getPassRegistry());
- }
+ /// \brief Set up the EarlyCSE runner for a particular function.
+ EarlyCSE(const TargetLibraryInfo &TLI, const TargetTransformInfo &TTI,
+ DominatorTree &DT, AssumptionCache &AC)
+ : TLI(TLI), TTI(TTI), DT(DT), AC(AC), CurrentGeneration(0) {}
- bool runOnFunction(Function &F);
+ bool run();
private:
-
- // NodeScope - almost a POD, but needs to call the constructors for the
- // scoped hash tables so that a new scope gets pushed on. These are RAII so
- // that the scope gets popped when the NodeScope is destroyed.
+ // Almost a POD, but needs to call the constructors for the scoped hash
+ // tables so that a new scope gets pushed on. These are RAII so that the
+ // scope gets popped when the NodeScope is destroyed.
class NodeScope {
- public:
- NodeScope(ScopedHTType *availableValues,
- LoadHTType *availableLoads,
- CallHTType *availableCalls) :
- Scope(*availableValues),
- LoadScope(*availableLoads),
- CallScope(*availableCalls) {}
-
- private:
- NodeScope(const NodeScope&) LLVM_DELETED_FUNCTION;
- void operator=(const NodeScope&) LLVM_DELETED_FUNCTION;
+ public:
+ NodeScope(ScopedHTType &AvailableValues, LoadHTType &AvailableLoads,
+ CallHTType &AvailableCalls)
+ : Scope(AvailableValues), LoadScope(AvailableLoads),
+ CallScope(AvailableCalls) {}
+
+ private:
+ NodeScope(const NodeScope &) = delete;
+ void operator=(const NodeScope &) = delete;
ScopedHTType::ScopeTy Scope;
LoadHTType::ScopeTy LoadScope;
CallHTType::ScopeTy CallScope;
};
- // StackNode - contains all the needed information to create a stack for
- // doing a depth first tranversal of the tree. This includes scopes for
- // values, loads, and calls as well as the generation. There is a child
- // iterator so that the children do not need to be store spearately.
+ // Contains all the needed information to create a stack for doing a depth
+ // first tranversal of the tree. This includes scopes for values, loads, and
+ // calls as well as the generation. There is a child iterator so that the
+ // children do not need to be store spearately.
class StackNode {
- public:
- StackNode(ScopedHTType *availableValues,
- LoadHTType *availableLoads,
- CallHTType *availableCalls,
- unsigned cg, DomTreeNode *n,
- DomTreeNode::iterator child, DomTreeNode::iterator end) :
- CurrentGeneration(cg), ChildGeneration(cg), Node(n),
- ChildIter(child), EndIter(end),
- Scopes(availableValues, availableLoads, availableCalls),
- Processed(false) {}
+ public:
+ StackNode(ScopedHTType &AvailableValues, LoadHTType &AvailableLoads,
+ CallHTType &AvailableCalls, unsigned cg, DomTreeNode *n,
+ DomTreeNode::iterator child, DomTreeNode::iterator end)
+ : CurrentGeneration(cg), ChildGeneration(cg), Node(n), ChildIter(child),
+ EndIter(end), Scopes(AvailableValues, AvailableLoads, AvailableCalls),
+ Processed(false) {}
// Accessors.
unsigned currentGeneration() { return CurrentGeneration; }
bool isProcessed() { return Processed; }
void process() { Processed = true; }
- private:
- StackNode(const StackNode&) LLVM_DELETED_FUNCTION;
- void operator=(const StackNode&) LLVM_DELETED_FUNCTION;
+ private:
+ StackNode(const StackNode &) = delete;
+ void operator=(const StackNode &) = delete;
// Members.
unsigned CurrentGeneration;
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)
+ : IsTargetMemInst(false), Inst(Inst) {
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
+ if (TTI.getTgtMemIntrinsic(II, Info) && Info.NumMemRefs == 1)
+ IsTargetMemInst = true;
+ }
+ bool isLoad() const {
+ if (IsTargetMemInst) return Info.ReadMem;
+ return isa<LoadInst>(Inst);
+ }
+ bool isStore() const {
+ if (IsTargetMemInst) return Info.WriteMem;
+ return isa<StoreInst>(Inst);
+ }
+ bool isAtomic() const {
+ if (IsTargetMemInst) {
+ assert(Info.IsSimple && "need to refine IsSimple in TTI");
+ return false;
+ }
+ return Inst->isAtomic();
+ }
+ bool isUnordered() const {
+ if (IsTargetMemInst) {
+ assert(Info.IsSimple && "need to refine IsSimple in TTI");
+ return true;
+ }
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ return LI->isUnordered();
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ return SI->isUnordered();
+ }
+ // Conservative answer
+ return !Inst->isAtomic();
+ }
+
+ bool isVolatile() const {
+ if (IsTargetMemInst) {
+ assert(Info.IsSimple && "need to refine IsSimple in TTI");
+ return false;
+ }
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ return LI->isVolatile();
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ return SI->isVolatile();
+ }
+ // Conservative answer
+ return true;
+ }
+
+
+ bool isMatchingMemLoc(const ParseMemoryInst &Inst) const {
+ return (getPointerOperand() == Inst.getPointerOperand() &&
+ getMatchingId() == Inst.getMatchingId());
+ }
+ bool isValid() const { return getPointerOperand() != nullptr; }
+
+ // 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 getMatchingId() const {
+ if (IsTargetMemInst) return Info.MatchingId;
+ return -1;
+ }
+ Value *getPointerOperand() const {
+ if (IsTargetMemInst) return Info.PtrVal;
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ return LI->getPointerOperand();
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ return SI->getPointerOperand();
+ }
+ return nullptr;
+ }
+ bool mayReadFromMemory() const {
+ if (IsTargetMemInst) return Info.ReadMem;
+ return Inst->mayReadFromMemory();
+ }
+ bool mayWriteToMemory() const {
+ if (IsTargetMemInst) return Info.WriteMem;
+ return Inst->mayWriteToMemory();
+ }
+
+ private:
+ bool IsTargetMemInst;
+ MemIntrinsicInfo Info;
+ Instruction *Inst;
+ };
+
bool processNode(DomTreeNode *Node);
- // This transformation requires dominator postdominator info
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<DominatorTree>();
- AU.addRequired<TargetLibraryInfo>();
- 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);
}
};
}
-char EarlyCSE::ID = 0;
-
-// createEarlyCSEPass - The public interface to this file.
-FunctionPass *llvm::createEarlyCSEPass() {
- return new EarlyCSE();
-}
-
-INITIALIZE_PASS_BEGIN(EarlyCSE, "early-cse", "Early CSE", false, false)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
-INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
-INITIALIZE_PASS_END(EarlyCSE, "early-cse", "Early CSE", false, false)
-
bool EarlyCSE::processNode(DomTreeNode *Node) {
BasicBlock *BB = Node->getBlock();
// have invalidated the live-out memory values of our parent value. For now,
// just be conservative and invalidate memory if this block has multiple
// predecessors.
- if (BB->getSinglePredecessor() == 0)
+ 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
/// stores which can occur in bitfield code among other things.
- StoreInst *LastStore = 0;
+ 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++;
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
+ Instruction *Inst = &*I++;
// Dead instructions should just be removed.
- if (isInstructionTriviallyDead(Inst, TLI)) {
+ if (isInstructionTriviallyDead(Inst, &TLI)) {
DEBUG(dbgs() << "EarlyCSE DCE: " << *Inst << '\n');
Inst->eraseFromParent();
Changed = true;
continue;
}
+ // Skip assume intrinsics, they don't really have side effects (although
+ // they're marked as such to ensure preservation of control dependencies),
+ // and this pass will not disturb any of the assumption's control
+ // dependencies.
+ if (match(Inst, m_Intrinsic<Intrinsic::assume>())) {
+ DEBUG(dbgs() << "EarlyCSE skipping assumption: " << *Inst << '\n');
+ continue;
+ }
+
// If the instruction can be simplified (e.g. X+0 = X) then replace it with
// its simpler value.
- if (Value *V = SimplifyInstruction(Inst, TD, TLI, DT)) {
+ if (Value *V = SimplifyInstruction(Inst, DL, &TLI, &DT, &AC)) {
DEBUG(dbgs() << "EarlyCSE Simplify: " << *Inst << " to: " << *V << '\n');
Inst->replaceAllUsesWith(V);
Inst->eraseFromParent();
// If this is a simple instruction that we can value number, process it.
if (SimpleValue::canHandle(Inst)) {
// See if the instruction has an available value. If so, use it.
- if (Value *V = AvailableValues->lookup(Inst)) {
+ if (Value *V = AvailableValues.lookup(Inst)) {
DEBUG(dbgs() << "EarlyCSE CSE: " << *Inst << " to: " << *V << '\n');
Inst->replaceAllUsesWith(V);
Inst->eraseFromParent();
}
// Otherwise, just remember that this value is available.
- AvailableValues->insert(Inst, Inst);
+ AvailableValues.insert(Inst, Inst);
continue;
}
+ ParseMemoryInst MemInst(Inst, TTI);
// If this is a non-volatile load, process it.
- if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
- // Ignore volatile loads.
- if (!LI->isSimple()) {
- LastStore = 0;
- continue;
+ if (MemInst.isValid() && MemInst.isLoad()) {
+ // (conservatively) we can't peak past the ordering implied by this
+ // operation, but we can add this load to our set of available values
+ if (MemInst.isVolatile() || !MemInst.isUnordered()) {
+ LastStore = nullptr;
+ ++CurrentGeneration;
}
// 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));
- if (InVal.first != 0 && 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;
+ LoadValue InVal = AvailableLoads.lookup(MemInst.getPointerOperand());
+ if (InVal.Data != nullptr && InVal.Generation == CurrentGeneration &&
+ InVal.MatchingId == MemInst.getMatchingId() &&
+ // We don't yet handle removing loads with ordering of any kind.
+ !MemInst.isVolatile() && MemInst.isUnordered() &&
+ // We can't replace an atomic load with one which isn't also atomic.
+ InVal.IsAtomic >= MemInst.isAtomic()) {
+ Value *Op = getOrCreateResult(InVal.Data, Inst->getType());
+ if (Op != nullptr) {
+ DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst
+ << " to: " << *InVal.Data << '\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));
- LastStore = 0;
+ AvailableLoads.insert(
+ MemInst.getPointerOperand(),
+ LoadValue(Inst, CurrentGeneration, MemInst.getMatchingId(),
+ MemInst.isAtomic()));
+ LastStore = nullptr;
continue;
}
// If this instruction may read from memory, forget LastStore.
- if (Inst->mayReadFromMemory())
- LastStore = 0;
+ // 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 (CallValue::canHandle(Inst)) {
// If we have an available version of this call, and if it is the right
// generation, replace this instruction.
- std::pair<Value*, unsigned> InVal = AvailableCalls->lookup(Inst);
- if (InVal.first != 0 && InVal.second == CurrentGeneration) {
- DEBUG(dbgs() << "EarlyCSE CSE CALL: " << *Inst << " to: "
- << *InVal.first << '\n');
- if (!Inst->use_empty()) Inst->replaceAllUsesWith(InVal.first);
+ std::pair<Value *, unsigned> InVal = AvailableCalls.lookup(Inst);
+ if (InVal.first != nullptr && InVal.second == CurrentGeneration) {
+ DEBUG(dbgs() << "EarlyCSE CSE CALL: " << *Inst
+ << " to: " << *InVal.first << '\n');
+ if (!Inst->use_empty())
+ Inst->replaceAllUsesWith(InVal.first);
Inst->eraseFromParent();
Changed = true;
++NumCSECall;
}
// Otherwise, remember that we have this instruction.
- AvailableCalls->insert(Inst,
- std::pair<Value*, unsigned>(Inst, CurrentGeneration));
+ AvailableCalls.insert(
+ Inst, std::pair<Value *, unsigned>(Inst, CurrentGeneration));
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;
+ }
+
+ // write back DSE - If we write back the same value we just loaded from
+ // the same location and haven't passed any intervening writes or ordering
+ // operations, we can remove the write. The primary benefit is in allowing
+ // the available load table to remain valid and value forward past where
+ // the store originally was.
+ if (MemInst.isValid() && MemInst.isStore()) {
+ LoadValue InVal = AvailableLoads.lookup(MemInst.getPointerOperand());
+ if (InVal.Data &&
+ InVal.Data == getOrCreateResult(Inst, InVal.Data->getType()) &&
+ InVal.Generation == CurrentGeneration &&
+ InVal.MatchingId == MemInst.getMatchingId() &&
+ // We don't yet handle removing stores with ordering of any kind.
+ !MemInst.isVolatile() && MemInst.isUnordered()) {
+ assert((!LastStore ||
+ ParseMemoryInst(LastStore, TTI).getPointerOperand() ==
+ MemInst.getPointerOperand()) &&
+ "can't have an intervening store!");
+ DEBUG(dbgs() << "EarlyCSE DSE (writeback): " << *Inst << '\n');
+ Inst->eraseFromParent();
+ Changed = true;
+ ++NumDSE;
+ // We can avoid incrementing the generation count since we were able
+ // to eliminate this store.
+ 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.
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 = 0;
- continue;
+ // At the moment, we don't remove ordered stores, but do remove
+ // unordered atomic stores. There's no special requirement (for
+ // unordered atomics) about removing atomic stores only in favor of
+ // other atomic stores since we we're going to execute the non-atomic
+ // one anyway and the atomic one might never have become visible.
+ if (LastStore) {
+ ParseMemoryInst LastStoreMemInst(LastStore, TTI);
+ assert(LastStoreMemInst.isUnordered() &&
+ !LastStoreMemInst.isVolatile() &&
+ "Violated invariant");
+ 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
}
// Okay, we just invalidated anything we knew about loaded values. Try
// 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));
-
- // Remember that this was the last store we saw for DSE.
- if (SI->isSimple())
- LastStore = SI;
+ AvailableLoads.insert(
+ MemInst.getPointerOperand(),
+ LoadValue(Inst, CurrentGeneration, MemInst.getMatchingId(),
+ MemInst.isAtomic()));
+
+ // Remember that this was the last unordered store we saw for DSE. We
+ // don't yet handle DSE on ordered or volatile stores since we don't
+ // have a good way to model the ordering requirement for following
+ // passes once the store is removed. We could insert a fence, but
+ // since fences are slightly stronger than stores in their ordering,
+ // it's not clear this is a profitable transform. Another option would
+ // be to merge the ordering with that of the post dominating store.
+ if (MemInst.isUnordered() && !MemInst.isVolatile())
+ LastStore = Inst;
+ else
+ LastStore = nullptr;
}
}
}
return Changed;
}
-
-bool EarlyCSE::runOnFunction(Function &F) {
+bool EarlyCSE::run() {
+ // Note, deque is being used here because there is significant performance
+ // 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.llvm.org/pipermail/llvm-commits/Week-of-Mon-20120116/135228.html
std::deque<StackNode *> nodesToProcess;
- TD = getAnalysisIfAvailable<DataLayout>();
- TLI = &getAnalysis<TargetLibraryInfo>();
- DT = &getAnalysis<DominatorTree>();
-
- // Tables that the pass uses when walking the domtree.
- ScopedHTType AVTable;
- AvailableValues = &AVTable;
- LoadHTType LoadTable;
- AvailableLoads = &LoadTable;
- CallHTType CallTable;
- AvailableCalls = &CallTable;
-
- CurrentGeneration = 0;
bool Changed = false;
// Process the root node.
- nodesToProcess.push_front(
- new StackNode(AvailableValues, AvailableLoads, AvailableCalls,
- CurrentGeneration, DT->getRootNode(),
- DT->getRootNode()->begin(),
- DT->getRootNode()->end()));
+ nodesToProcess.push_back(new StackNode(
+ AvailableValues, AvailableLoads, AvailableCalls, CurrentGeneration,
+ DT.getRootNode(), DT.getRootNode()->begin(), DT.getRootNode()->end()));
// Save the current generation.
unsigned LiveOutGeneration = CurrentGeneration;
while (!nodesToProcess.empty()) {
// Grab the first item off the stack. Set the current generation, remove
// the node from the stack, and process it.
- StackNode *NodeToProcess = nodesToProcess.front();
+ StackNode *NodeToProcess = nodesToProcess.back();
// Initialize class members.
CurrentGeneration = NodeToProcess->currentGeneration();
} else if (NodeToProcess->childIter() != NodeToProcess->end()) {
// Push the next child onto the stack.
DomTreeNode *child = NodeToProcess->nextChild();
- nodesToProcess.push_front(
- new StackNode(AvailableValues,
- AvailableLoads,
- AvailableCalls,
- NodeToProcess->childGeneration(), child,
- child->begin(), child->end()));
+ nodesToProcess.push_back(
+ new StackNode(AvailableValues, AvailableLoads, AvailableCalls,
+ NodeToProcess->childGeneration(), child, child->begin(),
+ child->end()));
} else {
// It has been processed, and there are no more children to process,
// so delete it and pop it off the stack.
delete NodeToProcess;
- nodesToProcess.pop_front();
+ nodesToProcess.pop_back();
}
} // while (!nodes...)
return Changed;
}
+
+PreservedAnalyses EarlyCSEPass::run(Function &F,
+ AnalysisManager<Function> *AM) {
+ 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(TLI, TTI, DT, AC);
+
+ if (!CSE.run())
+ return PreservedAnalyses::all();
+
+ // CSE preserves the dominator tree because it doesn't mutate the CFG.
+ // FIXME: Bundle this with other CFG-preservation.
+ PreservedAnalyses PA;
+ PA.preserve<DominatorTreeAnalysis>();
+ return PA;
+}
+
+namespace {
+/// \brief A simple and fast domtree-based CSE pass.
+///
+/// This pass does a simple depth-first walk over the dominator tree,
+/// eliminating trivially redundant instructions and using instsimplify to
+/// canonicalize things as it goes. It is intended to be fast and catch obvious
+/// cases so that instcombine and other passes are more effective. It is
+/// expected that a later pass of GVN will catch the interesting/hard cases.
+class EarlyCSELegacyPass : public FunctionPass {
+public:
+ static char ID;
+
+ EarlyCSELegacyPass() : FunctionPass(ID) {
+ initializeEarlyCSELegacyPassPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnFunction(Function &F) override {
+ if (skipOptnoneFunction(F))
+ return false;
+
+ auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
+ auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+
+ EarlyCSE CSE(TLI, TTI, DT, AC);
+
+ return CSE.run();
+ }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<AssumptionCacheTracker>();
+ AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+ AU.addRequired<TargetTransformInfoWrapperPass>();
+ AU.addPreserved<GlobalsAAWrapperPass>();
+ AU.setPreservesCFG();
+ }
+};
+}
+
+char EarlyCSELegacyPass::ID = 0;
+
+FunctionPass *llvm::createEarlyCSEPass() { return new EarlyCSELegacyPass(); }
+
+INITIALIZE_PASS_BEGIN(EarlyCSELegacyPass, "early-cse", "Early CSE", false,
+ false)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_END(EarlyCSELegacyPass, "early-cse", "Early CSE", false, false)
projects / oota-llvm.git / blobdiff