//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "memdep"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/PHITransAddr.h"
+#include "llvm/Analysis/OrderedBasicBlock.h"
#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/PredIteratorCache.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/PredIteratorCache.h"
using namespace llvm;
+#define DEBUG_TYPE "memdep"
+
STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
"Number of block queries that were completely cached");
// Limit for the number of instructions to scan in a block.
-static const int BlockScanLimit = 100;
+
+static cl::opt<unsigned> BlockScanLimit(
+ "memdep-block-scan-limit", cl::Hidden, cl::init(100),
+ cl::desc("The number of instructions to scan in a block in memory "
+ "dependency analysis (default = 100)"));
+
+// Limit on the number of memdep results to process.
+static const unsigned int NumResultsLimit = 100;
char MemoryDependenceAnalysis::ID = 0;
// Register this pass...
INITIALIZE_PASS_BEGIN(MemoryDependenceAnalysis, "memdep",
"Memory Dependence Analysis", false, true)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_END(MemoryDependenceAnalysis, "memdep",
"Memory Dependence Analysis", false, true)
MemoryDependenceAnalysis::MemoryDependenceAnalysis()
-: FunctionPass(ID), PredCache(0) {
+ : FunctionPass(ID) {
initializeMemoryDependenceAnalysisPass(*PassRegistry::getPassRegistry());
}
MemoryDependenceAnalysis::~MemoryDependenceAnalysis() {
ReverseLocalDeps.clear();
ReverseNonLocalDeps.clear();
ReverseNonLocalPtrDeps.clear();
- PredCache->clear();
+ PredCache.clear();
}
-
-
/// getAnalysisUsage - Does not modify anything. It uses Alias Analysis.
///
void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
+ AU.addRequired<AssumptionCacheTracker>();
AU.addRequiredTransitive<AliasAnalysis>();
+ AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
}
-bool MemoryDependenceAnalysis::runOnFunction(Function &) {
+bool MemoryDependenceAnalysis::runOnFunction(Function &F) {
AA = &getAnalysis<AliasAnalysis>();
- TD = getAnalysisIfAvailable<DataLayout>();
- DT = getAnalysisIfAvailable<DominatorTree>();
- if (!PredCache)
- PredCache.reset(new PredIteratorCache());
+ AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+ DominatorTreeWrapperPass *DTWP =
+ getAnalysisIfAvailable<DominatorTreeWrapperPass>();
+ DT = DTWP ? &DTWP->getDomTree() : nullptr;
+ TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
return false;
}
/// location, fill in Loc with the details, otherwise set Loc.Ptr to null.
/// Return a ModRefInfo value describing the general behavior of the
/// instruction.
-static
-AliasAnalysis::ModRefResult GetLocation(const Instruction *Inst,
- AliasAnalysis::Location &Loc,
- AliasAnalysis *AA) {
+static ModRefInfo GetLocation(const Instruction *Inst, MemoryLocation &Loc,
+ const TargetLibraryInfo &TLI) {
if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
if (LI->isUnordered()) {
- Loc = AA->getLocation(LI);
- return AliasAnalysis::Ref;
+ Loc = MemoryLocation::get(LI);
+ return MRI_Ref;
}
if (LI->getOrdering() == Monotonic) {
- Loc = AA->getLocation(LI);
- return AliasAnalysis::ModRef;
+ Loc = MemoryLocation::get(LI);
+ return MRI_ModRef;
}
- Loc = AliasAnalysis::Location();
- return AliasAnalysis::ModRef;
+ Loc = MemoryLocation();
+ return MRI_ModRef;
}
if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
if (SI->isUnordered()) {
- Loc = AA->getLocation(SI);
- return AliasAnalysis::Mod;
+ Loc = MemoryLocation::get(SI);
+ return MRI_Mod;
}
if (SI->getOrdering() == Monotonic) {
- Loc = AA->getLocation(SI);
- return AliasAnalysis::ModRef;
+ Loc = MemoryLocation::get(SI);
+ return MRI_ModRef;
}
- Loc = AliasAnalysis::Location();
- return AliasAnalysis::ModRef;
+ Loc = MemoryLocation();
+ return MRI_ModRef;
}
if (const VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
- Loc = AA->getLocation(V);
- return AliasAnalysis::ModRef;
+ Loc = MemoryLocation::get(V);
+ return MRI_ModRef;
}
- if (const CallInst *CI = isFreeCall(Inst, AA->getTargetLibraryInfo())) {
+ if (const CallInst *CI = isFreeCall(Inst, &TLI)) {
// calls to free() deallocate the entire structure
- Loc = AliasAnalysis::Location(CI->getArgOperand(0));
- return AliasAnalysis::Mod;
+ Loc = MemoryLocation(CI->getArgOperand(0));
+ return MRI_Mod;
}
- if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
+ if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
+ AAMDNodes AAInfo;
+
switch (II->getIntrinsicID()) {
case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
case Intrinsic::invariant_start:
- Loc = AliasAnalysis::Location(II->getArgOperand(1),
- cast<ConstantInt>(II->getArgOperand(0))
- ->getZExtValue(),
- II->getMetadata(LLVMContext::MD_tbaa));
+ II->getAAMetadata(AAInfo);
+ Loc = MemoryLocation(
+ II->getArgOperand(1),
+ cast<ConstantInt>(II->getArgOperand(0))->getZExtValue(), AAInfo);
// These intrinsics don't really modify the memory, but returning Mod
// will allow them to be handled conservatively.
- return AliasAnalysis::Mod;
+ return MRI_Mod;
case Intrinsic::invariant_end:
- Loc = AliasAnalysis::Location(II->getArgOperand(2),
- cast<ConstantInt>(II->getArgOperand(1))
- ->getZExtValue(),
- II->getMetadata(LLVMContext::MD_tbaa));
+ II->getAAMetadata(AAInfo);
+ Loc = MemoryLocation(
+ II->getArgOperand(2),
+ cast<ConstantInt>(II->getArgOperand(1))->getZExtValue(), AAInfo);
// These intrinsics don't really modify the memory, but returning Mod
// will allow them to be handled conservatively.
- return AliasAnalysis::Mod;
+ return MRI_Mod;
default:
break;
}
+ }
// Otherwise, just do the coarse-grained thing that always works.
if (Inst->mayWriteToMemory())
- return AliasAnalysis::ModRef;
+ return MRI_ModRef;
if (Inst->mayReadFromMemory())
- return AliasAnalysis::Ref;
- return AliasAnalysis::NoModRef;
+ return MRI_Ref;
+ return MRI_NoModRef;
}
/// getCallSiteDependencyFrom - Private helper for finding the local
Instruction *Inst = --ScanIt;
// If this inst is a memory op, get the pointer it accessed
- AliasAnalysis::Location Loc;
- AliasAnalysis::ModRefResult MR = GetLocation(Inst, Loc, AA);
+ MemoryLocation Loc;
+ ModRefInfo MR = GetLocation(Inst, Loc, *TLI);
if (Loc.Ptr) {
// A simple instruction.
- if (AA->getModRefInfo(CS, Loc) != AliasAnalysis::NoModRef)
+ if (AA->getModRefInfo(CS, Loc) != MRI_NoModRef)
return MemDepResult::getClobber(Inst);
continue;
}
- if (CallSite InstCS = cast<Value>(Inst)) {
+ if (auto InstCS = CallSite(Inst)) {
// Debug intrinsics don't cause dependences.
if (isa<DbgInfoIntrinsic>(Inst)) continue;
// If these two calls do not interfere, look past it.
switch (AA->getModRefInfo(CS, InstCS)) {
- case AliasAnalysis::NoModRef:
+ case MRI_NoModRef:
// If the two calls are the same, return InstCS as a Def, so that
// CS can be found redundant and eliminated.
- if (isReadOnlyCall && !(MR & AliasAnalysis::Mod) &&
+ if (isReadOnlyCall && !(MR & MRI_Mod) &&
CS.getInstruction()->isIdenticalToWhenDefined(Inst))
return MemDepResult::getDef(Inst);
// If we could not obtain a pointer for the instruction and the instruction
// touches memory then assume that this is a dependency.
- if (MR != AliasAnalysis::NoModRef)
+ if (MR != MRI_NoModRef)
return MemDepResult::getClobber(Inst);
}
///
/// MemLocBase, MemLocOffset are lazily computed here the first time the
/// base/offs of memloc is needed.
-static bool
-isLoadLoadClobberIfExtendedToFullWidth(const AliasAnalysis::Location &MemLoc,
- const Value *&MemLocBase,
- int64_t &MemLocOffs,
- const LoadInst *LI,
- const DataLayout *TD) {
- // If we have no target data, we can't do this.
- if (TD == 0) return false;
+static bool isLoadLoadClobberIfExtendedToFullWidth(const MemoryLocation &MemLoc,
+ const Value *&MemLocBase,
+ int64_t &MemLocOffs,
+ const LoadInst *LI) {
+ const DataLayout &DL = LI->getModule()->getDataLayout();
// If we haven't already computed the base/offset of MemLoc, do so now.
- if (MemLocBase == 0)
- MemLocBase = GetPointerBaseWithConstantOffset(MemLoc.Ptr, MemLocOffs, TD);
+ if (!MemLocBase)
+ MemLocBase = GetPointerBaseWithConstantOffset(MemLoc.Ptr, MemLocOffs, DL);
- unsigned Size = MemoryDependenceAnalysis::
- getLoadLoadClobberFullWidthSize(MemLocBase, MemLocOffs, MemLoc.Size,
- LI, *TD);
+ unsigned Size = MemoryDependenceAnalysis::getLoadLoadClobberFullWidthSize(
+ MemLocBase, MemLocOffs, MemLoc.Size, LI);
return Size != 0;
}
/// 2) safe for the target, and 3) would provide the specified memory
/// location value, then this function returns the size in bytes of the
/// load width to use. If not, this returns zero.
-unsigned MemoryDependenceAnalysis::
-getLoadLoadClobberFullWidthSize(const Value *MemLocBase, int64_t MemLocOffs,
- unsigned MemLocSize, const LoadInst *LI,
- const DataLayout &TD) {
+unsigned MemoryDependenceAnalysis::getLoadLoadClobberFullWidthSize(
+ const Value *MemLocBase, int64_t MemLocOffs, unsigned MemLocSize,
+ const LoadInst *LI) {
// We can only extend simple integer loads.
if (!isa<IntegerType>(LI->getType()) || !LI->isSimple()) return 0;
// Load widening is hostile to ThreadSanitizer: it may cause false positives
// or make the reports more cryptic (access sizes are wrong).
- if (LI->getParent()->getParent()->getAttributes().
- hasAttribute(AttributeSet::FunctionIndex, Attribute::SanitizeThread))
+ if (LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeThread))
return 0;
+ const DataLayout &DL = LI->getModule()->getDataLayout();
+
// Get the base of this load.
int64_t LIOffs = 0;
const Value *LIBase =
- GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, &TD);
+ GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, DL);
// If the two pointers are not based on the same pointer, we can't tell that
// they are related.
// If this load size is bigger than our known alignment or would not fit
// into a native integer register, then we fail.
if (NewLoadByteSize > LoadAlign ||
- !TD.fitsInLegalInteger(NewLoadByteSize*8))
+ !DL.fitsInLegalInteger(NewLoadByteSize*8))
return 0;
- if (LIOffs+NewLoadByteSize > MemLocEnd &&
- LI->getParent()->getParent()->getAttributes().
- hasAttribute(AttributeSet::FunctionIndex, Attribute::SanitizeAddress))
+ if (LIOffs + NewLoadByteSize > MemLocEnd &&
+ LI->getParent()->getParent()->hasFnAttribute(
+ Attribute::SanitizeAddress))
// We will be reading past the location accessed by the original program.
// While this is safe in a regular build, Address Safety analysis tools
// may start reporting false warnings. So, don't do widening.
}
}
+static bool isVolatile(Instruction *Inst) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
+ return LI->isVolatile();
+ else if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
+ return SI->isVolatile();
+ else if (AtomicCmpXchgInst *AI = dyn_cast<AtomicCmpXchgInst>(Inst))
+ return AI->isVolatile();
+ return false;
+}
+
+
/// getPointerDependencyFrom - Return the instruction on which a memory
/// location depends. If isLoad is true, this routine ignores may-aliases with
/// read-only operations. If isLoad is false, this routine ignores may-aliases
/// with reads from read-only locations. If possible, pass the query
/// instruction as well; this function may take advantage of the metadata
/// annotated to the query instruction to refine the result.
-MemDepResult MemoryDependenceAnalysis::
-getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad,
- BasicBlock::iterator ScanIt, BasicBlock *BB,
- Instruction *QueryInst) {
+MemDepResult MemoryDependenceAnalysis::getPointerDependencyFrom(
+ const MemoryLocation &MemLoc, bool isLoad, BasicBlock::iterator ScanIt,
+ BasicBlock *BB, Instruction *QueryInst) {
- const Value *MemLocBase = 0;
+ const Value *MemLocBase = nullptr;
int64_t MemLocOffset = 0;
unsigned Limit = BlockScanLimit;
bool isInvariantLoad = false;
+
+ // We must be careful with atomic accesses, as they may allow another thread
+ // to touch this location, cloberring it. We are conservative: if the
+ // QueryInst is not a simple (non-atomic) memory access, we automatically
+ // return getClobber.
+ // If it is simple, we know based on the results of
+ // "Compiler testing via a theory of sound optimisations in the C11/C++11
+ // memory model" in PLDI 2013, that a non-atomic location can only be
+ // clobbered between a pair of a release and an acquire action, with no
+ // access to the location in between.
+ // Here is an example for giving the general intuition behind this rule.
+ // In the following code:
+ // store x 0;
+ // release action; [1]
+ // acquire action; [4]
+ // %val = load x;
+ // It is unsafe to replace %val by 0 because another thread may be running:
+ // acquire action; [2]
+ // store x 42;
+ // release action; [3]
+ // with synchronization from 1 to 2 and from 3 to 4, resulting in %val
+ // being 42. A key property of this program however is that if either
+ // 1 or 4 were missing, there would be a race between the store of 42
+ // either the store of 0 or the load (making the whole progam racy).
+ // The paper mentionned above shows that the same property is respected
+ // by every program that can detect any optimisation of that kind: either
+ // it is racy (undefined) or there is a release followed by an acquire
+ // between the pair of accesses under consideration.
+
+ // If the load is invariant, we "know" that it doesn't alias *any* write. We
+ // do want to respect mustalias results since defs are useful for value
+ // forwarding, but any mayalias write can be assumed to be noalias.
+ // Arguably, this logic should be pushed inside AliasAnalysis itself.
if (isLoad && QueryInst) {
LoadInst *LI = dyn_cast<LoadInst>(QueryInst);
- if (LI && LI->getMetadata(LLVMContext::MD_invariant_load) != 0)
+ if (LI && LI->getMetadata(LLVMContext::MD_invariant_load) != nullptr)
isInvariantLoad = true;
}
+ const DataLayout &DL = BB->getModule()->getDataLayout();
+
+ // Create a numbered basic block to lazily compute and cache instruction
+ // positions inside a BB. This is used to provide fast queries for relative
+ // position between two instructions in a BB and can be used by
+ // AliasAnalysis::callCapturesBefore.
+ OrderedBasicBlock OBB(BB);
+
// Walk backwards through the basic block, looking for dependencies.
while (ScanIt != BB->begin()) {
Instruction *Inst = --ScanIt;
// pointer, not on query pointers that are indexed off of them. It'd
// be nice to handle that at some point (the right approach is to use
// GetPointerBaseWithConstantOffset).
- if (AA->isMustAlias(AliasAnalysis::Location(II->getArgOperand(1)),
- MemLoc))
+ if (AA->isMustAlias(MemoryLocation(II->getArgOperand(1)), MemLoc))
return MemDepResult::getDef(II);
continue;
}
// Values depend on loads if the pointers are must aliased. This means that
// a load depends on another must aliased load from the same value.
+ // One exception is atomic loads: a value can depend on an atomic load that it
+ // does not alias with when this atomic load indicates that another thread may
+ // be accessing the location.
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+
+ // While volatile access cannot be eliminated, they do not have to clobber
+ // non-aliasing locations, as normal accesses, for example, can be safely
+ // reordered with volatile accesses.
+ if (LI->isVolatile()) {
+ if (!QueryInst)
+ // Original QueryInst *may* be volatile
+ return MemDepResult::getClobber(LI);
+ if (isVolatile(QueryInst))
+ // Ordering required if QueryInst is itself volatile
+ return MemDepResult::getClobber(LI);
+ // Otherwise, volatile doesn't imply any special ordering
+ }
+
// Atomic loads have complications involved.
+ // A Monotonic (or higher) load is OK if the query inst is itself not atomic.
// FIXME: This is overly conservative.
- if (!LI->isUnordered())
- return MemDepResult::getClobber(LI);
+ if (LI->isAtomic() && LI->getOrdering() > Unordered) {
+ if (!QueryInst)
+ return MemDepResult::getClobber(LI);
+ if (LI->getOrdering() != Monotonic)
+ return MemDepResult::getClobber(LI);
+ if (auto *QueryLI = dyn_cast<LoadInst>(QueryInst)) {
+ if (!QueryLI->isSimple())
+ return MemDepResult::getClobber(LI);
+ } else if (auto *QuerySI = dyn_cast<StoreInst>(QueryInst)) {
+ if (!QuerySI->isSimple())
+ return MemDepResult::getClobber(LI);
+ } else if (QueryInst->mayReadOrWriteMemory()) {
+ return MemDepResult::getClobber(LI);
+ }
+ }
- AliasAnalysis::Location LoadLoc = AA->getLocation(LI);
+ MemoryLocation LoadLoc = MemoryLocation::get(LI);
// If we found a pointer, check if it could be the same as our pointer.
- AliasAnalysis::AliasResult R = AA->alias(LoadLoc, MemLoc);
+ AliasResult R = AA->alias(LoadLoc, MemLoc);
if (isLoad) {
- if (R == AliasAnalysis::NoAlias) {
+ if (R == NoAlias) {
// If this is an over-aligned integer load (for example,
// "load i8* %P, align 4") see if it would obviously overlap with the
// queried location if widened to a larger load (e.g. if the queried
// location is 1 byte at P+1). If so, return it as a load/load
// clobber result, allowing the client to decide to widen the load if
// it wants to.
- if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType()))
- if (LI->getAlignment()*8 > ITy->getPrimitiveSizeInBits() &&
+ if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType())) {
+ if (LI->getAlignment() * 8 > ITy->getPrimitiveSizeInBits() &&
isLoadLoadClobberIfExtendedToFullWidth(MemLoc, MemLocBase,
- MemLocOffset, LI, TD))
+ MemLocOffset, LI))
return MemDepResult::getClobber(Inst);
-
+ }
continue;
}
// Must aliased loads are defs of each other.
- if (R == AliasAnalysis::MustAlias)
+ if (R == MustAlias)
return MemDepResult::getDef(Inst);
#if 0 // FIXME: Temporarily disabled. GVN is cleverly rewriting loads
// If we have a partial alias, then return this as a clobber for the
// client to handle.
- if (R == AliasAnalysis::PartialAlias)
+ if (R == PartialAlias)
return MemDepResult::getClobber(Inst);
#endif
}
// Stores don't depend on other no-aliased accesses.
- if (R == AliasAnalysis::NoAlias)
+ if (R == NoAlias)
continue;
// Stores don't alias loads from read-only memory.
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
// Atomic stores have complications involved.
+ // A Monotonic store is OK if the query inst is itself not atomic.
// FIXME: This is overly conservative.
- if (!SI->isUnordered())
+ if (!SI->isUnordered()) {
+ if (!QueryInst)
+ return MemDepResult::getClobber(SI);
+ if (SI->getOrdering() != Monotonic)
+ return MemDepResult::getClobber(SI);
+ if (auto *QueryLI = dyn_cast<LoadInst>(QueryInst)) {
+ if (!QueryLI->isSimple())
+ return MemDepResult::getClobber(SI);
+ } else if (auto *QuerySI = dyn_cast<StoreInst>(QueryInst)) {
+ if (!QuerySI->isSimple())
+ return MemDepResult::getClobber(SI);
+ } else if (QueryInst->mayReadOrWriteMemory()) {
+ return MemDepResult::getClobber(SI);
+ }
+ }
+
+ // FIXME: this is overly conservative.
+ // While volatile access cannot be eliminated, they do not have to clobber
+ // non-aliasing locations, as normal accesses can for example be reordered
+ // with volatile accesses.
+ if (SI->isVolatile())
return MemDepResult::getClobber(SI);
// If alias analysis can tell that this store is guaranteed to not modify
// the query pointer, ignore it. Use getModRefInfo to handle cases where
// the query pointer points to constant memory etc.
- if (AA->getModRefInfo(SI, MemLoc) == AliasAnalysis::NoModRef)
+ if (AA->getModRefInfo(SI, MemLoc) == MRI_NoModRef)
continue;
// Ok, this store might clobber the query pointer. Check to see if it is
// a must alias: in this case, we want to return this as a def.
- AliasAnalysis::Location StoreLoc = AA->getLocation(SI);
+ MemoryLocation StoreLoc = MemoryLocation::get(SI);
// If we found a pointer, check if it could be the same as our pointer.
- AliasAnalysis::AliasResult R = AA->alias(StoreLoc, MemLoc);
+ AliasResult R = AA->alias(StoreLoc, MemLoc);
- if (R == AliasAnalysis::NoAlias)
+ if (R == NoAlias)
continue;
- if (R == AliasAnalysis::MustAlias)
+ if (R == MustAlias)
return MemDepResult::getDef(Inst);
if (isInvariantLoad)
continue;
// a subsequent bitcast of the malloc call result. There can be stores to
// the malloced memory between the malloc call and its bitcast uses, and we
// need to continue scanning until the malloc call.
- const TargetLibraryInfo *TLI = AA->getTargetLibraryInfo();
if (isa<AllocaInst>(Inst) || isNoAliasFn(Inst, TLI)) {
- const Value *AccessPtr = GetUnderlyingObject(MemLoc.Ptr, TD);
+ const Value *AccessPtr = GetUnderlyingObject(MemLoc.Ptr, DL);
if (AccessPtr == Inst || AA->isMustAlias(Inst, AccessPtr))
return MemDepResult::getDef(Inst);
+ if (isInvariantLoad)
+ continue;
// Be conservative if the accessed pointer may alias the allocation.
- if (AA->alias(Inst, AccessPtr) != AliasAnalysis::NoAlias)
+ if (AA->alias(Inst, AccessPtr) != NoAlias)
return MemDepResult::getClobber(Inst);
// If the allocation is not aliased and does not read memory (like
// strdup), it is safe to ignore.
continue;
}
+ if (isInvariantLoad)
+ continue;
+
// See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
- AliasAnalysis::ModRefResult MR = AA->getModRefInfo(Inst, MemLoc);
+ ModRefInfo MR = AA->getModRefInfo(Inst, MemLoc);
// If necessary, perform additional analysis.
- if (MR == AliasAnalysis::ModRef)
- MR = AA->callCapturesBefore(Inst, MemLoc, DT);
+ if (MR == MRI_ModRef)
+ MR = AA->callCapturesBefore(Inst, MemLoc, DT, &OBB);
switch (MR) {
- case AliasAnalysis::NoModRef:
+ case MRI_NoModRef:
// If the call has no effect on the queried pointer, just ignore it.
continue;
- case AliasAnalysis::Mod:
+ case MRI_Mod:
return MemDepResult::getClobber(Inst);
- case AliasAnalysis::Ref:
+ case MRI_Ref:
// If the call is known to never store to the pointer, and if this is a
// load query, we can safely ignore it (scan past it).
if (isLoad)
else
LocalCache = MemDepResult::getNonFuncLocal();
} else {
- AliasAnalysis::Location MemLoc;
- AliasAnalysis::ModRefResult MR = GetLocation(QueryInst, MemLoc, AA);
+ MemoryLocation MemLoc;
+ ModRefInfo MR = GetLocation(QueryInst, MemLoc, *TLI);
if (MemLoc.Ptr) {
// If we can do a pointer scan, make it happen.
- bool isLoad = !(MR & AliasAnalysis::Mod);
+ bool isLoad = !(MR & MRI_Mod);
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(QueryInst))
isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_start;
} else {
// Seed DirtyBlocks with each of the preds of QueryInst's block.
BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
- for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
- DirtyBlocks.push_back(*PI);
+ for (BasicBlock *Pred : PredCache.get(QueryBB))
+ DirtyBlocks.push_back(Pred);
++NumUncacheNonLocal;
}
DirtyBlocks.pop_back();
// Already processed this block?
- if (!Visited.insert(DirtyBB))
+ if (!Visited.insert(DirtyBB).second)
continue;
// Do a binary search to see if we already have an entry for this block in
NonLocalDepInfo::iterator Entry =
std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
NonLocalDepEntry(DirtyBB));
- if (Entry != Cache.begin() && prior(Entry)->getBB() == DirtyBB)
+ if (Entry != Cache.begin() && std::prev(Entry)->getBB() == DirtyBB)
--Entry;
- NonLocalDepEntry *ExistingResult = 0;
+ NonLocalDepEntry *ExistingResult = nullptr;
if (Entry != Cache.begin()+NumSortedEntries &&
Entry->getBB() == DirtyBB) {
// If we already have an entry, and if it isn't already dirty, the block
// If the block *is* completely transparent to the load, we need to check
// the predecessors of this block. Add them to our worklist.
- for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
- DirtyBlocks.push_back(*PI);
+ for (BasicBlock *Pred : PredCache.get(DirtyBB))
+ DirtyBlocks.push_back(Pred);
}
}
/// own block.
///
void MemoryDependenceAnalysis::
-getNonLocalPointerDependency(const AliasAnalysis::Location &Loc, bool isLoad,
- BasicBlock *FromBB,
+getNonLocalPointerDependency(Instruction *QueryInst,
SmallVectorImpl<NonLocalDepResult> &Result) {
+ const MemoryLocation Loc = MemoryLocation::get(QueryInst);
+ bool isLoad = isa<LoadInst>(QueryInst);
+ BasicBlock *FromBB = QueryInst->getParent();
+ assert(FromBB);
+
assert(Loc.Ptr->getType()->isPointerTy() &&
"Can't get pointer deps of a non-pointer!");
Result.clear();
-
- PHITransAddr Address(const_cast<Value *>(Loc.Ptr), TD);
+
+ // This routine does not expect to deal with volatile instructions.
+ // Doing so would require piping through the QueryInst all the way through.
+ // TODO: volatiles can't be elided, but they can be reordered with other
+ // non-volatile accesses.
+
+ // We currently give up on any instruction which is ordered, but we do handle
+ // atomic instructions which are unordered.
+ // TODO: Handle ordered instructions
+ auto isOrdered = [](Instruction *Inst) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ return !LI->isUnordered();
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ return !SI->isUnordered();
+ }
+ return false;
+ };
+ if (isVolatile(QueryInst) || isOrdered(QueryInst)) {
+ Result.push_back(NonLocalDepResult(FromBB,
+ MemDepResult::getUnknown(),
+ const_cast<Value *>(Loc.Ptr)));
+ return;
+ }
+ const DataLayout &DL = FromBB->getModule()->getDataLayout();
+ PHITransAddr Address(const_cast<Value *>(Loc.Ptr), DL, AC);
// This is the set of blocks we've inspected, and the pointer we consider in
// each block. Because of critical edges, we currently bail out if querying
// a block with multiple different pointers. This can happen during PHI
// translation.
DenseMap<BasicBlock*, Value*> Visited;
- if (!getNonLocalPointerDepFromBB(Address, Loc, isLoad, FromBB,
+ if (!getNonLocalPointerDepFromBB(QueryInst, Address, Loc, isLoad, FromBB,
Result, Visited, true))
return;
Result.clear();
/// Pointer/PointeeSize using either cached information in Cache or by doing a
/// lookup (which may use dirty cache info if available). If we do a lookup,
/// add the result to the cache.
-MemDepResult MemoryDependenceAnalysis::
-GetNonLocalInfoForBlock(const AliasAnalysis::Location &Loc,
- bool isLoad, BasicBlock *BB,
- NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
+MemDepResult MemoryDependenceAnalysis::GetNonLocalInfoForBlock(
+ Instruction *QueryInst, const MemoryLocation &Loc, bool isLoad,
+ BasicBlock *BB, NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
// Do a binary search to see if we already have an entry for this block in
// the cache set. If so, find it.
if (Entry != Cache->begin() && (Entry-1)->getBB() == BB)
--Entry;
- NonLocalDepEntry *ExistingResult = 0;
+ NonLocalDepEntry *ExistingResult = nullptr;
if (Entry != Cache->begin()+NumSortedEntries && Entry->getBB() == BB)
ExistingResult = &*Entry;
}
// Scan the block for the dependency.
- MemDepResult Dep = getPointerDependencyFrom(Loc, isLoad, ScanPos, BB);
+ MemDepResult Dep = getPointerDependencyFrom(Loc, isLoad, ScanPos, BB,
+ QueryInst);
// If we had a dirty entry for the block, update it. Otherwise, just add
// a new entry.
return Dep;
}
-/// SortNonLocalDepInfoCache - Sort the a NonLocalDepInfo cache, given a certain
+/// SortNonLocalDepInfoCache - Sort the NonLocalDepInfo cache, given a certain
/// number of elements in the array that are already properly ordered. This is
/// optimized for the case when only a few entries are added.
static void
/// This function returns false on success, or true to indicate that it could
/// not compute dependence information for some reason. This should be treated
/// as a clobber dependence on the first instruction in the predecessor block.
-bool MemoryDependenceAnalysis::
-getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
- const AliasAnalysis::Location &Loc,
- bool isLoad, BasicBlock *StartBB,
- SmallVectorImpl<NonLocalDepResult> &Result,
- DenseMap<BasicBlock*, Value*> &Visited,
- bool SkipFirstBlock) {
+bool MemoryDependenceAnalysis::getNonLocalPointerDepFromBB(
+ Instruction *QueryInst, const PHITransAddr &Pointer,
+ const MemoryLocation &Loc, bool isLoad, BasicBlock *StartBB,
+ SmallVectorImpl<NonLocalDepResult> &Result,
+ DenseMap<BasicBlock *, Value *> &Visited, bool SkipFirstBlock) {
// Look up the cached info for Pointer.
ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad);
// Set up a temporary NLPI value. If the map doesn't yet have an entry for
// CacheKey, this value will be inserted as the associated value. Otherwise,
// it'll be ignored, and we'll have to check to see if the cached size and
- // tbaa tag are consistent with the current query.
+ // aa tags are consistent with the current query.
NonLocalPointerInfo InitialNLPI;
InitialNLPI.Size = Loc.Size;
- InitialNLPI.TBAATag = Loc.TBAATag;
+ InitialNLPI.AATags = Loc.AATags;
// Get the NLPI for CacheKey, inserting one into the map if it doesn't
// already have one.
} else if (CacheInfo->Size > Loc.Size) {
// This query's Size is less than the cached one. Conservatively restart
// the query using the greater size.
- return getNonLocalPointerDepFromBB(Pointer,
+ return getNonLocalPointerDepFromBB(QueryInst, Pointer,
Loc.getWithNewSize(CacheInfo->Size),
isLoad, StartBB, Result, Visited,
SkipFirstBlock);
}
- // If the query's TBAATag is inconsistent with the cached one,
+ // If the query's AATags are inconsistent with the cached one,
// conservatively throw out the cached data and restart the query with
// no tag if needed.
- if (CacheInfo->TBAATag != Loc.TBAATag) {
- if (CacheInfo->TBAATag) {
+ if (CacheInfo->AATags != Loc.AATags) {
+ if (CacheInfo->AATags) {
CacheInfo->Pair = BBSkipFirstBlockPair();
- CacheInfo->TBAATag = 0;
+ CacheInfo->AATags = AAMDNodes();
for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(),
DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI)
if (Instruction *Inst = DI->getResult().getInst())
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
CacheInfo->NonLocalDeps.clear();
}
- if (Loc.TBAATag)
- return getNonLocalPointerDepFromBB(Pointer, Loc.getWithoutTBAATag(),
+ if (Loc.AATags)
+ return getNonLocalPointerDepFromBB(QueryInst,
+ Pointer, Loc.getWithoutAATags(),
isLoad, StartBB, Result, Visited,
SkipFirstBlock);
}
while (!Worklist.empty()) {
BasicBlock *BB = Worklist.pop_back_val();
+ // If we do process a large number of blocks it becomes very expensive and
+ // likely it isn't worth worrying about
+ if (Result.size() > NumResultsLimit) {
+ Worklist.clear();
+ // Sort it now (if needed) so that recursive invocations of
+ // getNonLocalPointerDepFromBB and other routines that could reuse the
+ // cache value will only see properly sorted cache arrays.
+ if (Cache && NumSortedEntries != Cache->size()) {
+ SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
+ }
+ // Since we bail out, the "Cache" set won't contain all of the
+ // results for the query. This is ok (we can still use it to accelerate
+ // specific block queries) but we can't do the fastpath "return all
+ // results from the set". Clear out the indicator for this.
+ CacheInfo->Pair = BBSkipFirstBlockPair();
+ return true;
+ }
+
// Skip the first block if we have it.
if (!SkipFirstBlock) {
// Analyze the dependency of *Pointer in FromBB. See if we already have
// Get the dependency info for Pointer in BB. If we have cached
// information, we will use it, otherwise we compute it.
DEBUG(AssertSorted(*Cache, NumSortedEntries));
- MemDepResult Dep = GetNonLocalInfoForBlock(Loc, isLoad, BB, Cache,
+ MemDepResult Dep = GetNonLocalInfoForBlock(QueryInst,
+ Loc, isLoad, BB, Cache,
NumSortedEntries);
// If we got a Def or Clobber, add this to the list of results.
if (!Pointer.NeedsPHITranslationFromBlock(BB)) {
SkipFirstBlock = false;
SmallVector<BasicBlock*, 16> NewBlocks;
- for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
+ for (BasicBlock *Pred : PredCache.get(BB)) {
// Verify that we haven't looked at this block yet.
std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
- InsertRes = Visited.insert(std::make_pair(*PI, Pointer.getAddr()));
+ InsertRes = Visited.insert(std::make_pair(Pred, Pointer.getAddr()));
if (InsertRes.second) {
// First time we've looked at *PI.
- NewBlocks.push_back(*PI);
+ NewBlocks.push_back(Pred);
continue;
}
SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
NumSortedEntries = Cache->size();
}
- Cache = 0;
+ Cache = nullptr;
PredList.clear();
- for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
- BasicBlock *Pred = *PI;
+ for (BasicBlock *Pred : PredCache.get(BB)) {
PredList.push_back(std::make_pair(Pred, Pointer));
// Get the PHI translated pointer in this predecessor. This can fail if
// not translatable, in which case the getAddr() returns null.
PHITransAddr &PredPointer = PredList.back().second;
- PredPointer.PHITranslateValue(BB, Pred, 0);
-
+ PredPointer.PHITranslateValue(BB, Pred, DT, /*MustDominate=*/false);
Value *PredPtrVal = PredPointer.getAddr();
// Check to see if we have already visited this pred block with another
// predecessor, then we have to assume that the pointer is clobbered in
// that predecessor. We can still do PRE of the load, which would insert
// a computation of the pointer in this predecessor.
- if (PredPtrVal == 0)
+ if (!PredPtrVal)
CanTranslate = false;
// FIXME: it is entirely possible that PHI translating will end up with
// result conflicted with the Visited list; we have to conservatively
// assume it is unknown, but this also does not block PRE of the load.
if (!CanTranslate ||
- getNonLocalPointerDepFromBB(PredPointer,
+ getNonLocalPointerDepFromBB(QueryInst, PredPointer,
Loc.getWithNewPtr(PredPtrVal),
isLoad, Pred,
Result, Visited)) {
// for the given block. It assumes that we haven't modified any of
// our datastructures while processing the current block.
- if (Cache == 0) {
+ if (!Cache) {
// Refresh the CacheInfo/Cache pointer if it got invalidated.
CacheInfo = &NonLocalPointerDeps[CacheKey];
Cache = &CacheInfo->NonLocalDeps;
if (I->getBB() != BB)
continue;
- assert(I->getResult().isNonLocal() &&
+ assert((I->getResult().isNonLocal() || !DT->isReachableFromEntry(BB)) &&
"Should only be here with transparent block");
I->setResult(MemDepResult::getUnknown());
Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(),
for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
Instruction *Target = PInfo[i].getResult().getInst();
- if (Target == 0) continue; // Ignore non-local dep results.
+ if (!Target) continue; // Ignore non-local dep results.
assert(Target->getParent() == PInfo[i].getBB());
// Eliminating the dirty entry from 'Cache', so update the reverse info.
/// This needs to be done when the CFG changes, e.g., due to splitting
/// critical edges.
void MemoryDependenceAnalysis::invalidateCachedPredecessors() {
- PredCache->clear();
+ PredCache.clear();
}
/// removeInstruction - Remove an instruction from the dependence analysis,
ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
if (ReverseDepIt != ReverseLocalDeps.end()) {
- SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
// RemInst can't be the terminator if it has local stuff depending on it.
- assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
+ assert(!ReverseDepIt->second.empty() && !isa<TerminatorInst>(RemInst) &&
"Nothing can locally depend on a terminator");
- for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
- E = ReverseDeps.end(); I != E; ++I) {
- Instruction *InstDependingOnRemInst = *I;
+ for (Instruction *InstDependingOnRemInst : ReverseDepIt->second) {
assert(InstDependingOnRemInst != RemInst &&
"Already removed our local dep info");
ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
if (ReverseDepIt != ReverseNonLocalDeps.end()) {
- SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
- for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
- I != E; ++I) {
- assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
+ for (Instruction *I : ReverseDepIt->second) {
+ assert(I != RemInst && "Already removed NonLocalDep info for RemInst");
- PerInstNLInfo &INLD = NonLocalDeps[*I];
+ PerInstNLInfo &INLD = NonLocalDeps[I];
// The information is now dirty!
INLD.second = true;
DI->setResult(NewDirtyVal);
if (Instruction *NextI = NewDirtyVal.getInst())
- ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
+ ReverseDepsToAdd.push_back(std::make_pair(NextI, I));
}
}
ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
ReverseNonLocalPtrDeps.find(RemInst);
if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
- SmallPtrSet<ValueIsLoadPair, 4> &Set = ReversePtrDepIt->second;
SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
- for (SmallPtrSet<ValueIsLoadPair, 4>::iterator I = Set.begin(),
- E = Set.end(); I != E; ++I) {
- ValueIsLoadPair P = *I;
+ for (ValueIsLoadPair P : ReversePtrDepIt->second) {
assert(P.getPointer() != RemInst &&
"Already removed NonLocalPointerDeps info for RemInst");
assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
- AA->deleteValue(RemInst);
DEBUG(verifyRemoved(RemInst));
}
/// verifyRemoved - Verify that the specified instruction does not occur
-/// in our internal data structures.
+/// in our internal data structures. This function verifies by asserting in
+/// debug builds.
void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
+#ifndef NDEBUG
for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
E = LocalDeps.end(); I != E; ++I) {
assert(I->first != D && "Inst occurs in data structures");
for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
E = ReverseLocalDeps.end(); I != E; ++I) {
assert(I->first != D && "Inst occurs in data structures");
- for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
- EE = I->second.end(); II != EE; ++II)
- assert(*II != D && "Inst occurs in data structures");
+ for (Instruction *Inst : I->second)
+ assert(Inst != D && "Inst occurs in data structures");
}
for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
E = ReverseNonLocalDeps.end();
I != E; ++I) {
assert(I->first != D && "Inst occurs in data structures");
- for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
- EE = I->second.end(); II != EE; ++II)
- assert(*II != D && "Inst occurs in data structures");
+ for (Instruction *Inst : I->second)
+ assert(Inst != D && "Inst occurs in data structures");
}
for (ReverseNonLocalPtrDepTy::const_iterator
E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
assert(I->first != D && "Inst occurs in rev NLPD map");
- for (SmallPtrSet<ValueIsLoadPair, 4>::const_iterator II = I->second.begin(),
- E = I->second.end(); II != E; ++II)
- assert(*II != ValueIsLoadPair(D, false) &&
- *II != ValueIsLoadPair(D, true) &&
+ for (ValueIsLoadPair P : I->second)
+ assert(P != ValueIsLoadPair(D, false) &&
+ P != ValueIsLoadPair(D, true) &&
"Inst occurs in ReverseNonLocalPtrDeps map");
}
-
+#endif
}
projects / oota-llvm.git / blobdiff