#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.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/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/Local.h"
-#include <list>
+#include <algorithm>
using namespace llvm;
#define DEBUG_TYPE "memcpyopt"
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 DataLayout &DL) {
Ptr1 = Ptr1->stripPointerCasts();
}
-/// 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
// 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
unsigned NumPointerStores = Bytes / MaxIntSize;
// Assume the remaining bytes if any are done a byte at a time.
- unsigned NumByteStores = Bytes - NumPointerStores * MaxIntSize;
+ unsigned NumByteStores = Bytes % 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;
+ /// A sorted list of the memset ranges.
+ SmallVector<MemsetRange, 8> Ranges;
+ typedef SmallVectorImpl<MemsetRange>::iterator range_iterator;
const DataLayout &DL;
public:
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(); }
} // 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)
AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<MemoryDependenceAnalysis>();
- AU.addRequired<AliasAnalysis>();
+ AU.addRequired<AAResultsWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
- AU.addPreserved<AliasAnalysis>();
+ 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);
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",
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(MemoryDependenceAnalysis)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
-INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+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) {
const DataLayout &DL = StartInst->getModule()->getDataLayout();
// are stored.
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
// 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 = nullptr;
- for (MemsetRanges::const_iterator I = Ranges.begin(), E = Ranges.end();
- I != E; ++I) {
- const MemsetRange &Range = *I;
+ for (const MemsetRange &Range : Ranges) {
if (Range.TheStores.size() == 1) continue;
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 (SmallVectorImpl<Instruction *>::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;
}
return AMemSet;
}
+static unsigned findCommonAlignment(const DataLayout &DL, const StoreInst *SI,
+ const LoadInst *LI) {
+ unsigned StoreAlign = SI->getAlignment();
+ if (!StoreAlign)
+ StoreAlign = DL.getABITypeAlignment(SI->getOperand(0)->getType());
+ unsigned LoadAlign = LI->getAlignment();
+ if (!LoadAlign)
+ LoadAlign = DL.getABITypeAlignment(LI->getType());
+
+ return std::min(StoreAlign, LoadAlign);
+}
bool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) {
if (!SI->isSimple()) 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
- // a memcpy.
+ // Load to store forwarding can be interpreted as memcpy.
if (LoadInst *LI = dyn_cast<LoadInst>(SI->getOperand(0))) {
if (LI->isSimple() && LI->hasOneUse() &&
LI->getParent() == SI->getParent()) {
+
+ auto *T = LI->getType();
+ if (T->isAggregateType()) {
+ AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
+ MemoryLocation LoadLoc = MemoryLocation::get(LI);
+
+ // We use alias analysis to check if an instruction may store to
+ // the memory we load from in between the load and the store. If
+ // such an instruction is found, we try to promote there instead
+ // of at the store position.
+ Instruction *P = SI;
+ for (BasicBlock::iterator I = ++LI->getIterator(), E = SI->getIterator();
+ I != E; ++I) {
+ if (!(AA.getModRefInfo(&*I, LoadLoc) & MRI_Mod))
+ continue;
+
+ // We found an instruction that may write to the loaded memory.
+ // We can try to promote at this position instead of the store
+ // position if nothing alias the store memory after this.
+ P = &*I;
+ for (; I != E; ++I) {
+ MemoryLocation StoreLoc = MemoryLocation::get(SI);
+ if (AA.getModRefInfo(&*I, StoreLoc) != MRI_NoModRef) {
+ P = nullptr;
+ break;
+ }
+ }
+
+ break;
+ }
+
+ // If a valid insertion position is found, then we can promote
+ // the load/store pair to a memcpy.
+ if (P) {
+ // If we load from memory that may alias the memory we store to,
+ // memmove must be used to preserve semantic. If not, memcpy can
+ // be used.
+ bool UseMemMove = false;
+ if (!AA.isNoAlias(MemoryLocation::get(SI), LoadLoc))
+ UseMemMove = true;
+
+ unsigned Align = findCommonAlignment(DL, SI, LI);
+ uint64_t Size = DL.getTypeStoreSize(T);
+
+ IRBuilder<> Builder(P);
+ Instruction *M;
+ if (UseMemMove)
+ M = Builder.CreateMemMove(SI->getPointerOperand(),
+ LI->getPointerOperand(), Size,
+ Align, SI->isVolatile());
+ else
+ M = Builder.CreateMemCpy(SI->getPointerOperand(),
+ LI->getPointerOperand(), Size,
+ Align, SI->isVolatile());
+
+ DEBUG(dbgs() << "Promoting " << *LI << " to " << *SI
+ << " => " << *M << "\n");
+
+ MD->removeInstruction(SI);
+ SI->eraseFromParent();
+ MD->removeInstruction(LI);
+ LI->eraseFromParent();
+ ++NumMemCpyInstr;
+
+ // Make sure we do not invalidate the iterator.
+ BBI = M->getIterator();
+ return true;
+ }
+ }
+
+ // Detect cases where we're performing call slot forwarding, but
+ // happen to be using a load-store pair to implement it, rather than
+ // a memcpy.
MemDepResult ldep = MD->getDependency(LI);
CallInst *C = nullptr;
if (ldep.isClobber() && !isa<MemCpyInst>(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 = MemoryLocation::get(SI);
- for (BasicBlock::iterator I = --BasicBlock::iterator(SI),
- E = C; I != E; --I) {
- if (AA.getModRefInfo(&*I, StoreLoc) != AliasAnalysis::NoModRef) {
+ 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) {
- 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);
+ findCommonAlignment(DL, SI, LI), 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,
// 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.
// 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,
- };
+ unsigned KnownIDs[] = {LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
+ LLVMContext::MD_noalias,
+ LLVMContext::MD_invariant_group};
combineMetadata(C, cpy, KnownIDs);
// Remove the memcpy.
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.
-///
+/// 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 (!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(
- MemoryLocation::getForSource(MDep), false, M, M->getParent());
+ MemDepResult SourceDep =
+ MD->getPointerDependencyFrom(MemoryLocation::getForSource(MDep), false,
+ M->getIterator(), M->getParent());
if (!SourceDep.isClobber() || SourceDep.getInst() != MDep)
return false;
return false;
// Check that there are no other dependencies on the memset destination.
- MemDepResult DstDepInfo = MD->getPointerDependencyFrom(
- MemoryLocation::getForDest(MemSet), false, MemCpy, MemCpy->getParent());
+ MemDepResult DstDepInfo =
+ MD->getPointerDependencyFrom(MemoryLocation::getForDest(MemSet), false,
+ MemCpy->getIterator(), MemCpy->getParent());
if (DstDepInfo.getInst() != MemSet)
return false;
return true;
}
-/// processMemCpy - perform simplification of memcpy's. If we have memcpy A
+/// 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
}
}
- AliasAnalysis::Location SrcLoc = MemoryLocation::getForSource(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 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;
DEBUG(dbgs() << "MemCpyOpt: Optimizing memmove -> memcpy: " << *M << "\n");
// If not, then we know we can transform this.
- Module *Mod = M->getParent()->getParent()->getParent();
Type *ArgTys[3] = { M->getRawDest()->getType(),
M->getRawSource()->getType(),
M->getLength()->getType() };
- M->setCalledFunction(Intrinsic::getDeclaration(Mod, Intrinsic::memcpy,
- ArgTys));
+ M->setCalledFunction(Intrinsic::getDeclaration(M->getModule(),
+ Intrinsic::memcpy, ArgTys));
// MemDep may have over conservative information about this instruction, just
// conservatively flush it from the cache.
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) {
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 = DL.getTypeAllocSize(ByValTy);
- MemDepResult DepInfo =
- MD->getPointerDependencyFrom(AliasAnalysis::Location(ByValArg, ByValSize),
- true, CS.getInstruction(),
- CS.getInstruction()->getParent());
+ MemDepResult DepInfo = MD->getPointerDependencyFrom(
+ MemoryLocation(ByValArg, ByValSize), true,
+ CS.getInstruction()->getIterator(), CS.getInstruction()->getParent());
if (!DepInfo.isClobber())
return false;
//
// NOTE: This is conservative, it will stop on any read from the source loc,
// not just the defining memcpy.
- MemDepResult SourceDep =
- MD->getPointerDependencyFrom(MemoryLocation::getForSource(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;
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;
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