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[SCEV] Use depth limit instead of local cache for SExt and ZExt

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In rL300494 there was an attempt to deal with excessive compile time on
invocations of getSign/ZeroExtExpr using local caching. This approach only
helps if we request the same SCEV multiple times throughout recursion. But
in the bug PR33431 we see a case where we request different values all the time,
so caching does not help and the size of the cache grows enormously.

In this patch we remove the local cache for this methods and add the recursion
depth limit instead, as we do for arithmetics. This gives us a guarantee that the
invocation sequence is limited and reasonably short.

Differential Revision: https://reviews.llvm.org/D34273

llvm-svn: 306785
This commit is contained in:
Max Kazantsev 2017-06-30 05:04:09 +00:00
parent 4db530fe97
commit 5cbed866a3
4 changed files with 183 additions and 144 deletions
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16
include/llvm/Analysis/ScalarEvolution.h
View File

@ -1197,20 +1197,8 @@ public:
const SCEV *getConstant(const APInt &Val);
const SCEV *getConstant(Type *Ty, uint64_t V, bool isSigned = false);
const SCEV *getTruncateExpr(const SCEV *Op, Type *Ty);
typedef SmallDenseMap<std::pair<const SCEV *, Type *>, const SCEV *, 8>
ExtendCacheTy;
const SCEV *getZeroExtendExpr(const SCEV *Op, Type *Ty);
const SCEV *getZeroExtendExprCached(const SCEV *Op, Type *Ty,
ExtendCacheTy &Cache);
const SCEV *getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
ExtendCacheTy &Cache);
const SCEV *getSignExtendExpr(const SCEV *Op, Type *Ty);
const SCEV *getSignExtendExprCached(const SCEV *Op, Type *Ty,
ExtendCacheTy &Cache);
const SCEV *getSignExtendExprImpl(const SCEV *Op, Type *Ty,
ExtendCacheTy &Cache);
const SCEV *getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth = 0);
const SCEV *getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth = 0);
const SCEV *getAnyExtendExpr(const SCEV *Op, Type *Ty);
const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap,

243
lib/Analysis/ScalarEvolution.cpp
View File

@ -157,6 +157,11 @@ static cl::opt<unsigned> MaxConstantEvolvingDepth(
"scalar-evolution-max-constant-evolving-depth", cl::Hidden,
cl::desc("Maximum depth of recursive constant evolving"), cl::init(32));
static cl::opt<unsigned>
MaxExtDepth("scalar-evolution-max-ext-depth", cl::Hidden,
cl::desc("Maximum depth of recursive SExt/ZExt"),
cl::init(8));
//===----------------------------------------------------------------------===//
// SCEV class definitions
//===----------------------------------------------------------------------===//
@ -1285,8 +1290,8 @@ static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
namespace {
struct ExtendOpTraitsBase {
typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(
const SCEV *, Type *, ScalarEvolution::ExtendCacheTy &Cache);
typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *,
unsigned);
};
// Used to make code generic over signed and unsigned overflow.
@ -1315,9 +1320,8 @@ struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
}
};
const ExtendOpTraitsBase::GetExtendExprTy
ExtendOpTraits<SCEVSignExtendExpr>::GetExtendExpr =
&ScalarEvolution::getSignExtendExprCached;
const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
template <>
struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
@ -1332,9 +1336,8 @@ struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
}
};
const ExtendOpTraitsBase::GetExtendExprTy
ExtendOpTraits<SCEVZeroExtendExpr>::GetExtendExpr =
&ScalarEvolution::getZeroExtendExprCached;
const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
}
// The recurrence AR has been shown to have no signed/unsigned wrap or something
@ -1346,8 +1349,7 @@ const ExtendOpTraitsBase::GetExtendExprTy
// "sext/zext(PostIncAR)"
template <typename ExtendOpTy>
static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
ScalarEvolution *SE,
ScalarEvolution::ExtendCacheTy &Cache) {
ScalarEvolution *SE, unsigned Depth) {
auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
@ -1394,9 +1396,9 @@ static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
const SCEV *OperandExtendedStart =
SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Cache),
(SE->*GetExtendExpr)(Step, WideTy, Cache));
if ((SE->*GetExtendExpr)(Start, WideTy, Cache) == OperandExtendedStart) {
SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth),
(SE->*GetExtendExpr)(Step, WideTy, Depth));
if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) {
if (PreAR && AR->getNoWrapFlags(WrapType)) {
// If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
// or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
@ -1422,16 +1424,16 @@ static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
template <typename ExtendOpTy>
static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
ScalarEvolution *SE,
ScalarEvolution::ExtendCacheTy &Cache) {
unsigned Depth) {
auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Cache);
const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth);
if (!PreStart)
return (SE->*GetExtendExpr)(AR->getStart(), Ty, Cache);
return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth);
return SE->getAddExpr(
(SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty, Cache),
(SE->*GetExtendExpr)(PreStart, Ty, Cache));
return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty,
Depth),
(SE->*GetExtendExpr)(PreStart, Ty, Depth));
}
// Try to prove away overflow by looking at "nearby" add recurrences. A
@ -1511,31 +1513,8 @@ bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
return false;
}
const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty) {
// Use the local cache to prevent exponential behavior of
// getZeroExtendExprImpl.
ExtendCacheTy Cache;
return getZeroExtendExprCached(Op, Ty, Cache);
}
/// Query \p Cache before calling getZeroExtendExprImpl. If there is no
/// related entry in the \p Cache, call getZeroExtendExprImpl and save
/// the result in the \p Cache.
const SCEV *ScalarEvolution::getZeroExtendExprCached(const SCEV *Op, Type *Ty,
ExtendCacheTy &Cache) {
auto It = Cache.find({Op, Ty});
if (It != Cache.end())
return It->second;
const SCEV *ZExt = getZeroExtendExprImpl(Op, Ty, Cache);
auto InsertResult = Cache.insert({{Op, Ty}, ZExt});
assert(InsertResult.second && "Expect the key was not in the cache");
(void)InsertResult;
return ZExt;
}
/// The real implementation of getZeroExtendExpr.
const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
ExtendCacheTy &Cache) {
const SCEV *
ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
"This is not an extending conversion!");
assert(isSCEVable(Ty) &&
@ -1545,11 +1524,11 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
// Fold if the operand is constant.
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
return getConstant(
cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
// zext(zext(x)) --> zext(x)
if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
return getZeroExtendExprCached(SZ->getOperand(), Ty, Cache);
return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
// Before doing any expensive analysis, check to see if we've already
// computed a SCEV for this Op and Ty.
@ -1559,6 +1538,12 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
ID.AddPointer(Ty);
void *IP = nullptr;
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
if (Depth > MaxExtDepth) {
SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
Op, Ty);
UniqueSCEVs.InsertNode(S, IP);
return S;
}
// zext(trunc(x)) --> zext(x) or x or trunc(x)
if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
@ -1593,8 +1578,8 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
// we don't need to do any further analysis.
if (AR->hasNoUnsignedWrap())
return getAddRecExpr(
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
getZeroExtendExprCached(Step, Ty, Cache), L, AR->getNoWrapFlags());
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
// Check whether the backedge-taken count is SCEVCouldNotCompute.
// Note that this serves two purposes: It filters out loops that are
@ -1618,22 +1603,29 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
if (MaxBECount == RecastedMaxBECount) {
Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
// Check whether Start+Step*MaxBECount has no unsigned overflow.
const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step);
const SCEV *ZAdd =
getZeroExtendExprCached(getAddExpr(Start, ZMul), WideTy, Cache);
const SCEV *WideStart = getZeroExtendExprCached(Start, WideTy, Cache);
const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step,
SCEV::FlagAnyWrap, Depth + 1);
const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul,
SCEV::FlagAnyWrap,
Depth + 1),
WideTy, Depth + 1);
const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1);
const SCEV *WideMaxBECount =
getZeroExtendExprCached(CastedMaxBECount, WideTy, Cache);
const SCEV *OperandExtendedAdd = getAddExpr(
WideStart, getMulExpr(WideMaxBECount, getZeroExtendExprCached(
Step, WideTy, Cache)));
getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
const SCEV *OperandExtendedAdd =
getAddExpr(WideStart,
getMulExpr(WideMaxBECount,
getZeroExtendExpr(Step, WideTy, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1);
if (ZAdd == OperandExtendedAdd) {
// Cache knowledge of AR NUW, which is propagated to this AddRec.
const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
getZeroExtendExprCached(Step, Ty, Cache), L,
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
Depth + 1),
getZeroExtendExpr(Step, Ty, Depth + 1), L,
AR->getNoWrapFlags());
}
// Similar to above, only this time treat the step value as signed.
@ -1641,15 +1633,19 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
OperandExtendedAdd =
getAddExpr(WideStart,
getMulExpr(WideMaxBECount,
getSignExtendExpr(Step, WideTy)));
getSignExtendExpr(Step, WideTy, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1);
if (ZAdd == OperandExtendedAdd) {
// Cache knowledge of AR NW, which is propagated to this AddRec.
// Negative step causes unsigned wrap, but it still can't self-wrap.
const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
Depth + 1),
getSignExtendExpr(Step, Ty, Depth + 1), L,
AR->getNoWrapFlags());
}
}
}
@ -1680,8 +1676,9 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
getZeroExtendExprCached(Step, Ty, Cache), L,
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
Depth + 1),
getZeroExtendExpr(Step, Ty, Depth + 1), L,
AR->getNoWrapFlags());
}
} else if (isKnownNegative(Step)) {
@ -1697,8 +1694,10 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
Depth + 1),
getSignExtendExpr(Step, Ty, Depth + 1), L,
AR->getNoWrapFlags());
}
}
}
@ -1706,8 +1705,8 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
return getAddRecExpr(
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
getZeroExtendExprCached(Step, Ty, Cache), L, AR->getNoWrapFlags());
getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
}
}
@ -1718,8 +1717,8 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
// commute the zero extension with the addition operation.
SmallVector<const SCEV *, 4> Ops;
for (const auto *Op : SA->operands())
Ops.push_back(getZeroExtendExprCached(Op, Ty, Cache));
return getAddExpr(Ops, SCEV::FlagNUW);
Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1);
}
}
@ -1732,31 +1731,8 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
return S;
}
const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty) {
// Use the local cache to prevent exponential behavior of
// getSignExtendExprImpl.
ExtendCacheTy Cache;
return getSignExtendExprCached(Op, Ty, Cache);
}
/// Query \p Cache before calling getSignExtendExprImpl. If there is no
/// related entry in the \p Cache, call getSignExtendExprImpl and save
/// the result in the \p Cache.
const SCEV *ScalarEvolution::getSignExtendExprCached(const SCEV *Op, Type *Ty,
ExtendCacheTy &Cache) {
auto It = Cache.find({Op, Ty});
if (It != Cache.end())
return It->second;
const SCEV *SExt = getSignExtendExprImpl(Op, Ty, Cache);
auto InsertResult = Cache.insert({{Op, Ty}, SExt});
assert(InsertResult.second && "Expect the key was not in the cache");
(void)InsertResult;
return SExt;
}
/// The real implementation of getSignExtendExpr.
const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
ExtendCacheTy &Cache) {
const SCEV *
ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
"This is not an extending conversion!");
assert(isSCEVable(Ty) &&
@ -1766,15 +1742,15 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
// Fold if the operand is constant.
if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
return getConstant(
cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
// sext(sext(x)) --> sext(x)
if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
return getSignExtendExprCached(SS->getOperand(), Ty, Cache);
return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1);
// sext(zext(x)) --> zext(x)
if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
return getZeroExtendExpr(SZ->getOperand(), Ty);
return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
// Before doing any expensive analysis, check to see if we've already
// computed a SCEV for this Op and Ty.
@ -1784,6 +1760,13 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
ID.AddPointer(Ty);
void *IP = nullptr;
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
// Limit recursion depth.
if (Depth > MaxExtDepth) {
SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
Op, Ty);
UniqueSCEVs.InsertNode(S, IP);
return S;
}
// sext(trunc(x)) --> sext(x) or x or trunc(x)
if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
@ -1809,8 +1792,9 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
const APInt &C2 = SC2->getAPInt();
if (C1.isStrictlyPositive() && C2.isStrictlyPositive() &&
C2.ugt(C1) && C2.isPowerOf2())
return getAddExpr(getSignExtendExprCached(SC1, Ty, Cache),
getSignExtendExprCached(SMul, Ty, Cache));
return getAddExpr(getSignExtendExpr(SC1, Ty, Depth + 1),
getSignExtendExpr(SMul, Ty, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1);
}
}
}
@ -1821,8 +1805,8 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
// commute the sign extension with the addition operation.
SmallVector<const SCEV *, 4> Ops;
for (const auto *Op : SA->operands())
Ops.push_back(getSignExtendExprCached(Op, Ty, Cache));
return getAddExpr(Ops, SCEV::FlagNSW);
Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1));
return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1);
}
}
// If the input value is a chrec scev, and we can prove that the value
@ -1845,8 +1829,8 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
// we don't need to do any further analysis.
if (AR->hasNoSignedWrap())
return getAddRecExpr(
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
getSignExtendExprCached(Step, Ty, Cache), L, SCEV::FlagNSW);
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW);
// Check whether the backedge-taken count is SCEVCouldNotCompute.
// Note that this serves two purposes: It filters out loops that are
@ -1870,22 +1854,29 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
if (MaxBECount == RecastedMaxBECount) {
Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
// Check whether Start+Step*MaxBECount has no signed overflow.
const SCEV *SMul = getMulExpr(CastedMaxBECount, Step);
const SCEV *SAdd =
getSignExtendExprCached(getAddExpr(Start, SMul), WideTy, Cache);
const SCEV *WideStart = getSignExtendExprCached(Start, WideTy, Cache);
const SCEV *SMul = getMulExpr(CastedMaxBECount, Step,
SCEV::FlagAnyWrap, Depth + 1);
const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul,
SCEV::FlagAnyWrap,
Depth + 1),
WideTy, Depth + 1);
const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1);
const SCEV *WideMaxBECount =
getZeroExtendExpr(CastedMaxBECount, WideTy);
const SCEV *OperandExtendedAdd = getAddExpr(
WideStart, getMulExpr(WideMaxBECount, getSignExtendExprCached(
Step, WideTy, Cache)));
getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
const SCEV *OperandExtendedAdd =
getAddExpr(WideStart,
getMulExpr(WideMaxBECount,
getSignExtendExpr(Step, WideTy, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1);
if (SAdd == OperandExtendedAdd) {
// Cache knowledge of AR NSW, which is propagated to this AddRec.
const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
// Return the expression with the addrec on the outside.
return getAddRecExpr(
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
getSignExtendExprCached(Step, Ty, Cache), L,
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
Depth + 1),
getSignExtendExpr(Step, Ty, Depth + 1), L,
AR->getNoWrapFlags());
}
// Similar to above, only this time treat the step value as unsigned.
@ -1893,7 +1884,9 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
OperandExtendedAdd =
getAddExpr(WideStart,
getMulExpr(WideMaxBECount,
getZeroExtendExpr(Step, WideTy)));
getZeroExtendExpr(Step, WideTy, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1);
if (SAdd == OperandExtendedAdd) {
// If AR wraps around then
//
@ -1907,8 +1900,10 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
// Return the expression with the addrec on the outside.
return getAddRecExpr(
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
Depth + 1),
getZeroExtendExpr(Step, Ty, Depth + 1), L,
AR->getNoWrapFlags());
}
}
}
@ -1939,9 +1934,8 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
// Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
return getAddRecExpr(
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
getSignExtendExprCached(Step, Ty, Cache), L,
AR->getNoWrapFlags());
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
}
}
@ -1955,25 +1949,26 @@ const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
const APInt &C2 = SC2->getAPInt();
if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) &&
C2.isPowerOf2()) {
Start = getSignExtendExprCached(Start, Ty, Cache);
Start = getSignExtendExpr(Start, Ty, Depth + 1);
const SCEV *NewAR = getAddRecExpr(getZero(AR->getType()), Step, L,
AR->getNoWrapFlags());
return getAddExpr(Start, getSignExtendExprCached(NewAR, Ty, Cache));
return getAddExpr(Start, getSignExtendExpr(NewAR, Ty, Depth + 1),
SCEV::FlagAnyWrap, Depth + 1);
}
}
if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
return getAddRecExpr(
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
getSignExtendExprCached(Step, Ty, Cache), L, AR->getNoWrapFlags());
getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
}
}
// If the input value is provably positive and we could not simplify
// away the sext build a zext instead.
if (isKnownNonNegative(Op))
return getZeroExtendExpr(Op, Ty);
return getZeroExtendExpr(Op, Ty, Depth + 1);
// The cast wasn't folded; create an explicit cast node.
// Recompute the insert position, as it may have been invalidated.

10
lib/Transforms/Utils/SimplifyIndVar.cpp
View File

@ -354,7 +354,7 @@ bool SimplifyIndvar::eliminateOverflowIntrinsic(CallInst *CI) {
typedef const SCEV *(ScalarEvolution::*OperationFunctionTy)(
const SCEV *, const SCEV *, SCEV::NoWrapFlags, unsigned);
typedef const SCEV *(ScalarEvolution::*ExtensionFunctionTy)(
const SCEV *, Type *);
const SCEV *, Type *, unsigned);
OperationFunctionTy Operation;
ExtensionFunctionTy Extension;
@ -406,11 +406,11 @@ bool SimplifyIndvar::eliminateOverflowIntrinsic(CallInst *CI) {
IntegerType::get(NarrowTy->getContext(), NarrowTy->getBitWidth() * 2);
const SCEV *A =
(SE->*Extension)((SE->*Operation)(LHS, RHS, SCEV::FlagAnyWrap, 0u),
WideTy);
(SE->*Extension)((SE->*Operation)(LHS, RHS, SCEV::FlagAnyWrap, 0),
WideTy, 0);
const SCEV *B =
(SE->*Operation)((SE->*Extension)(LHS, WideTy),
(SE->*Extension)(RHS, WideTy), SCEV::FlagAnyWrap, 0u);
(SE->*Operation)((SE->*Extension)(LHS, WideTy, 0),
(SE->*Extension)(RHS, WideTy, 0), SCEV::FlagAnyWrap, 0);
if (A != B)
return false;

58
test/Analysis/ScalarEvolution/limit-depth.ll
View File

@ -1,4 +1,4 @@
; RUN: opt -scalar-evolution-max-arith-depth=0 -analyze -scalar-evolution < %s | FileCheck %s
; RUN: opt -scalar-evolution-max-arith-depth=0 -scalar-evolution-max-ext-depth=0 -analyze -scalar-evolution < %s | FileCheck %s
; Check that depth set to 0 prevents getAddExpr and getMulExpr from making
; transformations in SCEV. We expect the result to be very straightforward.
@ -42,3 +42,59 @@ define void @test_mul(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f) {
%s2 = mul i32 %s1, %p3
ret void
}
define void @test_sext(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f) {
; CHECK-LABEL: @test_sext
; CHECK: %se2 = sext i64 %iv2.inc to i128
; CHECK-NEXT: --> {(1 + (sext i64 {(sext i32 (1 + %a) to i64),+,1}<nsw><%loop> to i128))<nsw>,+,1}<nsw><%loop2>
entry:
br label %loop
loop:
%iv = phi i32 [ %a, %entry ], [ %iv.inc, %loop ]
%iv.inc = add nsw i32 %iv, 1
%cond = icmp sle i32 %iv.inc, 50
br i1 %cond, label %loop, label %between
between:
%se = sext i32 %iv.inc to i64
br label %loop2
loop2:
%iv2 = phi i64 [ %se, %between ], [ %iv2.inc, %loop2 ]
%iv2.inc = add nsw i64 %iv2, 1
%cond2 = icmp sle i64 %iv2.inc, 50
br i1 %cond2, label %loop2, label %exit
exit:
%se2 = sext i64 %iv2.inc to i128
ret void
}
define void @test_zext(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f) {
; CHECK-LABEL: @test_zext
; CHECK: %ze2 = zext i64 %iv2.inc to i128
; CHECK-NEXT: --> {(1 + (zext i64 {7,+,1}<nuw><nsw><%loop> to i128))<nuw><nsw>,+,1}<nuw><%loop2>
entry:
br label %loop
loop:
%iv = phi i32 [ 6, %entry ], [ %iv.inc, %loop ]
%iv.inc = add nsw i32 %iv, 1
%cond = icmp sle i32 %iv.inc, 50
br i1 %cond, label %loop, label %between
between:
%ze = zext i32 %iv.inc to i64
br label %loop2
loop2:
%iv2 = phi i64 [ %ze, %between ], [ %iv2.inc, %loop2 ]
%iv2.inc = add nuw i64 %iv2, 1
%cond2 = icmp sle i64 %iv2.inc, 50
br i1 %cond2, label %loop2, label %exit
exit:
%ze2 = zext i64 %iv2.inc to i128
ret void
}