//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "memcpyopt"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/IRBuilder.h"
-#include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/GetElementPtrTypeIterator.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Transforms/Utils/Local.h"
-#include <list>
+#include <algorithm>
using namespace llvm;
+#define DEBUG_TYPE "memcpyopt"
+
STATISTIC(NumMemCpyInstr, "Number of memcpy instructions deleted");
STATISTIC(NumMemSetInfer, "Number of memsets inferred");
STATISTIC(NumMoveToCpy, "Number of memmoves converted to memcpy");
STATISTIC(NumCpyToSet, "Number of memcpys converted to memset");
static int64_t GetOffsetFromIndex(const GEPOperator *GEP, unsigned Idx,
- bool &VariableIdxFound, const TargetData &TD){
+ bool &VariableIdxFound,
+ const DataLayout &DL) {
// Skip over the first indices.
gep_type_iterator GTI = gep_type_begin(GEP);
for (unsigned i = 1; i != Idx; ++i, ++GTI)
int64_t Offset = 0;
for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i));
- if (OpC == 0)
+ if (!OpC)
return VariableIdxFound = true;
if (OpC->isZero()) continue; // No offset.
// Handle struct indices, which add their field offset to the pointer.
if (StructType *STy = dyn_cast<StructType>(*GTI)) {
- Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
+ Offset += DL.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
continue;
}
// Otherwise, we have a sequential type like an array or vector. Multiply
// the index by the ElementSize.
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+ uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
Offset += Size*OpC->getSExtValue();
}
return Offset;
}
-/// IsPointerOffset - Return true if Ptr1 is provably equal to Ptr2 plus a
-/// constant offset, and return that constant offset. For example, Ptr1 might
-/// be &A[42], and Ptr2 might be &A[40]. In this case offset would be -8.
+/// Return true if Ptr1 is provably equal to Ptr2 plus a constant offset, and
+/// return that constant offset. For example, Ptr1 might be &A[42], and Ptr2
+/// might be &A[40]. In this case offset would be -8.
static bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset,
- const TargetData &TD) {
+ const DataLayout &DL) {
Ptr1 = Ptr1->stripPointerCasts();
Ptr2 = Ptr2->stripPointerCasts();
+
+ // Handle the trivial case first.
+ if (Ptr1 == Ptr2) {
+ Offset = 0;
+ return true;
+ }
+
GEPOperator *GEP1 = dyn_cast<GEPOperator>(Ptr1);
GEPOperator *GEP2 = dyn_cast<GEPOperator>(Ptr2);
// If one pointer is a GEP and the other isn't, then see if the GEP is a
// constant offset from the base, as in "P" and "gep P, 1".
- if (GEP1 && GEP2 == 0 && GEP1->getOperand(0)->stripPointerCasts() == Ptr2) {
- Offset = -GetOffsetFromIndex(GEP1, 1, VariableIdxFound, TD);
+ if (GEP1 && !GEP2 && GEP1->getOperand(0)->stripPointerCasts() == Ptr2) {
+ Offset = -GetOffsetFromIndex(GEP1, 1, VariableIdxFound, DL);
return !VariableIdxFound;
}
- if (GEP2 && GEP1 == 0 && GEP2->getOperand(0)->stripPointerCasts() == Ptr1) {
- Offset = GetOffsetFromIndex(GEP2, 1, VariableIdxFound, TD);
+ if (GEP2 && !GEP1 && GEP2->getOperand(0)->stripPointerCasts() == Ptr1) {
+ Offset = GetOffsetFromIndex(GEP2, 1, VariableIdxFound, DL);
return !VariableIdxFound;
}
if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx))
break;
- int64_t Offset1 = GetOffsetFromIndex(GEP1, Idx, VariableIdxFound, TD);
- int64_t Offset2 = GetOffsetFromIndex(GEP2, Idx, VariableIdxFound, TD);
+ int64_t Offset1 = GetOffsetFromIndex(GEP1, Idx, VariableIdxFound, DL);
+ int64_t Offset2 = GetOffsetFromIndex(GEP2, Idx, VariableIdxFound, DL);
if (VariableIdxFound) return false;
Offset = Offset2-Offset1;
}
-/// MemsetRange - Represents a range of memset'd bytes with the ByteVal value.
+/// Represents a range of memset'd bytes with the ByteVal value.
/// This allows us to analyze stores like:
/// store 0 -> P+1
/// store 0 -> P+0
/// TheStores - The actual stores that make up this range.
SmallVector<Instruction*, 16> TheStores;
- bool isProfitableToUseMemset(const TargetData &TD) const;
-
+ bool isProfitableToUseMemset(const DataLayout &DL) const;
};
} // end anon namespace
-bool MemsetRange::isProfitableToUseMemset(const TargetData &TD) const {
+bool MemsetRange::isProfitableToUseMemset(const DataLayout &DL) const {
// If we found more than 4 stores to merge or 16 bytes, use memset.
if (TheStores.size() >= 4 || End-Start >= 16) return true;
// If any of the stores are a memset, then it is always good to extend the
// memset.
- for (unsigned i = 0, e = TheStores.size(); i != e; ++i)
- if (!isa<StoreInst>(TheStores[i]))
+ for (Instruction *SI : TheStores)
+ if (!isa<StoreInst>(SI))
return true;
// Assume that the code generator is capable of merging pairs of stores
// pessimize the llvm optimizer.
//
// Since we don't have perfect knowledge here, make some assumptions: assume
- // the maximum GPR width is the same size as the pointer size and assume that
- // this width can be stored. If so, check to see whether we will end up
- // actually reducing the number of stores used.
+ // the maximum GPR width is the same size as the largest legal integer
+ // size. If so, check to see whether we will end up actually reducing the
+ // number of stores used.
unsigned Bytes = unsigned(End-Start);
- unsigned NumPointerStores = Bytes/TD.getPointerSize();
+ unsigned MaxIntSize = DL.getLargestLegalIntTypeSize();
+ if (MaxIntSize == 0)
+ MaxIntSize = 1;
+ unsigned NumPointerStores = Bytes / MaxIntSize;
// Assume the remaining bytes if any are done a byte at a time.
- unsigned NumByteStores = Bytes - NumPointerStores*TD.getPointerSize();
+ unsigned NumByteStores = Bytes - NumPointerStores * MaxIntSize;
// If we will reduce the # stores (according to this heuristic), do the
// transformation. This encourages merging 4 x i8 -> i32 and 2 x i16 -> i32
namespace {
class MemsetRanges {
- /// Ranges - A sorted list of the memset ranges. We use std::list here
- /// because each element is relatively large and expensive to copy.
- std::list<MemsetRange> Ranges;
- typedef std::list<MemsetRange>::iterator range_iterator;
- const TargetData &TD;
+ /// A sorted list of the memset ranges.
+ SmallVector<MemsetRange, 8> Ranges;
+ typedef SmallVectorImpl<MemsetRange>::iterator range_iterator;
+ const DataLayout &DL;
public:
- MemsetRanges(const TargetData &td) : TD(td) {}
+ MemsetRanges(const DataLayout &DL) : DL(DL) {}
- typedef std::list<MemsetRange>::const_iterator const_iterator;
+ typedef SmallVectorImpl<MemsetRange>::const_iterator const_iterator;
const_iterator begin() const { return Ranges.begin(); }
const_iterator end() const { return Ranges.end(); }
bool empty() const { return Ranges.empty(); }
}
void addStore(int64_t OffsetFromFirst, StoreInst *SI) {
- int64_t StoreSize = TD.getTypeStoreSize(SI->getOperand(0)->getType());
+ int64_t StoreSize = DL.getTypeStoreSize(SI->getOperand(0)->getType());
addRange(OffsetFromFirst, StoreSize,
SI->getPointerOperand(), SI->getAlignment(), SI);
} // end anon namespace
-/// addRange - Add a new store to the MemsetRanges data structure. This adds a
+/// Add a new store to the MemsetRanges data structure. This adds a
/// new range for the specified store at the specified offset, merging into
/// existing ranges as appropriate.
-///
-/// Do a linear search of the ranges to see if this can be joined and/or to
-/// find the insertion point in the list. We keep the ranges sorted for
-/// simplicity here. This is a linear search of a linked list, which is ugly,
-/// however the number of ranges is limited, so this won't get crazy slow.
void MemsetRanges::addRange(int64_t Start, int64_t Size, Value *Ptr,
unsigned Alignment, Instruction *Inst) {
int64_t End = Start+Size;
- range_iterator I = Ranges.begin(), E = Ranges.end();
- while (I != E && Start > I->End)
- ++I;
+ range_iterator I = std::lower_bound(Ranges.begin(), Ranges.end(), Start,
+ [](const MemsetRange &LHS, int64_t RHS) { return LHS.End < RHS; });
// We now know that I == E, in which case we didn't find anything to merge
// with, or that Start <= I->End. If End < I->Start or I == E, then we need
// to insert a new range. Handle this now.
- if (I == E || End < I->Start) {
+ if (I == Ranges.end() || End < I->Start) {
MemsetRange &R = *Ranges.insert(I, MemsetRange());
R.Start = Start;
R.End = End;
if (End > I->End) {
I->End = End;
range_iterator NextI = I;
- while (++NextI != E && End >= NextI->Start) {
+ while (++NextI != Ranges.end() && End >= NextI->Start) {
// Merge the range in.
I->TheStores.append(NextI->TheStores.begin(), NextI->TheStores.end());
if (NextI->End > I->End)
class MemCpyOpt : public FunctionPass {
MemoryDependenceAnalysis *MD;
TargetLibraryInfo *TLI;
- const TargetData *TD;
public:
static char ID; // Pass identification, replacement for typeid
MemCpyOpt() : FunctionPass(ID) {
initializeMemCpyOptPass(*PassRegistry::getPassRegistry());
- MD = 0;
- TLI = 0;
- TD = 0;
+ MD = nullptr;
+ TLI = nullptr;
}
- bool runOnFunction(Function &F);
+ bool runOnFunction(Function &F) override;
private:
// This transformation requires dominator postdominator info
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
- AU.addRequired<DominatorTree>();
+ AU.addRequired<AssumptionCacheTracker>();
+ AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<MemoryDependenceAnalysis>();
- AU.addRequired<AliasAnalysis>();
- AU.addRequired<TargetLibraryInfo>();
- AU.addPreserved<AliasAnalysis>();
+ AU.addRequired<AAResultsWrapperPass>();
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+ AU.addPreserved<GlobalsAAWrapperPass>();
AU.addPreserved<MemoryDependenceAnalysis>();
}
- // Helper fuctions
+ // Helper functions
bool processStore(StoreInst *SI, BasicBlock::iterator &BBI);
bool processMemSet(MemSetInst *SI, BasicBlock::iterator &BBI);
bool processMemCpy(MemCpyInst *M);
bool processMemMove(MemMoveInst *M);
bool performCallSlotOptzn(Instruction *cpy, Value *cpyDst, Value *cpySrc,
- uint64_t cpyLen, CallInst *C);
- bool processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep,
- uint64_t MSize);
+ uint64_t cpyLen, unsigned cpyAlign, CallInst *C);
+ bool processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep);
+ bool processMemSetMemCpyDependence(MemCpyInst *M, MemSetInst *MDep);
+ bool performMemCpyToMemSetOptzn(MemCpyInst *M, MemSetInst *MDep);
bool processByValArgument(CallSite CS, unsigned ArgNo);
Instruction *tryMergingIntoMemset(Instruction *I, Value *StartPtr,
Value *ByteVal);
char MemCpyOpt::ID = 0;
}
-// createMemCpyOptPass - The public interface to this file...
+/// The public interface to this file...
FunctionPass *llvm::createMemCpyOptPass() { return new MemCpyOpt(); }
INITIALIZE_PASS_BEGIN(MemCpyOpt, "memcpyopt", "MemCpy Optimization",
false, false)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(MemoryDependenceAnalysis)
-INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
-INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
INITIALIZE_PASS_END(MemCpyOpt, "memcpyopt", "MemCpy Optimization",
false, false)
-/// tryMergingIntoMemset - When scanning forward over instructions, we look for
-/// some other patterns to fold away. In particular, this looks for stores to
-/// neighboring locations of memory. If it sees enough consecutive ones, it
-/// attempts to merge them together into a memcpy/memset.
+/// When scanning forward over instructions, we look for some other patterns to
+/// fold away. In particular, this looks for stores to neighboring locations of
+/// memory. If it sees enough consecutive ones, it attempts to merge them
+/// together into a memcpy/memset.
Instruction *MemCpyOpt::tryMergingIntoMemset(Instruction *StartInst,
Value *StartPtr, Value *ByteVal) {
- if (TD == 0) return 0;
+ const DataLayout &DL = StartInst->getModule()->getDataLayout();
// Okay, so we now have a single store that can be splatable. Scan to find
// all subsequent stores of the same value to offset from the same pointer.
// Join these together into ranges, so we can decide whether contiguous blocks
// are stored.
- MemsetRanges Ranges(*TD);
+ MemsetRanges Ranges(DL);
- BasicBlock::iterator BI = StartInst;
+ BasicBlock::iterator BI(StartInst);
for (++BI; !isa<TerminatorInst>(BI); ++BI) {
if (!isa<StoreInst>(BI) && !isa<MemSetInst>(BI)) {
// If the instruction is readnone, ignore it, otherwise bail out. We
// Check to see if this store is to a constant offset from the start ptr.
int64_t Offset;
- if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(),
- Offset, *TD))
+ if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset,
+ DL))
break;
Ranges.addStore(Offset, NextStore);
// Check to see if this store is to a constant offset from the start ptr.
int64_t Offset;
- if (!IsPointerOffset(StartPtr, MSI->getDest(), Offset, *TD))
+ if (!IsPointerOffset(StartPtr, MSI->getDest(), Offset, DL))
break;
Ranges.addMemSet(Offset, MSI);
// If we have no ranges, then we just had a single store with nothing that
// could be merged in. This is a very common case of course.
if (Ranges.empty())
- return 0;
+ return nullptr;
// If we had at least one store that could be merged in, add the starting
// store as well. We try to avoid this unless there is at least something
// If we create any memsets, we put it right before the first instruction that
// isn't part of the memset block. This ensure that the memset is dominated
// by any addressing instruction needed by the start of the block.
- IRBuilder<> Builder(BI);
+ IRBuilder<> Builder(&*BI);
// Now that we have full information about ranges, loop over the ranges and
// emit memset's for anything big enough to be worthwhile.
- Instruction *AMemSet = 0;
- for (MemsetRanges::const_iterator I = Ranges.begin(), E = Ranges.end();
- I != E; ++I) {
- const MemsetRange &Range = *I;
+ Instruction *AMemSet = nullptr;
+ for (const MemsetRange &Range : Ranges) {
if (Range.TheStores.size() == 1) continue;
// If it is profitable to lower this range to memset, do so now.
- if (!Range.isProfitableToUseMemset(*TD))
+ if (!Range.isProfitableToUseMemset(DL))
continue;
// Otherwise, we do want to transform this! Create a new memset.
if (Alignment == 0) {
Type *EltType =
cast<PointerType>(StartPtr->getType())->getElementType();
- Alignment = TD->getABITypeAlignment(EltType);
+ Alignment = DL.getABITypeAlignment(EltType);
}
AMemSet =
Builder.CreateMemSet(StartPtr, ByteVal, Range.End-Range.Start, Alignment);
DEBUG(dbgs() << "Replace stores:\n";
- for (unsigned i = 0, e = Range.TheStores.size(); i != e; ++i)
- dbgs() << *Range.TheStores[i] << '\n';
+ for (Instruction *SI : Range.TheStores)
+ dbgs() << *SI << '\n';
dbgs() << "With: " << *AMemSet << '\n');
if (!Range.TheStores.empty())
AMemSet->setDebugLoc(Range.TheStores[0]->getDebugLoc());
// Zap all the stores.
- for (SmallVector<Instruction*, 16>::const_iterator
- SI = Range.TheStores.begin(),
- SE = Range.TheStores.end(); SI != SE; ++SI) {
- MD->removeInstruction(*SI);
- (*SI)->eraseFromParent();
+ for (Instruction *SI : Range.TheStores) {
+ MD->removeInstruction(SI);
+ SI->eraseFromParent();
}
++NumMemSetInfer;
}
bool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) {
if (!SI->isSimple()) return false;
- if (TD == 0) return false;
+ // Avoid merging nontemporal stores since the resulting
+ // memcpy/memset would not be able to preserve the nontemporal hint.
+ // In theory we could teach how to propagate the !nontemporal metadata to
+ // memset calls. However, that change would force the backend to
+ // conservatively expand !nontemporal memset calls back to sequences of
+ // store instructions (effectively undoing the merging).
+ if (SI->getMetadata(LLVMContext::MD_nontemporal))
+ return false;
+
+ const DataLayout &DL = SI->getModule()->getDataLayout();
// Detect cases where we're performing call slot forwarding, but
// happen to be using a load-store pair to implement it, rather than
if (LI->isSimple() && LI->hasOneUse() &&
LI->getParent() == SI->getParent()) {
MemDepResult ldep = MD->getDependency(LI);
- CallInst *C = 0;
+ CallInst *C = nullptr;
if (ldep.isClobber() && !isa<MemCpyInst>(ldep.getInst()))
C = dyn_cast<CallInst>(ldep.getInst());
if (C) {
// Check that nothing touches the dest of the "copy" between
// the call and the store.
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- AliasAnalysis::Location StoreLoc = AA.getLocation(SI);
- for (BasicBlock::iterator I = --BasicBlock::iterator(SI),
- E = C; I != E; --I) {
- if (AA.getModRefInfo(&*I, StoreLoc) != AliasAnalysis::NoModRef) {
- C = 0;
+ AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
+ MemoryLocation StoreLoc = MemoryLocation::get(SI);
+ for (BasicBlock::iterator I = --SI->getIterator(), E = C->getIterator();
+ I != E; --I) {
+ if (AA.getModRefInfo(&*I, StoreLoc) != MRI_NoModRef) {
+ C = nullptr;
break;
}
}
}
if (C) {
- bool changed = performCallSlotOptzn(LI,
- SI->getPointerOperand()->stripPointerCasts(),
- LI->getPointerOperand()->stripPointerCasts(),
- TD->getTypeStoreSize(SI->getOperand(0)->getType()), C);
+ unsigned storeAlign = SI->getAlignment();
+ if (!storeAlign)
+ storeAlign = DL.getABITypeAlignment(SI->getOperand(0)->getType());
+ unsigned loadAlign = LI->getAlignment();
+ if (!loadAlign)
+ loadAlign = DL.getABITypeAlignment(LI->getType());
+
+ bool changed = performCallSlotOptzn(
+ LI, SI->getPointerOperand()->stripPointerCasts(),
+ LI->getPointerOperand()->stripPointerCasts(),
+ DL.getTypeStoreSize(SI->getOperand(0)->getType()),
+ std::min(storeAlign, loadAlign), C);
if (changed) {
MD->removeInstruction(SI);
SI->eraseFromParent();
if (Value *ByteVal = isBytewiseValue(SI->getOperand(0)))
if (Instruction *I = tryMergingIntoMemset(SI, SI->getPointerOperand(),
ByteVal)) {
- BBI = I; // Don't invalidate iterator.
+ BBI = I->getIterator(); // Don't invalidate iterator.
return true;
}
if (isa<ConstantInt>(MSI->getLength()) && !MSI->isVolatile())
if (Instruction *I = tryMergingIntoMemset(MSI, MSI->getDest(),
MSI->getValue())) {
- BBI = I; // Don't invalidate iterator.
+ BBI = I->getIterator(); // Don't invalidate iterator.
return true;
}
return false;
}
-/// performCallSlotOptzn - takes a memcpy and a call that it depends on,
+/// Takes a memcpy and a call that it depends on,
/// and checks for the possibility of a call slot optimization by having
/// the call write its result directly into the destination of the memcpy.
bool MemCpyOpt::performCallSlotOptzn(Instruction *cpy,
Value *cpyDest, Value *cpySrc,
- uint64_t cpyLen, CallInst *C) {
+ uint64_t cpyLen, unsigned cpyAlign,
+ CallInst *C) {
// The general transformation to keep in mind is
//
// call @func(..., src, ...)
if (!srcAlloca)
return false;
- // Check that all of src is copied to dest.
- if (TD == 0) return false;
-
ConstantInt *srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize());
if (!srcArraySize)
return false;
- uint64_t srcSize = TD->getTypeAllocSize(srcAlloca->getAllocatedType()) *
- srcArraySize->getZExtValue();
+ const DataLayout &DL = cpy->getModule()->getDataLayout();
+ uint64_t srcSize = DL.getTypeAllocSize(srcAlloca->getAllocatedType()) *
+ srcArraySize->getZExtValue();
if (cpyLen < srcSize)
return false;
if (!destArraySize)
return false;
- uint64_t destSize = TD->getTypeAllocSize(A->getAllocatedType()) *
- destArraySize->getZExtValue();
+ uint64_t destSize = DL.getTypeAllocSize(A->getAllocatedType()) *
+ destArraySize->getZExtValue();
if (destSize < srcSize)
return false;
} else if (Argument *A = dyn_cast<Argument>(cpyDest)) {
- // If the destination is an sret parameter then only accesses that are
- // outside of the returned struct type can trap.
- if (!A->hasStructRetAttr())
- return false;
+ if (A->getDereferenceableBytes() < srcSize) {
+ // If the destination is an sret parameter then only accesses that are
+ // outside of the returned struct type can trap.
+ if (!A->hasStructRetAttr())
+ return false;
- Type *StructTy = cast<PointerType>(A->getType())->getElementType();
- uint64_t destSize = TD->getTypeAllocSize(StructTy);
+ Type *StructTy = cast<PointerType>(A->getType())->getElementType();
+ if (!StructTy->isSized()) {
+ // The call may never return and hence the copy-instruction may never
+ // be executed, and therefore it's not safe to say "the destination
+ // has at least <cpyLen> bytes, as implied by the copy-instruction",
+ return false;
+ }
- if (destSize < srcSize)
- return false;
+ uint64_t destSize = DL.getTypeAllocSize(StructTy);
+ if (destSize < srcSize)
+ return false;
+ }
} else {
return false;
}
+ // Check that dest points to memory that is at least as aligned as src.
+ unsigned srcAlign = srcAlloca->getAlignment();
+ if (!srcAlign)
+ srcAlign = DL.getABITypeAlignment(srcAlloca->getAllocatedType());
+ bool isDestSufficientlyAligned = srcAlign <= cpyAlign;
+ // If dest is not aligned enough and we can't increase its alignment then
+ // bail out.
+ if (!isDestSufficientlyAligned && !isa<AllocaInst>(cpyDest))
+ return false;
+
// Check that src is not accessed except via the call and the memcpy. This
// guarantees that it holds only undefined values when passed in (so the final
// memcpy can be dropped), that it is not read or written between the call and
// the memcpy, and that writing beyond the end of it is undefined.
- SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(),
- srcAlloca->use_end());
+ SmallVector<User*, 8> srcUseList(srcAlloca->user_begin(),
+ srcAlloca->user_end());
while (!srcUseList.empty()) {
- User *UI = srcUseList.pop_back_val();
-
- if (isa<BitCastInst>(UI)) {
- for (User::use_iterator I = UI->use_begin(), E = UI->use_end();
- I != E; ++I)
- srcUseList.push_back(*I);
- } else if (GetElementPtrInst *G = dyn_cast<GetElementPtrInst>(UI)) {
- if (G->hasAllZeroIndices())
- for (User::use_iterator I = UI->use_begin(), E = UI->use_end();
- I != E; ++I)
- srcUseList.push_back(*I);
- else
+ User *U = srcUseList.pop_back_val();
+
+ if (isa<BitCastInst>(U) || isa<AddrSpaceCastInst>(U)) {
+ for (User *UU : U->users())
+ srcUseList.push_back(UU);
+ continue;
+ }
+ if (GetElementPtrInst *G = dyn_cast<GetElementPtrInst>(U)) {
+ if (!G->hasAllZeroIndices())
return false;
- } else if (UI != C && UI != cpy) {
- return false;
+
+ for (User *UU : U->users())
+ srcUseList.push_back(UU);
+ continue;
}
+ if (const IntrinsicInst *IT = dyn_cast<IntrinsicInst>(U))
+ if (IT->getIntrinsicID() == Intrinsic::lifetime_start ||
+ IT->getIntrinsicID() == Intrinsic::lifetime_end)
+ continue;
+
+ if (U != C && U != cpy)
+ return false;
}
+ // Check that src isn't captured by the called function since the
+ // transformation can cause aliasing issues in that case.
+ for (unsigned i = 0, e = CS.arg_size(); i != e; ++i)
+ if (CS.getArgument(i) == cpySrc && !CS.doesNotCapture(i))
+ return false;
+
// Since we're changing the parameter to the callsite, we need to make sure
// that what would be the new parameter dominates the callsite.
- DominatorTree &DT = getAnalysis<DominatorTree>();
+ DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
if (Instruction *cpyDestInst = dyn_cast<Instruction>(cpyDest))
if (!DT.dominates(cpyDestInst, C))
return false;
// unexpected manner, for example via a global, which we deduce from
// the use analysis, we also need to know that it does not sneakily
// access dest. We rely on AA to figure this out for us.
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- AliasAnalysis::ModRefResult MR = AA.getModRefInfo(C, cpyDest, srcSize);
+ AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
+ ModRefInfo MR = AA.getModRefInfo(C, cpyDest, srcSize);
// If necessary, perform additional analysis.
- if (MR != AliasAnalysis::NoModRef)
+ if (MR != MRI_NoModRef)
MR = AA.callCapturesBefore(C, cpyDest, srcSize, &DT);
- if (MR != AliasAnalysis::NoModRef)
+ if (MR != MRI_NoModRef)
return false;
// All the checks have passed, so do the transformation.
bool changedArgument = false;
for (unsigned i = 0; i < CS.arg_size(); ++i)
if (CS.getArgument(i)->stripPointerCasts() == cpySrc) {
- if (cpySrc->getType() != cpyDest->getType())
- cpyDest = CastInst::CreatePointerCast(cpyDest, cpySrc->getType(),
- cpyDest->getName(), C);
+ Value *Dest = cpySrc->getType() == cpyDest->getType() ? cpyDest
+ : CastInst::CreatePointerCast(cpyDest, cpySrc->getType(),
+ cpyDest->getName(), C);
changedArgument = true;
- if (CS.getArgument(i)->getType() == cpyDest->getType())
- CS.setArgument(i, cpyDest);
+ if (CS.getArgument(i)->getType() == Dest->getType())
+ CS.setArgument(i, Dest);
else
- CS.setArgument(i, CastInst::CreatePointerCast(cpyDest,
- CS.getArgument(i)->getType(), cpyDest->getName(), C));
+ CS.setArgument(i, CastInst::CreatePointerCast(Dest,
+ CS.getArgument(i)->getType(), Dest->getName(), C));
}
if (!changedArgument)
return false;
+ // If the destination wasn't sufficiently aligned then increase its alignment.
+ if (!isDestSufficientlyAligned) {
+ assert(isa<AllocaInst>(cpyDest) && "Can only increase alloca alignment!");
+ cast<AllocaInst>(cpyDest)->setAlignment(srcAlign);
+ }
+
// Drop any cached information about the call, because we may have changed
// its dependence information by changing its parameter.
MD->removeInstruction(C);
+ // Update AA metadata
+ // FIXME: MD_tbaa_struct and MD_mem_parallel_loop_access should also be
+ // handled here, but combineMetadata doesn't support them yet
+ unsigned KnownIDs[] = {LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
+ LLVMContext::MD_noalias,
+ LLVMContext::MD_invariant_group};
+ combineMetadata(C, cpy, KnownIDs);
+
// Remove the memcpy.
MD->removeInstruction(cpy);
++NumMemCpyInstr;
return true;
}
-/// processMemCpyMemCpyDependence - We've found that the (upward scanning)
-/// memory dependence of memcpy 'M' is the memcpy 'MDep'. Try to simplify M to
-/// copy from MDep's input if we can. MSize is the size of M's copy.
-///
-bool MemCpyOpt::processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep,
- uint64_t MSize) {
+/// We've found that the (upward scanning) memory dependence of memcpy 'M' is
+/// the memcpy 'MDep'. Try to simplify M to copy from MDep's input if we can.
+bool MemCpyOpt::processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep) {
// We can only transforms memcpy's where the dest of one is the source of the
// other.
if (M->getSource() != MDep->getDest() || MDep->isVolatile())
if (!MDepLen || !MLen || MDepLen->getZExtValue() < MLen->getZExtValue())
return false;
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+ AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
// Verify that the copied-from memory doesn't change in between the two
// transfers. For example, in:
// NOTE: This is conservative, it will stop on any read from the source loc,
// not just the defining memcpy.
MemDepResult SourceDep =
- MD->getPointerDependencyFrom(AA.getLocationForSource(MDep),
- false, M, M->getParent());
+ MD->getPointerDependencyFrom(MemoryLocation::getForSource(MDep), false,
+ M->getIterator(), M->getParent());
if (!SourceDep.isClobber() || SourceDep.getInst() != MDep)
return false;
// source and dest might overlap. We still want to eliminate the intermediate
// value, but we have to generate a memmove instead of memcpy.
bool UseMemMove = false;
- if (!AA.isNoAlias(AA.getLocationForDest(M), AA.getLocationForSource(MDep)))
+ if (!AA.isNoAlias(MemoryLocation::getForDest(M),
+ MemoryLocation::getForSource(MDep)))
UseMemMove = true;
// If all checks passed, then we can transform M.
return true;
}
+/// We've found that the (upward scanning) memory dependence of \p MemCpy is
+/// \p MemSet. Try to simplify \p MemSet to only set the trailing bytes that
+/// weren't copied over by \p MemCpy.
+///
+/// In other words, transform:
+/// \code
+/// memset(dst, c, dst_size);
+/// memcpy(dst, src, src_size);
+/// \endcode
+/// into:
+/// \code
+/// memcpy(dst, src, src_size);
+/// memset(dst + src_size, c, dst_size <= src_size ? 0 : dst_size - src_size);
+/// \endcode
+bool MemCpyOpt::processMemSetMemCpyDependence(MemCpyInst *MemCpy,
+ MemSetInst *MemSet) {
+ // We can only transform memset/memcpy with the same destination.
+ if (MemSet->getDest() != MemCpy->getDest())
+ return false;
+
+ // Check that there are no other dependencies on the memset destination.
+ MemDepResult DstDepInfo =
+ MD->getPointerDependencyFrom(MemoryLocation::getForDest(MemSet), false,
+ MemCpy->getIterator(), MemCpy->getParent());
+ if (DstDepInfo.getInst() != MemSet)
+ return false;
-/// processMemCpy - perform simplification of memcpy's. If we have memcpy A
+ // Use the same i8* dest as the memcpy, killing the memset dest if different.
+ Value *Dest = MemCpy->getRawDest();
+ Value *DestSize = MemSet->getLength();
+ Value *SrcSize = MemCpy->getLength();
+
+ // By default, create an unaligned memset.
+ unsigned Align = 1;
+ // If Dest is aligned, and SrcSize is constant, use the minimum alignment
+ // of the sum.
+ const unsigned DestAlign =
+ std::max(MemSet->getAlignment(), MemCpy->getAlignment());
+ if (DestAlign > 1)
+ if (ConstantInt *SrcSizeC = dyn_cast<ConstantInt>(SrcSize))
+ Align = MinAlign(SrcSizeC->getZExtValue(), DestAlign);
+
+ IRBuilder<> Builder(MemCpy);
+
+ // If the sizes have different types, zext the smaller one.
+ if (DestSize->getType() != SrcSize->getType()) {
+ if (DestSize->getType()->getIntegerBitWidth() >
+ SrcSize->getType()->getIntegerBitWidth())
+ SrcSize = Builder.CreateZExt(SrcSize, DestSize->getType());
+ else
+ DestSize = Builder.CreateZExt(DestSize, SrcSize->getType());
+ }
+
+ Value *MemsetLen =
+ Builder.CreateSelect(Builder.CreateICmpULE(DestSize, SrcSize),
+ ConstantInt::getNullValue(DestSize->getType()),
+ Builder.CreateSub(DestSize, SrcSize));
+ Builder.CreateMemSet(Builder.CreateGEP(Dest, SrcSize), MemSet->getOperand(1),
+ MemsetLen, Align);
+
+ MD->removeInstruction(MemSet);
+ MemSet->eraseFromParent();
+ return true;
+}
+
+/// Transform memcpy to memset when its source was just memset.
+/// In other words, turn:
+/// \code
+/// memset(dst1, c, dst1_size);
+/// memcpy(dst2, dst1, dst2_size);
+/// \endcode
+/// into:
+/// \code
+/// memset(dst1, c, dst1_size);
+/// memset(dst2, c, dst2_size);
+/// \endcode
+/// When dst2_size <= dst1_size.
+///
+/// The \p MemCpy must have a Constant length.
+bool MemCpyOpt::performMemCpyToMemSetOptzn(MemCpyInst *MemCpy,
+ MemSetInst *MemSet) {
+ // This only makes sense on memcpy(..., memset(...), ...).
+ if (MemSet->getRawDest() != MemCpy->getRawSource())
+ return false;
+
+ ConstantInt *CopySize = cast<ConstantInt>(MemCpy->getLength());
+ ConstantInt *MemSetSize = dyn_cast<ConstantInt>(MemSet->getLength());
+ // Make sure the memcpy doesn't read any more than what the memset wrote.
+ // Don't worry about sizes larger than i64.
+ if (!MemSetSize || CopySize->getZExtValue() > MemSetSize->getZExtValue())
+ return false;
+
+ IRBuilder<> Builder(MemCpy);
+ Builder.CreateMemSet(MemCpy->getRawDest(), MemSet->getOperand(1),
+ CopySize, MemCpy->getAlignment());
+ return true;
+}
+
+/// Perform simplification of memcpy's. If we have memcpy A
/// which copies X to Y, and memcpy B which copies Y to Z, then we can rewrite
/// B to be a memcpy from X to Z (or potentially a memmove, depending on
/// circumstances). This allows later passes to remove the first memcpy
/// altogether.
bool MemCpyOpt::processMemCpy(MemCpyInst *M) {
- // We can only optimize statically-sized memcpy's that are non-volatile.
- ConstantInt *CopySize = dyn_cast<ConstantInt>(M->getLength());
- if (CopySize == 0 || M->isVolatile()) return false;
+ // We can only optimize non-volatile memcpy's.
+ if (M->isVolatile()) return false;
// If the source and destination of the memcpy are the same, then zap it.
if (M->getSource() == M->getDest()) {
if (GV->isConstant() && GV->hasDefinitiveInitializer())
if (Value *ByteVal = isBytewiseValue(GV->getInitializer())) {
IRBuilder<> Builder(M);
- Builder.CreateMemSet(M->getRawDest(), ByteVal, CopySize,
+ Builder.CreateMemSet(M->getRawDest(), ByteVal, M->getLength(),
M->getAlignment(), false);
MD->removeInstruction(M);
M->eraseFromParent();
return true;
}
- // The are two possible optimizations we can do for memcpy:
+ MemDepResult DepInfo = MD->getDependency(M);
+
+ // Try to turn a partially redundant memset + memcpy into
+ // memcpy + smaller memset. We don't need the memcpy size for this.
+ if (DepInfo.isClobber())
+ if (MemSetInst *MDep = dyn_cast<MemSetInst>(DepInfo.getInst()))
+ if (processMemSetMemCpyDependence(M, MDep))
+ return true;
+
+ // The optimizations after this point require the memcpy size.
+ ConstantInt *CopySize = dyn_cast<ConstantInt>(M->getLength());
+ if (!CopySize) return false;
+
+ // There are four possible optimizations we can do for memcpy:
// a) memcpy-memcpy xform which exposes redundance for DSE.
// b) call-memcpy xform for return slot optimization.
- MemDepResult DepInfo = MD->getDependency(M);
+ // c) memcpy from freshly alloca'd space or space that has just started its
+ // lifetime copies undefined data, and we can therefore eliminate the
+ // memcpy in favor of the data that was already at the destination.
+ // d) memcpy from a just-memset'd source can be turned into memset.
if (DepInfo.isClobber()) {
if (CallInst *C = dyn_cast<CallInst>(DepInfo.getInst())) {
if (performCallSlotOptzn(M, M->getDest(), M->getSource(),
- CopySize->getZExtValue(), C)) {
+ CopySize->getZExtValue(), M->getAlignment(),
+ C)) {
MD->removeInstruction(M);
M->eraseFromParent();
return true;
}
}
- AliasAnalysis::Location SrcLoc = AliasAnalysis::getLocationForSource(M);
- MemDepResult SrcDepInfo = MD->getPointerDependencyFrom(SrcLoc, true,
- M, M->getParent());
+ MemoryLocation SrcLoc = MemoryLocation::getForSource(M);
+ MemDepResult SrcDepInfo = MD->getPointerDependencyFrom(
+ SrcLoc, true, M->getIterator(), M->getParent());
+
if (SrcDepInfo.isClobber()) {
if (MemCpyInst *MDep = dyn_cast<MemCpyInst>(SrcDepInfo.getInst()))
- return processMemCpyMemCpyDependence(M, MDep, CopySize->getZExtValue());
+ return processMemCpyMemCpyDependence(M, MDep);
+ } else if (SrcDepInfo.isDef()) {
+ Instruction *I = SrcDepInfo.getInst();
+ bool hasUndefContents = false;
+
+ if (isa<AllocaInst>(I)) {
+ hasUndefContents = true;
+ } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+ if (II->getIntrinsicID() == Intrinsic::lifetime_start)
+ if (ConstantInt *LTSize = dyn_cast<ConstantInt>(II->getArgOperand(0)))
+ if (LTSize->getZExtValue() >= CopySize->getZExtValue())
+ hasUndefContents = true;
+ }
+
+ if (hasUndefContents) {
+ MD->removeInstruction(M);
+ M->eraseFromParent();
+ ++NumMemCpyInstr;
+ return true;
+ }
}
+ if (SrcDepInfo.isClobber())
+ if (MemSetInst *MDep = dyn_cast<MemSetInst>(SrcDepInfo.getInst()))
+ if (performMemCpyToMemSetOptzn(M, MDep)) {
+ MD->removeInstruction(M);
+ M->eraseFromParent();
+ ++NumCpyToSet;
+ return true;
+ }
+
return false;
}
-/// processMemMove - Transforms memmove calls to memcpy calls when the src/dst
-/// are guaranteed not to alias.
+/// Transforms memmove calls to memcpy calls when the src/dst are guaranteed
+/// not to alias.
bool MemCpyOpt::processMemMove(MemMoveInst *M) {
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+ AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
if (!TLI->has(LibFunc::memmove))
return false;
// See if the pointers alias.
- if (!AA.isNoAlias(AA.getLocationForDest(M), AA.getLocationForSource(M)))
+ if (!AA.isNoAlias(MemoryLocation::getForDest(M),
+ MemoryLocation::getForSource(M)))
return false;
DEBUG(dbgs() << "MemCpyOpt: Optimizing memmove -> memcpy: " << *M << "\n");
return true;
}
-/// processByValArgument - This is called on every byval argument in call sites.
+/// This is called on every byval argument in call sites.
bool MemCpyOpt::processByValArgument(CallSite CS, unsigned ArgNo) {
- if (TD == 0) return false;
-
+ const DataLayout &DL = CS.getCaller()->getParent()->getDataLayout();
// Find out what feeds this byval argument.
Value *ByValArg = CS.getArgument(ArgNo);
Type *ByValTy = cast<PointerType>(ByValArg->getType())->getElementType();
- uint64_t ByValSize = TD->getTypeAllocSize(ByValTy);
- MemDepResult DepInfo =
- MD->getPointerDependencyFrom(AliasAnalysis::Location(ByValArg, ByValSize),
- true, CS.getInstruction(),
- CS.getInstruction()->getParent());
+ uint64_t ByValSize = DL.getTypeAllocSize(ByValTy);
+ MemDepResult DepInfo = MD->getPointerDependencyFrom(
+ MemoryLocation(ByValArg, ByValSize), true,
+ CS.getInstruction()->getIterator(), CS.getInstruction()->getParent());
if (!DepInfo.isClobber())
return false;
// a memcpy, see if we can byval from the source of the memcpy instead of the
// result.
MemCpyInst *MDep = dyn_cast<MemCpyInst>(DepInfo.getInst());
- if (MDep == 0 || MDep->isVolatile() ||
+ if (!MDep || MDep->isVolatile() ||
ByValArg->stripPointerCasts() != MDep->getDest())
return false;
// The length of the memcpy must be larger or equal to the size of the byval.
ConstantInt *C1 = dyn_cast<ConstantInt>(MDep->getLength());
- if (C1 == 0 || C1->getValue().getZExtValue() < ByValSize)
+ if (!C1 || C1->getValue().getZExtValue() < ByValSize)
return false;
// Get the alignment of the byval. If the call doesn't specify the alignment,
// If it is greater than the memcpy, then we check to see if we can force the
// source of the memcpy to the alignment we need. If we fail, we bail out.
+ AssumptionCache &AC =
+ getAnalysis<AssumptionCacheTracker>().getAssumptionCache(
+ *CS->getParent()->getParent());
+ DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
if (MDep->getAlignment() < ByValAlign &&
- getOrEnforceKnownAlignment(MDep->getSource(),ByValAlign, TD) < ByValAlign)
+ getOrEnforceKnownAlignment(MDep->getSource(), ByValAlign, DL,
+ CS.getInstruction(), &AC, &DT) < ByValAlign)
return false;
// Verify that the copied-from memory doesn't change in between the memcpy and
//
// NOTE: This is conservative, it will stop on any read from the source loc,
// not just the defining memcpy.
- MemDepResult SourceDep =
- MD->getPointerDependencyFrom(AliasAnalysis::getLocationForSource(MDep),
- false, CS.getInstruction(), MDep->getParent());
+ MemDepResult SourceDep = MD->getPointerDependencyFrom(
+ MemoryLocation::getForSource(MDep), false,
+ CS.getInstruction()->getIterator(), MDep->getParent());
if (!SourceDep.isClobber() || SourceDep.getInst() != MDep)
return false;
return true;
}
-/// iterateOnFunction - Executes one iteration of MemCpyOpt.
+/// Executes one iteration of MemCpyOpt.
bool MemCpyOpt::iterateOnFunction(Function &F) {
bool MadeChange = false;
for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB) {
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
// Avoid invalidating the iterator.
- Instruction *I = BI++;
+ Instruction *I = &*BI++;
bool RepeatInstruction = false;
RepeatInstruction = processMemCpy(M);
else if (MemMoveInst *M = dyn_cast<MemMoveInst>(I))
RepeatInstruction = processMemMove(M);
- else if (CallSite CS = (Value*)I) {
+ else if (auto CS = CallSite(I)) {
for (unsigned i = 0, e = CS.arg_size(); i != e; ++i)
if (CS.isByValArgument(i))
MadeChange |= processByValArgument(CS, i);
return MadeChange;
}
-// MemCpyOpt::runOnFunction - This is the main transformation entry point for a
-// function.
-//
+/// This is the main transformation entry point for a function.
bool MemCpyOpt::runOnFunction(Function &F) {
+ if (skipOptnoneFunction(F))
+ return false;
+
bool MadeChange = false;
MD = &getAnalysis<MemoryDependenceAnalysis>();
- TD = getAnalysisIfAvailable<TargetData>();
- TLI = &getAnalysis<TargetLibraryInfo>();
+ TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
// If we don't have at least memset and memcpy, there is little point of doing
// anything here. These are required by a freestanding implementation, so if
MadeChange = true;
}
- MD = 0;
+ MD = nullptr;
return MadeChange;
}
projects / oota-llvm.git / blobdiff