[RISCV][TTI] Enable masked interleave access for scalable vector #149981

Mel-Chen · 2025-07-22T09:14:50Z

Now that support for masked loads/stores of interleave groups has landed, we can enable the loop vectorizer to generate masked interleave access where applicable.

This improves vectorization in several ways:

Internal predication support: This enables interleave group vectorization for loops with internal control flow predication, provided all members of the group share the same predicate. Gaps in interleave groups are still not efficiently handled by masking, so masking for gaps remains disabled for now.
Tail folding: This allows tail folding of loops with interleave groups by using masking. Without this, vectorized loops with interleaves would fall back to using separate gather/scatter accesses, which can be significantly less efficient.
Scalable vector support: Currently, only scalable vector types are supported for masked interleave lowering. Fixed-length vector support will be enabled in the future.

As interleave access is not yet supported with tail folding by EVL, that functionality is temporarily disabled. We are going to create another patch to support it.

Co-authored-by: Philip Reames [email protected]

llvmbot · 2025-07-22T09:15:21Z

@llvm/pr-subscribers-vectorizers

@llvm/pr-subscribers-backend-risc-v

Author: Mel Chen (Mel-Chen)

Changes

Enable masked interleave access since RISC-V segment accesses support condition masks. This allows support for interleave access with tail folding by mask.
As interleave access is not yet supported with tail folding by EVL, that functionality is temporarily disabled.

Patch is 52.21 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/149981.diff

5 Files Affected:

(modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp (+1-2)
(modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h (+4)
(modified) llvm/lib/Transforms/Vectorize/LoopVectorize.cpp (+2)
(modified) llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll (+121-167)
(modified) llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-interleave.ll (+19-22)

diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 56ead92187b04..f134e50c91dba 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -982,8 +982,7 @@ InstructionCost RISCVTTIImpl::getInterleavedMemoryOpCost(
   // The interleaved memory access pass will lower interleaved memory ops (i.e
   // a load and store followed by a specific shuffle) to vlseg/vsseg
   // intrinsics.
-  if (!UseMaskForCond && !UseMaskForGaps &&
-      Factor <= TLI->getMaxSupportedInterleaveFactor()) {
+  if (!UseMaskForGaps && Factor <= TLI->getMaxSupportedInterleaveFactor()) {
     auto *VTy = cast<VectorType>(VecTy);
     std::pair<InstructionCost, MVT> LT = getTypeLegalizationCost(VTy);
     // Need to make sure type has't been scalarized
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
index 12bf8c1b4de70..6e8e84a40fb12 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
@@ -398,6 +398,10 @@ class RISCVTTIImpl final : public BasicTTIImplBase<RISCVTTIImpl> {
 
   bool enableInterleavedAccessVectorization() const override { return true; }
 
+  bool enableMaskedInterleavedAccessVectorization() const override {
+    return true;
+  }
+
   unsigned getMinTripCountTailFoldingThreshold() const override;
 
   enum RISCVRegisterClass { GPRRC, FPRRC, VRRC };
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 3ce9d29d34553..f51fd8ad3f838 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -1358,7 +1358,9 @@ class LoopVectorizationCostModel {
       return;
     // Override forced styles if needed.
     // FIXME: Investigate opportunity for fixed vector factor.
+    // FIXME: Support interleave accesses.
     bool EVLIsLegal = UserIC <= 1 && IsScalableVF &&
+                      !InterleaveInfo.hasGroups() &&
                       TTI.hasActiveVectorLength() && !EnableVPlanNativePath;
     if (EVLIsLegal)
       return;
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll b/llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll
index 45357dd6bf0d6..c02f76abb6621 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll
@@ -30,26 +30,25 @@ define void @masked_strided_factor2(ptr noalias nocapture readonly %p, ptr noali
 ; SCALAR_EPILOGUE-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; SCALAR_EPILOGUE-NEXT:    [[VEC_IND:%.*]] = phi <vscale x 16 x i32> [ [[TMP5]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; SCALAR_EPILOGUE-NEXT:    [[TMP6:%.*]] = icmp ugt <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT]]
-; SCALAR_EPILOGUE-NEXT:    [[TMP7:%.*]] = shl nuw nsw <vscale x 16 x i32> [[VEC_IND]], splat (i32 1)
-; SCALAR_EPILOGUE-NEXT:    [[TMP8:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; SCALAR_EPILOGUE-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP8]]
-; SCALAR_EPILOGUE-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 16 x i8> @llvm.masked.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> [[TMP9]], i32 1, <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i8> poison)
-; SCALAR_EPILOGUE-NEXT:    [[TMP10:%.*]] = or disjoint <vscale x 16 x i32> [[TMP7]], splat (i32 1)
-; SCALAR_EPILOGUE-NEXT:    [[TMP11:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; SCALAR_EPILOGUE-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP11]]
-; SCALAR_EPILOGUE-NEXT:    [[WIDE_MASKED_GATHER3:%.*]] = call <vscale x 16 x i8> @llvm.masked.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> [[TMP12]], i32 1, <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i8> poison)
-; SCALAR_EPILOGUE-NEXT:    [[TMP13:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[WIDE_MASKED_GATHER]], <vscale x 16 x i8> [[WIDE_MASKED_GATHER3]])
-; SCALAR_EPILOGUE-NEXT:    [[TMP14:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; SCALAR_EPILOGUE-NEXT:    [[TMP15:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP14]]
-; SCALAR_EPILOGUE-NEXT:    call void @llvm.masked.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP13]], <vscale x 16 x ptr> [[TMP15]], i32 1, <vscale x 16 x i1> [[TMP6]])
-; SCALAR_EPILOGUE-NEXT:    [[TMP16:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP13]]
-; SCALAR_EPILOGUE-NEXT:    [[TMP17:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; SCALAR_EPILOGUE-NEXT:    [[TMP18:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP17]]
-; SCALAR_EPILOGUE-NEXT:    call void @llvm.masked.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP16]], <vscale x 16 x ptr> [[TMP18]], i32 1, <vscale x 16 x i1> [[TMP6]])
+; SCALAR_EPILOGUE-NEXT:    [[TMP7:%.*]] = shl i32 [[INDEX]], 1
+; SCALAR_EPILOGUE-NEXT:    [[TMP8:%.*]] = sext i32 [[TMP7]] to i64
+; SCALAR_EPILOGUE-NEXT:    [[TMP9:%.*]] = getelementptr i8, ptr [[P]], i64 [[TMP8]]
+; SCALAR_EPILOGUE-NEXT:    [[INTERLEAVED_MASK:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; SCALAR_EPILOGUE-NEXT:    [[WIDE_MASKED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.masked.load.nxv32i8.p0(ptr [[TMP9]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK]], <vscale x 32 x i8> poison)
+; SCALAR_EPILOGUE-NEXT:    [[STRIDED_VEC:%.*]] = call { <vscale x 16 x i8>, <vscale x 16 x i8> } @llvm.vector.deinterleave2.nxv32i8(<vscale x 32 x i8> [[WIDE_MASKED_VEC]])
+; SCALAR_EPILOGUE-NEXT:    [[TMP10:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 0
+; SCALAR_EPILOGUE-NEXT:    [[TMP11:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 1
+; SCALAR_EPILOGUE-NEXT:    [[TMP12:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[TMP10]], <vscale x 16 x i8> [[TMP11]])
+; SCALAR_EPILOGUE-NEXT:    [[TMP13:%.*]] = sext i32 [[TMP7]] to i64
+; SCALAR_EPILOGUE-NEXT:    [[TMP14:%.*]] = getelementptr i8, ptr [[Q]], i64 [[TMP13]]
+; SCALAR_EPILOGUE-NEXT:    [[TMP15:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP12]]
+; SCALAR_EPILOGUE-NEXT:    [[INTERLEAVED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.vector.interleave2.nxv32i8(<vscale x 16 x i8> [[TMP12]], <vscale x 16 x i8> [[TMP15]])
+; SCALAR_EPILOGUE-NEXT:    [[INTERLEAVED_MASK3:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; SCALAR_EPILOGUE-NEXT:    call void @llvm.masked.store.nxv32i8.p0(<vscale x 32 x i8> [[INTERLEAVED_VEC]], ptr [[TMP14]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK3]])
 ; SCALAR_EPILOGUE-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP4]]
 ; SCALAR_EPILOGUE-NEXT:    [[VEC_IND_NEXT]] = add <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT2]]
-; SCALAR_EPILOGUE-NEXT:    [[TMP19:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
-; SCALAR_EPILOGUE-NEXT:    br i1 [[TMP19]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; SCALAR_EPILOGUE-NEXT:    [[TMP16:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
+; SCALAR_EPILOGUE-NEXT:    br i1 [[TMP16]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; SCALAR_EPILOGUE:       middle.block:
 ; SCALAR_EPILOGUE-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
 ; SCALAR_EPILOGUE-NEXT:    br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
@@ -80,26 +79,25 @@ define void @masked_strided_factor2(ptr noalias nocapture readonly %p, ptr noali
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[ACTIVE_LANE_MASK:%.*]] = call <vscale x 16 x i1> @llvm.get.active.lane.mask.nxv16i1.i32(i32 [[INDEX]], i32 1024)
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP5:%.*]] = icmp ugt <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT]]
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP6:%.*]] = select <vscale x 16 x i1> [[ACTIVE_LANE_MASK]], <vscale x 16 x i1> [[TMP5]], <vscale x 16 x i1> zeroinitializer
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP7:%.*]] = shl nuw nsw <vscale x 16 x i32> [[VEC_IND]], splat (i32 1)
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP8:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP8]]
-; PREDICATED_TAIL_FOLDING-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 16 x i8> @llvm.masked.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> [[TMP9]], i32 1, <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i8> poison)
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP10:%.*]] = or disjoint <vscale x 16 x i32> [[TMP7]], splat (i32 1)
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP11:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP11]]
-; PREDICATED_TAIL_FOLDING-NEXT:    [[WIDE_MASKED_GATHER3:%.*]] = call <vscale x 16 x i8> @llvm.masked.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> [[TMP12]], i32 1, <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i8> poison)
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP13:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[WIDE_MASKED_GATHER]], <vscale x 16 x i8> [[WIDE_MASKED_GATHER3]])
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP14:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP15:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP14]]
-; PREDICATED_TAIL_FOLDING-NEXT:    call void @llvm.masked.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP13]], <vscale x 16 x ptr> [[TMP15]], i32 1, <vscale x 16 x i1> [[TMP6]])
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP16:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP13]]
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP17:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP18:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP17]]
-; PREDICATED_TAIL_FOLDING-NEXT:    call void @llvm.masked.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP16]], <vscale x 16 x ptr> [[TMP18]], i32 1, <vscale x 16 x i1> [[TMP6]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP7:%.*]] = shl i32 [[INDEX]], 1
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP8:%.*]] = sext i32 [[TMP7]] to i64
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP9:%.*]] = getelementptr i8, ptr [[P]], i64 [[TMP8]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[INTERLEAVED_MASK:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[WIDE_MASKED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.masked.load.nxv32i8.p0(ptr [[TMP9]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK]], <vscale x 32 x i8> poison)
+; PREDICATED_TAIL_FOLDING-NEXT:    [[STRIDED_VEC:%.*]] = call { <vscale x 16 x i8>, <vscale x 16 x i8> } @llvm.vector.deinterleave2.nxv32i8(<vscale x 32 x i8> [[WIDE_MASKED_VEC]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP10:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 0
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP11:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 1
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP12:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[TMP10]], <vscale x 16 x i8> [[TMP11]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP13:%.*]] = sext i32 [[TMP7]] to i64
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP14:%.*]] = getelementptr i8, ptr [[Q]], i64 [[TMP13]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP15:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP12]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[INTERLEAVED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.vector.interleave2.nxv32i8(<vscale x 16 x i8> [[TMP12]], <vscale x 16 x i8> [[TMP15]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[INTERLEAVED_MASK3:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; PREDICATED_TAIL_FOLDING-NEXT:    call void @llvm.masked.store.nxv32i8.p0(<vscale x 32 x i8> [[INTERLEAVED_VEC]], ptr [[TMP14]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK3]])
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP3]]
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[VEC_IND_NEXT]] = add <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT2]]
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP19:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
-; PREDICATED_TAIL_FOLDING-NEXT:    br i1 [[TMP19]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP16:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
+; PREDICATED_TAIL_FOLDING-NEXT:    br i1 [[TMP16]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; PREDICATED_TAIL_FOLDING:       middle.block:
 ; PREDICATED_TAIL_FOLDING-NEXT:    br label [[FOR_END:%.*]]
 ; PREDICATED_TAIL_FOLDING:       scalar.ph:
@@ -120,37 +118,34 @@ define void @masked_strided_factor2(ptr noalias nocapture readonly %p, ptr noali
 ; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 16 x i32> poison, i32 [[CONV]], i64 0
 ; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 16 x i32> [[BROADCAST_SPLATINSERT]], <vscale x 16 x i32> poison, <vscale x 16 x i32> zeroinitializer
 ; PREDICATED_EVL-NEXT:    [[TMP4:%.*]] = call <vscale x 16 x i32> @llvm.stepvector.nxv16i32()
+; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 16 x i32> poison, i32 [[TMP3]], i64 0
+; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 16 x i32> [[BROADCAST_SPLATINSERT1]], <vscale x 16 x i32> poison, <vscale x 16 x i32> zeroinitializer
 ; PREDICATED_EVL-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; PREDICATED_EVL:       vector.body:
 ; PREDICATED_EVL-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
-; PREDICATED_EVL-NEXT:    [[EVL_BASED_IV:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_EVL_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; PREDICATED_EVL-NEXT:    [[VEC_IND:%.*]] = phi <vscale x 16 x i32> [ [[TMP4]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
-; PREDICATED_EVL-NEXT:    [[AVL:%.*]] = sub i32 1024, [[EVL_BASED_IV]]
-; PREDICATED_EVL-NEXT:    [[TMP5:%.*]] = call i32 @llvm.experimental.get.vector.length.i32(i32 [[AVL]], i32 16, i1 true)
-; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 16 x i32> poison, i32 [[TMP5]], i64 0
-; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 16 x i32> [[BROADCAST_SPLATINSERT1]], <vscale x 16 x i32> poison, <vscale x 16 x i32> zeroinitializer
+; PREDICATED_EVL-NEXT:    [[TMP5:%.*]] = icmp ult <vscale x 16 x i32> [[VEC_IND]], splat (i32 1024)
 ; PREDICATED_EVL-NEXT:    [[TMP6:%.*]] = icmp ugt <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT]]
-; PREDICATED_EVL-NEXT:    [[TMP7:%.*]] = shl nuw nsw <vscale x 16 x i32> [[VEC_IND]], splat (i32 1)
-; PREDICATED_EVL-NEXT:    [[TMP8:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; PREDICATED_EVL-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP8]]
-; PREDICATED_EVL-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 16 x i8> @llvm.vp.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> align 1 [[TMP9]], <vscale x 16 x i1> [[TMP6]], i32 [[TMP5]])
-; PREDICATED_EVL-NEXT:    [[TMP10:%.*]] = or disjoint <vscale x 16 x i32> [[TMP7]], splat (i32 1)
-; PREDICATED_EVL-NEXT:    [[TMP11:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; PREDICATED_EVL-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP11]]
-; PREDICATED_EVL-NEXT:    [[WIDE_MASKED_GATHER3:%.*]] = call <vscale x 16 x i8> @llvm.vp.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> align 1 [[TMP12]], <vscale x 16 x i1> [[TMP6]], i32 [[TMP5]])
-; PREDICATED_EVL-NEXT:    [[TMP13:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[WIDE_MASKED_GATHER]], <vscale x 16 x i8> [[WIDE_MASKED_GATHER3]])
-; PREDICATED_EVL-NEXT:    [[TMP14:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; PREDICATED_EVL-NEXT:    [[TMP15:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP14]]
-; PREDICATED_EVL-NEXT:    call void @llvm.vp.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP13]], <vscale x 16 x ptr> align 1 [[TMP15]], <vscale x 16 x i1> [[TMP6]], i32 [[TMP5]])
+; PREDICATED_EVL-NEXT:    [[TMP7:%.*]] = select <vscale x 16 x i1> [[TMP5]], <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> zeroinitializer
+; PREDICATED_EVL-NEXT:    [[TMP8:%.*]] = shl i32 [[INDEX]], 1
+; PREDICATED_EVL-NEXT:    [[TMP9:%.*]] = sext i32 [[TMP8]] to i64
+; PREDICATED_EVL-NEXT:    [[TMP10:%.*]] = getelementptr i8, ptr [[P]], i64 [[TMP9]]
+; PREDICATED_EVL-NEXT:    [[INTERLEAVED_MASK:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP7]], <vscale x 16 x i1> [[TMP7]])
+; PREDICATED_EVL-NEXT:    [[WIDE_MASKED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.masked.load.nxv32i8.p0(ptr [[TMP10]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK]], <vscale x 32 x i8> poison)
+; PREDICATED_EVL-NEXT:    [[STRIDED_VEC:%.*]] = call { <vscale x 16 x i8>, <vscale x 16 x i8> } @llvm.vector.deinterleave2.nxv32i8(<vscale x 32 x i8> [[WIDE_MASKED_VEC]])
+; PREDICATED_EVL-NEXT:    [[TMP11:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 0
+; PREDICATED_EVL-NEXT:    [[TMP12:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 1
+; PREDICATED_EVL-NEXT:    [[TMP13:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[TMP11]], <vscale x 16 x i8> [[TMP12]])
+; PREDICATED_EVL-NEXT:    [[TMP14:%.*]] = sext i32 [[TMP8]] to i64
+; PREDICATED_EVL-NEXT:    [[TMP15:%.*]] = getelementptr i8, ptr [[Q]], i64 [[TMP14]]
 ; PREDICATED_EVL-NEXT:    [[TMP16:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP13]]
-; PREDICATED_EVL-NEXT:    [[TMP17:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; PREDICATED_EVL-NEXT:    [[TMP18:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP17]]
-; PREDICATED_EVL-NEXT:    call void @llvm.vp.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP16]], <vscale x 16 x ptr> align 1 [[TMP18]], <vscale x 16 x i1> [[TMP6]], i32 [[TMP5]])
-; PREDICATED_EVL-NEXT:    [[INDEX_EVL_NEXT]] = add nuw i32 [[TMP5]], [[EVL_BASED_IV]]
+; PREDICATED_EVL-NEXT:    [[INTERLEAVED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.vector.interleave2.nxv32i8(<vscale x 16 x i8> [[TMP13]], <vscale x 16 x i8> [[TMP16]])
+; PREDICATED_EVL-NEXT:    [[INTERLEAVED_MASK3:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP7]], <vscale x 16 x i1> [[TMP7]])
+; PREDICATED_EVL-NEXT:    call void @llvm.masked.store.nxv32i8.p0(<vscale x 32 x i8> [[INTERLEAVED_VEC]], ptr [[TMP15]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK3]])
 ; PREDICATED_EVL-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP3]]
 ; PREDICATED_EVL-NEXT:    [[VEC_IND_NEXT]] = add <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT2]]
-; PREDICATED_EVL-NEXT:    [[TMP19:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
-; PREDICATED_EVL-NEXT:    br i1 [[TMP19]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; PREDICATED_EVL-NEXT:    [[TMP17:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
+; PREDICATED_EVL-NEXT:    br i1 [[TMP17]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; PREDICATED_EVL:       middle.block:
 ; PREDICATED_EVL-NEXT:    br label [[FOR_END:%.*]]
 ; PREDICATED_EVL:       scalar.ph:
@@ -215,42 +210,29 @@ define void @masked_strided_factor4(ptr noalias nocapture readonly %p, ptr noali
 ; SCALAR_EPILOGUE-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; SCALAR_EPILOGUE-NEXT:    [[VEC_IND:%...
[truncated]

llvmbot · 2025-07-22T09:15:21Z

@llvm/pr-subscribers-llvm-transforms

Author: Mel Chen (Mel-Chen)

Changes

Enable masked interleave access since RISC-V segment accesses support condition masks. This allows support for interleave access with tail folding by mask.
As interleave access is not yet supported with tail folding by EVL, that functionality is temporarily disabled.

Patch is 52.21 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/149981.diff

5 Files Affected:

(modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp (+1-2)
(modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h (+4)
(modified) llvm/lib/Transforms/Vectorize/LoopVectorize.cpp (+2)
(modified) llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll (+121-167)
(modified) llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-interleave.ll (+19-22)

diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 56ead92187b04..f134e50c91dba 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -982,8 +982,7 @@ InstructionCost RISCVTTIImpl::getInterleavedMemoryOpCost(
   // The interleaved memory access pass will lower interleaved memory ops (i.e
   // a load and store followed by a specific shuffle) to vlseg/vsseg
   // intrinsics.
-  if (!UseMaskForCond && !UseMaskForGaps &&
-      Factor <= TLI->getMaxSupportedInterleaveFactor()) {
+  if (!UseMaskForGaps && Factor <= TLI->getMaxSupportedInterleaveFactor()) {
     auto *VTy = cast<VectorType>(VecTy);
     std::pair<InstructionCost, MVT> LT = getTypeLegalizationCost(VTy);
     // Need to make sure type has't been scalarized
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
index 12bf8c1b4de70..6e8e84a40fb12 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h
@@ -398,6 +398,10 @@ class RISCVTTIImpl final : public BasicTTIImplBase<RISCVTTIImpl> {
 
   bool enableInterleavedAccessVectorization() const override { return true; }
 
+  bool enableMaskedInterleavedAccessVectorization() const override {
+    return true;
+  }
+
   unsigned getMinTripCountTailFoldingThreshold() const override;
 
   enum RISCVRegisterClass { GPRRC, FPRRC, VRRC };
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 3ce9d29d34553..f51fd8ad3f838 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -1358,7 +1358,9 @@ class LoopVectorizationCostModel {
       return;
     // Override forced styles if needed.
     // FIXME: Investigate opportunity for fixed vector factor.
+    // FIXME: Support interleave accesses.
     bool EVLIsLegal = UserIC <= 1 && IsScalableVF &&
+                      !InterleaveInfo.hasGroups() &&
                       TTI.hasActiveVectorLength() && !EnableVPlanNativePath;
     if (EVLIsLegal)
       return;
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll b/llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll
index 45357dd6bf0d6..c02f76abb6621 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll
@@ -30,26 +30,25 @@ define void @masked_strided_factor2(ptr noalias nocapture readonly %p, ptr noali
 ; SCALAR_EPILOGUE-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; SCALAR_EPILOGUE-NEXT:    [[VEC_IND:%.*]] = phi <vscale x 16 x i32> [ [[TMP5]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; SCALAR_EPILOGUE-NEXT:    [[TMP6:%.*]] = icmp ugt <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT]]
-; SCALAR_EPILOGUE-NEXT:    [[TMP7:%.*]] = shl nuw nsw <vscale x 16 x i32> [[VEC_IND]], splat (i32 1)
-; SCALAR_EPILOGUE-NEXT:    [[TMP8:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; SCALAR_EPILOGUE-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP8]]
-; SCALAR_EPILOGUE-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 16 x i8> @llvm.masked.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> [[TMP9]], i32 1, <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i8> poison)
-; SCALAR_EPILOGUE-NEXT:    [[TMP10:%.*]] = or disjoint <vscale x 16 x i32> [[TMP7]], splat (i32 1)
-; SCALAR_EPILOGUE-NEXT:    [[TMP11:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; SCALAR_EPILOGUE-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP11]]
-; SCALAR_EPILOGUE-NEXT:    [[WIDE_MASKED_GATHER3:%.*]] = call <vscale x 16 x i8> @llvm.masked.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> [[TMP12]], i32 1, <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i8> poison)
-; SCALAR_EPILOGUE-NEXT:    [[TMP13:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[WIDE_MASKED_GATHER]], <vscale x 16 x i8> [[WIDE_MASKED_GATHER3]])
-; SCALAR_EPILOGUE-NEXT:    [[TMP14:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; SCALAR_EPILOGUE-NEXT:    [[TMP15:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP14]]
-; SCALAR_EPILOGUE-NEXT:    call void @llvm.masked.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP13]], <vscale x 16 x ptr> [[TMP15]], i32 1, <vscale x 16 x i1> [[TMP6]])
-; SCALAR_EPILOGUE-NEXT:    [[TMP16:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP13]]
-; SCALAR_EPILOGUE-NEXT:    [[TMP17:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; SCALAR_EPILOGUE-NEXT:    [[TMP18:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP17]]
-; SCALAR_EPILOGUE-NEXT:    call void @llvm.masked.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP16]], <vscale x 16 x ptr> [[TMP18]], i32 1, <vscale x 16 x i1> [[TMP6]])
+; SCALAR_EPILOGUE-NEXT:    [[TMP7:%.*]] = shl i32 [[INDEX]], 1
+; SCALAR_EPILOGUE-NEXT:    [[TMP8:%.*]] = sext i32 [[TMP7]] to i64
+; SCALAR_EPILOGUE-NEXT:    [[TMP9:%.*]] = getelementptr i8, ptr [[P]], i64 [[TMP8]]
+; SCALAR_EPILOGUE-NEXT:    [[INTERLEAVED_MASK:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; SCALAR_EPILOGUE-NEXT:    [[WIDE_MASKED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.masked.load.nxv32i8.p0(ptr [[TMP9]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK]], <vscale x 32 x i8> poison)
+; SCALAR_EPILOGUE-NEXT:    [[STRIDED_VEC:%.*]] = call { <vscale x 16 x i8>, <vscale x 16 x i8> } @llvm.vector.deinterleave2.nxv32i8(<vscale x 32 x i8> [[WIDE_MASKED_VEC]])
+; SCALAR_EPILOGUE-NEXT:    [[TMP10:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 0
+; SCALAR_EPILOGUE-NEXT:    [[TMP11:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 1
+; SCALAR_EPILOGUE-NEXT:    [[TMP12:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[TMP10]], <vscale x 16 x i8> [[TMP11]])
+; SCALAR_EPILOGUE-NEXT:    [[TMP13:%.*]] = sext i32 [[TMP7]] to i64
+; SCALAR_EPILOGUE-NEXT:    [[TMP14:%.*]] = getelementptr i8, ptr [[Q]], i64 [[TMP13]]
+; SCALAR_EPILOGUE-NEXT:    [[TMP15:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP12]]
+; SCALAR_EPILOGUE-NEXT:    [[INTERLEAVED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.vector.interleave2.nxv32i8(<vscale x 16 x i8> [[TMP12]], <vscale x 16 x i8> [[TMP15]])
+; SCALAR_EPILOGUE-NEXT:    [[INTERLEAVED_MASK3:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; SCALAR_EPILOGUE-NEXT:    call void @llvm.masked.store.nxv32i8.p0(<vscale x 32 x i8> [[INTERLEAVED_VEC]], ptr [[TMP14]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK3]])
 ; SCALAR_EPILOGUE-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP4]]
 ; SCALAR_EPILOGUE-NEXT:    [[VEC_IND_NEXT]] = add <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT2]]
-; SCALAR_EPILOGUE-NEXT:    [[TMP19:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
-; SCALAR_EPILOGUE-NEXT:    br i1 [[TMP19]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; SCALAR_EPILOGUE-NEXT:    [[TMP16:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
+; SCALAR_EPILOGUE-NEXT:    br i1 [[TMP16]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; SCALAR_EPILOGUE:       middle.block:
 ; SCALAR_EPILOGUE-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
 ; SCALAR_EPILOGUE-NEXT:    br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
@@ -80,26 +79,25 @@ define void @masked_strided_factor2(ptr noalias nocapture readonly %p, ptr noali
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[ACTIVE_LANE_MASK:%.*]] = call <vscale x 16 x i1> @llvm.get.active.lane.mask.nxv16i1.i32(i32 [[INDEX]], i32 1024)
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP5:%.*]] = icmp ugt <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT]]
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP6:%.*]] = select <vscale x 16 x i1> [[ACTIVE_LANE_MASK]], <vscale x 16 x i1> [[TMP5]], <vscale x 16 x i1> zeroinitializer
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP7:%.*]] = shl nuw nsw <vscale x 16 x i32> [[VEC_IND]], splat (i32 1)
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP8:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP8]]
-; PREDICATED_TAIL_FOLDING-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 16 x i8> @llvm.masked.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> [[TMP9]], i32 1, <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i8> poison)
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP10:%.*]] = or disjoint <vscale x 16 x i32> [[TMP7]], splat (i32 1)
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP11:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP11]]
-; PREDICATED_TAIL_FOLDING-NEXT:    [[WIDE_MASKED_GATHER3:%.*]] = call <vscale x 16 x i8> @llvm.masked.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> [[TMP12]], i32 1, <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i8> poison)
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP13:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[WIDE_MASKED_GATHER]], <vscale x 16 x i8> [[WIDE_MASKED_GATHER3]])
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP14:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP15:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP14]]
-; PREDICATED_TAIL_FOLDING-NEXT:    call void @llvm.masked.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP13]], <vscale x 16 x ptr> [[TMP15]], i32 1, <vscale x 16 x i1> [[TMP6]])
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP16:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP13]]
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP17:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP18:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP17]]
-; PREDICATED_TAIL_FOLDING-NEXT:    call void @llvm.masked.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP16]], <vscale x 16 x ptr> [[TMP18]], i32 1, <vscale x 16 x i1> [[TMP6]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP7:%.*]] = shl i32 [[INDEX]], 1
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP8:%.*]] = sext i32 [[TMP7]] to i64
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP9:%.*]] = getelementptr i8, ptr [[P]], i64 [[TMP8]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[INTERLEAVED_MASK:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[WIDE_MASKED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.masked.load.nxv32i8.p0(ptr [[TMP9]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK]], <vscale x 32 x i8> poison)
+; PREDICATED_TAIL_FOLDING-NEXT:    [[STRIDED_VEC:%.*]] = call { <vscale x 16 x i8>, <vscale x 16 x i8> } @llvm.vector.deinterleave2.nxv32i8(<vscale x 32 x i8> [[WIDE_MASKED_VEC]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP10:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 0
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP11:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 1
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP12:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[TMP10]], <vscale x 16 x i8> [[TMP11]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP13:%.*]] = sext i32 [[TMP7]] to i64
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP14:%.*]] = getelementptr i8, ptr [[Q]], i64 [[TMP13]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP15:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP12]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[INTERLEAVED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.vector.interleave2.nxv32i8(<vscale x 16 x i8> [[TMP12]], <vscale x 16 x i8> [[TMP15]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[INTERLEAVED_MASK3:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; PREDICATED_TAIL_FOLDING-NEXT:    call void @llvm.masked.store.nxv32i8.p0(<vscale x 32 x i8> [[INTERLEAVED_VEC]], ptr [[TMP14]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK3]])
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP3]]
 ; PREDICATED_TAIL_FOLDING-NEXT:    [[VEC_IND_NEXT]] = add <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT2]]
-; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP19:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
-; PREDICATED_TAIL_FOLDING-NEXT:    br i1 [[TMP19]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP16:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
+; PREDICATED_TAIL_FOLDING-NEXT:    br i1 [[TMP16]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; PREDICATED_TAIL_FOLDING:       middle.block:
 ; PREDICATED_TAIL_FOLDING-NEXT:    br label [[FOR_END:%.*]]
 ; PREDICATED_TAIL_FOLDING:       scalar.ph:
@@ -120,37 +118,34 @@ define void @masked_strided_factor2(ptr noalias nocapture readonly %p, ptr noali
 ; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 16 x i32> poison, i32 [[CONV]], i64 0
 ; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 16 x i32> [[BROADCAST_SPLATINSERT]], <vscale x 16 x i32> poison, <vscale x 16 x i32> zeroinitializer
 ; PREDICATED_EVL-NEXT:    [[TMP4:%.*]] = call <vscale x 16 x i32> @llvm.stepvector.nxv16i32()
+; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 16 x i32> poison, i32 [[TMP3]], i64 0
+; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 16 x i32> [[BROADCAST_SPLATINSERT1]], <vscale x 16 x i32> poison, <vscale x 16 x i32> zeroinitializer
 ; PREDICATED_EVL-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; PREDICATED_EVL:       vector.body:
 ; PREDICATED_EVL-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
-; PREDICATED_EVL-NEXT:    [[EVL_BASED_IV:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_EVL_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; PREDICATED_EVL-NEXT:    [[VEC_IND:%.*]] = phi <vscale x 16 x i32> [ [[TMP4]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
-; PREDICATED_EVL-NEXT:    [[AVL:%.*]] = sub i32 1024, [[EVL_BASED_IV]]
-; PREDICATED_EVL-NEXT:    [[TMP5:%.*]] = call i32 @llvm.experimental.get.vector.length.i32(i32 [[AVL]], i32 16, i1 true)
-; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 16 x i32> poison, i32 [[TMP5]], i64 0
-; PREDICATED_EVL-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 16 x i32> [[BROADCAST_SPLATINSERT1]], <vscale x 16 x i32> poison, <vscale x 16 x i32> zeroinitializer
+; PREDICATED_EVL-NEXT:    [[TMP5:%.*]] = icmp ult <vscale x 16 x i32> [[VEC_IND]], splat (i32 1024)
 ; PREDICATED_EVL-NEXT:    [[TMP6:%.*]] = icmp ugt <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT]]
-; PREDICATED_EVL-NEXT:    [[TMP7:%.*]] = shl nuw nsw <vscale x 16 x i32> [[VEC_IND]], splat (i32 1)
-; PREDICATED_EVL-NEXT:    [[TMP8:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; PREDICATED_EVL-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP8]]
-; PREDICATED_EVL-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <vscale x 16 x i8> @llvm.vp.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> align 1 [[TMP9]], <vscale x 16 x i1> [[TMP6]], i32 [[TMP5]])
-; PREDICATED_EVL-NEXT:    [[TMP10:%.*]] = or disjoint <vscale x 16 x i32> [[TMP7]], splat (i32 1)
-; PREDICATED_EVL-NEXT:    [[TMP11:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; PREDICATED_EVL-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i8, ptr [[P]], <vscale x 16 x i64> [[TMP11]]
-; PREDICATED_EVL-NEXT:    [[WIDE_MASKED_GATHER3:%.*]] = call <vscale x 16 x i8> @llvm.vp.gather.nxv16i8.nxv16p0(<vscale x 16 x ptr> align 1 [[TMP12]], <vscale x 16 x i1> [[TMP6]], i32 [[TMP5]])
-; PREDICATED_EVL-NEXT:    [[TMP13:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[WIDE_MASKED_GATHER]], <vscale x 16 x i8> [[WIDE_MASKED_GATHER3]])
-; PREDICATED_EVL-NEXT:    [[TMP14:%.*]] = zext nneg <vscale x 16 x i32> [[TMP7]] to <vscale x 16 x i64>
-; PREDICATED_EVL-NEXT:    [[TMP15:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP14]]
-; PREDICATED_EVL-NEXT:    call void @llvm.vp.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP13]], <vscale x 16 x ptr> align 1 [[TMP15]], <vscale x 16 x i1> [[TMP6]], i32 [[TMP5]])
+; PREDICATED_EVL-NEXT:    [[TMP7:%.*]] = select <vscale x 16 x i1> [[TMP5]], <vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> zeroinitializer
+; PREDICATED_EVL-NEXT:    [[TMP8:%.*]] = shl i32 [[INDEX]], 1
+; PREDICATED_EVL-NEXT:    [[TMP9:%.*]] = sext i32 [[TMP8]] to i64
+; PREDICATED_EVL-NEXT:    [[TMP10:%.*]] = getelementptr i8, ptr [[P]], i64 [[TMP9]]
+; PREDICATED_EVL-NEXT:    [[INTERLEAVED_MASK:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP7]], <vscale x 16 x i1> [[TMP7]])
+; PREDICATED_EVL-NEXT:    [[WIDE_MASKED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.masked.load.nxv32i8.p0(ptr [[TMP10]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK]], <vscale x 32 x i8> poison)
+; PREDICATED_EVL-NEXT:    [[STRIDED_VEC:%.*]] = call { <vscale x 16 x i8>, <vscale x 16 x i8> } @llvm.vector.deinterleave2.nxv32i8(<vscale x 32 x i8> [[WIDE_MASKED_VEC]])
+; PREDICATED_EVL-NEXT:    [[TMP11:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 0
+; PREDICATED_EVL-NEXT:    [[TMP12:%.*]] = extractvalue { <vscale x 16 x i8>, <vscale x 16 x i8> } [[STRIDED_VEC]], 1
+; PREDICATED_EVL-NEXT:    [[TMP13:%.*]] = call <vscale x 16 x i8> @llvm.smax.nxv16i8(<vscale x 16 x i8> [[TMP11]], <vscale x 16 x i8> [[TMP12]])
+; PREDICATED_EVL-NEXT:    [[TMP14:%.*]] = sext i32 [[TMP8]] to i64
+; PREDICATED_EVL-NEXT:    [[TMP15:%.*]] = getelementptr i8, ptr [[Q]], i64 [[TMP14]]
 ; PREDICATED_EVL-NEXT:    [[TMP16:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP13]]
-; PREDICATED_EVL-NEXT:    [[TMP17:%.*]] = zext nneg <vscale x 16 x i32> [[TMP10]] to <vscale x 16 x i64>
-; PREDICATED_EVL-NEXT:    [[TMP18:%.*]] = getelementptr inbounds i8, ptr [[Q]], <vscale x 16 x i64> [[TMP17]]
-; PREDICATED_EVL-NEXT:    call void @llvm.vp.scatter.nxv16i8.nxv16p0(<vscale x 16 x i8> [[TMP16]], <vscale x 16 x ptr> align 1 [[TMP18]], <vscale x 16 x i1> [[TMP6]], i32 [[TMP5]])
-; PREDICATED_EVL-NEXT:    [[INDEX_EVL_NEXT]] = add nuw i32 [[TMP5]], [[EVL_BASED_IV]]
+; PREDICATED_EVL-NEXT:    [[INTERLEAVED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.vector.interleave2.nxv32i8(<vscale x 16 x i8> [[TMP13]], <vscale x 16 x i8> [[TMP16]])
+; PREDICATED_EVL-NEXT:    [[INTERLEAVED_MASK3:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP7]], <vscale x 16 x i1> [[TMP7]])
+; PREDICATED_EVL-NEXT:    call void @llvm.masked.store.nxv32i8.p0(<vscale x 32 x i8> [[INTERLEAVED_VEC]], ptr [[TMP15]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK3]])
 ; PREDICATED_EVL-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP3]]
 ; PREDICATED_EVL-NEXT:    [[VEC_IND_NEXT]] = add <vscale x 16 x i32> [[VEC_IND]], [[BROADCAST_SPLAT2]]
-; PREDICATED_EVL-NEXT:    [[TMP19:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
-; PREDICATED_EVL-NEXT:    br i1 [[TMP19]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; PREDICATED_EVL-NEXT:    [[TMP17:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
+; PREDICATED_EVL-NEXT:    br i1 [[TMP17]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; PREDICATED_EVL:       middle.block:
 ; PREDICATED_EVL-NEXT:    br label [[FOR_END:%.*]]
 ; PREDICATED_EVL:       scalar.ph:
@@ -215,42 +210,29 @@ define void @masked_strided_factor4(ptr noalias nocapture readonly %p, ptr noali
 ; SCALAR_EPILOGUE-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; SCALAR_EPILOGUE-NEXT:    [[VEC_IND:%...
[truncated]

lukel97 · 2025-07-22T10:23:24Z

llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll

+; PREDICATED_TAIL_FOLDING-NEXT:    [[TMP15:%.*]] = sub <vscale x 16 x i8> zeroinitializer, [[TMP12]]
+; PREDICATED_TAIL_FOLDING-NEXT:    [[INTERLEAVED_VEC:%.*]] = call <vscale x 32 x i8> @llvm.vector.interleave2.nxv32i8(<vscale x 16 x i8> [[TMP12]], <vscale x 16 x i8> [[TMP15]])
+; PREDICATED_TAIL_FOLDING-NEXT:    [[INTERLEAVED_MASK3:%.*]] = call <vscale x 32 x i1> @llvm.vector.interleave2.nxv32i1(<vscale x 16 x i1> [[TMP6]], <vscale x 16 x i1> [[TMP6]])
+; PREDICATED_TAIL_FOLDING-NEXT:    call void @llvm.masked.store.nxv32i8.p0(<vscale x 32 x i8> [[INTERLEAVED_VEC]], ptr [[TMP14]], i32 1, <vscale x 32 x i1> [[INTERLEAVED_MASK3]])


Just want to check, this should be ok now that #149893 and #149556 is landed now? I.e. the InterleavedAccessPass should be able to lower these to masked vlseg/vsseg intrinsics now?

llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-interleave.ll

lukel97 · 2025-07-23T03:03:58Z

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

    bool EVLIsLegal = UserIC <= 1 && IsScalableVF &&
+                      !InterleaveInfo.hasGroups() &&


It's a bit unfortunate the timing of these patches, but I just LGTM'd #150074, since I think we don't actually need the EVLIsLegal check, it should be ok to keep around the mask for now and we can optimise it away to a VP intrinsic later.

I guess it looks like we also need to account for the fact that we don't handle masked.{load,store} for shufflevector [de]interleaves?

In any case we still need to do the actual VP intrinsic transform so I will create an issue on github for that

I’ve completed the simplest initial implementation of VPInterleaveEVLRecipe in my local, but I found it couldn’t be converted into EVL recipe. That’s when I realized that masked interleave access hasn’t been enabled upstream yet.

However, I believe enabling both tail folding by mask and EVL at the same time is unsafe.
Consider this scenario: the VF is 4, and the trip count is 5. With EVL, the vectorized loop gets two iterations, fetching 3 and 2 elements (EVL) respectively. The VPWidenInductionRecipe with EVL would then produce [0, 1, 2, 3(X)] and [3, 4, 5(X), 6(X)], where the lanes marked (X) are the lanes that should not be used.

If there is an interleaved store with factor 2 using the values produced by the VPWidenInductionRecipe, and apply interleaved masks [T, T, T, T, T, T, T, T] and [T, T, F, F, F, F, F, F], we might end up storing incorrect values like [0, 0, 1, 1, 2, 2, 3(X), 3(X)] and [3, 3, X, X, X, X, X, X].

Wouldn’t that lead to storing incorrect values in memory?

IIUC the mask is interleaved with itself before being fed into the widen load, i.e. see these lines: https://github.com/llvm/llvm-project/pull/150074/files#diff-8b722352f6c665b720f4318006f7ae773cfaddd722fd211fdcf8ef18d8d115dcR42-R43

So the widen load's mask is actually interleave([T, T, T, F], [T, T, T, F]) = [T, T, T, T, T, T, F, F] on the first iteration, and interleave([T, T, F, F], [T, T, F, F]) = [T, T, T, T, F, F, F, F] on the second iteration

The interleaved access pass then checks to make sure that the mask is actually interleaved before deinterleaving it again for the vlseg/vsseg intrinsic:

llvm-project/llvm/lib/CodeGen/InterleavedAccessPass.cpp

Lines 536 to 543 in b7889a6

static Value *getMask(Value *WideMask, unsigned Factor,

ElementCount LeafValueEC) {

if (auto *IMI = dyn_cast<IntrinsicInst>(WideMask)) {

if (unsigned F = getInterleaveIntrinsicFactor(IMI->getIntrinsicID());

F && F == Factor && llvm::all_equal(IMI->args())) {

return IMI->getArgOperand(0);

}

}

So it should emit a vlseg with mask [T, T, T, F] on the first iteration, and [T, T, F, F] on the second iteration

Hmm, although I previously said the mask might be incorrect, it’s actually different from what you described.

; IF-EVL-NEXT: [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 4 x i64> poison, i64 [[EVL_BASED_IV]], i64 0 ; IF-EVL-NEXT: [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 4 x i64> [[BROADCAST_SPLATINSERT1]], <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer ; IF-EVL-NEXT: [[TMP10:%.*]] = call <vscale x 4 x i64> @llvm.stepvector.nxv4i64() ; IF-EVL-NEXT: [[TMP12:%.*]] = add <vscale x 4 x i64> zeroinitializer, [[TMP10]] ; IF-EVL-NEXT: [[VEC_IV:%.*]] = add <vscale x 4 x i64> [[BROADCAST_SPLAT2]], [[TMP12]] ; IF-EVL-NEXT: [[TMP13:%.*]] = icmp ule <vscale x 4 x i64> [[VEC_IV]], [[BROADCAST_SPLAT]]

In reality, the two masks should be: [T, T, T, T, T, T, T, T] and [T, T, T, T, F, F, F, F].

For the first iteration:
([0, 0, 0, 0] + [0, 1, 2, 3]) <= [4, 4, 4, 4], where 4 is TripCount - 1.

For the second iteration:
([3, 3, 3, 3] + [0, 1, 2, 3]) <= [4, 4, 4, 4].

Is that correct?

I think you're right. This looks like an underlying issue with mixing the header masks and EVL based IV.

I think we need to convert the header masks from icmp ule wide-canonical-iv, backedge-tc to icmp ult step-vector, EVL.

Because on the second-to-last iteration the original header mask isn't going to take into account the possible truncation.

So on the first iteration, it should really be:

[0, 1, 2, 3] < 3 = [T, T, T, F]

And on the second iteration

[0, 1, 2, 3] < 2 = [T, T, F, F].

I'll create an issue for this, this is a good find.

; IF-EVL-NEXT: [[TMP9:%.*]] = getelementptr inbounds [2 x i32], ptr [[B:%.*]], i64 [[EVL_BASED_IV]], i32 0

But thinking about it more carefully, since the GEP has already been adjusted based on the EVL base PHI, even though the header mask is not in sync with the EVL, the final store result in the example should still be correct. It's just that addresses which were originally written to only once may now be written to multiple times. The value written the first time might be incorrect, but it will eventually be overwritten with the correct value. However, I'm not sure if this could cause other issues. In any case, I still recommend avoiding mixing tail folding modes—it doesn’t seem entirely safe.

It's just that addresses which were originally written to only once may now be written to multiple times. The value written the first time might be incorrect, but it will eventually be overwritten with the correct value.

Just FYI, this reasoning is suspect. Introducing a duplicate write to the same location is possibly a violation of the memory model. I'd have to think that through carefully to see if it was, but it's definitely undesirable if we can reasonable avoid.

(Topic switch)

If I'm following this thread correctly, the issue being theorized here is a problem for any interleave group with EVL right? Not just the masked variants?

Replying to myself after reading more context - yeah, this is a generic EVL bug.

@Mel-Chen Would you mind separating your EVLIsLegal change into a separate review with a test case which shows the bug? I'd like to get EVL disabled for this case while Luke's correctness change works it way through review.

Edit: Once we do that, I can enable the masked interleave support (for what ends up being masking and non-predicated only), then we can remove the limitation once the root issue is properly fixed.

I was thinking about this later today, and realized I'd missed the obvious here. While the bug is theoretically reachable through other paths, the combination of predicatation and interleave-groups currently only happens with this patch to enable the predication. EVL without this patch can't hit this code path; I'd missed that when thinking about this earlier.

@Mel-Chen I'm tempted to just take your patch as the primary path forward here towards enabling masking interleave. Any concerns with that? On reflection, I don't know the splitting I'd suggested earlier is actually worthwhile.

Oh of course, no problem! I pulled in some changes I thought were really good from #150074, rewrote a new description based on your commit message, and listed you as a co-author.
4688b4c

With EVL tail folding, the EVL may not always be VF on the second-to-last iteration. Recipes that have been converted to VP intrinsics via optimizeMaskToEVL account for this, but recipes that are left behind will still use the old header mask which may end up having a different vector length. This is effectively the same as llvm#95368, and fixes this by converting header masks from icmp ule wide-canonical-iv, backedge-trip-count -> icmp ult step-vector, evl. Without it, recipes that fall through optimizeMaskToEVL may use the wrong vector length, e.g. in llvm#150074 and llvm#149981. We really need to split off optimizeMaskToEVL into VPlanTransforms::optimize and move transformRecipestoEVLRecipes into tryToBuildVPlanWithVPRecipes, so we don't mix up what is needed for correctness and what is needed to optimize away the mask computations. We should be able to still generate a correct albeit suboptimal VPlan without running optimizeMaskToEVL. I've added a TODO for this. Fixes llvm#150197

Co-authored-by: Philip Reames <[email protected]>

preames

LGTM

preames · 2025-07-25T04:14:47Z

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

+  // only support masking per-iteration (i.e. condition), not per-segment (i.e.
+  // gap).
+  // TODO: Support masked interleaved access for fixed length vector.
+  if ((isa<ScalableVectorType>(VecTy) || !UseMaskForCond) && !UseMaskForGaps &&


FYI, I've landed the last change for the fixed vector path. You can delete UseMaskForCand entirely if you want, if not, I'll do it as a follow up review.

asb · 2025-07-25T15:13:48Z

This patch has caused an assertion on the zvl1024b builder [1] (actually the first zvl-specific failure the recently added builders have caught I think, so good to see the infra paying off):

clang-21: ../../llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7132: VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): Assertion `(BestFactor.Width == LegacyVF.Width || BestPlan.hasEarlyExit() || planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width), CostCtx, OrigLoop, BestFactor.Width) || planContainsAdditionalSimplifications( getPlanFor(LegacyVF.Width), CostCtx, OrigLoop, LegacyVF.Width)) && " VPlan cost model and legacy cost model disagreed"' failed.

I'm reverting it now so the issue can be resolved without undue time pressure, but this minimised test case should help:

cat - <<'EOF' > reduced.ll
; ModuleID = '<stdin>'
source_filename = "<stdin>"
target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128"
target triple = "riscv64-unknown-linux-gnu"

define ptr @ham(ptr %arg) {
bb:
  store ptr null, ptr %arg, align 8
  ret ptr null
}

define ptr @zot(i64 %arg) {
bb:
  br label %bb1

bb1:                                              ; preds = %bb4, %bb
  %phi = phi ptr [ null, %bb ], [ %getelementptr, %bb4 ]
  %phi2 = phi i64 [ %arg, %bb ], [ %add, %bb4 ]
  %icmp = icmp sgt i64 %phi2, 0
  br i1 %icmp, label %bb4, label %bb3

bb3:                                              ; preds = %bb1
  ret ptr null

bb4:                                              ; preds = %bb1
  %call = call ptr @ham(ptr %phi)
  %getelementptr = getelementptr nusw i8, ptr %phi, i64 16
  %add = add i64 %phi2, -1
  br label %bb1
}
EOF
./build/rvrel/bin/clang++ --target=riscv64-linux-gnu -march=rva23u64_zvl1024b -O3 reduced.ll

…tor (#149981)" This reverts commit ee3a771. Causes an assertion for the zvl1024b RISC-V build configuration. See comment with reproducer at <#149981 (comment)>

…calable vector (#149981)" This reverts commit ee3a771. Causes an assertion for the zvl1024b RISC-V build configuration. See comment with reproducer at <llvm/llvm-project#149981 (comment)>

preames · 2025-07-25T17:23:06Z

This is another instance of:

../llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7126: llvm::VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): 
Assertion `(BestFactor.Width == LegacyVF.Width || BestPlan.hasEarlyExit() || planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width), CostCtx, OrigLoop, BestFactor.Width) || planContainsAdditionalSimplifications( getPlanFor(LegacyVF.Width), CostCtx, OrigLoop, LegacyVF.Width)) && " VPlan cost model and legacy cost model disagreed"' failed.

Mel-Chen · 2025-07-28T06:22:57Z

This is another instance of:

../llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7126: llvm::VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): 
Assertion `(BestFactor.Width == LegacyVF.Width || BestPlan.hasEarlyExit() || planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width), CostCtx, OrigLoop, BestFactor.Width) || planContainsAdditionalSimplifications( getPlanFor(LegacyVF.Width), CostCtx, OrigLoop, LegacyVF.Width)) && " VPlan cost model and legacy cost model disagreed"' failed.

Thanks for the bug report! I’ll take a look.

…m#149981) Now that support for masked loads/stores of interleave groups has landed, we can enable the loop vectorizer to generate masked interleave access where applicable. This improves vectorization in several ways: * Internal predication support: This enables interleave group vectorization for loops with internal control flow predication, provided all members of the group share the same predicate. Gaps in interleave groups are still not efficiently handled by masking, so masking for gaps remains disabled for now. * Tail folding: This allows tail folding of loops with interleave groups by using masking. Without this, vectorized loops with interleaves would fall back to using separate gather/scatter accesses, which can be significantly less efficient. * Scalable vector support: Currently, only scalable vector types are supported for masked interleave lowering. Fixed-length vector support will be enabled in the future. As interleave access is not yet supported with tail folding by EVL, that functionality is temporarily disabled. We are going to create another patch to support it. Co-authored-by: Philip Reames <[email protected]> --------- Co-authored-by: Philip Reames <[email protected]>

…tor (llvm#149981)" This reverts commit ee3a771. Causes an assertion for the zvl1024b RISC-V build configuration. See comment with reproducer at <llvm#149981 (comment)>

…m#149981) Now that support for masked loads/stores of interleave groups has landed, we can enable the loop vectorizer to generate masked interleave access where applicable. This improves vectorization in several ways: * Internal predication support: This enables interleave group vectorization for loops with internal control flow predication, provided all members of the group share the same predicate. Gaps in interleave groups are still not efficiently handled by masking, so masking for gaps remains disabled for now. * Tail folding: This allows tail folding of loops with interleave groups by using masking. Without this, vectorized loops with interleaves would fall back to using separate gather/scatter accesses, which can be significantly less efficient. * Scalable vector support: Currently, only scalable vector types are supported for masked interleave lowering. Fixed-length vector support will be enabled in the future. As interleave access is not yet supported with tail folding by EVL, that functionality is temporarily disabled. We are going to create another patch to support it. Co-authored-by: Philip Reames <[email protected]> --------- Co-authored-by: Philip Reames <[email protected]>

…tor (llvm#149981)" This reverts commit ee3a771. Causes an assertion for the zvl1024b RISC-V build configuration. See comment with reproducer at <llvm#149981 (comment)>

With EVL tail folding, the EVL may not always be VF on the second-to-last iteration. Recipes that have been converted to VP intrinsics via optimizeMaskToEVL account for this, but recipes that are left behind will still use the old header mask which may end up having a different vector length. This is effectively the same as #95368, and fixes this by converting header masks from icmp ule wide-canonical-iv, backedge-trip-count -> icmp ult step-vector, evl. Without it, recipes that fall through optimizeMaskToEVL may use the wrong vector length, e.g. in #150074 and #149981. We really need to split off optimizeMaskToEVL into VPlanTransforms::optimize and move transformRecipestoEVLRecipes into tryToBuildVPlanWithVPRecipes, so we don't mix up what is needed for correctness and what is needed to optimize away the mask computations. We should be able to still generate a correct albeit suboptimal VPlan without running optimizeMaskToEVL. I've added a TODO for this, which I think we can do after #148274 Fixes #150197

When interleaved stores contain gaps, a mask is required to skip the gaps, regardless of whether scalar epilogues are allowed. This patch corrects the condition under which a gap mask is needed, ensuring consistency between the legacy and VPlan-based cost models and avoiding assertion failures. Related #149981

…tor (llvm#149981)" The patch "[LV] Fix gap mask requirement for interleaved access (llvm#151105)" fixed the an assertion for the RISC-V arch string zvl1024b.

…tor (llvm#149981)" Now that support for masked loads/stores of interleave groups has landed, we can enable the loop vectorizer to generate masked interleave access where applicable. This improves vectorization in several ways: * Internal predication support: This enables interleave group vectorization for loops with internal control flow predication, provided all members of the group share the same predicate. Gaps in interleave groups are still not efficiently handled by masking, so masking for gaps remains disabled for now. * Tail folding: This allows tail folding of loops with interleave groups by using masking. Without this, vectorized loops with interleaves would fall back to using separate gather/scatter accesses, which can be significantly less efficient. * Scalable vector support: Currently, only scalable vector types are supported for masked interleave lowering. Fixed-length vector support will be enabled in the future. As interleave access is not yet supported with tail folding by EVL, that functionality is temporarily disabled. We are going to create another patch to support it. Co-authored-by: Philip Reames <[email protected]>

Mel-Chen · 2025-08-01T07:52:06Z

Try to reland this. #151665

Mel-Chen requested review from fhahn, preames, lukel97, mshockwave, alexey-bataev, LiqinWeng, topperc and wangpc-pp July 22, 2025 09:14

llvmbot added backend:RISC-V vectorizers llvm:transforms labels Jul 22, 2025

lukel97 reviewed Jul 22, 2025

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lukel97 mentioned this pull request Jul 23, 2025

[RISCV][TTI] Enable masked interleave vectorization #150074

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lukel97 reviewed Jul 23, 2025

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This was referenced Jul 23, 2025

Remove header mask from EVL tail folded VPInterleaveRecipes #150162

Open

Unoptimized header masks mixed with VP intrinsics may have different lengths during EVL tail folding #150197

Closed

[VPlan] Fix header masks in EVL tail folding #150202

Merged

Mel-Chen and others added 2 commits July 24, 2025 02:39

enable masked interleave

a74859d

Pick some good change from llvm#150074, thanks

4688b4c

Co-authored-by: Philip Reames <[email protected]>

Mel-Chen force-pushed the enable-masked-interleave branch from d0acf99 to 4688b4c Compare July 24, 2025 10:01

Mel-Chen changed the title ~~[RISCV] Enabled masked interleaved access~~ [RISCV][TTI] Enable masked interleave access for scalable vector Jul 24, 2025

preames approved these changes Jul 24, 2025

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lukel97 approved these changes Jul 24, 2025

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preames reviewed Jul 25, 2025

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Mel-Chen merged commit ee3a771 into llvm:main Jul 25, 2025
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Mel-Chen mentioned this pull request Jul 29, 2025

[LV] Fix gap mask requirement for interleaved access #151105

Merged

		bool EVLIsLegal = UserIC <= 1 && IsScalableVF &&
		!InterleaveInfo.hasGroups() &&

	static Value getMask(Value WideMask, unsigned Factor,
	ElementCount LeafValueEC) {
	if (auto *IMI = dyn_cast<IntrinsicInst>(WideMask)) {
	if (unsigned F = getInterleaveIntrinsicFactor(IMI->getIntrinsicID());
	F && F == Factor && llvm::all_equal(IMI->args())) {
	return IMI->getArgOperand(0);
	}
	}

[RISCV][TTI] Enable masked interleave access for scalable vector #149981

[RISCV][TTI] Enable masked interleave access for scalable vector #149981

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