/// different operations.
class LoopVectorizationCostModel {
public:
- LoopVectorizationCostModel(Loop *L, ScalarEvolution *SE, LoopInfo *LI,
- LoopVectorizationLegality *Legal,
+ LoopVectorizationCostModel(Loop *L, PredicatedScalarEvolution &PSE,
+ LoopInfo *LI, LoopVectorizationLegality *Legal,
const TargetTransformInfo &TTI,
const TargetLibraryInfo *TLI, DemandedBits *DB,
AssumptionCache *AC, const Function *F,
- const LoopVectorizeHints *Hints,
- SmallPtrSetImpl<const Value *> &ValuesToIgnore)
- : TheLoop(L), SE(SE), LI(LI), Legal(Legal), TTI(TTI), TLI(TLI), DB(DB),
- TheFunction(F), Hints(Hints), ValuesToIgnore(ValuesToIgnore) {}
+ const LoopVectorizeHints *Hints)
+ : TheLoop(L), PSE(PSE), LI(LI), Legal(Legal), TTI(TTI), TLI(TLI), DB(DB),
+ AC(AC), TheFunction(F), Hints(Hints) {}
/// Information about vectorization costs
struct VectorizationFactor {
SmallVector<RegisterUsage, 8>
calculateRegisterUsage(const SmallVector<unsigned, 8> &VFs);
+ /// Collect values we want to ignore in the cost model.
+ void collectValuesToIgnore();
+
private:
/// Returns the expected execution cost. The unit of the cost does
/// not matter because we use the 'cost' units to compare different
/// The loop that we evaluate.
Loop *TheLoop;
- /// Scev analysis.
- ScalarEvolution *SE;
+ /// Predicated scalar evolution analysis.
+ PredicatedScalarEvolution &PSE;
/// Loop Info analysis.
LoopInfo *LI;
/// Vectorization legality.
const TargetTransformInfo &TTI;
/// Target Library Info.
const TargetLibraryInfo *TLI;
- /// Demanded bits analysis
+ /// Demanded bits analysis.
DemandedBits *DB;
+ /// Assumption cache.
+ AssumptionCache *AC;
const Function *TheFunction;
- // Loop Vectorize Hint.
+ /// Loop Vectorize Hint.
const LoopVectorizeHints *Hints;
- // Values to ignore in the cost model.
- const SmallPtrSetImpl<const Value *> &ValuesToIgnore;
+ /// Values to ignore in the cost model.
+ SmallPtrSet<const Value *, 16> ValuesToIgnore;
+ /// Values to ignore in the cost model when VF > 1.
+ SmallPtrSet<const Value *, 16> VecValuesToIgnore;
};
/// \brief This holds vectorization requirements that must be verified late in
return false;
}
- // Collect values we want to ignore in the cost model. This includes
- // type-promoting instructions we identified during reduction detection.
- SmallPtrSet<const Value *, 32> ValuesToIgnore;
- CodeMetrics::collectEphemeralValues(L, AC, ValuesToIgnore);
- for (auto &Reduction : *LVL.getReductionVars()) {
- RecurrenceDescriptor &RedDes = Reduction.second;
- SmallPtrSetImpl<Instruction *> &Casts = RedDes.getCastInsts();
- ValuesToIgnore.insert(Casts.begin(), Casts.end());
- }
-
// Use the cost model.
- LoopVectorizationCostModel CM(L, PSE.getSE(), LI, &LVL, *TTI, TLI, DB, AC,
- F, &Hints, ValuesToIgnore);
+ LoopVectorizationCostModel CM(L, PSE, LI, &LVL, *TTI, TLI, DB, AC, F,
+ &Hints);
+ CM.collectValuesToIgnore();
// Check the function attributes to find out if this function should be
// optimized for size.
}
// Find the trip count.
- unsigned TC = SE->getSmallConstantTripCount(TheLoop);
+ unsigned TC = PSE.getSE()->getSmallConstantTripCount(TheLoop);
DEBUG(dbgs() << "LV: Found trip count: " << TC << '\n');
MinBWs = computeMinimumValueSizes(TheLoop->getBlocks(), *DB, &TTI);
return 1;
// Do not interleave loops with a relatively small trip count.
- unsigned TC = SE->getSmallConstantTripCount(TheLoop);
+ unsigned TC = PSE.getSE()->getSmallConstantTripCount(TheLoop);
if (TC > 1 && TC < TinyTripCountInterleaveThreshold)
return 1;
// Ignore instructions that are never used within the loop.
if (!Ends.count(I)) continue;
- // Skip ignored values.
- if (ValuesToIgnore.count(I))
- continue;
-
// Remove all of the instructions that end at this location.
InstrList &List = TransposeEnds[i];
for (unsigned int j = 0, e = List.size(); j < e; ++j)
OpenIntervals.erase(List[j]);
+ // Skip ignored values.
+ if (ValuesToIgnore.count(I))
+ continue;
+
// For each VF find the maximum usage of registers.
for (unsigned j = 0, e = VFs.size(); j < e; ++j) {
if (VFs[j] == 1) {
// Count the number of live intervals.
unsigned RegUsage = 0;
- for (auto Inst : OpenIntervals)
+ for (auto Inst : OpenIntervals) {
+ // Skip ignored values for VF > 1.
+ if (VecValuesToIgnore.count(Inst))
+ continue;
RegUsage += GetRegUsage(Inst->getType(), VFs[j]);
+ }
MaxUsages[j] = std::max(MaxUsages[j], RegUsage);
}
if (VF > 1 && MinBWs.count(I))
RetTy = IntegerType::get(RetTy->getContext(), MinBWs[I]);
Type *VectorTy = ToVectorTy(RetTy, VF);
+ auto SE = PSE.getSE();
// TODO: We need to estimate the cost of intrinsic calls.
switch (I->getOpcode()) {
return false;
}
+void LoopVectorizationCostModel::collectValuesToIgnore() {
+ // Ignore ephemeral values.
+ CodeMetrics::collectEphemeralValues(TheLoop, AC, ValuesToIgnore);
+
+ // Ignore type-promoting instructions we identified during reduction
+ // detection.
+ for (auto &Reduction : *Legal->getReductionVars()) {
+ RecurrenceDescriptor &RedDes = Reduction.second;
+ SmallPtrSetImpl<Instruction *> &Casts = RedDes.getCastInsts();
+ VecValuesToIgnore.insert(Casts.begin(), Casts.end());
+ }
+
+ // Ignore induction phis that are only used in either GetElementPtr or ICmp
+ // instruction to exit loop. Induction variables usually have large types and
+ // can have big impact when estimating register usage.
+ // This is for when VF > 1.
+ for (auto &Induction : *Legal->getInductionVars()) {
+ auto *PN = Induction.first;
+ auto *UpdateV = PN->getIncomingValueForBlock(TheLoop->getLoopLatch());
+
+ // Check that the PHI is only used by the induction increment (UpdateV) or
+ // by GEPs. Then check that UpdateV is only used by a compare instruction or
+ // the loop header PHI.
+ // FIXME: Need precise def-use analysis to determine if this instruction
+ // variable will be vectorized.
+ if (std::all_of(PN->user_begin(), PN->user_end(),
+ [&](const User *U) -> bool {
+ return U == UpdateV || isa<GetElementPtrInst>(U);
+ }) &&
+ std::all_of(UpdateV->user_begin(), UpdateV->user_end(),
+ [&](const User *U) -> bool {
+ return U == PN || isa<ICmpInst>(U);
+ })) {
+ VecValuesToIgnore.insert(PN);
+ VecValuesToIgnore.insert(UpdateV);
+ }
+ }
+
+ // Ignore instructions that will not be vectorized.
+ // This is for when VF > 1.
+ for (auto bb = TheLoop->block_begin(), be = TheLoop->block_end(); bb != be;
+ ++bb) {
+ for (auto &Inst : **bb) {
+ switch (Inst.getOpcode()) {
+ case Instruction::GetElementPtr: {
+ // Ignore GEP if its last operand is an induction variable so that it is
+ // a consecutive load/store and won't be vectorized as scatter/gather
+ // pattern.
+
+ GetElementPtrInst *Gep = cast<GetElementPtrInst>(&Inst);
+ unsigned NumOperands = Gep->getNumOperands();
+ unsigned InductionOperand = getGEPInductionOperand(Gep);
+ bool GepToIgnore = true;
+
+ // Check that all of the gep indices are uniform except for the
+ // induction operand.
+ for (unsigned i = 0; i != NumOperands; ++i) {
+ if (i != InductionOperand &&
+ !PSE.getSE()->isLoopInvariant(PSE.getSCEV(Gep->getOperand(i)),
+ TheLoop)) {
+ GepToIgnore = false;
+ break;
+ }
+ }
+
+ if (GepToIgnore)
+ VecValuesToIgnore.insert(&Inst);
+ break;
+ }
+ }
+ }
+ }
+}
void InnerLoopUnroller::scalarizeInstruction(Instruction *Instr,
bool IfPredicateStore) {
--- /dev/null
+; RUN: opt < %s -debug-only=loop-vectorize -loop-vectorize -vectorizer-maximize-bandwidth -O2 -S 2>&1 | FileCheck %s
+; REQUIRES: asserts
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = global [1024 x i8] zeroinitializer, align 16
+@b = global [1024 x i8] zeroinitializer, align 16
+
+define i32 @foo() {
+; This function has a loop of SAD pattern. Here we check when VF = 16 the
+; register usage doesn't exceed 16.
+;
+; CHECK-LABEL: foo
+; CHECK: LV(REG): VF = 4
+; CHECK-NEXT: LV(REG): Found max usage: 4
+; CHECK: LV(REG): VF = 8
+; CHECK-NEXT: LV(REG): Found max usage: 7
+; CHECK: LV(REG): VF = 16
+; CHECK-NEXT: LV(REG): Found max usage: 13
+
+entry:
+ br label %for.body
+
+for.cond.cleanup:
+ %add.lcssa = phi i32 [ %add, %for.body ]
+ ret i32 %add.lcssa
+
+for.body:
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %s.015 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+ %arrayidx = getelementptr inbounds [1024 x i8], [1024 x i8]* @a, i64 0, i64 %indvars.iv
+ %0 = load i8, i8* %arrayidx, align 1
+ %conv = zext i8 %0 to i32
+ %arrayidx2 = getelementptr inbounds [1024 x i8], [1024 x i8]* @b, i64 0, i64 %indvars.iv
+ %1 = load i8, i8* %arrayidx2, align 1
+ %conv3 = zext i8 %1 to i32
+ %sub = sub nsw i32 %conv, %conv3
+ %ispos = icmp sgt i32 %sub, -1
+ %neg = sub nsw i32 0, %sub
+ %2 = select i1 %ispos, i32 %sub, i32 %neg
+ %add = add nsw i32 %2, %s.015
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ %exitcond = icmp eq i64 %indvars.iv.next, 1024
+ br i1 %exitcond, label %for.cond.cleanup, label %for.body
+}
+
+define i64 @bar(i64* nocapture %a) {
+; CHECK-LABEL: bar
+; CHECK: LV(REG): VF = 2
+; CHECK: LV(REG): Found max usage: 4
+;
+entry:
+ br label %for.body
+
+for.cond.cleanup:
+ %add2.lcssa = phi i64 [ %add2, %for.body ]
+ ret i64 %add2.lcssa
+
+for.body:
+ %i.012 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
+ %s.011 = phi i64 [ 0, %entry ], [ %add2, %for.body ]
+ %arrayidx = getelementptr inbounds i64, i64* %a, i64 %i.012
+ %0 = load i64, i64* %arrayidx, align 8
+ %add = add nsw i64 %0, %i.012
+ store i64 %add, i64* %arrayidx, align 8
+ %add2 = add nsw i64 %add, %s.011
+ %inc = add nuw nsw i64 %i.012, 1
+ %exitcond = icmp eq i64 %inc, 1024
+ br i1 %exitcond, label %for.cond.cleanup, label %for.body
+}
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