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-rw-r--r--llvm/lib/Analysis/LoopAccessAnalysis.cpp65
1 files changed, 40 insertions, 25 deletions
diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index 770e0e2..25025db 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -89,8 +89,8 @@ Value *llvm::stripIntegerCast(Value *V) {
const SCEV *llvm::replaceSymbolicStrideSCEV(ScalarEvolution *SE,
const ValueToValueMap &PtrToStride,
+ SCEVUnionPredicate &Preds,
Value *Ptr, Value *OrigPtr) {
-
const SCEV *OrigSCEV = SE->getSCEV(Ptr);
// If there is an entry in the map return the SCEV of the pointer with the
@@ -108,22 +108,28 @@ const SCEV *llvm::replaceSymbolicStrideSCEV(ScalarEvolution *SE,
ValueToValueMap RewriteMap;
RewriteMap[StrideVal] = One;
- const SCEV *ByOne =
- SCEVParameterRewriter::rewrite(OrigSCEV, *SE, RewriteMap, true);
+ const auto *U = cast<SCEVUnknown>(SE->getSCEV(StrideVal));
+ const auto *CT =
+ static_cast<const SCEVConstant *>(SE->getOne(StrideVal->getType()));
+
+ Preds.add(SE->getEqualPredicate(U, CT));
+
+ const SCEV *ByOne = SE->rewriteUsingPredicate(OrigSCEV, Preds);
DEBUG(dbgs() << "LAA: Replacing SCEV: " << *OrigSCEV << " by: " << *ByOne
<< "\n");
return ByOne;
}
// Otherwise, just return the SCEV of the original pointer.
- return SE->getSCEV(Ptr);
+ return OrigSCEV;
}
void RuntimePointerChecking::insert(Loop *Lp, Value *Ptr, bool WritePtr,
unsigned DepSetId, unsigned ASId,
- const ValueToValueMap &Strides) {
+ const ValueToValueMap &Strides,
+ SCEVUnionPredicate &Preds) {
// Get the stride replaced scev.
- const SCEV *Sc = replaceSymbolicStrideSCEV(SE, Strides, Ptr);
+ const SCEV *Sc = replaceSymbolicStrideSCEV(SE, Strides, Preds, Ptr);
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Sc);
assert(AR && "Invalid addrec expression");
const SCEV *Ex = SE->getBackedgeTakenCount(Lp);
@@ -417,9 +423,9 @@ public:
typedef SmallPtrSet<MemAccessInfo, 8> MemAccessInfoSet;
AccessAnalysis(const DataLayout &Dl, AliasAnalysis *AA, LoopInfo *LI,
- MemoryDepChecker::DepCandidates &DA)
- : DL(Dl), AST(*AA), LI(LI), DepCands(DA),
- IsRTCheckAnalysisNeeded(false) {}
+ MemoryDepChecker::DepCandidates &DA, SCEVUnionPredicate &Preds)
+ : DL(Dl), AST(*AA), LI(LI), DepCands(DA), IsRTCheckAnalysisNeeded(false),
+ Preds(Preds) {}
/// \brief Register a load and whether it is only read from.
void addLoad(MemoryLocation &Loc, bool IsReadOnly) {
@@ -504,14 +510,18 @@ private:
/// (i.e. ShouldRetryWithRuntimeCheck), isDependencyCheckNeeded is cleared
/// while this remains set if we have potentially dependent accesses.
bool IsRTCheckAnalysisNeeded;
+
+ /// The SCEV predicate containing all the SCEV-related assumptions.
+ SCEVUnionPredicate &Preds;
};
} // end anonymous namespace
/// \brief Check whether a pointer can participate in a runtime bounds check.
static bool hasComputableBounds(ScalarEvolution *SE,
- const ValueToValueMap &Strides, Value *Ptr) {
- const SCEV *PtrScev = replaceSymbolicStrideSCEV(SE, Strides, Ptr);
+ const ValueToValueMap &Strides, Value *Ptr,
+ Loop *L, SCEVUnionPredicate &Preds) {
+ const SCEV *PtrScev = replaceSymbolicStrideSCEV(SE, Strides, Preds, Ptr);
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PtrScev);
if (!AR)
return false;
@@ -554,11 +564,11 @@ bool AccessAnalysis::canCheckPtrAtRT(RuntimePointerChecking &RtCheck,
else
++NumReadPtrChecks;
- if (hasComputableBounds(SE, StridesMap, Ptr) &&
+ if (hasComputableBounds(SE, StridesMap, Ptr, TheLoop, Preds) &&
// When we run after a failing dependency check we have to make sure
// we don't have wrapping pointers.
(!ShouldCheckStride ||
- isStridedPtr(SE, Ptr, TheLoop, StridesMap) == 1)) {
+ isStridedPtr(SE, Ptr, TheLoop, StridesMap, Preds) == 1)) {
// The id of the dependence set.
unsigned DepId;
@@ -572,7 +582,7 @@ bool AccessAnalysis::canCheckPtrAtRT(RuntimePointerChecking &RtCheck,
// Each access has its own dependence set.
DepId = RunningDepId++;
- RtCheck.insert(TheLoop, Ptr, IsWrite, DepId, ASId, StridesMap);
+ RtCheck.insert(TheLoop, Ptr, IsWrite, DepId, ASId, StridesMap, Preds);
DEBUG(dbgs() << "LAA: Found a runtime check ptr:" << *Ptr << '\n');
} else {
@@ -803,7 +813,8 @@ static bool isNoWrapAddRec(Value *Ptr, const SCEVAddRecExpr *AR,
/// \brief Check whether the access through \p Ptr has a constant stride.
int llvm::isStridedPtr(ScalarEvolution *SE, Value *Ptr, const Loop *Lp,
- const ValueToValueMap &StridesMap) {
+ const ValueToValueMap &StridesMap,
+ SCEVUnionPredicate &Preds) {
Type *Ty = Ptr->getType();
assert(Ty->isPointerTy() && "Unexpected non-ptr");
@@ -815,7 +826,7 @@ int llvm::isStridedPtr(ScalarEvolution *SE, Value *Ptr, const Loop *Lp,
return 0;
}
- const SCEV *PtrScev = replaceSymbolicStrideSCEV(SE, StridesMap, Ptr);
+ const SCEV *PtrScev = replaceSymbolicStrideSCEV(SE, StridesMap, Preds, Ptr);
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PtrScev);
if (!AR) {
@@ -1026,11 +1037,11 @@ MemoryDepChecker::isDependent(const MemAccessInfo &A, unsigned AIdx,
BPtr->getType()->getPointerAddressSpace())
return Dependence::Unknown;
- const SCEV *AScev = replaceSymbolicStrideSCEV(SE, Strides, APtr);
- const SCEV *BScev = replaceSymbolicStrideSCEV(SE, Strides, BPtr);
+ const SCEV *AScev = replaceSymbolicStrideSCEV(SE, Strides, Preds, APtr);
+ const SCEV *BScev = replaceSymbolicStrideSCEV(SE, Strides, Preds, BPtr);
- int StrideAPtr = isStridedPtr(SE, APtr, InnermostLoop, Strides);
- int StrideBPtr = isStridedPtr(SE, BPtr, InnermostLoop, Strides);
+ int StrideAPtr = isStridedPtr(SE, APtr, InnermostLoop, Strides, Preds);
+ int StrideBPtr = isStridedPtr(SE, BPtr, InnermostLoop, Strides, Preds);
const SCEV *Src = AScev;
const SCEV *Sink = BScev;
@@ -1429,7 +1440,7 @@ void LoopAccessInfo::analyzeLoop(const ValueToValueMap &Strides) {
MemoryDepChecker::DepCandidates DependentAccesses;
AccessAnalysis Accesses(TheLoop->getHeader()->getModule()->getDataLayout(),
- AA, LI, DependentAccesses);
+ AA, LI, DependentAccesses, Preds);
// Holds the analyzed pointers. We don't want to call GetUnderlyingObjects
// multiple times on the same object. If the ptr is accessed twice, once
@@ -1480,7 +1491,8 @@ void LoopAccessInfo::analyzeLoop(const ValueToValueMap &Strides) {
// read a few words, modify, and write a few words, and some of the
// words may be written to the same address.
bool IsReadOnlyPtr = false;
- if (Seen.insert(Ptr).second || !isStridedPtr(SE, Ptr, TheLoop, Strides)) {
+ if (Seen.insert(Ptr).second ||
+ !isStridedPtr(SE, Ptr, TheLoop, Strides, Preds)) {
++NumReads;
IsReadOnlyPtr = true;
}
@@ -1730,7 +1742,7 @@ LoopAccessInfo::LoopAccessInfo(Loop *L, ScalarEvolution *SE,
const TargetLibraryInfo *TLI, AliasAnalysis *AA,
DominatorTree *DT, LoopInfo *LI,
const ValueToValueMap &Strides)
- : PtrRtChecking(SE), DepChecker(SE, L), TheLoop(L), SE(SE), DL(DL),
+ : PtrRtChecking(SE), DepChecker(SE, L, Preds), TheLoop(L), SE(SE), DL(DL),
TLI(TLI), AA(AA), DT(DT), LI(LI), NumLoads(0), NumStores(0),
MaxSafeDepDistBytes(-1U), CanVecMem(false),
StoreToLoopInvariantAddress(false) {
@@ -1765,6 +1777,9 @@ void LoopAccessInfo::print(raw_ostream &OS, unsigned Depth) const {
OS.indent(Depth) << "Store to invariant address was "
<< (StoreToLoopInvariantAddress ? "" : "not ")
<< "found in loop.\n";
+
+ OS.indent(Depth) << "SCEV assumptions:\n";
+ Preds.print(OS, Depth);
}
const LoopAccessInfo &
@@ -1778,8 +1793,8 @@ LoopAccessAnalysis::getInfo(Loop *L, const ValueToValueMap &Strides) {
if (!LAI) {
const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
- LAI = llvm::make_unique<LoopAccessInfo>(L, SE, DL, TLI, AA, DT, LI,
- Strides);
+ LAI =
+ llvm::make_unique<LoopAccessInfo>(L, SE, DL, TLI, AA, DT, LI, Strides);
#ifndef NDEBUG
LAI->NumSymbolicStrides = Strides.size();
#endif
generated by cgit v1.1 at 2025-10-27 14:34:55 +0000