cl::desc("Maximum factor for an interleaved access group (default = 8)"),
cl::init(8));
-/// We don't unroll loops with a known constant trip count below this number.
-static const unsigned TinyTripCountUnrollThreshold = 128;
+/// We don't interleave loops with a known constant trip count below this
+/// number.
+static const unsigned TinyTripCountInterleaveThreshold = 128;
static cl::opt<unsigned> ForceTargetNumScalarRegs(
"force-target-num-scalar-regs", cl::init(0), cl::Hidden,
static cl::opt<unsigned> SmallLoopCost(
"small-loop-cost", cl::init(20), cl::Hidden,
- cl::desc("The cost of a loop that is considered 'small' by the unroller."));
+ cl::desc(
+ "The cost of a loop that is considered 'small' by the interleaver."));
static cl::opt<bool> LoopVectorizeWithBlockFrequency(
"loop-vectorize-with-block-frequency", cl::init(false), cl::Hidden,
"heuristics minimizing code growth in cold regions and being more "
"aggressive in hot regions."));
-// Runtime unroll loops for load/store throughput.
-static cl::opt<bool> EnableLoadStoreRuntimeUnroll(
- "enable-loadstore-runtime-unroll", cl::init(true), cl::Hidden,
- cl::desc("Enable runtime unrolling until load/store ports are saturated"));
+// Runtime interleave loops for load/store throughput.
+static cl::opt<bool> EnableLoadStoreRuntimeInterleave(
+ "enable-loadstore-runtime-interleave", cl::init(true), cl::Hidden,
+ cl::desc(
+ "Enable runtime interleaving until load/store ports are saturated"));
/// The number of stores in a loop that are allowed to need predication.
static cl::opt<unsigned> NumberOfStoresToPredicate(
static cl::opt<bool> EnableIndVarRegisterHeur(
"enable-ind-var-reg-heur", cl::init(true), cl::Hidden,
- cl::desc("Count the induction variable only once when unrolling"));
+ cl::desc("Count the induction variable only once when interleaving"));
static cl::opt<bool> EnableCondStoresVectorization(
"enable-cond-stores-vec", cl::init(false), cl::Hidden,
cl::desc("Enable if predication of stores during vectorization."));
-static cl::opt<unsigned> MaxNestedScalarReductionUF(
- "max-nested-scalar-reduction-unroll", cl::init(2), cl::Hidden,
- cl::desc("The maximum unroll factor to use when unrolling a scalar "
+static cl::opt<unsigned> MaxNestedScalarReductionIC(
+ "max-nested-scalar-reduction-interleave", cl::init(2), cl::Hidden,
+ cl::desc("The maximum interleave count to use when interleaving a scalar "
"reduction in a nested loop."));
namespace {
// Forward declarations.
+class LoopVectorizeHints;
class LoopVectorizationLegality;
class LoopVectorizationCostModel;
-class LoopVectorizeHints;
+class LoopVectorizationRequirements;
/// \brief This modifies LoopAccessReport to initialize message with
/// loop-vectorizer-specific part.
const ValueToValueMap &Strides);
};
+/// Utility class for getting and setting loop vectorizer hints in the form
+/// of loop metadata.
+/// This class keeps a number of loop annotations locally (as member variables)
+/// and can, upon request, write them back as metadata on the loop. It will
+/// initially scan the loop for existing metadata, and will update the local
+/// values based on information in the loop.
+/// We cannot write all values to metadata, as the mere presence of some info,
+/// for example 'force', means a decision has been made. So, we need to be
+/// careful NOT to add them if the user hasn't specifically asked so.
+class LoopVectorizeHints {
+ enum HintKind {
+ HK_WIDTH,
+ HK_UNROLL,
+ HK_FORCE
+ };
+
+ /// Hint - associates name and validation with the hint value.
+ struct Hint {
+ const char * Name;
+ unsigned Value; // This may have to change for non-numeric values.
+ HintKind Kind;
+
+ Hint(const char * Name, unsigned Value, HintKind Kind)
+ : Name(Name), Value(Value), Kind(Kind) { }
+
+ bool validate(unsigned Val) {
+ switch (Kind) {
+ case HK_WIDTH:
+ return isPowerOf2_32(Val) && Val <= VectorizerParams::MaxVectorWidth;
+ case HK_UNROLL:
+ return isPowerOf2_32(Val) && Val <= MaxInterleaveFactor;
+ case HK_FORCE:
+ return (Val <= 1);
+ }
+ return false;
+ }
+ };
+
+ /// Vectorization width.
+ Hint Width;
+ /// Vectorization interleave factor.
+ Hint Interleave;
+ /// Vectorization forced
+ Hint Force;
+
+ /// Return the loop metadata prefix.
+ static StringRef Prefix() { return "llvm.loop."; }
+
+public:
+ enum ForceKind {
+ FK_Undefined = -1, ///< Not selected.
+ FK_Disabled = 0, ///< Forcing disabled.
+ FK_Enabled = 1, ///< Forcing enabled.
+ };
+
+ LoopVectorizeHints(const Loop *L, bool DisableInterleaving)
+ : Width("vectorize.width", VectorizerParams::VectorizationFactor,
+ HK_WIDTH),
+ Interleave("interleave.count", DisableInterleaving, HK_UNROLL),
+ Force("vectorize.enable", FK_Undefined, HK_FORCE),
+ TheLoop(L) {
+ // Populate values with existing loop metadata.
+ getHintsFromMetadata();
+
+ // force-vector-interleave overrides DisableInterleaving.
+ if (VectorizerParams::isInterleaveForced())
+ Interleave.Value = VectorizerParams::VectorizationInterleave;
+
+ DEBUG(if (DisableInterleaving && Interleave.Value == 1) dbgs()
+ << "LV: Interleaving disabled by the pass manager\n");
+ }
+
+ /// Mark the loop L as already vectorized by setting the width to 1.
+ void setAlreadyVectorized() {
+ Width.Value = Interleave.Value = 1;
+ Hint Hints[] = {Width, Interleave};
+ writeHintsToMetadata(Hints);
+ }
+
+ bool allowVectorization(Function *F, Loop *L, bool AlwaysVectorize) const {
+ if (getForce() == LoopVectorizeHints::FK_Disabled) {
+ DEBUG(dbgs() << "LV: Not vectorizing: #pragma vectorize disable.\n");
+ emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F,
+ L->getStartLoc(), emitRemark());
+ return false;
+ }
+
+ if (!AlwaysVectorize && getForce() != LoopVectorizeHints::FK_Enabled) {
+ DEBUG(dbgs() << "LV: Not vectorizing: No #pragma vectorize enable.\n");
+ emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F,
+ L->getStartLoc(), emitRemark());
+ return false;
+ }
+
+ if (getWidth() == 1 && getInterleave() == 1) {
+ // FIXME: Add a separate metadata to indicate when the loop has already
+ // been vectorized instead of setting width and count to 1.
+ DEBUG(dbgs() << "LV: Not vectorizing: Disabled/already vectorized.\n");
+ // FIXME: Add interleave.disable metadata. This will allow
+ // vectorize.disable to be used without disabling the pass and errors
+ // to differentiate between disabled vectorization and a width of 1.
+ emitOptimizationRemarkAnalysis(
+ F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
+ "loop not vectorized: vectorization and interleaving are explicitly "
+ "disabled, or vectorize width and interleave count are both set to "
+ "1");
+ return false;
+ }
+
+ return true;
+ }
+
+ /// Dumps all the hint information.
+ std::string emitRemark() const {
+ VectorizationReport R;
+ if (Force.Value == LoopVectorizeHints::FK_Disabled)
+ R << "vectorization is explicitly disabled";
+ else {
+ R << "use -Rpass-analysis=loop-vectorize for more info";
+ if (Force.Value == LoopVectorizeHints::FK_Enabled) {
+ R << " (Force=true";
+ if (Width.Value != 0)
+ R << ", Vector Width=" << Width.Value;
+ if (Interleave.Value != 0)
+ R << ", Interleave Count=" << Interleave.Value;
+ R << ")";
+ }
+ }
+
+ return R.str();
+ }
+
+ unsigned getWidth() const { return Width.Value; }
+ unsigned getInterleave() const { return Interleave.Value; }
+ enum ForceKind getForce() const { return (ForceKind)Force.Value; }
+ bool isForced() const {
+ return getForce() == LoopVectorizeHints::FK_Enabled || getWidth() > 1 ||
+ getInterleave() > 1;
+ }
+
+private:
+ /// Find hints specified in the loop metadata and update local values.
+ void getHintsFromMetadata() {
+ MDNode *LoopID = TheLoop->getLoopID();
+ if (!LoopID)
+ return;
+
+ // First operand should refer to the loop id itself.
+ assert(LoopID->getNumOperands() > 0 && "requires at least one operand");
+ assert(LoopID->getOperand(0) == LoopID && "invalid loop id");
+
+ for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
+ const MDString *S = nullptr;
+ SmallVector<Metadata *, 4> Args;
+
+ // The expected hint is either a MDString or a MDNode with the first
+ // operand a MDString.
+ if (const MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i))) {
+ if (!MD || MD->getNumOperands() == 0)
+ continue;
+ S = dyn_cast<MDString>(MD->getOperand(0));
+ for (unsigned i = 1, ie = MD->getNumOperands(); i < ie; ++i)
+ Args.push_back(MD->getOperand(i));
+ } else {
+ S = dyn_cast<MDString>(LoopID->getOperand(i));
+ assert(Args.size() == 0 && "too many arguments for MDString");
+ }
+
+ if (!S)
+ continue;
+
+ // Check if the hint starts with the loop metadata prefix.
+ StringRef Name = S->getString();
+ if (Args.size() == 1)
+ setHint(Name, Args[0]);
+ }
+ }
+
+ /// Checks string hint with one operand and set value if valid.
+ void setHint(StringRef Name, Metadata *Arg) {
+ if (!Name.startswith(Prefix()))
+ return;
+ Name = Name.substr(Prefix().size(), StringRef::npos);
+
+ const ConstantInt *C = mdconst::dyn_extract<ConstantInt>(Arg);
+ if (!C) return;
+ unsigned Val = C->getZExtValue();
+
+ Hint *Hints[] = {&Width, &Interleave, &Force};
+ for (auto H : Hints) {
+ if (Name == H->Name) {
+ if (H->validate(Val))
+ H->Value = Val;
+ else
+ DEBUG(dbgs() << "LV: ignoring invalid hint '" << Name << "'\n");
+ break;
+ }
+ }
+ }
+
+ /// Create a new hint from name / value pair.
+ MDNode *createHintMetadata(StringRef Name, unsigned V) const {
+ LLVMContext &Context = TheLoop->getHeader()->getContext();
+ Metadata *MDs[] = {MDString::get(Context, Name),
+ ConstantAsMetadata::get(
+ ConstantInt::get(Type::getInt32Ty(Context), V))};
+ return MDNode::get(Context, MDs);
+ }
+
+ /// Matches metadata with hint name.
+ bool matchesHintMetadataName(MDNode *Node, ArrayRef<Hint> HintTypes) {
+ MDString* Name = dyn_cast<MDString>(Node->getOperand(0));
+ if (!Name)
+ return false;
+
+ for (auto H : HintTypes)
+ if (Name->getString().endswith(H.Name))
+ return true;
+ return false;
+ }
+
+ /// Sets current hints into loop metadata, keeping other values intact.
+ void writeHintsToMetadata(ArrayRef<Hint> HintTypes) {
+ if (HintTypes.size() == 0)
+ return;
+
+ // Reserve the first element to LoopID (see below).
+ SmallVector<Metadata *, 4> MDs(1);
+ // If the loop already has metadata, then ignore the existing operands.
+ MDNode *LoopID = TheLoop->getLoopID();
+ if (LoopID) {
+ for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
+ MDNode *Node = cast<MDNode>(LoopID->getOperand(i));
+ // If node in update list, ignore old value.
+ if (!matchesHintMetadataName(Node, HintTypes))
+ MDs.push_back(Node);
+ }
+ }
+
+ // Now, add the missing hints.
+ for (auto H : HintTypes)
+ MDs.push_back(createHintMetadata(Twine(Prefix(), H.Name).str(), H.Value));
+
+ // Replace current metadata node with new one.
+ LLVMContext &Context = TheLoop->getHeader()->getContext();
+ MDNode *NewLoopID = MDNode::get(Context, MDs);
+ // Set operand 0 to refer to the loop id itself.
+ NewLoopID->replaceOperandWith(0, NewLoopID);
+
+ TheLoop->setLoopID(NewLoopID);
+ }
+
+ /// The loop these hints belong to.
+ const Loop *TheLoop;
+};
+
+static void emitAnalysisDiag(const Function *TheFunction, const Loop *TheLoop,
+ const LoopVectorizeHints &Hints,
+ const LoopAccessReport &Message) {
+ // If a loop hint is provided the diagnostic is always produced.
+ const char *Name = Hints.isForced() ? DiagnosticInfo::AlwaysPrint : LV_NAME;
+ LoopAccessReport::emitAnalysis(Message, TheFunction, TheLoop, Name);
+}
+
+static void emitMissedWarning(Function *F, Loop *L,
+ const LoopVectorizeHints &LH) {
+ emitOptimizationRemarkMissed(F->getContext(), DEBUG_TYPE, *F,
+ L->getStartLoc(), LH.emitRemark());
+
+ if (LH.getForce() == LoopVectorizeHints::FK_Enabled) {
+ if (LH.getWidth() != 1)
+ emitLoopVectorizeWarning(
+ F->getContext(), *F, L->getStartLoc(),
+ "failed explicitly specified loop vectorization");
+ else if (LH.getInterleave() != 1)
+ emitLoopInterleaveWarning(
+ F->getContext(), *F, L->getStartLoc(),
+ "failed explicitly specified loop interleaving");
+ }
+}
+
/// LoopVectorizationLegality checks if it is legal to vectorize a loop, and
/// to what vectorization factor.
/// This class does not look at the profitability of vectorization, only the
LoopVectorizationLegality(Loop *L, ScalarEvolution *SE, DominatorTree *DT,
TargetLibraryInfo *TLI, AliasAnalysis *AA,
Function *F, const TargetTransformInfo *TTI,
- LoopAccessAnalysis *LAA)
+ LoopAccessAnalysis *LAA,
+ LoopVectorizationRequirements *R,
+ const LoopVectorizeHints *H)
: NumPredStores(0), TheLoop(L), SE(SE), TLI(TLI), TheFunction(F),
TTI(TTI), DT(DT), LAA(LAA), LAI(nullptr), InterleaveInfo(SE, L, DT),
- Induction(nullptr), WidestIndTy(nullptr), HasFunNoNaNAttr(false) {}
+ Induction(nullptr), WidestIndTy(nullptr), HasFunNoNaNAttr(false),
+ Requirements(R), Hints(H) {}
/// This enum represents the kinds of inductions that we support.
enum InductionKind {
bool isUniformAfterVectorization(Instruction* I) { return Uniforms.count(I); }
/// Returns the information that we collected about runtime memory check.
- const LoopAccessInfo::RuntimePointerCheck *getRuntimePointerCheck() const {
- return LAI->getRuntimePointerCheck();
+ const RuntimePointerChecking *getRuntimePointerChecking() const {
+ return LAI->getRuntimePointerChecking();
}
const LoopAccessInfo *getLAI() const {
/// not vectorized. These are handled as LoopAccessReport rather than
/// VectorizationReport because the << operator of VectorizationReport returns
/// LoopAccessReport.
- void emitAnalysis(const LoopAccessReport &Message) {
- LoopAccessReport::emitAnalysis(Message, TheFunction, TheLoop, LV_NAME);
+ void emitAnalysis(const LoopAccessReport &Message) const {
+ emitAnalysisDiag(TheFunction, TheLoop, *Hints, Message);
}
unsigned NumPredStores;
/// Can we assume the absence of NaNs.
bool HasFunNoNaNAttr;
+ /// Vectorization requirements that will go through late-evaluation.
+ LoopVectorizationRequirements *Requirements;
+
+ /// Used to emit an analysis of any legality issues.
+ const LoopVectorizeHints *Hints;
+
ValueToValueMap Strides;
SmallPtrSet<Value *, 8> StrideSet;
struct VectorizationFactor {
unsigned Width; // Vector width with best cost
unsigned Cost; // Cost of the loop with that width
- };
- /// \return The most profitable vectorization factor and the cost of that VF.
- /// This method checks every power of two up to VF. If UserVF is not ZERO
- /// then this vectorization factor will be selected if vectorization is
- /// possible.
- VectorizationFactor selectVectorizationFactor(bool OptForSize);
-
- /// \return The size (in bits) of the widest type in the code that
- /// needs to be vectorized. We ignore values that remain scalar such as
- /// 64 bit loop indices.
- unsigned getWidestType();
-
- /// \return The most profitable unroll factor.
- /// If UserUF is non-zero then this method finds the best unroll-factor
- /// based on register pressure and other parameters.
- /// VF and LoopCost are the selected vectorization factor and the cost of the
- /// selected VF.
- unsigned selectUnrollFactor(bool OptForSize, unsigned VF, unsigned LoopCost);
-
- /// \brief A struct that represents some properties of the register usage
- /// of a loop.
- struct RegisterUsage {
- /// Holds the number of loop invariant values that are used in the loop.
- unsigned LoopInvariantRegs;
- /// Holds the maximum number of concurrent live intervals in the loop.
- unsigned MaxLocalUsers;
- /// Holds the number of instructions in the loop.
- unsigned NumInstructions;
- };
-
- /// \return information about the register usage of the loop.
- RegisterUsage calculateRegisterUsage();
-
-private:
- /// Returns the expected execution cost. The unit of the cost does
- /// not matter because we use the 'cost' units to compare different
- /// vector widths. The cost that is returned is *not* normalized by
- /// the factor width.
- unsigned expectedCost(unsigned VF);
-
- /// Returns the execution time cost of an instruction for a given vector
- /// width. Vector width of one means scalar.
- unsigned getInstructionCost(Instruction *I, unsigned VF);
-
- /// Returns whether the instruction is a load or store and will be a emitted
- /// as a vector operation.
- bool isConsecutiveLoadOrStore(Instruction *I);
-
- /// Report an analysis message to assist the user in diagnosing loops that are
- /// not vectorized. These are handled as LoopAccessReport rather than
- /// VectorizationReport because the << operator of VectorizationReport returns
- /// LoopAccessReport.
- void emitAnalysis(const LoopAccessReport &Message) {
- LoopAccessReport::emitAnalysis(Message, TheFunction, TheLoop, LV_NAME);
- }
-
- /// Values used only by @llvm.assume calls.
- SmallPtrSet<const Value *, 32> EphValues;
-
- /// The loop that we evaluate.
- Loop *TheLoop;
- /// Scev analysis.
- ScalarEvolution *SE;
- /// Loop Info analysis.
- LoopInfo *LI;
- /// Vectorization legality.
- LoopVectorizationLegality *Legal;
- /// Vector target information.
- const TargetTransformInfo &TTI;
- /// Target Library Info.
- const TargetLibraryInfo *TLI;
- const Function *TheFunction;
- // Loop Vectorize Hint.
- const LoopVectorizeHints *Hints;
-};
-
-/// Utility class for getting and setting loop vectorizer hints in the form
-/// of loop metadata.
-/// This class keeps a number of loop annotations locally (as member variables)
-/// and can, upon request, write them back as metadata on the loop. It will
-/// initially scan the loop for existing metadata, and will update the local
-/// values based on information in the loop.
-/// We cannot write all values to metadata, as the mere presence of some info,
-/// for example 'force', means a decision has been made. So, we need to be
-/// careful NOT to add them if the user hasn't specifically asked so.
-class LoopVectorizeHints {
- enum HintKind {
- HK_WIDTH,
- HK_UNROLL,
- HK_FORCE
- };
-
- /// Hint - associates name and validation with the hint value.
- struct Hint {
- const char * Name;
- unsigned Value; // This may have to change for non-numeric values.
- HintKind Kind;
-
- Hint(const char * Name, unsigned Value, HintKind Kind)
- : Name(Name), Value(Value), Kind(Kind) { }
-
- bool validate(unsigned Val) {
- switch (Kind) {
- case HK_WIDTH:
- return isPowerOf2_32(Val) && Val <= VectorizerParams::MaxVectorWidth;
- case HK_UNROLL:
- return isPowerOf2_32(Val) && Val <= MaxInterleaveFactor;
- case HK_FORCE:
- return (Val <= 1);
- }
- return false;
- }
- };
-
- /// Vectorization width.
- Hint Width;
- /// Vectorization interleave factor.
- Hint Interleave;
- /// Vectorization forced
- Hint Force;
-
- /// Return the loop metadata prefix.
- static StringRef Prefix() { return "llvm.loop."; }
-
-public:
- enum ForceKind {
- FK_Undefined = -1, ///< Not selected.
- FK_Disabled = 0, ///< Forcing disabled.
- FK_Enabled = 1, ///< Forcing enabled.
- };
-
- LoopVectorizeHints(const Loop *L, bool DisableInterleaving)
- : Width("vectorize.width", VectorizerParams::VectorizationFactor,
- HK_WIDTH),
- Interleave("interleave.count", DisableInterleaving, HK_UNROLL),
- Force("vectorize.enable", FK_Undefined, HK_FORCE),
- TheLoop(L) {
- // Populate values with existing loop metadata.
- getHintsFromMetadata();
-
- // force-vector-interleave overrides DisableInterleaving.
- if (VectorizerParams::isInterleaveForced())
- Interleave.Value = VectorizerParams::VectorizationInterleave;
-
- DEBUG(if (DisableInterleaving && Interleave.Value == 1) dbgs()
- << "LV: Interleaving disabled by the pass manager\n");
- }
-
- /// Mark the loop L as already vectorized by setting the width to 1.
- void setAlreadyVectorized() {
- Width.Value = Interleave.Value = 1;
- Hint Hints[] = {Width, Interleave};
- writeHintsToMetadata(Hints);
- }
-
- /// Dumps all the hint information.
- std::string emitRemark() const {
- VectorizationReport R;
- if (Force.Value == LoopVectorizeHints::FK_Disabled)
- R << "vectorization is explicitly disabled";
- else {
- R << "use -Rpass-analysis=loop-vectorize for more info";
- if (Force.Value == LoopVectorizeHints::FK_Enabled) {
- R << " (Force=true";
- if (Width.Value != 0)
- R << ", Vector Width=" << Width.Value;
- if (Interleave.Value != 0)
- R << ", Interleave Count=" << Interleave.Value;
- R << ")";
- }
- }
-
- return R.str();
- }
-
- unsigned getWidth() const { return Width.Value; }
- unsigned getInterleave() const { return Interleave.Value; }
- enum ForceKind getForce() const { return (ForceKind)Force.Value; }
-
-private:
- /// Find hints specified in the loop metadata and update local values.
- void getHintsFromMetadata() {
- MDNode *LoopID = TheLoop->getLoopID();
- if (!LoopID)
- return;
+ };
+ /// \return The most profitable vectorization factor and the cost of that VF.
+ /// This method checks every power of two up to VF. If UserVF is not ZERO
+ /// then this vectorization factor will be selected if vectorization is
+ /// possible.
+ VectorizationFactor selectVectorizationFactor(bool OptForSize);
- // First operand should refer to the loop id itself.
- assert(LoopID->getNumOperands() > 0 && "requires at least one operand");
- assert(LoopID->getOperand(0) == LoopID && "invalid loop id");
+ /// \return The size (in bits) of the widest type in the code that
+ /// needs to be vectorized. We ignore values that remain scalar such as
+ /// 64 bit loop indices.
+ unsigned getWidestType();
- for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
- const MDString *S = nullptr;
- SmallVector<Metadata *, 4> Args;
+ /// \return The desired interleave count.
+ /// If interleave count has been specified by metadata it will be returned.
+ /// Otherwise, the interleave count is computed and returned. VF and LoopCost
+ /// are the selected vectorization factor and the cost of the selected VF.
+ unsigned selectInterleaveCount(bool OptForSize, unsigned VF,
+ unsigned LoopCost);
- // The expected hint is either a MDString or a MDNode with the first
- // operand a MDString.
- if (const MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i))) {
- if (!MD || MD->getNumOperands() == 0)
- continue;
- S = dyn_cast<MDString>(MD->getOperand(0));
- for (unsigned i = 1, ie = MD->getNumOperands(); i < ie; ++i)
- Args.push_back(MD->getOperand(i));
- } else {
- S = dyn_cast<MDString>(LoopID->getOperand(i));
- assert(Args.size() == 0 && "too many arguments for MDString");
- }
+ /// \return The most profitable unroll factor.
+ /// This method finds the best unroll-factor based on register pressure and
+ /// other parameters. VF and LoopCost are the selected vectorization factor
+ /// and the cost of the selected VF.
+ unsigned computeInterleaveCount(bool OptForSize, unsigned VF,
+ unsigned LoopCost);
- if (!S)
- continue;
+ /// \brief A struct that represents some properties of the register usage
+ /// of a loop.
+ struct RegisterUsage {
+ /// Holds the number of loop invariant values that are used in the loop.
+ unsigned LoopInvariantRegs;
+ /// Holds the maximum number of concurrent live intervals in the loop.
+ unsigned MaxLocalUsers;
+ /// Holds the number of instructions in the loop.
+ unsigned NumInstructions;
+ };
- // Check if the hint starts with the loop metadata prefix.
- StringRef Name = S->getString();
- if (Args.size() == 1)
- setHint(Name, Args[0]);
- }
- }
+ /// \return information about the register usage of the loop.
+ RegisterUsage calculateRegisterUsage();
- /// Checks string hint with one operand and set value if valid.
- void setHint(StringRef Name, Metadata *Arg) {
- if (!Name.startswith(Prefix()))
- return;
- Name = Name.substr(Prefix().size(), StringRef::npos);
+private:
+ /// Returns the expected execution cost. The unit of the cost does
+ /// not matter because we use the 'cost' units to compare different
+ /// vector widths. The cost that is returned is *not* normalized by
+ /// the factor width.
+ unsigned expectedCost(unsigned VF);
- const ConstantInt *C = mdconst::dyn_extract<ConstantInt>(Arg);
- if (!C) return;
- unsigned Val = C->getZExtValue();
+ /// Returns the execution time cost of an instruction for a given vector
+ /// width. Vector width of one means scalar.
+ unsigned getInstructionCost(Instruction *I, unsigned VF);
- Hint *Hints[] = {&Width, &Interleave, &Force};
- for (auto H : Hints) {
- if (Name == H->Name) {
- if (H->validate(Val))
- H->Value = Val;
- else
- DEBUG(dbgs() << "LV: ignoring invalid hint '" << Name << "'\n");
- break;
- }
- }
- }
+ /// Returns whether the instruction is a load or store and will be a emitted
+ /// as a vector operation.
+ bool isConsecutiveLoadOrStore(Instruction *I);
- /// Create a new hint from name / value pair.
- MDNode *createHintMetadata(StringRef Name, unsigned V) const {
- LLVMContext &Context = TheLoop->getHeader()->getContext();
- Metadata *MDs[] = {MDString::get(Context, Name),
- ConstantAsMetadata::get(
- ConstantInt::get(Type::getInt32Ty(Context), V))};
- return MDNode::get(Context, MDs);
+ /// Report an analysis message to assist the user in diagnosing loops that are
+ /// not vectorized. These are handled as LoopAccessReport rather than
+ /// VectorizationReport because the << operator of VectorizationReport returns
+ /// LoopAccessReport.
+ void emitAnalysis(const LoopAccessReport &Message) const {
+ emitAnalysisDiag(TheFunction, TheLoop, *Hints, Message);
}
- /// Matches metadata with hint name.
- bool matchesHintMetadataName(MDNode *Node, ArrayRef<Hint> HintTypes) {
- MDString* Name = dyn_cast<MDString>(Node->getOperand(0));
- if (!Name)
- return false;
-
- for (auto H : HintTypes)
- if (Name->getString().endswith(H.Name))
- return true;
- return false;
- }
+ /// Values used only by @llvm.assume calls.
+ SmallPtrSet<const Value *, 32> EphValues;
- /// Sets current hints into loop metadata, keeping other values intact.
- void writeHintsToMetadata(ArrayRef<Hint> HintTypes) {
- if (HintTypes.size() == 0)
- return;
+ /// The loop that we evaluate.
+ Loop *TheLoop;
+ /// Scev analysis.
+ ScalarEvolution *SE;
+ /// Loop Info analysis.
+ LoopInfo *LI;
+ /// Vectorization legality.
+ LoopVectorizationLegality *Legal;
+ /// Vector target information.
+ const TargetTransformInfo &TTI;
+ /// Target Library Info.
+ const TargetLibraryInfo *TLI;
+ const Function *TheFunction;
+ // Loop Vectorize Hint.
+ const LoopVectorizeHints *Hints;
+};
- // Reserve the first element to LoopID (see below).
- SmallVector<Metadata *, 4> MDs(1);
- // If the loop already has metadata, then ignore the existing operands.
- MDNode *LoopID = TheLoop->getLoopID();
- if (LoopID) {
- for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
- MDNode *Node = cast<MDNode>(LoopID->getOperand(i));
- // If node in update list, ignore old value.
- if (!matchesHintMetadataName(Node, HintTypes))
- MDs.push_back(Node);
- }
+/// \brief This holds vectorization requirements that must be verified late in
+/// the process. The requirements are set by legalize and costmodel. Once
+/// vectorization has been determined to be possible and profitable the
+/// requirements can be verified by looking for metadata or compiler options.
+/// For example, some loops require FP commutativity which is only allowed if
+/// vectorization is explicitly specified or if the fast-math compiler option
+/// has been provided.
+/// Late evaluation of these requirements allows helpful diagnostics to be
+/// composed that tells the user what need to be done to vectorize the loop. For
+/// example, by specifying #pragma clang loop vectorize or -ffast-math. Late
+/// evaluation should be used only when diagnostics can generated that can be
+/// followed by a non-expert user.
+class LoopVectorizationRequirements {
+public:
+ LoopVectorizationRequirements()
+ : NumRuntimePointerChecks(0), UnsafeAlgebraInst(nullptr) {}
+
+ void addUnsafeAlgebraInst(Instruction *I) {
+ // First unsafe algebra instruction.
+ if (!UnsafeAlgebraInst)
+ UnsafeAlgebraInst = I;
+ }
+
+ void addRuntimePointerChecks(unsigned Num) { NumRuntimePointerChecks = Num; }
+
+ bool doesNotMeet(Function *F, Loop *L, const LoopVectorizeHints &Hints) {
+ // If a loop hint is provided the diagnostic is always produced.
+ const char *Name = Hints.isForced() ? DiagnosticInfo::AlwaysPrint : LV_NAME;
+ bool failed = false;
+ if (UnsafeAlgebraInst &&
+ Hints.getForce() == LoopVectorizeHints::FK_Undefined &&
+ Hints.getWidth() == 0) {
+ emitOptimizationRemarkAnalysisFPCommute(
+ F->getContext(), Name, *F, UnsafeAlgebraInst->getDebugLoc(),
+ VectorizationReport() << "vectorization requires changes in the "
+ "order of operations, however IEEE 754 "
+ "floating-point operations are not "
+ "commutative");
+ failed = true;
}
- // Now, add the missing hints.
- for (auto H : HintTypes)
- MDs.push_back(createHintMetadata(Twine(Prefix(), H.Name).str(), H.Value));
-
- // Replace current metadata node with new one.
- LLVMContext &Context = TheLoop->getHeader()->getContext();
- MDNode *NewLoopID = MDNode::get(Context, MDs);
- // Set operand 0 to refer to the loop id itself.
- NewLoopID->replaceOperandWith(0, NewLoopID);
+ if (NumRuntimePointerChecks >
+ VectorizerParams::RuntimeMemoryCheckThreshold) {
+ emitOptimizationRemarkAnalysisAliasing(
+ F->getContext(), Name, *F, L->getStartLoc(),
+ VectorizationReport()
+ << "cannot prove pointers refer to independent arrays in memory. "
+ "The loop requires "
+ << NumRuntimePointerChecks
+ << " runtime independence checks to vectorize the loop, but that "
+ "would exceed the limit of "
+ << VectorizerParams::RuntimeMemoryCheckThreshold << " checks");
+ DEBUG(dbgs() << "LV: Too many memory checks needed.\n");
+ failed = true;
+ }
- TheLoop->setLoopID(NewLoopID);
+ return failed;
}
- /// The loop these hints belong to.
- const Loop *TheLoop;
+private:
+ unsigned NumRuntimePointerChecks;
+ Instruction *UnsafeAlgebraInst;
};
-static void emitMissedWarning(Function *F, Loop *L,
- const LoopVectorizeHints &LH) {
- emitOptimizationRemarkMissed(F->getContext(), DEBUG_TYPE, *F,
- L->getStartLoc(), LH.emitRemark());
-
- if (LH.getForce() == LoopVectorizeHints::FK_Enabled) {
- if (LH.getWidth() != 1)
- emitLoopVectorizeWarning(
- F->getContext(), *F, L->getStartLoc(),
- "failed explicitly specified loop vectorization");
- else if (LH.getInterleave() != 1)
- emitLoopInterleaveWarning(
- F->getContext(), *F, L->getStartLoc(),
- "failed explicitly specified loop interleaving");
- }
-}
-
static void addInnerLoop(Loop &L, SmallVectorImpl<Loop *> &V) {
if (L.empty())
return V.push_back(&L);
LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
- BFI = &getAnalysis<BlockFrequencyInfo>();
+ BFI = &getAnalysis<BlockFrequencyInfoWrapperPass>().getBFI();
auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
TLI = TLIP ? &TLIP->getTLI() : nullptr;
AA = &getAnalysis<AliasAnalysis>();
const BranchProbability ColdProb(1, 5); // 20%
ColdEntryFreq = BlockFrequency(BFI->getEntryFreq()) * ColdProb;
- // If the target claims to have no vector registers don't attempt
- // vectorization.
- if (!TTI->getNumberOfRegisters(true))
+ // Don't attempt if
+ // 1. the target claims to have no vector registers, and
+ // 2. interleaving won't help ILP.
+ //
+ // The second condition is necessary because, even if the target has no
+ // vector registers, loop vectorization may still enable scalar
+ // interleaving.
+ if (!TTI->getNumberOfRegisters(true) && TTI->getMaxInterleaveFactor(1) < 2)
return false;
// Build up a worklist of inner-loops to vectorize. This is necessary as
// less verbose reporting vectorized loops and unvectorized loops that may
// benefit from vectorization, respectively.
- if (Hints.getForce() == LoopVectorizeHints::FK_Disabled) {
- DEBUG(dbgs() << "LV: Not vectorizing: #pragma vectorize disable.\n");
- emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F,
- L->getStartLoc(), Hints.emitRemark());
- return false;
- }
-
- if (!AlwaysVectorize && Hints.getForce() != LoopVectorizeHints::FK_Enabled) {
- DEBUG(dbgs() << "LV: Not vectorizing: No #pragma vectorize enable.\n");
- emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F,
- L->getStartLoc(), Hints.emitRemark());
- return false;
- }
-
- if (Hints.getWidth() == 1 && Hints.getInterleave() == 1) {
- DEBUG(dbgs() << "LV: Not vectorizing: Disabled/already vectorized.\n");
- emitOptimizationRemarkAnalysis(
- F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
- "loop not vectorized: vector width and interleave count are "
- "explicitly set to 1");
+ if (!Hints.allowVectorization(F, L, AlwaysVectorize)) {
+ DEBUG(dbgs() << "LV: Loop hints prevent vectorization.\n");
return false;
}
DEBUG(dbgs() << " But vectorizing was explicitly forced.\n");
else {
DEBUG(dbgs() << "\n");
- emitOptimizationRemarkAnalysis(
- F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
- "vectorization is not beneficial and is not explicitly forced");
+ emitAnalysisDiag(F, L, Hints, VectorizationReport()
+ << "vectorization is not beneficial "
+ "and is not explicitly forced");
return false;
}
}
// Check if it is legal to vectorize the loop.
- LoopVectorizationLegality LVL(L, SE, DT, TLI, AA, F, TTI, LAA);
+ LoopVectorizationRequirements Requirements;
+ LoopVectorizationLegality LVL(L, SE, DT, TLI, AA, F, TTI, LAA,
+ &Requirements, &Hints);
if (!LVL.canVectorize()) {
DEBUG(dbgs() << "LV: Not vectorizing: Cannot prove legality.\n");
emitMissedWarning(F, L, Hints);
// Check the function attributes to find out if this function should be
// optimized for size.
bool OptForSize = Hints.getForce() != LoopVectorizeHints::FK_Enabled &&
+ // FIXME: Use Function::optForSize().
F->hasFnAttribute(Attribute::OptimizeForSize);
// Compute the weighted frequency of this loop being executed and see if it
if (F->hasFnAttribute(Attribute::NoImplicitFloat)) {
DEBUG(dbgs() << "LV: Can't vectorize when the NoImplicitFloat"
"attribute is used.\n");
- emitOptimizationRemarkAnalysis(
- F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
- "loop not vectorized due to NoImplicitFloat attribute");
+ emitAnalysisDiag(
+ F, L, Hints,
+ VectorizationReport()
+ << "loop not vectorized due to NoImplicitFloat attribute");
emitMissedWarning(F, L, Hints);
return false;
}
const LoopVectorizationCostModel::VectorizationFactor VF =
CM.selectVectorizationFactor(OptForSize);
- // Select the unroll factor.
- const unsigned UF =
- CM.selectUnrollFactor(OptForSize, VF.Width, VF.Cost);
+ // Select the interleave count.
+ unsigned IC = CM.selectInterleaveCount(OptForSize, VF.Width, VF.Cost);
+
+ // Get user interleave count.
+ unsigned UserIC = Hints.getInterleave();
- DEBUG(dbgs() << "LV: Found a vectorizable loop (" << VF.Width << ") in "
- << DebugLocStr << '\n');
- DEBUG(dbgs() << "LV: Unroll Factor is " << UF << '\n');
+ // Identify the diagnostic messages that should be produced.
+ std::string VecDiagMsg, IntDiagMsg;
+ bool VectorizeLoop = true, InterleaveLoop = true;
+
+ if (Requirements.doesNotMeet(F, L, Hints)) {
+ DEBUG(dbgs() << "LV: Not vectorizing: loop did not meet vectorization "
+ "requirements.\n");
+ emitMissedWarning(F, L, Hints);
+ return false;
+ }
if (VF.Width == 1) {
- DEBUG(dbgs() << "LV: Vectorization is possible but not beneficial\n");
+ DEBUG(dbgs() << "LV: Vectorization is possible but not beneficial.\n");
+ VecDiagMsg =
+ "the cost-model indicates that vectorization is not beneficial";
+ VectorizeLoop = false;
+ }
- if (UF == 1) {
- emitOptimizationRemarkAnalysis(
- F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
- "not beneficial to vectorize and user disabled interleaving");
- return false;
- }
- DEBUG(dbgs() << "LV: Trying to at least unroll the loops.\n");
+ if (IC == 1 && UserIC <= 1) {
+ // Tell the user interleaving is not beneficial.
+ DEBUG(dbgs() << "LV: Interleaving is not beneficial.\n");
+ IntDiagMsg =
+ "the cost-model indicates that interleaving is not beneficial";
+ InterleaveLoop = false;
+ if (UserIC == 1)
+ IntDiagMsg +=
+ " and is explicitly disabled or interleave count is set to 1";
+ } else if (IC > 1 && UserIC == 1) {
+ // Tell the user interleaving is beneficial, but it explicitly disabled.
+ DEBUG(dbgs()
+ << "LV: Interleaving is beneficial but is explicitly disabled.");
+ IntDiagMsg = "the cost-model indicates that interleaving is beneficial "
+ "but is explicitly disabled or interleave count is set to 1";
+ InterleaveLoop = false;
+ }
- // Report the unrolling decision.
- emitOptimizationRemark(F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
- Twine("unrolled with interleaving factor " +
- Twine(UF) +
- " (vectorization not beneficial)"));
+ // Override IC if user provided an interleave count.
+ IC = UserIC > 0 ? UserIC : IC;
- // We decided not to vectorize, but we may want to unroll.
+ // Emit diagnostic messages, if any.
+ if (!VectorizeLoop && !InterleaveLoop) {
+ // Do not vectorize or interleaving the loop.
+ emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F,
+ L->getStartLoc(), VecDiagMsg);
+ emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F,
+ L->getStartLoc(), IntDiagMsg);
+ return false;
+ } else if (!VectorizeLoop && InterleaveLoop) {
+ DEBUG(dbgs() << "LV: Interleave Count is " << IC << '\n');
+ emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F,
+ L->getStartLoc(), VecDiagMsg);
+ } else if (VectorizeLoop && !InterleaveLoop) {
+ DEBUG(dbgs() << "LV: Found a vectorizable loop (" << VF.Width << ") in "
+ << DebugLocStr << '\n');
+ emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F,
+ L->getStartLoc(), IntDiagMsg);
+ } else if (VectorizeLoop && InterleaveLoop) {
+ DEBUG(dbgs() << "LV: Found a vectorizable loop (" << VF.Width << ") in "
+ << DebugLocStr << '\n');
+ DEBUG(dbgs() << "LV: Interleave Count is " << IC << '\n');
+ }
- InnerLoopUnroller Unroller(L, SE, LI, DT, TLI, TTI, UF);
+ if (!VectorizeLoop) {
+ assert(IC > 1 && "interleave count should not be 1 or 0");
+ // If we decided that it is not legal to vectorize the loop then
+ // interleave it.
+ InnerLoopUnroller Unroller(L, SE, LI, DT, TLI, TTI, IC);
Unroller.vectorize(&LVL);
+
+ emitOptimizationRemark(F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
+ Twine("interleaved loop (interleaved count: ") +
+ Twine(IC) + ")");
} else {
// If we decided that it is *legal* to vectorize the loop then do it.
- InnerLoopVectorizer LB(L, SE, LI, DT, TLI, TTI, VF.Width, UF);
+ InnerLoopVectorizer LB(L, SE, LI, DT, TLI, TTI, VF.Width, IC);
LB.vectorize(&LVL);
++LoopsVectorized;
AddRuntimeUnrollDisableMetaData(L);
// Report the vectorization decision.
- emitOptimizationRemark(
- F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
- Twine("vectorized loop (vectorization factor: ") + Twine(VF.Width) +
- ", unrolling interleave factor: " + Twine(UF) + ")");
+ emitOptimizationRemark(F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(),
+ Twine("vectorized loop (vectorization width: ") +
+ Twine(VF.Width) + ", interleaved count: " +
+ Twine(IC) + ")");
}
// Mark the loop as already vectorized to avoid vectorizing again.
AU.addRequired<AssumptionCacheTracker>();
AU.addRequiredID(LoopSimplifyID);
AU.addRequiredID(LCSSAID);
- AU.addRequired<BlockFrequencyInfo>();
+ AU.addRequired<BlockFrequencyInfoWrapperPass>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<LoopInfoWrapperPass>();
AU.addRequired<ScalarEvolution>();
return Builder.CreateAdd(Val, Step, "induction");
}
-/// \brief Find the operand of the GEP that should be checked for consecutive
-/// stores. This ignores trailing indices that have no effect on the final
-/// pointer.
-static unsigned getGEPInductionOperand(const GetElementPtrInst *Gep) {
- const DataLayout &DL = Gep->getModule()->getDataLayout();
- unsigned LastOperand = Gep->getNumOperands() - 1;
- unsigned GEPAllocSize = DL.getTypeAllocSize(
- cast<PointerType>(Gep->getType()->getScalarType())->getElementType());
-
- // Walk backwards and try to peel off zeros.
- while (LastOperand > 1 && match(Gep->getOperand(LastOperand), m_Zero())) {
- // Find the type we're currently indexing into.
- gep_type_iterator GEPTI = gep_type_begin(Gep);
- std::advance(GEPTI, LastOperand - 1);
-
- // If it's a type with the same allocation size as the result of the GEP we
- // can peel off the zero index.
- if (DL.getTypeAllocSize(*GEPTI) != GEPAllocSize)
- break;
- --LastOperand;
- }
-
- return LastOperand;
-}
-
int LoopVectorizationLegality::isConsecutivePtr(Value *Ptr) {
assert(Ptr->getType()->isPointerTy() && "Unexpected non-ptr");
// Make sure that the pointer does not point to structs.
// faster.
Instruction *MemRuntimeCheck;
std::tie(FirstCheckInst, MemRuntimeCheck) =
- Legal->getLAI()->addRuntimeCheck(VectorPH->getTerminator());
+ Legal->getLAI()->addRuntimeChecks(VectorPH->getTerminator());
if (MemRuntimeCheck) {
AddedSafetyChecks = true;
// Create a new block containing the memory check.
}
// We can only vectorize innermost loops.
- if (!TheLoop->getSubLoopsVector().empty()) {
+ if (!TheLoop->empty()) {
emitAnalysis(VectorizationReport() << "loop is not the innermost loop");
return false;
}
// Collect all of the variables that remain uniform after vectorization.
collectLoopUniforms();
- DEBUG(dbgs() << "LV: We can vectorize this loop" <<
- (LAI->getRuntimePointerCheck()->Need ? " (with a runtime bound check)" :
- "")
- <<"!\n");
+ DEBUG(dbgs() << "LV: We can vectorize this loop"
+ << (LAI->getRuntimePointerChecking()->Need
+ ? " (with a runtime bound check)"
+ : "")
+ << "!\n");
+
+ bool UseInterleaved = TTI->enableInterleavedAccessVectorization();
+
+ // If an override option has been passed in for interleaved accesses, use it.
+ if (EnableInterleavedMemAccesses.getNumOccurrences() > 0)
+ UseInterleaved = EnableInterleavedMemAccesses;
// Analyze interleaved memory accesses.
- if (EnableInterleavedMemAccesses)
- InterleaveInfo.analyzeInterleaving(Strides);
+ if (UseInterleaved)
+ InterleaveInfo.analyzeInterleaving(Strides);
// Okay! We can vectorize. At this point we don't have any other mem analysis
// which may limit our maximum vectorization factor, so just return true with
if (RecurrenceDescriptor::isReductionPHI(Phi, TheLoop,
Reductions[Phi])) {
+ if (Reductions[Phi].hasUnsafeAlgebra())
+ Requirements->addUnsafeAlgebraInst(
+ Reductions[Phi].getUnsafeAlgebraInst());
AllowedExit.insert(Reductions[Phi].getLoopExitInstr());
continue;
}
return true;
}
-///\brief Remove GEPs whose indices but the last one are loop invariant and
-/// return the induction operand of the gep pointer.
-static Value *stripGetElementPtr(Value *Ptr, ScalarEvolution *SE, Loop *Lp) {
- GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr);
- if (!GEP)
- return Ptr;
-
- unsigned InductionOperand = getGEPInductionOperand(GEP);
-
- // Check that all of the gep indices are uniform except for our induction
- // operand.
- for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i)
- if (i != InductionOperand &&
- !SE->isLoopInvariant(SE->getSCEV(GEP->getOperand(i)), Lp))
- return Ptr;
- return GEP->getOperand(InductionOperand);
-}
-
-///\brief Look for a cast use of the passed value.
-static Value *getUniqueCastUse(Value *Ptr, Loop *Lp, Type *Ty) {
- Value *UniqueCast = nullptr;
- for (User *U : Ptr->users()) {
- CastInst *CI = dyn_cast<CastInst>(U);
- if (CI && CI->getType() == Ty) {
- if (!UniqueCast)
- UniqueCast = CI;
- else
- return nullptr;
- }
- }
- return UniqueCast;
-}
-
-///\brief Get the stride of a pointer access in a loop.
-/// Looks for symbolic strides "a[i*stride]". Returns the symbolic stride as a
-/// pointer to the Value, or null otherwise.
-static Value *getStrideFromPointer(Value *Ptr, ScalarEvolution *SE, Loop *Lp) {
- const PointerType *PtrTy = dyn_cast<PointerType>(Ptr->getType());
- if (!PtrTy || PtrTy->isAggregateType())
- return nullptr;
-
- // Try to remove a gep instruction to make the pointer (actually index at this
- // point) easier analyzable. If OrigPtr is equal to Ptr we are analzying the
- // pointer, otherwise, we are analyzing the index.
- Value *OrigPtr = Ptr;
-
- // The size of the pointer access.
- int64_t PtrAccessSize = 1;
-
- Ptr = stripGetElementPtr(Ptr, SE, Lp);
- const SCEV *V = SE->getSCEV(Ptr);
-
- if (Ptr != OrigPtr)
- // Strip off casts.
- while (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V))
- V = C->getOperand();
-
- const SCEVAddRecExpr *S = dyn_cast<SCEVAddRecExpr>(V);
- if (!S)
- return nullptr;
-
- V = S->getStepRecurrence(*SE);
- if (!V)
- return nullptr;
-
- // Strip off the size of access multiplication if we are still analyzing the
- // pointer.
- if (OrigPtr == Ptr) {
- const DataLayout &DL = Lp->getHeader()->getModule()->getDataLayout();
- DL.getTypeAllocSize(PtrTy->getElementType());
- if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(V)) {
- if (M->getOperand(0)->getSCEVType() != scConstant)
- return nullptr;
-
- const APInt &APStepVal =
- cast<SCEVConstant>(M->getOperand(0))->getValue()->getValue();
-
- // Huge step value - give up.
- if (APStepVal.getBitWidth() > 64)
- return nullptr;
-
- int64_t StepVal = APStepVal.getSExtValue();
- if (PtrAccessSize != StepVal)
- return nullptr;
- V = M->getOperand(1);
- }
- }
-
- // Strip off casts.
- Type *StripedOffRecurrenceCast = nullptr;
- if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V)) {
- StripedOffRecurrenceCast = C->getType();
- V = C->getOperand();
- }
-
- // Look for the loop invariant symbolic value.
- const SCEVUnknown *U = dyn_cast<SCEVUnknown>(V);
- if (!U)
- return nullptr;
-
- Value *Stride = U->getValue();
- if (!Lp->isLoopInvariant(Stride))
- return nullptr;
-
- // If we have stripped off the recurrence cast we have to make sure that we
- // return the value that is used in this loop so that we can replace it later.
- if (StripedOffRecurrenceCast)
- Stride = getUniqueCastUse(Stride, Lp, StripedOffRecurrenceCast);
-
- return Stride;
-}
-
void LoopVectorizationLegality::collectStridedAccess(Value *MemAccess) {
Value *Ptr = nullptr;
if (LoadInst *LI = dyn_cast<LoadInst>(MemAccess))
return false;
}
- if (LAI->getNumRuntimePointerChecks() >
- VectorizerParams::RuntimeMemoryCheckThreshold) {
- emitAnalysis(VectorizationReport()
- << LAI->getNumRuntimePointerChecks() << " exceeds limit of "
- << VectorizerParams::RuntimeMemoryCheckThreshold
- << " dependent memory operations checked at runtime");
- DEBUG(dbgs() << "LV: Too many memory checks needed.\n");
- return false;
- }
+ Requirements->addRuntimePointerChecks(LAI->getNumRuntimePointerChecks());
+
return true;
}
LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize) {
// Width 1 means no vectorize
VectorizationFactor Factor = { 1U, 0U };
- if (OptForSize && Legal->getRuntimePointerCheck()->Need) {
+ if (OptForSize && Legal->getRuntimePointerChecking()->Need) {
emitAnalysis(VectorizationReport() <<
"runtime pointer checks needed. Enable vectorization of this "
"loop with '#pragma clang loop vectorize(enable)' when "
return MaxWidth;
}
-unsigned
-LoopVectorizationCostModel::selectUnrollFactor(bool OptForSize,
- unsigned VF,
- unsigned LoopCost) {
+unsigned LoopVectorizationCostModel::selectInterleaveCount(bool OptForSize,
+ unsigned VF,
+ unsigned LoopCost) {
- // -- The unroll heuristics --
- // We unroll the loop in order to expose ILP and reduce the loop overhead.
+ // -- The interleave heuristics --
+ // We interleave the loop in order to expose ILP and reduce the loop overhead.
// There are many micro-architectural considerations that we can't predict
// at this level. For example, frontend pressure (on decode or fetch) due to
// code size, or the number and capabilities of the execution ports.
//
- // We use the following heuristics to select the unroll factor:
- // 1. If the code has reductions, then we unroll in order to break the cross
+ // We use the following heuristics to select the interleave count:
+ // 1. If the code has reductions, then we interleave to break the cross
// iteration dependency.
- // 2. If the loop is really small, then we unroll in order to reduce the loop
+ // 2. If the loop is really small, then we interleave to reduce the loop
// overhead.
- // 3. We don't unroll if we think that we will spill registers to memory due
- // to the increased register pressure.
-
- // Use the user preference, unless 'auto' is selected.
- int UserUF = Hints->getInterleave();
- if (UserUF != 0)
- return UserUF;
+ // 3. We don't interleave if we think that we will spill registers to memory
+ // due to the increased register pressure.
- // When we optimize for size, we don't unroll.
+ // When we optimize for size, we don't interleave.
if (OptForSize)
return 1;
- // We used the distance for the unroll factor.
+ // We used the distance for the interleave count.
if (Legal->getMaxSafeDepDistBytes() != -1U)
return 1;
- // Do not unroll loops with a relatively small trip count.
+ // Do not interleave loops with a relatively small trip count.
unsigned TC = SE->getSmallConstantTripCount(TheLoop);
- if (TC > 1 && TC < TinyTripCountUnrollThreshold)
+ if (TC > 1 && TC < TinyTripCountInterleaveThreshold)
return 1;
unsigned TargetNumRegisters = TTI.getNumberOfRegisters(VF > 1);
R.MaxLocalUsers = std::max(R.MaxLocalUsers, 1U);
R.NumInstructions = std::max(R.NumInstructions, 1U);
- // We calculate the unroll factor using the following formula.
+ // We calculate the interleave count using the following formula.
// Subtract the number of loop invariants from the number of available
- // registers. These registers are used by all of the unrolled instances.
+ // registers. These registers are used by all of the interleaved instances.
// Next, divide the remaining registers by the number of registers that is
// required by the loop, in order to estimate how many parallel instances
// fit without causing spills. All of this is rounded down if necessary to be
- // a power of two. We want power of two unroll factors to simplify any
+ // a power of two. We want power of two interleave count to simplify any
// addressing operations or alignment considerations.
- unsigned UF = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs) /
+ unsigned IC = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs) /
R.MaxLocalUsers);
- // Don't count the induction variable as unrolled.
+ // Don't count the induction variable as interleaved.
if (EnableIndVarRegisterHeur)
- UF = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs - 1) /
+ IC = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs - 1) /
std::max(1U, (R.MaxLocalUsers - 1)));
- // Clamp the unroll factor ranges to reasonable factors.
- unsigned MaxInterleaveSize = TTI.getMaxInterleaveFactor(VF);
+ // Clamp the interleave ranges to reasonable counts.
+ unsigned MaxInterleaveCount = TTI.getMaxInterleaveFactor(VF);
- // Check if the user has overridden the unroll max.
+ // Check if the user has overridden the max.
if (VF == 1) {
if (ForceTargetMaxScalarInterleaveFactor.getNumOccurrences() > 0)
- MaxInterleaveSize = ForceTargetMaxScalarInterleaveFactor;
+ MaxInterleaveCount = ForceTargetMaxScalarInterleaveFactor;
} else {
if (ForceTargetMaxVectorInterleaveFactor.getNumOccurrences() > 0)
- MaxInterleaveSize = ForceTargetMaxVectorInterleaveFactor;
+ MaxInterleaveCount = ForceTargetMaxVectorInterleaveFactor;
}
// If we did not calculate the cost for VF (because the user selected the VF)
if (LoopCost == 0)
LoopCost = expectedCost(VF);
- // Clamp the calculated UF to be between the 1 and the max unroll factor
+ // Clamp the calculated IC to be between the 1 and the max interleave count
// that the target allows.
- if (UF > MaxInterleaveSize)
- UF = MaxInterleaveSize;
- else if (UF < 1)
- UF = 1;
+ if (IC > MaxInterleaveCount)
+ IC = MaxInterleaveCount;
+ else if (IC < 1)
+ IC = 1;
- // Unroll if we vectorized this loop and there is a reduction that could
- // benefit from unrolling.
+ // Interleave if we vectorized this loop and there is a reduction that could
+ // benefit from interleaving.
if (VF > 1 && Legal->getReductionVars()->size()) {
- DEBUG(dbgs() << "LV: Unrolling because of reductions.\n");
- return UF;
+ DEBUG(dbgs() << "LV: Interleaving because of reductions.\n");
+ return IC;
}
// Note that if we've already vectorized the loop we will have done the
- // runtime check and so unrolling won't require further checks.
- bool UnrollingRequiresRuntimePointerCheck =
- (VF == 1 && Legal->getRuntimePointerCheck()->Need);
+ // runtime check and so interleaving won't require further checks.
+ bool InterleavingRequiresRuntimePointerCheck =
+ (VF == 1 && Legal->getRuntimePointerChecking()->Need);
- // We want to unroll small loops in order to reduce the loop overhead and
+ // We want to interleave small loops in order to reduce the loop overhead and
// potentially expose ILP opportunities.
DEBUG(dbgs() << "LV: Loop cost is " << LoopCost << '\n');
- if (!UnrollingRequiresRuntimePointerCheck &&
- LoopCost < SmallLoopCost) {
+ if (!InterleavingRequiresRuntimePointerCheck && LoopCost < SmallLoopCost) {
// We assume that the cost overhead is 1 and we use the cost model
- // to estimate the cost of the loop and unroll until the cost of the
+ // to estimate the cost of the loop and interleave until the cost of the
// loop overhead is about 5% of the cost of the loop.
- unsigned SmallUF = std::min(UF, (unsigned)PowerOf2Floor(SmallLoopCost / LoopCost));
+ unsigned SmallIC =
+ std::min(IC, (unsigned)PowerOf2Floor(SmallLoopCost / LoopCost));
- // Unroll until store/load ports (estimated by max unroll factor) are
+ // Interleave until store/load ports (estimated by max interleave count) are
// saturated.
unsigned NumStores = Legal->getNumStores();
unsigned NumLoads = Legal->getNumLoads();
- unsigned StoresUF = UF / (NumStores ? NumStores : 1);
- unsigned LoadsUF = UF / (NumLoads ? NumLoads : 1);
+ unsigned StoresIC = IC / (NumStores ? NumStores : 1);
+ unsigned LoadsIC = IC / (NumLoads ? NumLoads : 1);
// If we have a scalar reduction (vector reductions are already dealt with
// by this point), we can increase the critical path length if the loop
- // we're unrolling is inside another loop. Limit, by default to 2, so the
+ // we're interleaving is inside another loop. Limit, by default to 2, so the
// critical path only gets increased by one reduction operation.
if (Legal->getReductionVars()->size() &&
TheLoop->getLoopDepth() > 1) {
- unsigned F = static_cast<unsigned>(MaxNestedScalarReductionUF);
- SmallUF = std::min(SmallUF, F);
- StoresUF = std::min(StoresUF, F);
- LoadsUF = std::min(LoadsUF, F);
+ unsigned F = static_cast<unsigned>(MaxNestedScalarReductionIC);
+ SmallIC = std::min(SmallIC, F);
+ StoresIC = std::min(StoresIC, F);
+ LoadsIC = std::min(LoadsIC, F);
}
- if (EnableLoadStoreRuntimeUnroll && std::max(StoresUF, LoadsUF) > SmallUF) {
- DEBUG(dbgs() << "LV: Unrolling to saturate store or load ports.\n");
- return std::max(StoresUF, LoadsUF);
+ if (EnableLoadStoreRuntimeInterleave &&
+ std::max(StoresIC, LoadsIC) > SmallIC) {
+ DEBUG(dbgs() << "LV: Interleaving to saturate store or load ports.\n");
+ return std::max(StoresIC, LoadsIC);
}
- DEBUG(dbgs() << "LV: Unrolling to reduce branch cost.\n");
- return SmallUF;
+ DEBUG(dbgs() << "LV: Interleaving to reduce branch cost.\n");
+ return SmallIC;
}
- // Unroll if this is a large loop (small loops are already dealt with by this
- // point) that could benefit from interleaved unrolling.
+ // Interleave if this is a large loop (small loops are already dealt with by
+ // this
+ // point) that could benefit from interleaving.
bool HasReductions = (Legal->getReductionVars()->size() > 0);
if (TTI.enableAggressiveInterleaving(HasReductions)) {
- DEBUG(dbgs() << "LV: Unrolling to expose ILP.\n");
- return UF;
+ DEBUG(dbgs() << "LV: Interleaving to expose ILP.\n");
+ return IC;
}
- DEBUG(dbgs() << "LV: Not Unrolling.\n");
+ DEBUG(dbgs() << "LV: Not Interleaving.\n");
return 1;
}
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfo)
+INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
INITIALIZE_PASS_DEPENDENCY(LCSSA)
projects / oota-llvm.git / blobdiff