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LV: generalize profitability criterion over TC #93300
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@llvm/pr-subscribers-llvm-transforms Author: Ramkumar Ramachandra (artagnon) ChangesGeneralize LoopVectorizationPlanner::isMoreProfitable smoothly across the fixed-vector and scalable-vector cases, taking the trip-count into account, and fixing logical pitfalls that arise from a lack of generality. Patch is 32.00 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/93300.diff 4 Files Affected:
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 52cb8c9f88f94..b48bff7b74e0a 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4870,28 +4870,6 @@ bool LoopVectorizationPlanner::isMoreProfitable(
unsigned MaxTripCount = PSE.getSE()->getSmallConstantMaxTripCount(OrigLoop);
- if (!A.Width.isScalable() && !B.Width.isScalable() && MaxTripCount) {
- // If the trip count is a known (possibly small) constant, the trip count
- // will be rounded up to an integer number of iterations under
- // FoldTailByMasking. The total cost in that case will be
- // VecCost*ceil(TripCount/VF). When not folding the tail, the total
- // cost will be VecCost*floor(TC/VF) + ScalarCost*(TC%VF). There will be
- // some extra overheads, but for the purpose of comparing the costs of
- // different VFs we can use this to compare the total loop-body cost
- // expected after vectorization.
- auto GetCostForTC = [MaxTripCount, this](unsigned VF,
- InstructionCost VectorCost,
- InstructionCost ScalarCost) {
- return CM.foldTailByMasking() ? VectorCost * divideCeil(MaxTripCount, VF)
- : VectorCost * (MaxTripCount / VF) +
- ScalarCost * (MaxTripCount % VF);
- };
- auto RTCostA = GetCostForTC(A.Width.getFixedValue(), CostA, A.ScalarCost);
- auto RTCostB = GetCostForTC(B.Width.getFixedValue(), CostB, B.ScalarCost);
-
- return RTCostA < RTCostB;
- }
-
// Improve estimate for the vector width if it is scalable.
unsigned EstimatedWidthA = A.Width.getKnownMinValue();
unsigned EstimatedWidthB = B.Width.getKnownMinValue();
@@ -4905,13 +4883,36 @@ bool LoopVectorizationPlanner::isMoreProfitable(
// Assume vscale may be larger than 1 (or the value being tuned for),
// so that scalable vectorization is slightly favorable over fixed-width
// vectorization.
- if (A.Width.isScalable() && !B.Width.isScalable())
- return (CostA * B.Width.getFixedValue()) <= (CostB * EstimatedWidthA);
+ bool AXorBScalable = A.Width.isScalable() ^ B.Width.isScalable();
+ auto CmpFn = [AXorBScalable](const InstructionCost &LHS,
+ const InstructionCost &RHS) {
+ return AXorBScalable ? LHS <= RHS : LHS < RHS;
+ };
// To avoid the need for FP division:
- // (CostA / A.Width) < (CostB / B.Width)
- // <=> (CostA * B.Width) < (CostB * A.Width)
- return (CostA * EstimatedWidthB) < (CostB * EstimatedWidthA);
+ // (CostA / EstimatedWidthA) < (CostB / EstimatedWidthB)
+ // <=> (CostA * EstimatedWidthB) < (CostB * EstimatedWidthA)
+ if (!MaxTripCount)
+ return CmpFn(CostA * EstimatedWidthB, CostB * EstimatedWidthA);
+
+ auto GetCost = [MaxTripCount, this](unsigned VF, InstructionCost VectorCost,
+ InstructionCost ScalarCost) {
+ // If the trip count is a known (possibly small) constant, the trip count
+ // will be rounded up to an integer number of iterations under
+ // FoldTailByMasking. The total cost in that case will be
+ // VecCost*ceil(TripCount/VF). When not folding the tail, the total
+ // cost will be VecCost*floor(TC/VF) + ScalarCost*(TC%VF). There will be
+ // some extra overheads, but for the purpose of comparing the costs of
+ // different VFs we can use this to compare the total loop-body cost
+ // expected after vectorization.
+ if (CM.foldTailByMasking())
+ return VectorCost * divideCeil(MaxTripCount, VF);
+ return VectorCost * (MaxTripCount / VF) + ScalarCost * (MaxTripCount % VF);
+ };
+
+ auto RTCostA = GetCost(EstimatedWidthA, CostA, A.ScalarCost);
+ auto RTCostB = GetCost(EstimatedWidthB, CostB, B.ScalarCost);
+ return CmpFn(RTCostA, RTCostB);
}
static void emitInvalidCostRemarks(SmallVector<InstructionVFPair> InvalidCosts,
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/clamped-trip-count.ll b/llvm/test/Transforms/LoopVectorize/AArch64/clamped-trip-count.ll
index afd49aa9f0b81..ba4c2376d7922 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/clamped-trip-count.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/clamped-trip-count.ll
@@ -8,44 +8,46 @@ define void @clamped_tc_8(ptr nocapture %dst, i32 %n, i64 %val) vscale_range(1,1
; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP1:%.*]] = mul i64 [[TMP0]], 8
+; CHECK-NEXT: [[TMP1:%.*]] = mul i64 [[TMP0]], 4
; CHECK-NEXT: [[TMP2:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[TMP2]], 8
+; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[TMP2]], 4
; CHECK-NEXT: [[TMP4:%.*]] = sub i64 [[TMP3]], 1
; CHECK-NEXT: [[N_RND_UP:%.*]] = add i64 8, [[TMP4]]
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[N_RND_UP]], [[TMP1]]
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[N_RND_UP]], [[N_MOD_VF]]
; CHECK-NEXT: [[IND_END:%.*]] = getelementptr i8, ptr [[DST]], i64 [[N_VEC]]
; CHECK-NEXT: [[TMP5:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP6:%.*]] = mul i64 [[TMP5]], 8
-; CHECK-NEXT: [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 8 x i1> @llvm.get.active.lane.mask.nxv8i1.i64(i64 0, i64 8)
-; CHECK-NEXT: [[TMP7:%.*]] = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT: [[TMP8:%.*]] = add <vscale x 8 x i64> [[TMP7]], zeroinitializer
-; CHECK-NEXT: [[TMP9:%.*]] = mul <vscale x 8 x i64> [[TMP8]], shufflevector (<vscale x 8 x i64> insertelement (<vscale x 8 x i64> poison, i64 1, i64 0), <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer)
-; CHECK-NEXT: [[INDUCTION:%.*]] = add <vscale x 8 x i64> zeroinitializer, [[TMP9]]
+; CHECK-NEXT: [[TMP6:%.*]] = mul i64 [[TMP5]], 4
+; CHECK-NEXT: [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i64(i64 0, i64 8)
+; CHECK-NEXT: [[TMP7:%.*]] = call <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()
+; CHECK-NEXT: [[TMP8:%.*]] = add <vscale x 4 x i64> [[TMP7]], zeroinitializer
+; CHECK-NEXT: [[TMP9:%.*]] = mul <vscale x 4 x i64> [[TMP8]], shufflevector (<vscale x 4 x i64> insertelement (<vscale x 4 x i64> poison, i64 1, i64 0), <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer)
+; CHECK-NEXT: [[INDUCTION:%.*]] = add <vscale x 4 x i64> zeroinitializer, [[TMP9]]
; CHECK-NEXT: [[TMP10:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP11:%.*]] = mul i64 [[TMP10]], 8
+; CHECK-NEXT: [[TMP11:%.*]] = mul i64 [[TMP10]], 4
; CHECK-NEXT: [[TMP12:%.*]] = mul i64 1, [[TMP11]]
-; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <vscale x 8 x i64> poison, i64 [[TMP12]], i64 0
-; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <vscale x 8 x i64> [[DOTSPLATINSERT]], <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 8 x i64> poison, i64 [[VAL]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 8 x i64> [[BROADCAST_SPLATINSERT]], <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer
+; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <vscale x 4 x i64> poison, i64 [[TMP12]], i64 0
+; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <vscale x 4 x i64> [[DOTSPLATINSERT]], <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer
+; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 4 x i64> poison, i64 [[VAL]], i64 0
+; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 4 x i64> [[BROADCAST_SPLATINSERT]], <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT: [[ACTIVE_LANE_MASK:%.*]] = phi <vscale x 8 x i1> [ [[ACTIVE_LANE_MASK_ENTRY]], [[VECTOR_PH]] ], [ [[ACTIVE_LANE_MASK_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT: [[VEC_IND:%.*]] = phi <vscale x 8 x i64> [ [[INDUCTION]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[ACTIVE_LANE_MASK:%.*]] = phi <vscale x 4 x i1> [ [[ACTIVE_LANE_MASK_ENTRY]], [[VECTOR_PH]] ], [ [[ACTIVE_LANE_MASK_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[VEC_IND:%.*]] = phi <vscale x 4 x i64> [ [[INDUCTION]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP13:%.*]] = add i64 [[INDEX]], 0
; CHECK-NEXT: [[NEXT_GEP:%.*]] = getelementptr i8, ptr [[DST]], i64 [[TMP13]]
-; CHECK-NEXT: [[TMP14:%.*]] = shl nuw nsw <vscale x 8 x i64> [[VEC_IND]], shufflevector (<vscale x 8 x i64> insertelement (<vscale x 8 x i64> poison, i64 3, i64 0), <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer)
-; CHECK-NEXT: [[TMP15:%.*]] = lshr <vscale x 8 x i64> [[BROADCAST_SPLAT]], [[TMP14]]
-; CHECK-NEXT: [[TMP16:%.*]] = trunc <vscale x 8 x i64> [[TMP15]] to <vscale x 8 x i8>
+; CHECK-NEXT: [[TMP14:%.*]] = shl nuw nsw <vscale x 4 x i64> [[VEC_IND]], shufflevector (<vscale x 4 x i64> insertelement (<vscale x 4 x i64> poison, i64 3, i64 0), <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer)
+; CHECK-NEXT: [[TMP15:%.*]] = lshr <vscale x 4 x i64> [[BROADCAST_SPLAT]], [[TMP14]]
+; CHECK-NEXT: [[TMP16:%.*]] = trunc <vscale x 4 x i64> [[TMP15]] to <vscale x 4 x i8>
; CHECK-NEXT: [[TMP17:%.*]] = getelementptr i8, ptr [[NEXT_GEP]], i32 0
-; CHECK-NEXT: call void @llvm.masked.store.nxv8i8.p0(<vscale x 8 x i8> [[TMP16]], ptr [[TMP17]], i32 1, <vscale x 8 x i1> [[ACTIVE_LANE_MASK]])
+; CHECK-NEXT: call void @llvm.masked.store.nxv4i8.p0(<vscale x 4 x i8> [[TMP16]], ptr [[TMP17]], i32 1, <vscale x 4 x i1> [[ACTIVE_LANE_MASK]])
; CHECK-NEXT: [[INDEX_NEXT]] = add i64 [[INDEX]], [[TMP6]]
-; CHECK-NEXT: [[VEC_IND_NEXT]] = add <vscale x 8 x i64> [[VEC_IND]], [[DOTSPLAT]]
-; CHECK-NEXT: [[ACTIVE_LANE_MASK_NEXT]] = call <vscale x 8 x i1> @llvm.get.active.lane.mask.nxv8i1.i64(i64 [[INDEX_NEXT]], i64 8)
-; CHECK-NEXT: br i1 true, label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK-NEXT: [[ACTIVE_LANE_MASK_NEXT]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i64(i64 [[INDEX_NEXT]], i64 8)
+; CHECK-NEXT: [[TMP18:%.*]] = xor <vscale x 4 x i1> [[ACTIVE_LANE_MASK_NEXT]], shufflevector (<vscale x 4 x i1> insertelement (<vscale x 4 x i1> poison, i1 true, i64 0), <vscale x 4 x i1> poison, <vscale x 4 x i32> zeroinitializer)
+; CHECK-NEXT: [[VEC_IND_NEXT]] = add <vscale x 4 x i64> [[VEC_IND]], [[DOTSPLAT]]
+; CHECK-NEXT: [[TMP20:%.*]] = extractelement <vscale x 4 x i1> [[TMP18]], i32 0
+; CHECK-NEXT: br i1 [[TMP20]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: br i1 true, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
@@ -99,44 +101,46 @@ define void @clamped_tc_max_8(ptr nocapture %dst, i32 %n, i64 %val) vscale_range
; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP1:%.*]] = mul i64 [[TMP0]], 8
+; CHECK-NEXT: [[TMP1:%.*]] = mul i64 [[TMP0]], 4
; CHECK-NEXT: [[TMP2:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[TMP2]], 8
+; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[TMP2]], 4
; CHECK-NEXT: [[TMP4:%.*]] = sub i64 [[TMP3]], 1
; CHECK-NEXT: [[N_RND_UP:%.*]] = add i64 [[WIDE_TRIP_COUNT]], [[TMP4]]
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[N_RND_UP]], [[TMP1]]
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[N_RND_UP]], [[N_MOD_VF]]
; CHECK-NEXT: [[IND_END:%.*]] = getelementptr i8, ptr [[DST]], i64 [[N_VEC]]
; CHECK-NEXT: [[TMP5:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP6:%.*]] = mul i64 [[TMP5]], 8
-; CHECK-NEXT: [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 8 x i1> @llvm.get.active.lane.mask.nxv8i1.i64(i64 0, i64 [[WIDE_TRIP_COUNT]])
-; CHECK-NEXT: [[TMP7:%.*]] = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT: [[TMP8:%.*]] = add <vscale x 8 x i64> [[TMP7]], zeroinitializer
-; CHECK-NEXT: [[TMP9:%.*]] = mul <vscale x 8 x i64> [[TMP8]], shufflevector (<vscale x 8 x i64> insertelement (<vscale x 8 x i64> poison, i64 1, i64 0), <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer)
-; CHECK-NEXT: [[INDUCTION:%.*]] = add <vscale x 8 x i64> zeroinitializer, [[TMP9]]
+; CHECK-NEXT: [[TMP6:%.*]] = mul i64 [[TMP5]], 4
+; CHECK-NEXT: [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i64(i64 0, i64 [[WIDE_TRIP_COUNT]])
+; CHECK-NEXT: [[TMP7:%.*]] = call <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()
+; CHECK-NEXT: [[TMP8:%.*]] = add <vscale x 4 x i64> [[TMP7]], zeroinitializer
+; CHECK-NEXT: [[TMP9:%.*]] = mul <vscale x 4 x i64> [[TMP8]], shufflevector (<vscale x 4 x i64> insertelement (<vscale x 4 x i64> poison, i64 1, i64 0), <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer)
+; CHECK-NEXT: [[INDUCTION:%.*]] = add <vscale x 4 x i64> zeroinitializer, [[TMP9]]
; CHECK-NEXT: [[TMP10:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP11:%.*]] = mul i64 [[TMP10]], 8
+; CHECK-NEXT: [[TMP11:%.*]] = mul i64 [[TMP10]], 4
; CHECK-NEXT: [[TMP12:%.*]] = mul i64 1, [[TMP11]]
-; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <vscale x 8 x i64> poison, i64 [[TMP12]], i64 0
-; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <vscale x 8 x i64> [[DOTSPLATINSERT]], <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer
-; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 8 x i64> poison, i64 [[VAL]], i64 0
-; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 8 x i64> [[BROADCAST_SPLATINSERT]], <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer
+; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <vscale x 4 x i64> poison, i64 [[TMP12]], i64 0
+; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <vscale x 4 x i64> [[DOTSPLATINSERT]], <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer
+; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 4 x i64> poison, i64 [[VAL]], i64 0
+; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 4 x i64> [[BROADCAST_SPLATINSERT]], <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT: [[ACTIVE_LANE_MASK:%.*]] = phi <vscale x 8 x i1> [ [[ACTIVE_LANE_MASK_ENTRY]], [[VECTOR_PH]] ], [ [[ACTIVE_LANE_MASK_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT: [[VEC_IND:%.*]] = phi <vscale x 8 x i64> [ [[INDUCTION]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[ACTIVE_LANE_MASK:%.*]] = phi <vscale x 4 x i1> [ [[ACTIVE_LANE_MASK_ENTRY]], [[VECTOR_PH]] ], [ [[ACTIVE_LANE_MASK_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[VEC_IND:%.*]] = phi <vscale x 4 x i64> [ [[INDUCTION]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP13:%.*]] = add i64 [[INDEX]], 0
; CHECK-NEXT: [[NEXT_GEP:%.*]] = getelementptr i8, ptr [[DST]], i64 [[TMP13]]
-; CHECK-NEXT: [[TMP14:%.*]] = shl nuw nsw <vscale x 8 x i64> [[VEC_IND]], shufflevector (<vscale x 8 x i64> insertelement (<vscale x 8 x i64> poison, i64 3, i64 0), <vscale x 8 x i64> poison, <vscale x 8 x i32> zeroinitializer)
-; CHECK-NEXT: [[TMP15:%.*]] = lshr <vscale x 8 x i64> [[BROADCAST_SPLAT]], [[TMP14]]
-; CHECK-NEXT: [[TMP16:%.*]] = trunc <vscale x 8 x i64> [[TMP15]] to <vscale x 8 x i8>
+; CHECK-NEXT: [[TMP14:%.*]] = shl nuw nsw <vscale x 4 x i64> [[VEC_IND]], shufflevector (<vscale x 4 x i64> insertelement (<vscale x 4 x i64> poison, i64 3, i64 0), <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer)
+; CHECK-NEXT: [[TMP15:%.*]] = lshr <vscale x 4 x i64> [[BROADCAST_SPLAT]], [[TMP14]]
+; CHECK-NEXT: [[TMP16:%.*]] = trunc <vscale x 4 x i64> [[TMP15]] to <vscale x 4 x i8>
; CHECK-NEXT: [[TMP17:%.*]] = getelementptr i8, ptr [[NEXT_GEP]], i32 0
-; CHECK-NEXT: call void @llvm.masked.store.nxv8i8.p0(<vscale x 8 x i8> [[TMP16]], ptr [[TMP17]], i32 1, <vscale x 8 x i1> [[ACTIVE_LANE_MASK]])
+; CHECK-NEXT: call void @llvm.masked.store.nxv4i8.p0(<vscale x 4 x i8> [[TMP16]], ptr [[TMP17]], i32 1, <vscale x 4 x i1> [[ACTIVE_LANE_MASK]])
; CHECK-NEXT: [[INDEX_NEXT]] = add i64 [[INDEX]], [[TMP6]]
-; CHECK-NEXT: [[VEC_IND_NEXT]] = add <vscale x 8 x i64> [[VEC_IND]], [[DOTSPLAT]]
-; CHECK-NEXT: [[ACTIVE_LANE_MASK_NEXT]] = call <vscale x 8 x i1> @llvm.get.active.lane.mask.nxv8i1.i64(i64 [[INDEX_NEXT]], i64 [[WIDE_TRIP_COUNT]])
-; CHECK-NEXT: br i1 true, label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
+; CHECK-NEXT: [[ACTIVE_LANE_MASK_NEXT]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i64(i64 [[INDEX_NEXT]], i64 [[WIDE_TRIP_COUNT]])
+; CHECK-NEXT: [[TMP18:%.*]] = xor <vscale x 4 x i1> [[ACTIVE_LANE_MASK_NEXT]], shufflevector (<vscale x 4 x i1> insertelement (<vscale x 4 x i1> poison, i1 true, i64 0), <vscale x 4 x i1> poison, <vscale x 4 x i32> zeroinitializer)
+; CHECK-NEXT: [[VEC_IND_NEXT]] = add <vscale x 4 x i64> [[VEC_IND]], [[DOTSPLAT]]
+; CHECK-NEXT: [[TMP20:%.*]] = extractelement <vscale x 4 x i1> [[TMP18]], i32 0
+; CHECK-NEXT: br i1 [[TMP20]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: br i1 true, label [[FOR_COND_CLEANUP_LOOPEXIT:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/low-trip-count.ll b/llvm/test/Transforms/LoopVectorize/RISCV/low-trip-count.ll
index 7ccbc98d26567..2ce42c332a9c2 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/low-trip-count.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/low-trip-count.ll
@@ -48,29 +48,29 @@ define void @trip3_i8(ptr noalias nocapture noundef %dst, ptr noalias nocapture
; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP1:%.*]] = mul i64 [[TMP0]], 16
+; CHECK-NEXT: [[TMP1:%.*]] = mul i64 [[TMP0]], 2
; CHECK-NEXT: [[TMP2:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[TMP2]], 16
+; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[TMP2]], 2
; CHECK-NEXT: [[TMP4:%.*]] = sub i64 [[TMP3]], 1
; CHECK-NEXT: [[N_RND_UP:%.*]] = add i64 3, [[TMP4]]
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[N_RND_UP]], [[TMP1]]
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[N_RND_UP]], [[N_MOD_VF]]
; CHECK-NEXT: [[TMP5:%.*]] = call i64 @llvm.vscale.i64()
-; CHECK-NEXT: [[TMP6:%.*]] = mul i64 [[TMP5]], 16
+; CHECK-NEXT: [[TMP6:%.*]] = mul i64 [[TMP5]], 2
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP7:%.*]] = add i64 [[INDEX]], 0
-; CHECK-NEXT: [[ACTIVE_LANE_MASK:%.*]] = call <vscale x 16 x i1> @llvm.get.active.lane.mask.nxv16i1.i64(i64 [[TMP7]], i64 3)
+; CHECK-NEXT: [[ACTIVE_LANE_MASK:%.*]] = call <vscale x 2 x i1> @llvm.get.active.lane.mask.nxv2i1.i64(i64 [[TMP7]], i64 3)
; CHECK-NEXT: [[TMP8:%.*]] = getelementptr inbounds i8, ptr [[SRC:%.*]], i64 [[TMP7]]
; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[TMP8]], i32 0
-; CHECK-NEXT: [[WIDE_MASKED_LOAD:%.*]] = call <vscale x 16 x i8> @llvm.masked.load.nxv16i8.p0(ptr [[TMP9]], i32 1, <vscale x 16 x i1> [[ACTIVE_LANE_MASK]], <vscale x 16 x i8> poison)
-; CHECK-NEXT: [[TMP10:%.*]] = shl <vscale x 16 x i8> [[WIDE_MASKED_LOAD]], shufflevector (<vscale x 16 x i8> insertelement (<vscale x 16 x i8> poison, i8 1, i64 0), <vscale x 16 x i8> po...
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Generalize LoopVectorizationPlanner::isMoreProfitable smoothly across the fixed-vector and scalable-vector cases, taking the trip-count into account, and fixing logical pitfalls that arise from a lack of generality.
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This sounds good to me, so long as it is taking VScaleForTuning into account which I believe it does. LGTM, thanks.
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Generalize LoopVectorizationPlanner::isMoreProfitable smoothly across the fixed-vector and scalable-vector cases, taking the trip-count into account, and fixing logical pitfalls that arise from a lack of generality.