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Revert r260086 and r260085. They have broken the memory 

sanitizer bots.

llvm-svn: 260087
This commit is contained in:
Silviu Baranga 2016-02-08 11:56:15 +00:00
parent 70a98bb9e8
commit 41b4973329
10 changed files with 41 additions and 727 deletions
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4
llvm/include/llvm/Analysis/LoopAccessAnalysis.h
View File

@ -656,10 +656,8 @@ const SCEV *replaceSymbolicStrideSCEV(PredicatedScalarEvolution &PSE,
///
/// If necessary this method will version the stride of the pointer according
/// to \p PtrToStride and therefore add a new predicate to \p Preds.
/// The \p Assume parameter indicates if we are allowed to make additional
/// run-time assumptions.
int isStridedPtr(PredicatedScalarEvolution &PSE, Value *Ptr, const Loop *Lp,
const ValueToValueMap &StridesMap, bool Assume = false);
const ValueToValueMap &StridesMap);
/// \brief Returns true if the memory operations \p A and \p B are consecutive.
/// This is a simple API that does not depend on the analysis pass.

124
llvm/include/llvm/Analysis/ScalarEvolution.h
View File

@ -31,7 +31,6 @@
#include "llvm/IR/Operator.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/IR/ValueMap.h"
#include "llvm/Pass.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/DataTypes.h"
@ -180,7 +179,7 @@ namespace llvm {
FoldingSetNodeIDRef FastID;
public:
enum SCEVPredicateKind { P_Union, P_Equal, P_Wrap };
enum SCEVPredicateKind { P_Union, P_Equal };
protected:
SCEVPredicateKind Kind;
@ -270,98 +269,6 @@ namespace llvm {
}
};
/// SCEVWrapPredicate - This class represents an assumption
/// made on an AddRec expression. Given an affine AddRec expression
/// {a,+,b}, we assume that it has the nssw or nusw flags (defined
/// below).
class SCEVWrapPredicate final : public SCEVPredicate {
public:
/// Similar to SCEV::NoWrapFlags, but with slightly different semantics
/// for FlagNUSW. The increment is considered to be signed, and a + b
/// (where b is the increment) is considered to wrap if:
/// zext(a + b) != zext(a) + sext(b)
///
/// If Signed is a function that takes an n-bit tuple and maps to the
/// integer domain as the tuples value interpreted as twos complement,
/// and Unsigned a function that takes an n-bit tuple and maps to the
/// integer domain as as the base two value of input tuple, then a + b
/// has IncrementNUSW iff:
///
/// 0 <= Unsigned(a) + Signed(b) < 2^n
///
/// The IncrementNSSW flag has identical semantics with SCEV::FlagNSW.
///
/// Note that the IncrementNUSW flag is not commutative: if base + inc
/// has IncrementNUSW, then inc + base doesn't neccessarily have this
/// property. The reason for this is that this is used for sign/zero
/// extending affine AddRec SCEV expressions when a SCEVWrapPredicate is
/// assumed. A {base,+,inc} expression is already non-commutative with
/// regards to base and inc, since it is interpreted as:
/// (((base + inc) + inc) + inc) ...
enum IncrementWrapFlags {
IncrementAnyWrap = 0, // No guarantee.
IncrementNUSW = (1 << 0), // No unsigned with signed increment wrap.
IncrementNSSW = (1 << 1), // No signed with signed increment wrap
// (equivalent with SCEV::NSW)
IncrementNoWrapMask = (1 << 2) - 1
};
/// Convenient IncrementWrapFlags manipulation methods.
static SCEVWrapPredicate::IncrementWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
clearFlags(SCEVWrapPredicate::IncrementWrapFlags Flags,
SCEVWrapPredicate::IncrementWrapFlags OffFlags) {
assert((Flags & IncrementNoWrapMask) == Flags && "Invalid flags value!");
assert((OffFlags & IncrementNoWrapMask) == OffFlags &&
"Invalid flags value!");
return (SCEVWrapPredicate::IncrementWrapFlags)(Flags & ~OffFlags);
}
static SCEVWrapPredicate::IncrementWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
maskFlags(SCEVWrapPredicate::IncrementWrapFlags Flags, int Mask) {
assert((Flags & IncrementNoWrapMask) == Flags && "Invalid flags value!");
assert((Mask & IncrementNoWrapMask) == Mask && "Invalid mask value!");
return (SCEVWrapPredicate::IncrementWrapFlags)(Flags & Mask);
}
static SCEVWrapPredicate::IncrementWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
setFlags(SCEVWrapPredicate::IncrementWrapFlags Flags,
SCEVWrapPredicate::IncrementWrapFlags OnFlags) {
assert((Flags & IncrementNoWrapMask) == Flags && "Invalid flags value!");
assert((OnFlags & IncrementNoWrapMask) == OnFlags &&
"Invalid flags value!");
return (SCEVWrapPredicate::IncrementWrapFlags)(Flags | OnFlags);
}
/// \brief Returns the set of SCEVWrapPredicate no wrap flags implied
/// by a SCEVAddRecExpr.
static SCEVWrapPredicate::IncrementWrapFlags
getImpliedFlags(const SCEVAddRecExpr *AR, ScalarEvolution &SE);
private:
const SCEVAddRecExpr *AR;
IncrementWrapFlags Flags;
public:
explicit SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
const SCEVAddRecExpr *AR,
IncrementWrapFlags Flags);
/// \brief Returns the set assumed no overflow flags.
IncrementWrapFlags getFlags() const { return Flags; }
/// Implementation of the SCEVPredicate interface
const SCEV *getExpr() const override;
bool implies(const SCEVPredicate *N) const override;
void print(raw_ostream &OS, unsigned Depth = 0) const override;
bool isAlwaysTrue() const override;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const SCEVPredicate *P) {
return P->getKind() == P_Wrap;
}
};
/// SCEVUnionPredicate - This class represents a composition of other
/// SCEV predicates, and is the class that most clients will interact with.
/// This is equivalent to a logical "AND" of all the predicates in the union.
@ -1373,18 +1280,8 @@ namespace llvm {
const SCEVPredicate *getEqualPredicate(const SCEVUnknown *LHS,
const SCEVConstant *RHS);
const SCEVPredicate *
getWrapPredicate(const SCEVAddRecExpr *AR,
SCEVWrapPredicate::IncrementWrapFlags AddedFlags);
/// Re-writes the SCEV according to the Predicates in \p Preds.
const SCEV *rewriteUsingPredicate(const SCEV *Scev, const Loop *L,
SCEVUnionPredicate &A);
/// Tries to convert the \p Scev expression to an AddRec expression,
/// adding additional predicates to \p Preds as required.
const SCEV *convertSCEVToAddRecWithPredicates(const SCEV *Scev,
const Loop *L,
SCEVUnionPredicate &Preds);
const SCEV *rewriteUsingPredicate(const SCEV *Scev, SCEVUnionPredicate &A);
private:
/// Compute the backedge taken count knowing the interval difference, the
@ -1475,7 +1372,7 @@ namespace llvm {
/// - lowers the number of expression rewrites.
class PredicatedScalarEvolution {
public:
PredicatedScalarEvolution(ScalarEvolution &SE, Loop &L);
PredicatedScalarEvolution(ScalarEvolution &SE);
const SCEVUnionPredicate &getUnionPredicate() const;
/// \brief Returns the SCEV expression of V, in the context of the current
/// SCEV predicate.
@ -1485,18 +1382,9 @@ namespace llvm {
const SCEV *getSCEV(Value *V);
/// \brief Adds a new predicate.
void addPredicate(const SCEVPredicate &Pred);
/// \brief Attempts to produce an AddRecExpr for V by adding additional
/// SCEV predicates.
const SCEV *getAsAddRec(Value *V);
/// \brief Proves that V doesn't overflow by adding SCEV predicate.
void setNoOverflow(Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags);
/// \brief Returns true if we've proved that V doesn't wrap by means of a
/// SCEV predicate.
bool hasNoOverflow(Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags);
/// \brief Returns the ScalarEvolution analysis used.
ScalarEvolution *getSE() const { return &SE; }
/// We need to explicitly define the copy constructor because of FlagsMap.
PredicatedScalarEvolution(const PredicatedScalarEvolution&);
private:
/// \brief Increments the version number of the predicate.
/// This needs to be called every time the SCEV predicate changes.
@ -1510,12 +1398,8 @@ namespace llvm {
/// rewrites, we will rewrite the previous result instead of the original
/// SCEV.
DenseMap<const SCEV *, RewriteEntry> RewriteMap;
/// Records what NoWrap flags we've added to a Value *.
ValueMap<Value *, SCEVWrapPredicate::IncrementWrapFlags> FlagsMap;
/// The ScalarEvolution analysis.
ScalarEvolution &SE;
/// The analyzed Loop.
const Loop &L;
/// The SCEVPredicate that forms our context. We will rewrite all
/// expressions assuming that this predicate true.
SCEVUnionPredicate Preds;

9
llvm/include/llvm/Analysis/ScalarEvolutionExpander.h
View File

@ -162,15 +162,6 @@ namespace llvm {
Value *expandEqualPredicate(const SCEVEqualPredicate *Pred,
Instruction *Loc);
/// \brief Generates code that evaluates if the \p AR expression will
/// overflow.
Value *generateOverflowCheck(const SCEVAddRecExpr *AR, Instruction *Loc,
bool Signed);
/// \brief A specialized variant of expandCodeForPredicate, handling the
/// case when we are expanding code for a SCEVWrapPredicate.
Value *expandWrapPredicate(const SCEVWrapPredicate *P, Instruction *Loc);
/// \brief A specialized variant of expandCodeForPredicate, handling the
/// case when we are expanding code for a SCEVUnionPredicate.
Value *expandUnionPredicate(const SCEVUnionPredicate *Pred,

61
llvm/lib/Analysis/LoopAccessAnalysis.cpp
View File

@ -773,7 +773,7 @@ static bool isInBoundsGep(Value *Ptr) {
/// \brief Return true if an AddRec pointer \p Ptr is unsigned non-wrapping,
/// i.e. monotonically increasing/decreasing.
static bool isNoWrapAddRec(Value *Ptr, const SCEVAddRecExpr *AR,
PredicatedScalarEvolution &PSE, const Loop *L) {
ScalarEvolution *SE, const Loop *L) {
// FIXME: This should probably only return true for NUW.
if (AR->getNoWrapFlags(SCEV::NoWrapMask))
return true;
@ -809,7 +809,7 @@ static bool isNoWrapAddRec(Value *Ptr, const SCEVAddRecExpr *AR,
// Assume constant for other the operand so that the AddRec can be
// easily found.
isa<ConstantInt>(OBO->getOperand(1))) {
auto *OpScev = PSE.getSCEV(OBO->getOperand(0));
auto *OpScev = SE->getSCEV(OBO->getOperand(0));
if (auto *OpAR = dyn_cast<SCEVAddRecExpr>(OpScev))
return OpAR->getLoop() == L && OpAR->getNoWrapFlags(SCEV::FlagNSW);
@ -820,35 +820,31 @@ static bool isNoWrapAddRec(Value *Ptr, const SCEVAddRecExpr *AR,
/// \brief Check whether the access through \p Ptr has a constant stride.
int llvm::isStridedPtr(PredicatedScalarEvolution &PSE, Value *Ptr,
const Loop *Lp, const ValueToValueMap &StridesMap,
bool Assume) {
const Loop *Lp, const ValueToValueMap &StridesMap) {
Type *Ty = Ptr->getType();
assert(Ty->isPointerTy() && "Unexpected non-ptr");
// Make sure that the pointer does not point to aggregate types.
auto *PtrTy = cast<PointerType>(Ty);
if (PtrTy->getElementType()->isAggregateType()) {
DEBUG(dbgs() << "LAA: Bad stride - Not a pointer to a scalar type" << *Ptr
<< "\n");
DEBUG(dbgs() << "LAA: Bad stride - Not a pointer to a scalar type"
<< *Ptr << "\n");
return 0;
}
const SCEV *PtrScev = replaceSymbolicStrideSCEV(PSE, StridesMap, Ptr);
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PtrScev);
if (Assume && !AR)
AR = dyn_cast<SCEVAddRecExpr>(PSE.getAsAddRec(Ptr));
if (!AR) {
DEBUG(dbgs() << "LAA: Bad stride - Not an AddRecExpr pointer " << *Ptr
<< " SCEV: " << *PtrScev << "\n");
DEBUG(dbgs() << "LAA: Bad stride - Not an AddRecExpr pointer "
<< *Ptr << " SCEV: " << *PtrScev << "\n");
return 0;
}
// The accesss function must stride over the innermost loop.
if (Lp != AR->getLoop()) {
DEBUG(dbgs() << "LAA: Bad stride - Not striding over innermost loop " <<
*Ptr << " SCEV: " << *AR << "\n");
*Ptr << " SCEV: " << *PtrScev << "\n");
return 0;
}
@ -860,23 +856,12 @@ int llvm::isStridedPtr(PredicatedScalarEvolution &PSE, Value *Ptr,
// to access the pointer value "0" which is undefined behavior in address
// space 0, therefore we can also vectorize this case.
bool IsInBoundsGEP = isInBoundsGep(Ptr);
bool IsNoWrapAddRec =
PSE.hasNoOverflow(Ptr, SCEVWrapPredicate::IncrementNUSW) ||
isNoWrapAddRec(Ptr, AR, PSE, Lp);
bool IsNoWrapAddRec = isNoWrapAddRec(Ptr, AR, PSE.getSE(), Lp);
bool IsInAddressSpaceZero = PtrTy->getAddressSpace() == 0;
if (!IsNoWrapAddRec && !IsInBoundsGEP && !IsInAddressSpaceZero) {
if (Assume) {
PSE.setNoOverflow(Ptr, SCEVWrapPredicate::IncrementNUSW);
IsNoWrapAddRec = true;
DEBUG(dbgs() << "LAA: Pointer may wrap in the address space:\n"
<< "LAA: Pointer: " << *Ptr << "\n"
<< "LAA: SCEV: " << *AR << "\n"
<< "LAA: Added an overflow assumption\n");
} else {
DEBUG(dbgs() << "LAA: Bad stride - Pointer may wrap in the address space "
<< *Ptr << " SCEV: " << *AR << "\n");
return 0;
}
DEBUG(dbgs() << "LAA: Bad stride - Pointer may wrap in the address space "
<< *Ptr << " SCEV: " << *PtrScev << "\n");
return 0;
}
// Check the step is constant.
@ -886,7 +871,7 @@ int llvm::isStridedPtr(PredicatedScalarEvolution &PSE, Value *Ptr,
const SCEVConstant *C = dyn_cast<SCEVConstant>(Step);
if (!C) {
DEBUG(dbgs() << "LAA: Bad stride - Not a constant strided " << *Ptr <<
" SCEV: " << *AR << "\n");
" SCEV: " << *PtrScev << "\n");
return 0;
}
@ -910,18 +895,8 @@ int llvm::isStridedPtr(PredicatedScalarEvolution &PSE, Value *Ptr,
// know we can't "wrap around the address space". In case of address space
// zero we know that this won't happen without triggering undefined behavior.
if (!IsNoWrapAddRec && (IsInBoundsGEP || IsInAddressSpaceZero) &&
Stride != 1 && Stride != -1) {
if (Assume) {
// We can avoid this case by adding a run-time check.
DEBUG(dbgs() << "LAA: Non unit strided pointer which is not either "
<< "inbouds or in address space 0 may wrap:\n"
<< "LAA: Pointer: " << *Ptr << "\n"
<< "LAA: SCEV: " << *AR << "\n"
<< "LAA: Added an overflow assumption\n");
PSE.setNoOverflow(Ptr, SCEVWrapPredicate::IncrementNUSW);
} else
return 0;
}
Stride != 1 && Stride != -1)
return 0;
return Stride;
}
@ -1148,8 +1123,8 @@ MemoryDepChecker::isDependent(const MemAccessInfo &A, unsigned AIdx,
const SCEV *AScev = replaceSymbolicStrideSCEV(PSE, Strides, APtr);
const SCEV *BScev = replaceSymbolicStrideSCEV(PSE, Strides, BPtr);
int StrideAPtr = isStridedPtr(PSE, APtr, InnermostLoop, Strides, true);
int StrideBPtr = isStridedPtr(PSE, BPtr, InnermostLoop, Strides, true);
int StrideAPtr = isStridedPtr(PSE, APtr, InnermostLoop, Strides);
int StrideBPtr = isStridedPtr(PSE, BPtr, InnermostLoop, Strides);
const SCEV *Src = AScev;
const SCEV *Sink = BScev;
@ -1849,7 +1824,7 @@ LoopAccessInfo::LoopAccessInfo(Loop *L, ScalarEvolution *SE,
const TargetLibraryInfo *TLI, AliasAnalysis *AA,
DominatorTree *DT, LoopInfo *LI,
const ValueToValueMap &Strides)
: PSE(*SE, *L), PtrRtChecking(SE), DepChecker(PSE, L), TheLoop(L), DL(DL),
: PSE(*SE), PtrRtChecking(SE), DepChecker(PSE, L), TheLoop(L), DL(DL),
TLI(TLI), AA(AA), DT(DT), LI(LI), NumLoads(0), NumStores(0),
MaxSafeDepDistBytes(-1U), CanVecMem(false),
StoreToLoopInvariantAddress(false) {

197
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -9627,40 +9627,17 @@ ScalarEvolution::getEqualPredicate(const SCEVUnknown *LHS,
return Eq;
}
const SCEVPredicate *ScalarEvolution::getWrapPredicate(
const SCEVAddRecExpr *AR,
SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
FoldingSetNodeID ID;
// Unique this node based on the arguments
ID.AddInteger(SCEVPredicate::P_Wrap);
ID.AddPointer(AR);
ID.AddInteger(AddedFlags);
void *IP = nullptr;
if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
return S;
auto *OF = new (SCEVAllocator)
SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags);
UniquePreds.InsertNode(OF, IP);
return OF;
}
namespace {
class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> {
public:
// Rewrites Scev in the context of a loop L and the predicate A.
// If Assume is true, rewrite is free to add further predicates to A
// such that the result will be an AddRecExpr.
static const SCEV *rewrite(const SCEV *Scev, const Loop *L,
ScalarEvolution &SE, SCEVUnionPredicate &A,
bool Assume) {
SCEVPredicateRewriter Rewriter(L, SE, A, Assume);
static const SCEV *rewrite(const SCEV *Scev, ScalarEvolution &SE,
SCEVUnionPredicate &A) {
SCEVPredicateRewriter Rewriter(SE, A);
return Rewriter.visit(Scev);
}
SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE,
SCEVUnionPredicate &P, bool Assume)
: SCEVRewriteVisitor(SE), P(P), L(L), Assume(Assume) {}
SCEVPredicateRewriter(ScalarEvolution &SE, SCEVUnionPredicate &P)
: SCEVRewriteVisitor(SE), P(P) {}
const SCEV *visitUnknown(const SCEVUnknown *Expr) {
auto ExprPreds = P.getPredicatesForExpr(Expr);
@ -9672,67 +9649,14 @@ public:
return Expr;
}
const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
const SCEV *Operand = visit(Expr->getOperand());
const SCEVAddRecExpr *AR = dyn_cast<const SCEVAddRecExpr>(Operand);
if (AR && AR->getLoop() == L && AR->isAffine()) {
// This couldn't be folded because the operand didn't have the nuw
// flag. Add the nusw flag as an assumption that we could make.
const SCEV *Step = AR->getStepRecurrence(SE);
Type *Ty = Expr->getType();
if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW))
return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty),
SE.getSignExtendExpr(Step, Ty), L,
AR->getNoWrapFlags());
}
return SE.getZeroExtendExpr(Operand, Expr->getType());
}
const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
const SCEV *Operand = visit(Expr->getOperand());
const SCEVAddRecExpr *AR = dyn_cast<const SCEVAddRecExpr>(Operand);
if (AR && AR->getLoop() == L && AR->isAffine()) {
// This couldn't be folded because the operand didn't have the nsw
// flag. Add the nssw flag as an assumption that we could make.
const SCEV *Step = AR->getStepRecurrence(SE);
Type *Ty = Expr->getType();
if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW))
return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty),
SE.getSignExtendExpr(Step, Ty), L,
AR->getNoWrapFlags());
}
return SE.getSignExtendExpr(Operand, Expr->getType());
}
private:
bool addOverflowAssumption(const SCEVAddRecExpr *AR,
SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
auto *A = SE.getWrapPredicate(AR, AddedFlags);
if (!Assume) {
// Check if we've already made this assumption.
if (P.implies(A))
return true;
return false;
}
P.add(A);
return true;
}
SCEVUnionPredicate &P;
const Loop *L;
bool Assume;
};
} // end anonymous namespace
const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *Scev,
const Loop *L,
SCEVUnionPredicate &Preds) {
return SCEVPredicateRewriter::rewrite(Scev, L, *this, Preds, false);
}
const SCEV *ScalarEvolution::convertSCEVToAddRecWithPredicates(
const SCEV *Scev, const Loop *L, SCEVUnionPredicate &Preds) {
return SCEVPredicateRewriter::rewrite(Scev, L, *this, Preds, true);
return SCEVPredicateRewriter::rewrite(Scev, *this, Preds);
}
/// SCEV predicates
@ -9762,59 +9686,6 @@ void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const {
OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n";
}
SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
const SCEVAddRecExpr *AR,
IncrementWrapFlags Flags)
: SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {}
const SCEV *SCEVWrapPredicate::getExpr() const { return AR; }
bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const {
const auto *Op = dyn_cast<SCEVWrapPredicate>(N);
return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags;
}
bool SCEVWrapPredicate::isAlwaysTrue() const {
SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags();
IncrementWrapFlags IFlags = Flags;
if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags)
IFlags = clearFlags(IFlags, IncrementNSSW);
return IFlags == IncrementAnyWrap;
}
void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const {
OS.indent(Depth) << *getExpr() << " Added Flags: ";
if (SCEVWrapPredicate::IncrementNUSW & getFlags())
OS << "<nusw>";
if (SCEVWrapPredicate::IncrementNSSW & getFlags())
OS << "<nssw>";
OS << "\n";
}
SCEVWrapPredicate::IncrementWrapFlags
SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR,
ScalarEvolution &SE) {
IncrementWrapFlags ImpliedFlags = IncrementAnyWrap;
SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags();
// We can safely transfer the NSW flag as NSSW.
if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags)
ImpliedFlags = IncrementNSSW;
if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) {
// If the increment is positive, the SCEV NUW flag will also imply the
// WrapPredicate NUSW flag.
if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE)))
if (Step->getValue()->getValue().isNonNegative())
ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW);
}
return ImpliedFlags;
}
/// Union predicates don't get cached so create a dummy set ID for it.
SCEVUnionPredicate::SCEVUnionPredicate()
: SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {}
@ -9871,9 +9742,8 @@ void SCEVUnionPredicate::add(const SCEVPredicate *N) {
Preds.push_back(N);
}
PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE,
Loop &L)
: SE(SE), L(L), Generation(0) {}
PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE)
: SE(SE), Generation(0) {}
const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) {
const SCEV *Expr = SE.getSCEV(V);
@ -9888,7 +9758,7 @@ const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) {
if (Entry.second)
Expr = Entry.second;
const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, Preds);
const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, Preds);
Entry = {Generation, NewSCEV};
return NewSCEV;
@ -9910,54 +9780,7 @@ void PredicatedScalarEvolution::updateGeneration() {
if (++Generation == 0) {
for (auto &II : RewriteMap) {
const SCEV *Rewritten = II.second.second;
II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, Preds)};
II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, Preds)};
}
}
}
void PredicatedScalarEvolution::setNoOverflow(
Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
const SCEV *Expr = getSCEV(V);
const auto *AR = cast<SCEVAddRecExpr>(Expr);
auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE);
// Clear the statically implied flags.
Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags);
addPredicate(*SE.getWrapPredicate(AR, Flags));
auto II = FlagsMap.insert({V, Flags});
if (!II.second)
II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second);
}
bool PredicatedScalarEvolution::hasNoOverflow(
Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
const SCEV *Expr = getSCEV(V);
const auto *AR = cast<SCEVAddRecExpr>(Expr);
Flags = SCEVWrapPredicate::clearFlags(
Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE));
auto II = FlagsMap.find(V);
if (II != FlagsMap.end())
Flags = SCEVWrapPredicate::clearFlags(Flags, II->second);
return Flags == SCEVWrapPredicate::IncrementAnyWrap;
}
const SCEV *PredicatedScalarEvolution::getAsAddRec(Value *V) {
const SCEV *Expr = this->getSCEV(V);
const SCEV *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, Preds);
updateGeneration();
RewriteMap[SE.getSCEV(V)] = {Generation, New};
return New;
}
PredicatedScalarEvolution::
PredicatedScalarEvolution(const PredicatedScalarEvolution &Init) :
RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L), Preds(Init.Preds) {
for (auto I = Init.FlagsMap.begin(), E = Init.FlagsMap.end(); I != E; ++I)
FlagsMap.insert(*I);
}

68
llvm/lib/Analysis/ScalarEvolutionExpander.cpp
View File

@ -1971,10 +1971,6 @@ Value *SCEVExpander::expandCodeForPredicate(const SCEVPredicate *Pred,
return expandUnionPredicate(cast<SCEVUnionPredicate>(Pred), IP);
case SCEVPredicate::P_Equal:
return expandEqualPredicate(cast<SCEVEqualPredicate>(Pred), IP);
case SCEVPredicate::P_Wrap: {
auto *AddRecPred = cast<SCEVWrapPredicate>(Pred);
return expandWrapPredicate(AddRecPred, IP);
}
}
llvm_unreachable("Unknown SCEV predicate type");
}
@ -1989,70 +1985,6 @@ Value *SCEVExpander::expandEqualPredicate(const SCEVEqualPredicate *Pred,
return I;
}
Value *SCEVExpander::generateOverflowCheck(const SCEVAddRecExpr *AR,
Instruction *Loc, bool Signed) {
assert(AR->isAffine() && "Cannot generate RT check for "
"non-affine expression");
const SCEV *ExitCount = SE.getBackedgeTakenCount(AR->getLoop());
const SCEV *Step = AR->getStepRecurrence(SE);
const SCEV *Start = AR->getStart();
unsigned DstBits = SE.getTypeSizeInBits(AR->getType());
unsigned SrcBits = SE.getTypeSizeInBits(ExitCount->getType());
unsigned MaxBits = 2 * std::max(DstBits, SrcBits);
auto *TripCount = SE.getTruncateOrZeroExtend(ExitCount, AR->getType());
IntegerType *MaxTy = IntegerType::get(Loc->getContext(), MaxBits);
assert(ExitCount != SE.getCouldNotCompute() && "Invalid loop count");
const auto *ExtendedTripCount = SE.getZeroExtendExpr(ExitCount, MaxTy);
const auto *ExtendedStep = SE.getSignExtendExpr(Step, MaxTy);
const auto *ExtendedStart = Signed ? SE.getSignExtendExpr(Start, MaxTy)
: SE.getZeroExtendExpr(Start, MaxTy);
const SCEV *End = SE.getAddExpr(Start, SE.getMulExpr(TripCount, Step));
const SCEV *RHS = Signed ? SE.getSignExtendExpr(End, MaxTy)
: SE.getZeroExtendExpr(End, MaxTy);
const SCEV *LHS = SE.getAddExpr(
ExtendedStart, SE.getMulExpr(ExtendedTripCount, ExtendedStep));
// Do all SCEV expansions now.
Value *LHSVal = expandCodeFor(LHS, MaxTy, Loc);
Value *RHSVal = expandCodeFor(RHS, MaxTy, Loc);
Builder.SetInsertPoint(Loc);
return Builder.CreateICmp(ICmpInst::ICMP_NE, RHSVal, LHSVal);
}
Value *SCEVExpander::expandWrapPredicate(const SCEVWrapPredicate *Pred,
Instruction *IP) {
const auto *A = cast<SCEVAddRecExpr>(Pred->getExpr());
Value *NSSWCheck = nullptr, *NUSWCheck = nullptr;
// Add a check for NUSW
if (Pred->getFlags() & SCEVWrapPredicate::IncrementNUSW)
NUSWCheck = generateOverflowCheck(A, IP, false);
// Add a check for NSSW
if (Pred->getFlags() & SCEVWrapPredicate::IncrementNSSW)
NSSWCheck = generateOverflowCheck(A, IP, true);
if (NUSWCheck && NSSWCheck)
return Builder.CreateOr(NUSWCheck, NSSWCheck);
if (NUSWCheck)
return NUSWCheck;
if (NSSWCheck)
return NSSWCheck;
return ConstantInt::getFalse(IP->getContext());
}
Value *SCEVExpander::expandUnionPredicate(const SCEVUnionPredicate *Union,
Instruction *IP) {
auto *BoolType = IntegerType::get(IP->getContext(), 1);

1
llvm/lib/Transforms/Utils/LoopVersioning.cpp
View File

@ -56,6 +56,7 @@ void LoopVersioning::versionLoop(
BasicBlock *RuntimeCheckBB = VersionedLoop->getLoopPreheader();
std::tie(FirstCheckInst, MemRuntimeCheck) =
LAI.addRuntimeChecks(RuntimeCheckBB->getTerminator(), AliasChecks);
assert(MemRuntimeCheck && "called even though needsAnyChecking = false");
const SCEVUnionPredicate &Pred = LAI.PSE.getUnionPredicate();
SCEVExpander Exp(*SE, RuntimeCheckBB->getModule()->getDataLayout(),

2
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -1751,7 +1751,7 @@ struct LoopVectorize : public FunctionPass {
}
}
PredicatedScalarEvolution PSE(*SE, *L);
PredicatedScalarEvolution PSE(*SE);
// Check if it is legal to vectorize the loop.
LoopVectorizationRequirements Requirements;

292
llvm/test/Analysis/LoopAccessAnalysis/wrapping-pointer-versioning.ll
View File

@ -1,292 +0,0 @@
; RUN: opt -basicaa -loop-accesses -analyze < %s | FileCheck %s -check-prefix=LAA
; RUN: opt -loop-versioning -S < %s | FileCheck %s -check-prefix=LV
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
; For this loop:
; unsigned index = 0;
; for (int i = 0; i < n; i++) {
; A[2 * index] = A[2 * index] + B[i];
; index++;
; }
;
; SCEV is unable to prove that A[2 * i] does not overflow.
;
; Analyzing the IR does not help us because the GEPs are not
; affine AddRecExprs. However, we can turn them into AddRecExprs
; using SCEV Predicates.
;
; Once we have an affine expression we need to add an additional NUSW
; to check that the pointers don't wrap since the GEPs are not
; inbound.
; LAA-LABEL: f1
; LAA: Memory dependences are safe{{$}}
; LAA: SCEV assumptions:
; LAA-NEXT: {0,+,2}<%for.body> Added Flags: <nusw>
; LAA-NEXT: {%a,+,4}<%for.body> Added Flags: <nusw>
; The expression for %mul_ext as analyzed by SCEV is
; (zext i32 {0,+,2}<%for.body> to i64)
; We have added the nusw flag to turn this expression into the SCEV expression:
; i64 {0,+,2}<%for.body>
; LV-LABEL: f1
; LV-LABEL: for.body.lver.check
; LV: [[PredCheck0:%[^ ]*]] = icmp ne i128
; LV: [[Or0:%[^ ]*]] = or i1 false, [[PredCheck0]]
; LV: [[PredCheck1:%[^ ]*]] = icmp ne i128
; LV: [[FinalCheck:%[^ ]*]] = or i1 [[Or0]], [[PredCheck1]]
; LV: br i1 [[FinalCheck]], label %for.body.ph.lver.orig, label %for.body.ph
define void @f1(i16* noalias %a,
i16* noalias %b, i64 %N) {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%ind1 = phi i32 [ 0, %entry ], [ %inc1, %for.body ]
%mul = mul i32 %ind1, 2
%mul_ext = zext i32 %mul to i64
%arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext
%loadA = load i16, i16* %arrayidxA, align 2
%arrayidxB = getelementptr i16, i16* %b, i64 %ind
%loadB = load i16, i16* %arrayidxB, align 2
%add = mul i16 %loadA, %loadB
store i16 %add, i16* %arrayidxA, align 2
%inc = add nuw nsw i64 %ind, 1
%inc1 = add i32 %ind1, 1
%exitcond = icmp eq i64 %inc, %N
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; For this loop:
; unsigned index = n;
; for (int i = 0; i < n; i++) {
; A[2 * index] = A[2 * index] + B[i];
; index--;
; }
;
; the SCEV expression for 2 * index is not an AddRecExpr
; (and implictly not affine). However, we are able to make assumptions
; that will turn the expression into an affine one and continue the
; analysis.
;
; Once we have an affine expression we need to add an additional NUSW
; to check that the pointers don't wrap since the GEPs are not
; inbounds.
;
; This loop has a negative stride for A, and the nusw flag is required in
; order to properly extend the increment from i32 -4 to i64 -4.
; LAA-LABEL: f2
; LAA: Memory dependences are safe{{$}}
; LAA: SCEV assumptions:
; LAA-NEXT: {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> Added Flags: <nusw>
; LAA-NEXT: {((2 * (zext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body> Added Flags: <nusw>
; The expression for %mul_ext as analyzed by SCEV is
; (zext i32 {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> to i64)
; We have added the nusw flag to turn this expression into the following SCEV:
; i64 {zext i32 (2 * (trunc i64 %N to i32)) to i64,+,-2}<%for.body>
; LV-LABEL: f2
; LV-LABEL: for.body.lver.check
; LV: [[PredCheck0:%[^ ]*]] = icmp ne i128
; LV: [[Or0:%[^ ]*]] = or i1 false, [[PredCheck0]]
; LV: [[PredCheck1:%[^ ]*]] = icmp ne i128
; LV: [[FinalCheck:%[^ ]*]] = or i1 [[Or0]], [[PredCheck1]]
; LV: br i1 [[FinalCheck]], label %for.body.ph.lver.orig, label %for.body.ph
define void @f2(i16* noalias %a,
i16* noalias %b, i64 %N) {
entry:
%TruncN = trunc i64 %N to i32
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%ind1 = phi i32 [ %TruncN, %entry ], [ %dec, %for.body ]
%mul = mul i32 %ind1, 2
%mul_ext = zext i32 %mul to i64
%arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext
%loadA = load i16, i16* %arrayidxA, align 2
%arrayidxB = getelementptr i16, i16* %b, i64 %ind
%loadB = load i16, i16* %arrayidxB, align 2
%add = mul i16 %loadA, %loadB
store i16 %add, i16* %arrayidxA, align 2
%inc = add nuw nsw i64 %ind, 1
%dec = sub i32 %ind1, 1
%exitcond = icmp eq i64 %inc, %N
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; We replicate the tests above, but this time sign extend 2 * index instead
; of zero extending it.
; LAA-LABEL: f3
; LAA: Memory dependences are safe{{$}}
; LAA: SCEV assumptions:
; LAA-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; LAA-NEXT: {%a,+,4}<%for.body> Added Flags: <nusw>
; The expression for %mul_ext as analyzed by SCEV is
; i64 (sext i32 {0,+,2}<%for.body> to i64)
; We have added the nssw flag to turn this expression into the following SCEV:
; i64 {0,+,2}<%for.body>
; LV-LABEL: f3
; LV-LABEL: for.body.lver.check
; LV: [[PredCheck0:%[^ ]*]] = icmp ne i128
; LV: [[Or0:%[^ ]*]] = or i1 false, [[PredCheck0]]
; LV: [[PredCheck1:%[^ ]*]] = icmp ne i128
; LV: [[FinalCheck:%[^ ]*]] = or i1 [[Or0]], [[PredCheck1]]
; LV: br i1 [[FinalCheck]], label %for.body.ph.lver.orig, label %for.body.ph
define void @f3(i16* noalias %a,
i16* noalias %b, i64 %N) {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%ind1 = phi i32 [ 0, %entry ], [ %inc1, %for.body ]
%mul = mul i32 %ind1, 2
%mul_ext = sext i32 %mul to i64
%arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext
%loadA = load i16, i16* %arrayidxA, align 2
%arrayidxB = getelementptr i16, i16* %b, i64 %ind
%loadB = load i16, i16* %arrayidxB, align 2
%add = mul i16 %loadA, %loadB
store i16 %add, i16* %arrayidxA, align 2
%inc = add nuw nsw i64 %ind, 1
%inc1 = add i32 %ind1, 1
%exitcond = icmp eq i64 %inc, %N
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; LAA-LABEL: f4
; LAA: Memory dependences are safe{{$}}
; LAA: SCEV assumptions:
; LAA-NEXT: {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> Added Flags: <nssw>
; LAA-NEXT: {((2 * (sext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body> Added Flags: <nusw>
; The expression for %mul_ext as analyzed by SCEV is
; i64 (sext i32 {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> to i64)
; We have added the nssw flag to turn this expression into the following SCEV:
; i64 {sext i32 (2 * (trunc i64 %N to i32)) to i64,+,-2}<%for.body>
; LV-LABEL: f4
; LV-LABEL: for.body.lver.check
; LV: [[PredCheck0:%[^ ]*]] = icmp ne i128
; LV: [[Or0:%[^ ]*]] = or i1 false, [[PredCheck0]]
; LV: [[PredCheck1:%[^ ]*]] = icmp ne i128
; LV: [[FinalCheck:%[^ ]*]] = or i1 [[Or0]], [[PredCheck1]]
; LV: br i1 [[FinalCheck]], label %for.body.ph.lver.orig, label %for.body.ph
define void @f4(i16* noalias %a,
i16* noalias %b, i64 %N) {
entry:
%TruncN = trunc i64 %N to i32
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%ind1 = phi i32 [ %TruncN, %entry ], [ %dec, %for.body ]
%mul = mul i32 %ind1, 2
%mul_ext = sext i32 %mul to i64
%arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext
%loadA = load i16, i16* %arrayidxA, align 2
%arrayidxB = getelementptr i16, i16* %b, i64 %ind
%loadB = load i16, i16* %arrayidxB, align 2
%add = mul i16 %loadA, %loadB
store i16 %add, i16* %arrayidxA, align 2
%inc = add nuw nsw i64 %ind, 1
%dec = sub i32 %ind1, 1
%exitcond = icmp eq i64 %inc, %N
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; The following function is similar to the one above, but has the GEP
; to pointer %A inbounds. The index %mul doesn't have the nsw flag.
; This means that the SCEV expression for %mul can wrap and we need
; a SCEV predicate to continue analysis.
;
; We can still analyze this by adding the required no wrap SCEV predicates.
; LAA-LABEL: f5
; LAA: Memory dependences are safe{{$}}
; LAA: SCEV assumptions:
; LAA-NEXT: {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> Added Flags: <nssw>
; LAA-NEXT: {((2 * (sext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body> Added Flags: <nusw>
; LV-LABEL: f5
; LV-LABEL: for.body.lver.check
define void @f5(i16* noalias %a,
i16* noalias %b, i64 %N) {
entry:
%TruncN = trunc i64 %N to i32
br label %for.body
for.body: ; preds = %for.body, %entry
%ind = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%ind1 = phi i32 [ %TruncN, %entry ], [ %dec, %for.body ]
%mul = mul i32 %ind1, 2
%arrayidxA = getelementptr inbounds i16, i16* %a, i32 %mul
%loadA = load i16, i16* %arrayidxA, align 2
%arrayidxB = getelementptr inbounds i16, i16* %b, i64 %ind
%loadB = load i16, i16* %arrayidxB, align 2
%add = mul i16 %loadA, %loadB
store i16 %add, i16* %arrayidxA, align 2
%inc = add nuw nsw i64 %ind, 1
%dec = sub i32 %ind1, 1
%exitcond = icmp eq i64 %inc, %N
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}

10
llvm/test/Transforms/LoopVectorize/same-base-access.ll
View File

@ -62,9 +62,11 @@ define i32 @kernel11(double* %x, double* %y, i32 %n) nounwind uwtable ssp {
}
; A[i*7] is scalarized, and the different scalars can in theory wrap
; around and overwrite other scalar elements. However we can still
; vectorize because we can version the loop to avoid this case.
; We don't vectorize this function because A[i*7] is scalarized, and the
; different scalars can in theory wrap around and overwrite other scalar
; elements. At the moment we only allow read/write access to arrays
; that are consecutive.
;
; void foo(int *a) {
; for (int i=0; i<256; ++i) {
@ -76,7 +78,7 @@ define i32 @kernel11(double* %x, double* %y, i32 %n) nounwind uwtable ssp {
; }
; CHECK-LABEL: @func2(
; CHECK: <4 x i32>
; CHECK-NOT: <4 x i32>
; CHECK: ret
define i32 @func2(i32* nocapture %a) nounwind uwtable ssp {
br label %1