[llvm] [LV]Partial replace the mask for div/rem safe-divisor select (PR #165530)

Liao Chunyu via llvm-commits llvm-commits at lists.llvm.org
Wed Oct 29 07:28:36 PDT 2025


https://github.com/ChunyuLiao updated https://github.com/llvm/llvm-project/pull/165530

>From 6416af19dc25ae6a23fc41ff2ad8f2837f5d21b0 Mon Sep 17 00:00:00 2001
From: Liao Chunyu <chunyu at iscas.ac.cn>
Date: Wed, 29 Oct 2025 00:45:18 -0400
Subject: [PATCH 1/2] [LV]Partial replace the mask for div/rem safe-divisor
 select Following up from #150368 and #156304.  Try to remove the header mask
 for div/rem. D130164 div and rem use safe-divisor select to avoid UB.  But
 the select use logial-and like:

```
  EMIT vp<%3> = step-vector i32
  EMIT vp<%4> = icmp ult vp<%3>, vp<%2>
  EMIT vp<%5> = logical-and vp<%4>, ir<%cmp1.not>
  EMIT vp<%6> = select vp<%5>, ir<%2>, ir<1>
  So can not remove header mask.
```
Insert an icmp as mask. I think we can also avoid UB and remove the header mask at the same time.
---
 .../Transforms/Vectorize/LoopVectorize.cpp    |  8 ++++
 .../Transforms/LoopVectorize/RISCV/divrem.ll  | 40 ++++++-------------
 2 files changed, 21 insertions(+), 27 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index f7968abbe5b6b..57aff15f8b254 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7745,6 +7745,14 @@ VPWidenRecipe *VPRecipeBuilder::tryToWiden(Instruction *I,
     if (CM.isPredicatedInst(I)) {
       SmallVector<VPValue *> Ops(Operands);
       VPValue *Mask = getBlockInMask(Builder.getInsertBlock());
+      if (auto *Inst = dyn_cast<VPInstruction>(Mask)) {
+        if (Inst->getOpcode() == VPInstruction::LogicalAnd) {
+          VPValue *Zero =
+              Plan.getOrAddLiveIn(ConstantInt::get(I->getType(), 0));
+          Mask = Builder.createICmp(CmpInst::ICMP_NE, Ops[1], Zero);
+        }
+      }
+
       VPValue *One =
           Plan.getOrAddLiveIn(ConstantInt::get(I->getType(), 1u, false));
       auto *SafeRHS = Builder.createSelect(Mask, Ops[1], One, I->getDebugLoc());
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/divrem.ll b/llvm/test/Transforms/LoopVectorize/RISCV/divrem.ll
index 01b4502308c95..0371f2a04078b 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/divrem.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/divrem.ll
@@ -271,19 +271,15 @@ define void @predicated_udiv(ptr noalias nocapture %a, i64 %v, i64 %n) {
 ; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 2 x i64> poison, i64 [[V:%.*]], i64 0
 ; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 2 x i64> [[BROADCAST_SPLATINSERT]], <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[TMP6:%.*]] = icmp ne <vscale x 2 x i64> [[BROADCAST_SPLAT]], zeroinitializer
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ne <vscale x 2 x i64> [[BROADCAST_SPLAT]], zeroinitializer
+; CHECK-NEXT:    [[TMP10:%.*]] = select <vscale x 2 x i1> [[TMP1]], <vscale x 2 x i64> [[BROADCAST_SPLAT]], <vscale x 2 x i64> splat (i64 1)
 ; CHECK-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK:       vector.body:
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[AVL:%.*]] = phi i64 [ 1024, [[VECTOR_PH]] ], [ [[AVL_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[TMP12:%.*]] = call i32 @llvm.experimental.get.vector.length.i64(i64 [[AVL]], i32 2, i1 true)
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 2 x i32> poison, i32 [[TMP12]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 2 x i32> [[BROADCAST_SPLATINSERT1]], <vscale x 2 x i32> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP7:%.*]] = call <vscale x 2 x i32> @llvm.stepvector.nxv2i32()
-; CHECK-NEXT:    [[TMP15:%.*]] = icmp ult <vscale x 2 x i32> [[TMP7]], [[BROADCAST_SPLAT2]]
 ; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds i64, ptr [[A:%.*]], i64 [[INDEX]]
 ; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = call <vscale x 2 x i64> @llvm.vp.load.nxv2i64.p0(ptr align 8 [[TMP8]], <vscale x 2 x i1> splat (i1 true), i32 [[TMP12]])
-; CHECK-NEXT:    [[TMP16:%.*]] = select <vscale x 2 x i1> [[TMP15]], <vscale x 2 x i1> [[TMP6]], <vscale x 2 x i1> zeroinitializer
-; CHECK-NEXT:    [[TMP10:%.*]] = select <vscale x 2 x i1> [[TMP16]], <vscale x 2 x i64> [[BROADCAST_SPLAT]], <vscale x 2 x i64> splat (i64 1)
 ; CHECK-NEXT:    [[TMP11:%.*]] = udiv <vscale x 2 x i64> [[WIDE_LOAD]], [[TMP10]]
 ; CHECK-NEXT:    [[PREDPHI:%.*]] = select <vscale x 2 x i1> [[TMP6]], <vscale x 2 x i64> [[TMP11]], <vscale x 2 x i64> [[WIDE_LOAD]]
 ; CHECK-NEXT:    call void @llvm.vp.store.nxv2i64.p0(<vscale x 2 x i64> [[PREDPHI]], ptr align 8 [[TMP8]], <vscale x 2 x i1> splat (i1 true), i32 [[TMP12]])
@@ -303,15 +299,15 @@ define void @predicated_udiv(ptr noalias nocapture %a, i64 %v, i64 %n) {
 ; FIXED:       vector.ph:
 ; FIXED-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i64> poison, i64 [[V:%.*]], i64 0
 ; FIXED-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT]], <4 x i64> poison, <4 x i32> zeroinitializer
-; FIXED-NEXT:    [[TMP0:%.*]] = icmp ne <4 x i64> [[BROADCAST_SPLAT]], zeroinitializer
-; FIXED-NEXT:    [[TMP5:%.*]] = select <4 x i1> [[TMP0]], <4 x i64> [[BROADCAST_SPLAT]], <4 x i64> splat (i64 1)
+; FIXED-NEXT:    [[TMP1:%.*]] = icmp ne <4 x i64> [[BROADCAST_SPLAT]], zeroinitializer
+; FIXED-NEXT:    [[TMP5:%.*]] = select <4 x i1> [[TMP1]], <4 x i64> [[BROADCAST_SPLAT]], <4 x i64> splat (i64 1)
 ; FIXED-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; FIXED:       vector.body:
 ; FIXED-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; FIXED-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i64, ptr [[A:%.*]], i64 [[INDEX]]
 ; FIXED-NEXT:    [[WIDE_LOAD1:%.*]] = load <4 x i64>, ptr [[TMP2]], align 8
 ; FIXED-NEXT:    [[TMP8:%.*]] = udiv <4 x i64> [[WIDE_LOAD1]], [[TMP5]]
-; FIXED-NEXT:    [[PREDPHI2:%.*]] = select <4 x i1> [[TMP0]], <4 x i64> [[TMP8]], <4 x i64> [[WIDE_LOAD1]]
+; FIXED-NEXT:    [[PREDPHI2:%.*]] = select <4 x i1> [[TMP1]], <4 x i64> [[TMP8]], <4 x i64> [[WIDE_LOAD1]]
 ; FIXED-NEXT:    store <4 x i64> [[PREDPHI2]], ptr [[TMP2]], align 8
 ; FIXED-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
 ; FIXED-NEXT:    [[TMP9:%.*]] = icmp eq i64 [[INDEX_NEXT]], 1024
@@ -352,19 +348,15 @@ define void @predicated_sdiv(ptr noalias nocapture %a, i64 %v, i64 %n) {
 ; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 2 x i64> poison, i64 [[V:%.*]], i64 0
 ; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 2 x i64> [[BROADCAST_SPLATINSERT]], <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[TMP6:%.*]] = icmp ne <vscale x 2 x i64> [[BROADCAST_SPLAT]], zeroinitializer
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ne <vscale x 2 x i64> [[BROADCAST_SPLAT]], zeroinitializer
+; CHECK-NEXT:    [[TMP10:%.*]] = select <vscale x 2 x i1> [[TMP1]], <vscale x 2 x i64> [[BROADCAST_SPLAT]], <vscale x 2 x i64> splat (i64 1)
 ; CHECK-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK:       vector.body:
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[AVL:%.*]] = phi i64 [ 1024, [[VECTOR_PH]] ], [ [[AVL_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[TMP12:%.*]] = call i32 @llvm.experimental.get.vector.length.i64(i64 [[AVL]], i32 2, i1 true)
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 2 x i32> poison, i32 [[TMP12]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 2 x i32> [[BROADCAST_SPLATINSERT1]], <vscale x 2 x i32> poison, <vscale x 2 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP7:%.*]] = call <vscale x 2 x i32> @llvm.stepvector.nxv2i32()
-; CHECK-NEXT:    [[TMP15:%.*]] = icmp ult <vscale x 2 x i32> [[TMP7]], [[BROADCAST_SPLAT2]]
 ; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds i64, ptr [[A:%.*]], i64 [[INDEX]]
 ; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = call <vscale x 2 x i64> @llvm.vp.load.nxv2i64.p0(ptr align 8 [[TMP8]], <vscale x 2 x i1> splat (i1 true), i32 [[TMP12]])
-; CHECK-NEXT:    [[TMP16:%.*]] = select <vscale x 2 x i1> [[TMP15]], <vscale x 2 x i1> [[TMP6]], <vscale x 2 x i1> zeroinitializer
-; CHECK-NEXT:    [[TMP10:%.*]] = select <vscale x 2 x i1> [[TMP16]], <vscale x 2 x i64> [[BROADCAST_SPLAT]], <vscale x 2 x i64> splat (i64 1)
 ; CHECK-NEXT:    [[TMP11:%.*]] = sdiv <vscale x 2 x i64> [[WIDE_LOAD]], [[TMP10]]
 ; CHECK-NEXT:    [[PREDPHI:%.*]] = select <vscale x 2 x i1> [[TMP6]], <vscale x 2 x i64> [[TMP11]], <vscale x 2 x i64> [[WIDE_LOAD]]
 ; CHECK-NEXT:    call void @llvm.vp.store.nxv2i64.p0(<vscale x 2 x i64> [[PREDPHI]], ptr align 8 [[TMP8]], <vscale x 2 x i1> splat (i1 true), i32 [[TMP12]])
@@ -384,15 +376,15 @@ define void @predicated_sdiv(ptr noalias nocapture %a, i64 %v, i64 %n) {
 ; FIXED:       vector.ph:
 ; FIXED-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i64> poison, i64 [[V:%.*]], i64 0
 ; FIXED-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT]], <4 x i64> poison, <4 x i32> zeroinitializer
-; FIXED-NEXT:    [[TMP0:%.*]] = icmp ne <4 x i64> [[BROADCAST_SPLAT]], zeroinitializer
-; FIXED-NEXT:    [[TMP5:%.*]] = select <4 x i1> [[TMP0]], <4 x i64> [[BROADCAST_SPLAT]], <4 x i64> splat (i64 1)
+; FIXED-NEXT:    [[TMP1:%.*]] = icmp ne <4 x i64> [[BROADCAST_SPLAT]], zeroinitializer
+; FIXED-NEXT:    [[TMP5:%.*]] = select <4 x i1> [[TMP1]], <4 x i64> [[BROADCAST_SPLAT]], <4 x i64> splat (i64 1)
 ; FIXED-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; FIXED:       vector.body:
 ; FIXED-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; FIXED-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i64, ptr [[A:%.*]], i64 [[INDEX]]
 ; FIXED-NEXT:    [[WIDE_LOAD1:%.*]] = load <4 x i64>, ptr [[TMP2]], align 8
 ; FIXED-NEXT:    [[TMP8:%.*]] = sdiv <4 x i64> [[WIDE_LOAD1]], [[TMP5]]
-; FIXED-NEXT:    [[PREDPHI2:%.*]] = select <4 x i1> [[TMP0]], <4 x i64> [[TMP8]], <4 x i64> [[WIDE_LOAD1]]
+; FIXED-NEXT:    [[PREDPHI2:%.*]] = select <4 x i1> [[TMP1]], <4 x i64> [[TMP8]], <4 x i64> [[WIDE_LOAD1]]
 ; FIXED-NEXT:    store <4 x i64> [[PREDPHI2]], ptr [[TMP2]], align 8
 ; FIXED-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
 ; FIXED-NEXT:    [[TMP9:%.*]] = icmp eq i64 [[INDEX_NEXT]], 1024
@@ -575,16 +567,10 @@ define void @predicated_sdiv_by_minus_one(ptr noalias nocapture %a, i64 %n) {
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[AVL:%.*]] = phi i64 [ 1024, [[VECTOR_PH]] ], [ [[AVL_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[TMP12:%.*]] = call i32 @llvm.experimental.get.vector.length.i64(i64 [[AVL]], i32 16, i1 true)
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 16 x i32> poison, i32 [[TMP12]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 16 x i32> [[BROADCAST_SPLATINSERT]], <vscale x 16 x i32> poison, <vscale x 16 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP6:%.*]] = call <vscale x 16 x i32> @llvm.stepvector.nxv16i32()
-; CHECK-NEXT:    [[TMP15:%.*]] = icmp ult <vscale x 16 x i32> [[TMP6]], [[BROADCAST_SPLAT]]
 ; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds i8, ptr [[A:%.*]], i64 [[INDEX]]
 ; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = call <vscale x 16 x i8> @llvm.vp.load.nxv16i8.p0(ptr align 1 [[TMP7]], <vscale x 16 x i1> splat (i1 true), i32 [[TMP12]])
 ; CHECK-NEXT:    [[TMP9:%.*]] = icmp ne <vscale x 16 x i8> [[WIDE_LOAD]], splat (i8 -128)
-; CHECK-NEXT:    [[TMP16:%.*]] = select <vscale x 16 x i1> [[TMP15]], <vscale x 16 x i1> [[TMP9]], <vscale x 16 x i1> zeroinitializer
-; CHECK-NEXT:    [[TMP10:%.*]] = select <vscale x 16 x i1> [[TMP16]], <vscale x 16 x i8> splat (i8 -1), <vscale x 16 x i8> splat (i8 1)
-; CHECK-NEXT:    [[TMP11:%.*]] = sdiv <vscale x 16 x i8> [[WIDE_LOAD]], [[TMP10]]
+; CHECK-NEXT:    [[TMP11:%.*]] = sdiv <vscale x 16 x i8> [[WIDE_LOAD]], splat (i8 -1)
 ; CHECK-NEXT:    [[PREDPHI:%.*]] = select <vscale x 16 x i1> [[TMP9]], <vscale x 16 x i8> [[TMP11]], <vscale x 16 x i8> [[WIDE_LOAD]]
 ; CHECK-NEXT:    call void @llvm.vp.store.nxv16i8.p0(<vscale x 16 x i8> [[PREDPHI]], ptr align 1 [[TMP7]], <vscale x 16 x i1> splat (i1 true), i32 [[TMP12]])
 ; CHECK-NEXT:    [[TMP13:%.*]] = zext i32 [[TMP12]] to i64
@@ -607,8 +593,8 @@ define void @predicated_sdiv_by_minus_one(ptr noalias nocapture %a, i64 %n) {
 ; FIXED-NEXT:    [[TMP1:%.*]] = getelementptr inbounds i8, ptr [[A:%.*]], i64 [[INDEX]]
 ; FIXED-NEXT:    [[WIDE_LOAD1:%.*]] = load <32 x i8>, ptr [[TMP1]], align 1
 ; FIXED-NEXT:    [[TMP5:%.*]] = icmp ne <32 x i8> [[WIDE_LOAD1]], splat (i8 -128)
-; FIXED-NEXT:    [[TMP7:%.*]] = select <32 x i1> [[TMP5]], <32 x i8> splat (i8 -1), <32 x i8> splat (i8 1)
-; FIXED-NEXT:    [[TMP9:%.*]] = sdiv <32 x i8> [[WIDE_LOAD1]], [[TMP7]]
+; FIXED-NEXT:    [[TMP2:%.*]] = select <32 x i1> [[TMP5]], <32 x i8> splat (i8 -1), <32 x i8> splat (i8 1)
+; FIXED-NEXT:    [[TMP9:%.*]] = sdiv <32 x i8> [[WIDE_LOAD1]], [[TMP2]]
 ; FIXED-NEXT:    [[PREDPHI2:%.*]] = select <32 x i1> [[TMP5]], <32 x i8> [[TMP9]], <32 x i8> [[WIDE_LOAD1]]
 ; FIXED-NEXT:    store <32 x i8> [[PREDPHI2]], ptr [[TMP1]], align 1
 ; FIXED-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 32

>From a38ee161650e16134d373196d7ff7822bc51abcc Mon Sep 17 00:00:00 2001
From: Liao Chunyu <chunyu at iscas.ac.cn>
Date: Wed, 29 Oct 2025 10:28:09 -0400
Subject: [PATCH 2/2] update aarch64 testcase

---
 .../AArch64/conditional-branches-cost.ll      | 64 +++++++++----------
 .../AArch64/divs-with-scalable-vfs.ll         | 12 ++--
 2 files changed, 38 insertions(+), 38 deletions(-)

diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/conditional-branches-cost.ll b/llvm/test/Transforms/LoopVectorize/AArch64/conditional-branches-cost.ll
index f16351720b20f..8a1a7237cd235 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/conditional-branches-cost.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/conditional-branches-cost.ll
@@ -660,16 +660,16 @@ define void @low_trip_count_fold_tail_scalarized_store(ptr %dst) {
 ; COMMON-NEXT:    store i8 6, ptr [[TMP6]], align 1
 ; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE12]]
 ; COMMON:       [[PRED_STORE_CONTINUE12]]:
-; COMMON-NEXT:    br i1 false, label %[[PRED_STORE_IF13:.*]], label %[[EXIT:.*]]
+; COMMON-NEXT:    br i1 false, label %[[PRED_STORE_IF13:.*]], label %[[PRED_STORE_CONTINUE14:.*]]
 ; COMMON:       [[PRED_STORE_IF13]]:
 ; COMMON-NEXT:    [[TMP7:%.*]] = getelementptr i8, ptr [[DST]], i64 7
 ; COMMON-NEXT:    store i8 7, ptr [[TMP7]], align 1
-; COMMON-NEXT:    br label %[[EXIT]]
+; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE14]]
+; COMMON:       [[PRED_STORE_CONTINUE14]]:
+; COMMON-NEXT:    br label %[[MIDDLE_BLOCK:.*]]
+; COMMON:       [[MIDDLE_BLOCK]]:
+; COMMON-NEXT:    br label %[[EXIT:.*]]
 ; COMMON:       [[EXIT]]:
-; COMMON-NEXT:    br label %[[SCALAR_PH:.*]]
-; COMMON:       [[SCALAR_PH]]:
-; COMMON-NEXT:    br label %[[EXIT1:.*]]
-; COMMON:       [[EXIT1]]:
 ; COMMON-NEXT:    ret void
 ;
 entry:
@@ -1303,7 +1303,7 @@ define void @pred_udiv_select_cost(ptr %A, ptr %B, ptr %C, i64 %n, i8 %y) #1 {
 ; PRED-NEXT:    br label %[[VECTOR_MEMCHECK:.*]]
 ; PRED:       [[VECTOR_MEMCHECK]]:
 ; PRED-NEXT:    [[TMP1:%.*]] = call i64 @llvm.vscale.i64()
-; PRED-NEXT:    [[TMP2:%.*]] = mul nuw i64 [[TMP1]], 16
+; PRED-NEXT:    [[TMP2:%.*]] = mul nuw i64 [[TMP1]], 4
 ; PRED-NEXT:    [[TMP3:%.*]] = sub i64 [[C1]], [[A2]]
 ; PRED-NEXT:    [[DIFF_CHECK:%.*]] = icmp ult i64 [[TMP3]], [[TMP2]]
 ; PRED-NEXT:    [[TMP4:%.*]] = sub i64 [[C1]], [[B3]]
@@ -1312,42 +1312,42 @@ define void @pred_udiv_select_cost(ptr %A, ptr %B, ptr %C, i64 %n, i8 %y) #1 {
 ; PRED-NEXT:    br i1 [[CONFLICT_RDX]], label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
 ; PRED:       [[VECTOR_PH]]:
 ; PRED-NEXT:    [[TMP5:%.*]] = call i64 @llvm.vscale.i64()
-; PRED-NEXT:    [[TMP6:%.*]] = mul nuw i64 [[TMP5]], 16
+; PRED-NEXT:    [[TMP6:%.*]] = mul nuw i64 [[TMP5]], 4
+; PRED-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 4 x i8> poison, i8 [[Y]], i64 0
+; PRED-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 4 x i8> [[BROADCAST_SPLATINSERT]], <vscale x 4 x i8> poison, <vscale x 4 x i32> zeroinitializer
 ; PRED-NEXT:    [[TMP7:%.*]] = call i64 @llvm.vscale.i64()
-; PRED-NEXT:    [[TMP8:%.*]] = shl nuw i64 [[TMP7]], 4
+; PRED-NEXT:    [[TMP8:%.*]] = shl nuw i64 [[TMP7]], 2
 ; PRED-NEXT:    [[TMP9:%.*]] = sub i64 [[TMP0]], [[TMP8]]
 ; PRED-NEXT:    [[TMP10:%.*]] = icmp ugt i64 [[TMP0]], [[TMP8]]
 ; PRED-NEXT:    [[TMP11:%.*]] = select i1 [[TMP10]], i64 [[TMP9]], i64 0
-; PRED-NEXT:    [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 16 x i1> @llvm.get.active.lane.mask.nxv16i1.i64(i64 0, i64 [[TMP0]])
-; PRED-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 16 x i8> poison, i8 [[Y]], i64 0
-; PRED-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 16 x i8> [[BROADCAST_SPLATINSERT]], <vscale x 16 x i8> poison, <vscale x 16 x i32> zeroinitializer
+; PRED-NEXT:    [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i64(i64 0, i64 [[TMP0]])
+; PRED-NEXT:    [[TMP16:%.*]] = icmp ne <vscale x 4 x i8> [[BROADCAST_SPLAT]], zeroinitializer
+; PRED-NEXT:    [[TMP13:%.*]] = select <vscale x 4 x i1> [[TMP16]], <vscale x 4 x i8> [[BROADCAST_SPLAT]], <vscale x 4 x i8> splat (i8 1)
 ; PRED-NEXT:    br label %[[VECTOR_BODY:.*]]
 ; PRED:       [[VECTOR_BODY]]:
 ; PRED-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; PRED-NEXT:    [[ACTIVE_LANE_MASK:%.*]] = phi <vscale x 16 x i1> [ [[ACTIVE_LANE_MASK_ENTRY]], %[[VECTOR_PH]] ], [ [[ACTIVE_LANE_MASK_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; PRED-NEXT:    [[ACTIVE_LANE_MASK:%.*]] = phi <vscale x 4 x i1> [ [[ACTIVE_LANE_MASK_ENTRY]], %[[VECTOR_PH]] ], [ [[ACTIVE_LANE_MASK_NEXT:%.*]], %[[VECTOR_BODY]] ]
 ; PRED-NEXT:    [[TMP12:%.*]] = getelementptr i8, ptr [[A]], i64 [[INDEX]]
-; PRED-NEXT:    [[WIDE_MASKED_LOAD:%.*]] = call <vscale x 16 x i8> @llvm.masked.load.nxv16i8.p0(ptr align 1 [[TMP12]], <vscale x 16 x i1> [[ACTIVE_LANE_MASK]], <vscale x 16 x i8> poison)
-; PRED-NEXT:    [[TMP13:%.*]] = uitofp <vscale x 16 x i8> [[WIDE_MASKED_LOAD]] to <vscale x 16 x float>
+; PRED-NEXT:    [[WIDE_MASKED_LOAD:%.*]] = call <vscale x 4 x i8> @llvm.masked.load.nxv4i8.p0(ptr align 1 [[TMP12]], <vscale x 4 x i1> [[ACTIVE_LANE_MASK]], <vscale x 4 x i8> poison)
+; PRED-NEXT:    [[TMP15:%.*]] = uitofp <vscale x 4 x i8> [[WIDE_MASKED_LOAD]] to <vscale x 4 x float>
 ; PRED-NEXT:    [[TMP14:%.*]] = getelementptr i8, ptr [[B]], i64 [[INDEX]]
-; PRED-NEXT:    [[WIDE_MASKED_LOAD5:%.*]] = call <vscale x 16 x i8> @llvm.masked.load.nxv16i8.p0(ptr align 1 [[TMP14]], <vscale x 16 x i1> [[ACTIVE_LANE_MASK]], <vscale x 16 x i8> poison)
-; PRED-NEXT:    [[TMP15:%.*]] = icmp ne <vscale x 16 x i8> [[WIDE_MASKED_LOAD5]], zeroinitializer
-; PRED-NEXT:    [[TMP16:%.*]] = select <vscale x 16 x i1> [[ACTIVE_LANE_MASK]], <vscale x 16 x i1> [[TMP15]], <vscale x 16 x i1> zeroinitializer
-; PRED-NEXT:    [[TMP17:%.*]] = xor <vscale x 16 x i8> [[WIDE_MASKED_LOAD]], splat (i8 1)
-; PRED-NEXT:    [[TMP18:%.*]] = select <vscale x 16 x i1> [[TMP16]], <vscale x 16 x i8> [[BROADCAST_SPLAT]], <vscale x 16 x i8> splat (i8 1)
-; PRED-NEXT:    [[TMP19:%.*]] = udiv <vscale x 16 x i8> [[TMP17]], [[TMP18]]
-; PRED-NEXT:    [[TMP20:%.*]] = icmp ugt <vscale x 16 x i8> [[TMP19]], splat (i8 1)
-; PRED-NEXT:    [[TMP21:%.*]] = select <vscale x 16 x i1> [[TMP20]], <vscale x 16 x i32> zeroinitializer, <vscale x 16 x i32> splat (i32 255)
-; PRED-NEXT:    [[PREDPHI:%.*]] = select <vscale x 16 x i1> [[TMP15]], <vscale x 16 x i32> [[TMP21]], <vscale x 16 x i32> zeroinitializer
-; PRED-NEXT:    [[TMP22:%.*]] = zext <vscale x 16 x i8> [[WIDE_MASKED_LOAD]] to <vscale x 16 x i32>
-; PRED-NEXT:    [[TMP23:%.*]] = sub <vscale x 16 x i32> [[PREDPHI]], [[TMP22]]
-; PRED-NEXT:    [[TMP24:%.*]] = sitofp <vscale x 16 x i32> [[TMP23]] to <vscale x 16 x float>
-; PRED-NEXT:    [[TMP25:%.*]] = call <vscale x 16 x float> @llvm.fmuladd.nxv16f32(<vscale x 16 x float> [[TMP24]], <vscale x 16 x float> splat (float 3.000000e+00), <vscale x 16 x float> [[TMP13]])
-; PRED-NEXT:    [[TMP26:%.*]] = fptoui <vscale x 16 x float> [[TMP25]] to <vscale x 16 x i8>
+; PRED-NEXT:    [[WIDE_MASKED_LOAD5:%.*]] = call <vscale x 4 x i8> @llvm.masked.load.nxv4i8.p0(ptr align 1 [[TMP14]], <vscale x 4 x i1> [[ACTIVE_LANE_MASK]], <vscale x 4 x i8> poison)
+; PRED-NEXT:    [[TMP17:%.*]] = icmp eq <vscale x 4 x i8> [[WIDE_MASKED_LOAD5]], zeroinitializer
+; PRED-NEXT:    [[TMP18:%.*]] = xor <vscale x 4 x i8> [[WIDE_MASKED_LOAD]], splat (i8 1)
+; PRED-NEXT:    [[TMP19:%.*]] = udiv <vscale x 4 x i8> [[TMP18]], [[TMP13]]
+; PRED-NEXT:    [[TMP20:%.*]] = icmp ugt <vscale x 4 x i8> [[TMP19]], splat (i8 1)
+; PRED-NEXT:    [[TMP21:%.*]] = select <vscale x 4 x i1> [[TMP20]], <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> splat (i32 255)
+; PRED-NEXT:    [[PREDPHI:%.*]] = select <vscale x 4 x i1> [[TMP17]], <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> [[TMP21]]
+; PRED-NEXT:    [[TMP22:%.*]] = zext <vscale x 4 x i8> [[WIDE_MASKED_LOAD]] to <vscale x 4 x i32>
+; PRED-NEXT:    [[TMP23:%.*]] = sub <vscale x 4 x i32> [[PREDPHI]], [[TMP22]]
+; PRED-NEXT:    [[TMP24:%.*]] = sitofp <vscale x 4 x i32> [[TMP23]] to <vscale x 4 x float>
+; PRED-NEXT:    [[TMP25:%.*]] = call <vscale x 4 x float> @llvm.fmuladd.nxv4f32(<vscale x 4 x float> [[TMP24]], <vscale x 4 x float> splat (float 3.000000e+00), <vscale x 4 x float> [[TMP15]])
+; PRED-NEXT:    [[TMP26:%.*]] = fptoui <vscale x 4 x float> [[TMP25]] to <vscale x 4 x i8>
 ; PRED-NEXT:    [[TMP27:%.*]] = getelementptr i8, ptr [[C]], i64 [[INDEX]]
-; PRED-NEXT:    call void @llvm.masked.store.nxv16i8.p0(<vscale x 16 x i8> [[TMP26]], ptr align 1 [[TMP27]], <vscale x 16 x i1> [[ACTIVE_LANE_MASK]])
+; PRED-NEXT:    call void @llvm.masked.store.nxv4i8.p0(<vscale x 4 x i8> [[TMP26]], ptr align 1 [[TMP27]], <vscale x 4 x i1> [[ACTIVE_LANE_MASK]])
 ; PRED-NEXT:    [[INDEX_NEXT]] = add i64 [[INDEX]], [[TMP6]]
-; PRED-NEXT:    [[ACTIVE_LANE_MASK_NEXT]] = call <vscale x 16 x i1> @llvm.get.active.lane.mask.nxv16i1.i64(i64 [[INDEX]], i64 [[TMP11]])
-; PRED-NEXT:    [[TMP28:%.*]] = extractelement <vscale x 16 x i1> [[ACTIVE_LANE_MASK_NEXT]], i32 0
+; PRED-NEXT:    [[ACTIVE_LANE_MASK_NEXT]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i64(i64 [[INDEX]], i64 [[TMP11]])
+; PRED-NEXT:    [[TMP28:%.*]] = extractelement <vscale x 4 x i1> [[ACTIVE_LANE_MASK_NEXT]], i32 0
 ; PRED-NEXT:    [[TMP29:%.*]] = xor i1 [[TMP28]], true
 ; PRED-NEXT:    br i1 [[TMP29]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP7:![0-9]+]]
 ; PRED:       [[MIDDLE_BLOCK]]:
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/divs-with-scalable-vfs.ll b/llvm/test/Transforms/LoopVectorize/AArch64/divs-with-scalable-vfs.ll
index 72e813b62025f..35bc986356816 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/divs-with-scalable-vfs.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/divs-with-scalable-vfs.ll
@@ -114,6 +114,12 @@ define void @sdiv_feeding_gep_predicated(ptr %dst, i32 %x, i64 %M, i64 %conv6, i
 ; CHECK-NEXT:    [[TMP13:%.*]] = icmp ugt i64 [[N]], [[TMP11]]
 ; CHECK-NEXT:    [[TMP14:%.*]] = select i1 [[TMP13]], i64 [[TMP12]], i64 0
 ; CHECK-NEXT:    [[ACTIVE_LANE_MASK_ENTRY:%.*]] = call <vscale x 2 x i1> @llvm.get.active.lane.mask.nxv2i1.i64(i64 0, i64 [[N]])
+; CHECK-NEXT:    [[TMP16:%.*]] = icmp ne i64 [[CONV6]], 0
+; CHECK-NEXT:    [[TMP18:%.*]] = select i1 [[TMP16]], i64 [[CONV6]], i64 1
+; CHECK-NEXT:    [[TMP19:%.*]] = sdiv i64 [[M]], [[TMP18]]
+; CHECK-NEXT:    [[TMP20:%.*]] = trunc i64 [[TMP19]] to i32
+; CHECK-NEXT:    [[TMP28:%.*]] = mul i64 [[TMP19]], [[CONV61]]
+; CHECK-NEXT:    [[TMP31:%.*]] = mul i32 [[X]], [[TMP20]]
 ; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 2 x i64> poison, i64 [[M]], i64 0
 ; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 2 x i64> [[BROADCAST_SPLATINSERT]], <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[TMP15:%.*]] = call <vscale x 2 x i64> @llvm.stepvector.nxv2i64()
@@ -128,14 +134,8 @@ define void @sdiv_feeding_gep_predicated(ptr %dst, i32 %x, i64 %M, i64 %conv6, i
 ; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <vscale x 2 x i64> [ [[INDUCTION]], %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[TMP22:%.*]] = icmp ule <vscale x 2 x i64> [[VEC_IND]], [[BROADCAST_SPLAT]]
 ; CHECK-NEXT:    [[TMP23:%.*]] = select <vscale x 2 x i1> [[ACTIVE_LANE_MASK]], <vscale x 2 x i1> [[TMP22]], <vscale x 2 x i1> zeroinitializer
-; CHECK-NEXT:    [[TMP24:%.*]] = extractelement <vscale x 2 x i1> [[TMP23]], i32 0
-; CHECK-NEXT:    [[TMP25:%.*]] = select i1 [[TMP24]], i64 [[CONV6]], i64 1
-; CHECK-NEXT:    [[TMP26:%.*]] = sdiv i64 [[M]], [[TMP25]]
-; CHECK-NEXT:    [[TMP27:%.*]] = trunc i64 [[TMP26]] to i32
-; CHECK-NEXT:    [[TMP28:%.*]] = mul i64 [[TMP26]], [[CONV61]]
 ; CHECK-NEXT:    [[TMP29:%.*]] = sub i64 [[INDEX]], [[TMP28]]
 ; CHECK-NEXT:    [[TMP30:%.*]] = trunc i64 [[TMP29]] to i32
-; CHECK-NEXT:    [[TMP31:%.*]] = mul i32 [[X]], [[TMP27]]
 ; CHECK-NEXT:    [[TMP32:%.*]] = add i32 [[TMP31]], [[TMP30]]
 ; CHECK-NEXT:    [[TMP33:%.*]] = sext i32 [[TMP32]] to i64
 ; CHECK-NEXT:    [[TMP34:%.*]] = getelementptr double, ptr [[DST]], i64 [[TMP33]]



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