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[LV] Optimize partial reduction extends before handling inloop subs#199665

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[LV] Optimize partial reduction extends before handling inloop subs#199665
MacDue wants to merge 2 commits into
users/MacDue/no_mul_sub_prfrom
users/MacDue/fix_inloop_sub_pr

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@MacDue MacDue commented May 26, 2026

The crash avoided in #194660 was caused by the extend optimizations failing to match as due to the extra sub/negation added to the "ExtendedOp".

A similar crash exists for [us]abs partial reductions (see https://godbolt.org/z/MerMon5rE), which is fixed with this patch.

This patch solves the underlying issue by running the extend optimizations before any inloop sub/fsub handling.

Fixes #194000

@MacDue
[LV] Optimize partial reduction extends before handling inloop subs
3bf5972 
The crash avoided in #194660 was caused by the extend optimizations
failing to match as due to the extra sub/negation added to the
"ExtendedOp".

A similar crash exists for [us]abs partial reductions
(see https://godbolt.org/z/MerMon5rE), which is fixed with this patch.

This patch solves the underlying issue by running the extend optimizations
before any inloop sub/fsub handling.

Fixes #194000
@MacDue MacDue mentioned this pull request May 26, 2026
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MacDue commented May 26, 2026

This is a stacked PR:

@MacDue MacDue marked this pull request as ready for review May 26, 2026 11:51
sdesmalen-arm
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LGTM

Comment thread llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-usabs.ll
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llvmorg-github-actions Bot commented May 27, 2026 •
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@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-vectorizers

Author: Benjamin Maxwell (MacDue)

Changes

The crash avoided in #194660 was caused by the extend optimizations failing to match as due to the extra sub/negation added to the "ExtendedOp".

A similar crash exists for [us]abs partial reductions (see https://godbolt.org/z/MerMon5rE), which is fixed with this patch.

This patch solves the underlying issue by running the extend optimizations before any inloop sub/fsub handling.

Fixes #194000

Patch is 22.35 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/199665.diff

3 Files Affected:

  • (modified) llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp (+3-6)
  • (modified) llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-chained.ll (+70-66)
  • (modified) llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-usabs.ll (+60)
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 4e406ad542e83..f3c65ab712cb1 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -6121,6 +6121,9 @@ static void transformToPartialReduction(const VPPartialReductionChain &Chain,
   auto *ExtendedOp = cast<VPSingleDefRecipe>(
       WidenRecipe->getOperand(1 - Chain.AccumulatorOpIdx));
 
+  // FIXME: Do these transforms before invoking the cost-model.
+  ExtendedOp = optimizeExtendsForPartialReduction(ExtendedOp, TypeInfo);
+
   // Sub-reductions can be implemented in two ways:
   // (1) negate the operand in the vector loop (the default way).
   // (2) subtract the reduced value from the init value in the middle block.
@@ -6156,9 +6159,6 @@ static void transformToPartialReduction(const VPPartialReductionChain &Chain,
     ExtendedOp = NegRecipe;
   }
 
-  // FIXME: Do these transforms before invoking the cost-model.
-  ExtendedOp = optimizeExtendsForPartialReduction(ExtendedOp, TypeInfo);
-
   // Check if WidenRecipe is the final result of the reduction. If so look
   // through selects for predicated reductions.
   VPValue *Cond = nullptr;
@@ -6324,9 +6324,6 @@ matchExtendedReductionOperand(VPWidenRecipe *UpdateR, VPValue *Op,
       // by widening the inner extends to match it. See
       // optimizeExtendsForPartialReduction.
       Op = CastSource;
-      // FIXME: createPartialReductionExpression can't handle sub(ext(mul(...)))
-      if (UpdateR->getOpcode() == Instruction::Sub)
-        return std::nullopt;
     } else {
       return ExtendedReductionOperand{
           UpdateR,
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-chained.ll b/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-chained.ll
index 5cfa3961fb180..435c8cd6f6f5e 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-chained.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-chained.ll
@@ -1378,8 +1378,8 @@ define i32 @chained_partial_reduce_add_sub_ext_mul(ptr %a, ptr %b, ptr %c, i64 %
 ; CHECK-NEON-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK-NEON:       vector.body:
 ; CHECK-NEON-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEON-NEXT:    [[VEC_PHI:%.*]] = phi <16 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP19:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEON-NEXT:    [[VEC_PHI1:%.*]] = phi <16 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP20:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEON-NEXT:    [[VEC_PHI:%.*]] = phi <4 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[PARTIAL_REDUCE8:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEON-NEXT:    [[VEC_PHI1:%.*]] = phi <4 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[PARTIAL_REDUCE9:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEON-NEXT:    [[TMP0:%.*]] = add i64 [[INDEX]], 1
 ; CHECK-NEON-NEXT:    [[TMP1:%.*]] = getelementptr i8, ptr [[A]], i64 [[TMP0]]
 ; CHECK-NEON-NEXT:    [[TMP2:%.*]] = getelementptr i8, ptr [[B]], i64 [[TMP0]]
@@ -1393,26 +1393,26 @@ define i32 @chained_partial_reduce_add_sub_ext_mul(ptr %a, ptr %b, ptr %c, i64 %
 ; CHECK-NEON-NEXT:    [[TMP6:%.*]] = getelementptr i8, ptr [[TMP3]], i64 16
 ; CHECK-NEON-NEXT:    [[WIDE_LOAD5:%.*]] = load <16 x i8>, ptr [[TMP3]], align 1
 ; CHECK-NEON-NEXT:    [[WIDE_LOAD6:%.*]] = load <16 x i8>, ptr [[TMP6]], align 1
-; CHECK-NEON-NEXT:    [[TMP7:%.*]] = sext <16 x i8> [[WIDE_LOAD]] to <16 x i16>
-; CHECK-NEON-NEXT:    [[TMP8:%.*]] = sext <16 x i8> [[WIDE_LOAD2]] to <16 x i16>
-; CHECK-NEON-NEXT:    [[TMP9:%.*]] = sext <16 x i8> [[WIDE_LOAD3]] to <16 x i16>
-; CHECK-NEON-NEXT:    [[TMP10:%.*]] = sext <16 x i8> [[WIDE_LOAD4]] to <16 x i16>
-; CHECK-NEON-NEXT:    [[TMP11:%.*]] = sext <16 x i8> [[WIDE_LOAD5]] to <16 x i32>
-; CHECK-NEON-NEXT:    [[TMP12:%.*]] = sext <16 x i8> [[WIDE_LOAD6]] to <16 x i32>
-; CHECK-NEON-NEXT:    [[TMP13:%.*]] = mul nsw <16 x i16> [[TMP7]], [[TMP9]]
-; CHECK-NEON-NEXT:    [[TMP14:%.*]] = mul nsw <16 x i16> [[TMP8]], [[TMP10]]
-; CHECK-NEON-NEXT:    [[TMP15:%.*]] = sext <16 x i16> [[TMP13]] to <16 x i32>
-; CHECK-NEON-NEXT:    [[TMP16:%.*]] = sext <16 x i16> [[TMP14]] to <16 x i32>
-; CHECK-NEON-NEXT:    [[TMP17:%.*]] = sub <16 x i32> [[VEC_PHI]], [[TMP15]]
-; CHECK-NEON-NEXT:    [[TMP18:%.*]] = sub <16 x i32> [[VEC_PHI1]], [[TMP16]]
-; CHECK-NEON-NEXT:    [[TMP19]] = add <16 x i32> [[TMP17]], [[TMP11]]
-; CHECK-NEON-NEXT:    [[TMP20]] = add <16 x i32> [[TMP18]], [[TMP12]]
+; CHECK-NEON-NEXT:    [[TMP7:%.*]] = sext <16 x i8> [[WIDE_LOAD]] to <16 x i32>
+; CHECK-NEON-NEXT:    [[TMP8:%.*]] = sext <16 x i8> [[WIDE_LOAD3]] to <16 x i32>
+; CHECK-NEON-NEXT:    [[TMP15:%.*]] = mul nsw <16 x i32> [[TMP7]], [[TMP8]]
+; CHECK-NEON-NEXT:    [[TMP19:%.*]] = sub <16 x i32> zeroinitializer, [[TMP15]]
+; CHECK-NEON-NEXT:    [[PARTIAL_REDUCE:%.*]] = call <4 x i32> @llvm.vector.partial.reduce.add.v4i32.v16i32(<4 x i32> [[VEC_PHI]], <16 x i32> [[TMP19]])
+; CHECK-NEON-NEXT:    [[TMP11:%.*]] = sext <16 x i8> [[WIDE_LOAD2]] to <16 x i32>
+; CHECK-NEON-NEXT:    [[TMP12:%.*]] = sext <16 x i8> [[WIDE_LOAD4]] to <16 x i32>
+; CHECK-NEON-NEXT:    [[TMP16:%.*]] = mul nsw <16 x i32> [[TMP11]], [[TMP12]]
+; CHECK-NEON-NEXT:    [[TMP22:%.*]] = sub <16 x i32> zeroinitializer, [[TMP16]]
+; CHECK-NEON-NEXT:    [[PARTIAL_REDUCE7:%.*]] = call <4 x i32> @llvm.vector.partial.reduce.add.v4i32.v16i32(<4 x i32> [[VEC_PHI1]], <16 x i32> [[TMP22]])
+; CHECK-NEON-NEXT:    [[TMP17:%.*]] = sext <16 x i8> [[WIDE_LOAD5]] to <16 x i32>
+; CHECK-NEON-NEXT:    [[PARTIAL_REDUCE8]] = call <4 x i32> @llvm.vector.partial.reduce.add.v4i32.v16i32(<4 x i32> [[PARTIAL_REDUCE]], <16 x i32> [[TMP17]])
+; CHECK-NEON-NEXT:    [[TMP18:%.*]] = sext <16 x i8> [[WIDE_LOAD6]] to <16 x i32>
+; CHECK-NEON-NEXT:    [[PARTIAL_REDUCE9]] = call <4 x i32> @llvm.vector.partial.reduce.add.v4i32.v16i32(<4 x i32> [[PARTIAL_REDUCE7]], <16 x i32> [[TMP18]])
 ; CHECK-NEON-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 32
 ; CHECK-NEON-NEXT:    [[TMP21:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
 ; CHECK-NEON-NEXT:    br i1 [[TMP21]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP20:![0-9]+]]
 ; CHECK-NEON:       middle.block:
-; CHECK-NEON-NEXT:    [[BIN_RDX:%.*]] = add <16 x i32> [[TMP20]], [[TMP19]]
-; CHECK-NEON-NEXT:    [[TMP22:%.*]] = call i32 @llvm.vector.reduce.add.v16i32(<16 x i32> [[BIN_RDX]])
+; CHECK-NEON-NEXT:    [[BIN_RDX:%.*]] = add <4 x i32> [[PARTIAL_REDUCE9]], [[PARTIAL_REDUCE8]]
+; CHECK-NEON-NEXT:    [[TMP20:%.*]] = call i32 @llvm.vector.reduce.add.v4i32(<4 x i32> [[BIN_RDX]])
 ; CHECK-NEON-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
 ; CHECK-NEON-NEXT:    br i1 [[CMP_N]], label [[EXIT:%.*]], label [[SCALAR_PH]]
 ; CHECK-NEON:       scalar.ph:
@@ -1420,49 +1420,53 @@ define i32 @chained_partial_reduce_add_sub_ext_mul(ptr %a, ptr %b, ptr %c, i64 %
 ; CHECK-SVE-LABEL: define i32 @chained_partial_reduce_add_sub_ext_mul(
 ; CHECK-SVE-SAME: ptr [[A:%.*]], ptr [[B:%.*]], ptr [[C:%.*]], i64 [[N:%.*]]) #[[ATTR0]] {
 ; CHECK-SVE-NEXT:  entry:
-; CHECK-SVE-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], 32
+; CHECK-SVE-NEXT:    [[TMP5:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-SVE-NEXT:    [[TMP6:%.*]] = shl nuw nsw i64 [[TMP5]], 5
+; CHECK-SVE-NEXT:    [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], [[TMP6]]
 ; CHECK-SVE-NEXT:    br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
 ; CHECK-SVE:       vector.ph:
-; CHECK-SVE-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[N]], 32
+; CHECK-SVE-NEXT:    [[TMP8:%.*]] = shl nuw i64 [[TMP5]], 4
+; CHECK-SVE-NEXT:    [[TMP4:%.*]] = shl nuw i64 [[TMP8]], 1
+; CHECK-SVE-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[N]], [[TMP4]]
 ; CHECK-SVE-NEXT:    [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
 ; CHECK-SVE-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK-SVE:       vector.body:
 ; CHECK-SVE-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-SVE-NEXT:    [[VEC_PHI:%.*]] = phi <16 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP19:%.*]], [[VECTOR_BODY]] ]
-; CHECK-SVE-NEXT:    [[VEC_PHI1:%.*]] = phi <16 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP20:%.*]], [[VECTOR_BODY]] ]
+; CHECK-SVE-NEXT:    [[VEC_PHI:%.*]] = phi <vscale x 4 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[PARTIAL_REDUCE8:%.*]], [[VECTOR_BODY]] ]
+; CHECK-SVE-NEXT:    [[VEC_PHI1:%.*]] = phi <vscale x 4 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[PARTIAL_REDUCE9:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-SVE-NEXT:    [[TMP0:%.*]] = add i64 [[INDEX]], 1
 ; CHECK-SVE-NEXT:    [[TMP1:%.*]] = getelementptr i8, ptr [[A]], i64 [[TMP0]]
 ; CHECK-SVE-NEXT:    [[TMP2:%.*]] = getelementptr i8, ptr [[B]], i64 [[TMP0]]
 ; CHECK-SVE-NEXT:    [[TMP3:%.*]] = getelementptr i8, ptr [[C]], i64 [[TMP0]]
-; CHECK-SVE-NEXT:    [[TMP4:%.*]] = getelementptr i8, ptr [[TMP1]], i64 16
-; CHECK-SVE-NEXT:    [[WIDE_LOAD:%.*]] = load <16 x i8>, ptr [[TMP1]], align 1
-; CHECK-SVE-NEXT:    [[WIDE_LOAD2:%.*]] = load <16 x i8>, ptr [[TMP4]], align 1
-; CHECK-SVE-NEXT:    [[TMP5:%.*]] = getelementptr i8, ptr [[TMP2]], i64 16
-; CHECK-SVE-NEXT:    [[WIDE_LOAD3:%.*]] = load <16 x i8>, ptr [[TMP2]], align 1
-; CHECK-SVE-NEXT:    [[WIDE_LOAD4:%.*]] = load <16 x i8>, ptr [[TMP5]], align 1
-; CHECK-SVE-NEXT:    [[TMP6:%.*]] = getelementptr i8, ptr [[TMP3]], i64 16
-; CHECK-SVE-NEXT:    [[WIDE_LOAD5:%.*]] = load <16 x i8>, ptr [[TMP3]], align 1
-; CHECK-SVE-NEXT:    [[WIDE_LOAD6:%.*]] = load <16 x i8>, ptr [[TMP6]], align 1
-; CHECK-SVE-NEXT:    [[TMP7:%.*]] = sext <16 x i8> [[WIDE_LOAD]] to <16 x i16>
-; CHECK-SVE-NEXT:    [[TMP8:%.*]] = sext <16 x i8> [[WIDE_LOAD2]] to <16 x i16>
-; CHECK-SVE-NEXT:    [[TMP9:%.*]] = sext <16 x i8> [[WIDE_LOAD3]] to <16 x i16>
-; CHECK-SVE-NEXT:    [[TMP10:%.*]] = sext <16 x i8> [[WIDE_LOAD4]] to <16 x i16>
-; CHECK-SVE-NEXT:    [[TMP11:%.*]] = sext <16 x i8> [[WIDE_LOAD5]] to <16 x i32>
-; CHECK-SVE-NEXT:    [[TMP12:%.*]] = sext <16 x i8> [[WIDE_LOAD6]] to <16 x i32>
-; CHECK-SVE-NEXT:    [[TMP13:%.*]] = mul nsw <16 x i16> [[TMP7]], [[TMP9]]
-; CHECK-SVE-NEXT:    [[TMP14:%.*]] = mul nsw <16 x i16> [[TMP8]], [[TMP10]]
-; CHECK-SVE-NEXT:    [[TMP15:%.*]] = sext <16 x i16> [[TMP13]] to <16 x i32>
-; CHECK-SVE-NEXT:    [[TMP16:%.*]] = sext <16 x i16> [[TMP14]] to <16 x i32>
-; CHECK-SVE-NEXT:    [[TMP17:%.*]] = sub <16 x i32> [[VEC_PHI]], [[TMP15]]
-; CHECK-SVE-NEXT:    [[TMP18:%.*]] = sub <16 x i32> [[VEC_PHI1]], [[TMP16]]
-; CHECK-SVE-NEXT:    [[TMP19]] = add <16 x i32> [[TMP17]], [[TMP11]]
-; CHECK-SVE-NEXT:    [[TMP20]] = add <16 x i32> [[TMP18]], [[TMP12]]
-; CHECK-SVE-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 32
+; CHECK-SVE-NEXT:    [[TMP9:%.*]] = getelementptr i8, ptr [[TMP1]], i64 [[TMP8]]
+; CHECK-SVE-NEXT:    [[WIDE_LOAD:%.*]] = load <vscale x 16 x i8>, ptr [[TMP1]], align 1
+; CHECK-SVE-NEXT:    [[WIDE_LOAD2:%.*]] = load <vscale x 16 x i8>, ptr [[TMP9]], align 1
+; CHECK-SVE-NEXT:    [[TMP10:%.*]] = getelementptr i8, ptr [[TMP2]], i64 [[TMP8]]
+; CHECK-SVE-NEXT:    [[WIDE_LOAD3:%.*]] = load <vscale x 16 x i8>, ptr [[TMP2]], align 1
+; CHECK-SVE-NEXT:    [[WIDE_LOAD4:%.*]] = load <vscale x 16 x i8>, ptr [[TMP10]], align 1
+; CHECK-SVE-NEXT:    [[TMP11:%.*]] = getelementptr i8, ptr [[TMP3]], i64 [[TMP8]]
+; CHECK-SVE-NEXT:    [[WIDE_LOAD5:%.*]] = load <vscale x 16 x i8>, ptr [[TMP3]], align 1
+; CHECK-SVE-NEXT:    [[WIDE_LOAD6:%.*]] = load <vscale x 16 x i8>, ptr [[TMP11]], align 1
+; CHECK-SVE-NEXT:    [[TMP12:%.*]] = sext <vscale x 16 x i8> [[WIDE_LOAD]] to <vscale x 16 x i32>
+; CHECK-SVE-NEXT:    [[TMP13:%.*]] = sext <vscale x 16 x i8> [[WIDE_LOAD3]] to <vscale x 16 x i32>
+; CHECK-SVE-NEXT:    [[TMP14:%.*]] = mul nsw <vscale x 16 x i32> [[TMP12]], [[TMP13]]
+; CHECK-SVE-NEXT:    [[TMP15:%.*]] = sub <vscale x 16 x i32> zeroinitializer, [[TMP14]]
+; CHECK-SVE-NEXT:    [[PARTIAL_REDUCE:%.*]] = call <vscale x 4 x i32> @llvm.vector.partial.reduce.add.nxv4i32.nxv16i32(<vscale x 4 x i32> [[VEC_PHI]], <vscale x 16 x i32> [[TMP15]])
+; CHECK-SVE-NEXT:    [[TMP16:%.*]] = sext <vscale x 16 x i8> [[WIDE_LOAD2]] to <vscale x 16 x i32>
+; CHECK-SVE-NEXT:    [[TMP17:%.*]] = sext <vscale x 16 x i8> [[WIDE_LOAD4]] to <vscale x 16 x i32>
+; CHECK-SVE-NEXT:    [[TMP18:%.*]] = mul nsw <vscale x 16 x i32> [[TMP16]], [[TMP17]]
+; CHECK-SVE-NEXT:    [[TMP19:%.*]] = sub <vscale x 16 x i32> zeroinitializer, [[TMP18]]
+; CHECK-SVE-NEXT:    [[PARTIAL_REDUCE7:%.*]] = call <vscale x 4 x i32> @llvm.vector.partial.reduce.add.nxv4i32.nxv16i32(<vscale x 4 x i32> [[VEC_PHI1]], <vscale x 16 x i32> [[TMP19]])
+; CHECK-SVE-NEXT:    [[TMP20:%.*]] = sext <vscale x 16 x i8> [[WIDE_LOAD5]] to <vscale x 16 x i32>
+; CHECK-SVE-NEXT:    [[PARTIAL_REDUCE8]] = call <vscale x 4 x i32> @llvm.vector.partial.reduce.add.nxv4i32.nxv16i32(<vscale x 4 x i32> [[PARTIAL_REDUCE]], <vscale x 16 x i32> [[TMP20]])
+; CHECK-SVE-NEXT:    [[TMP22:%.*]] = sext <vscale x 16 x i8> [[WIDE_LOAD6]] to <vscale x 16 x i32>
+; CHECK-SVE-NEXT:    [[PARTIAL_REDUCE9]] = call <vscale x 4 x i32> @llvm.vector.partial.reduce.add.nxv4i32.nxv16i32(<vscale x 4 x i32> [[PARTIAL_REDUCE7]], <vscale x 16 x i32> [[TMP22]])
+; CHECK-SVE-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], [[TMP4]]
 ; CHECK-SVE-NEXT:    [[TMP21:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
 ; CHECK-SVE-NEXT:    br i1 [[TMP21]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP20:![0-9]+]]
 ; CHECK-SVE:       middle.block:
-; CHECK-SVE-NEXT:    [[BIN_RDX:%.*]] = add <16 x i32> [[TMP20]], [[TMP19]]
-; CHECK-SVE-NEXT:    [[TMP22:%.*]] = call i32 @llvm.vector.reduce.add.v16i32(<16 x i32> [[BIN_RDX]])
+; CHECK-SVE-NEXT:    [[BIN_RDX:%.*]] = add <vscale x 4 x i32> [[PARTIAL_REDUCE9]], [[PARTIAL_REDUCE8]]
+; CHECK-SVE-NEXT:    [[TMP23:%.*]] = call i32 @llvm.vector.reduce.add.nxv4i32(<vscale x 4 x i32> [[BIN_RDX]])
 ; CHECK-SVE-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
 ; CHECK-SVE-NEXT:    br i1 [[CMP_N]], label [[EXIT:%.*]], label [[SCALAR_PH]]
 ; CHECK-SVE:       scalar.ph:
@@ -1478,8 +1482,8 @@ define i32 @chained_partial_reduce_add_sub_ext_mul(ptr %a, ptr %b, ptr %c, i64 %
 ; CHECK-SVE-MAXBW-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK-SVE-MAXBW:       vector.body:
 ; CHECK-SVE-MAXBW-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-SVE-MAXBW-NEXT:    [[VEC_PHI:%.*]] = phi <8 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP19:%.*]], [[VECTOR_BODY]] ]
-; CHECK-SVE-MAXBW-NEXT:    [[VEC_PHI1:%.*]] = phi <8 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP20:%.*]], [[VECTOR_BODY]] ]
+; CHECK-SVE-MAXBW-NEXT:    [[VEC_PHI:%.*]] = phi <2 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[PARTIAL_REDUCE8:%.*]], [[VECTOR_BODY]] ]
+; CHECK-SVE-MAXBW-NEXT:    [[VEC_PHI1:%.*]] = phi <2 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[PARTIAL_REDUCE9:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-SVE-MAXBW-NEXT:    [[TMP0:%.*]] = add i64 [[INDEX]], 1
 ; CHECK-SVE-MAXBW-NEXT:    [[TMP1:%.*]] = getelementptr i8, ptr [[A]], i64 [[TMP0]]
 ; CHECK-SVE-MAXBW-NEXT:    [[TMP2:%.*]] = getelementptr i8, ptr [[B]], i64 [[TMP0]]
@@ -1493,26 +1497,26 @@ define i32 @chained_partial_reduce_add_sub_ext_mul(ptr %a, ptr %b, ptr %c, i64 %
 ; CHECK-SVE-MAXBW-NEXT:    [[TMP6:%.*]] = getelementptr i8, ptr [[TMP3]], i64 8
 ; CHECK-SVE-MAXBW-NEXT:    [[WIDE_LOAD5:%.*]] = load <8 x i8>, ptr [[TMP3]], align 1
 ; CHECK-SVE-MAXBW-NEXT:    [[WIDE_LOAD6:%.*]] = load <8 x i8>, ptr [[TMP6]], align 1
-; CHECK-SVE-MAXBW-NEXT:    [[TMP7:%.*]] = sext <8 x i8> [[WIDE_LOAD]] to <8 x i16>
-; CHECK-SVE-MAXBW-NEXT:    [[TMP8:%.*]] = sext <8 x i8> [[WIDE_LOAD2]] to <8 x i16>
-; CHECK-SVE-MAXBW-NEXT:    [[TMP9:%.*]] = sext <8 x i8> [[WIDE_LOAD3]] to <8 x i16>
-; CHECK-SVE-MAXBW-NEXT:    [[TMP10:%.*]] = sext <8 x i8> [[WIDE_LOAD4]] to <8 x i16>
-; CHECK-SVE-MAXBW-NEXT:    [[TMP11:%.*]] = sext <8 x i8> [[WIDE_LOAD5]] to <8 x i32>
-; CHECK-SVE-MAXBW-NEXT:    [[TMP12:%.*]] = sext <8 x i8> [[WIDE_LOAD6]] to <8 x i32>
-; CHECK-SVE-MAXBW-NEXT:    [[TMP13:%.*]] = mul nsw <8 x i16> [[TMP7]], [[TMP9]]
-; CHECK-SVE-MAXBW-NEXT:    [[TMP14:%.*]] = mul nsw <8 x i16> [[TMP8]], [[TMP10]]
-; CHECK-SVE-MAXBW-NEXT:    [[TMP15:%.*]] = sext <8 x i16> [[TMP13]] to <8 x i32>
-; CHECK-SVE-MAXBW-NEXT:    [[TMP16:%.*]] = sext <8 x i16> [[TMP14]] to <8 x i32>
-; CHECK-SVE-MAXBW-NEXT:    [[TMP17:%.*]] = sub <8 x i32> [[VEC_PHI]], [[TMP15]]
-; CHECK-SVE-MAXBW-NEXT:    [[TMP18:%.*]] = sub <8 x i32> [[VEC_PHI1]], [[TMP16]]
-; CHECK-SVE-MAXBW-NEXT:    [[TMP19]] = add <8 x i32> [[TMP17]], [[TMP11]]
-; CHECK-SVE-MAXBW-NEXT:    [[TMP20]] = add <8 x i32> [[TMP18]], [[TMP12]]
+; CHECK-SVE-MAXBW-NEXT:    [[TMP7:%.*]] = sext <8 x i8> [[WIDE_LOAD]] to <8 x i32>
+; CHECK-SVE-MAXBW-NEXT:    [[TMP8:%.*]] = sext <8 x i8> [[WIDE_LOAD3]] to <8 x i32>
+; CHECK-SVE-MAXBW-NEXT:    [[TMP15:%.*]] = mul nsw <8 x i32> [[TMP7]], [[TMP8]]
+; CHECK-SVE-MAXBW-NEXT:    [[TMP19:%.*]] = sub <8 x i32> zeroinitializer, [[TMP15]]
+; CHECK-SVE-MAXBW-NEXT:    [[PARTIAL_REDUCE:%.*]] = call <2 x i32> @llvm.vector.partial.reduce.add.v2i32.v8i32(<2 x i32> [[VEC_PHI]], <8 x i32> [[TMP19]])
+; CHECK-SVE-MAXBW-NEXT:    [[TMP11:%.*]] = sext <8 x i8> [[WIDE_LOAD2]] to <8 x i32>
+; CHECK-SVE-MAXBW-NEXT:    [[TMP12:%.*]] = sext <8 x i8> [[WIDE_LOAD4]] to <8 x i32>
+; CHECK-SVE-MAXBW-NEXT:    [[TMP16:%.*]] = mul nsw <8 x i32> [[TMP11]], [[TMP12]]
+; CHECK-SVE-MAXBW-NEXT:    [[TMP22:%.*]] = sub <8 x i32> zeroinitializer, [[TMP16]]
+; CHECK-SVE-MAXBW-NEXT:    [[PARTIAL_REDUCE7:%.*]] = call <2 x i32> @llvm.vector.partial.reduce.add.v2i32.v8i32(<2 x i32> [[VEC_PHI1]], <8 x i32> [[TMP22]])
+; CHECK-SVE-MAXBW-NEXT:    [[TMP17:%.*]] = sext <8 x i8> [[WIDE_LOAD5]] to <8 x i32>
+; CHECK-SVE-MAXBW-NEXT:    [[PARTIAL_REDUCE8]] = call <2 x i32> @llvm.vector.partial.reduce.add.v2i32.v8i32(<2 x i32> [[PARTIAL_REDUCE]], <8 x i32> [[TMP17]])
+; CHECK-SVE-MAXBW-NEXT:    [[TMP18:%.*]] = sext <8 x i8> [[WIDE_LOAD6]] to <8 x i32>
+; CHECK-SVE-MAXBW-NEXT:    [[PARTIAL_REDUCE9]] = call <2 x i32> @llvm.vector.partial.reduce.add.v2i32.v8i32(<2 x i32> [[PARTIAL_REDUCE7]], <8 x i32> [[TMP18]])
 ; CHECK-SVE-MAXBW-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 16
 ; CHECK-SVE-MAXBW-NEXT:    [[TMP21:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
 ; CHECK-SVE-MAXBW-NEXT:    br i1 [[TMP21]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP20:![0-9]+]]
 ; CHECK-SVE-MAXBW:       middle.block:
-; CHECK-SVE-MAXBW-NEXT:    [[BIN_RDX:%.*]] = add <8 x i32> [[TMP20]], [[TMP19]]
-; CHECK-SVE-MAXBW-NEXT:    [[TMP22:%.*]] = call i32 @llvm.vector.reduce.add.v8i32(<8 x i32> [[BIN_RDX]])
+; CHECK-SVE-MAXBW-NEXT:    [[BIN_RDX:%.*]] = add <2 x i32> [[PARTIAL_REDUCE9]], [[PARTIAL_REDUCE8]]
+; CHECK-SVE-MAXBW-NEXT:    [[TMP20:%.*]] = call i32 @llvm.vector.reduce.add.v2i32(<2 x i32> [[BIN_RDX]])
 ; CHECK-SVE-MAXBW-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
 ; CHECK-SVE-MAXBW-NEXT:    br i1 [[CMP_N]], label [[EXIT:%.*]], label [[SCALAR_PH]]
 ; CHECK-SVE-MAXBW:       scalar.ph:
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-usabs.ll b/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-usabs.ll
index a4bfa47fa9850..0fcac876e8788 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-usabs.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-usabs.ll
@@ -380,3 +380,63 @@ for.body:
 exit:
   ret i32 %sum.1
 }
+
+; Tests an abs diff extended operand in a AddChainWithSubs reduction, where the
+; abs diff is negated (the operand of the sub). Previously, we'd crash handling
+; this as we would fail to match the negated abs diff.
+define i32 @sub_add_chain_unsigned_absolute_difference(ptr noalias %x, ptr noalias %y) {
+; CHECK-LABEL: define i32 @sub_add_chain_unsigned_absolute_difference(
+; CHECK-SAME: ptr noalias [[X:%.*]], ptr noalias [[Y:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <4 x i32> [ zeroinitializer, %[[VECTOR_PH]] ], [ [[PARTIAL_REDUCE2:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds nuw i8, ptr [[X]], i64 [[INDEX]]
+; CHECK-NEXT:    ...
[truncated]

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@sdesmalen-arm sdesmalen-arm sdesmalen-arm approved these changes

@fhahn fhahn Awaiting requested review from fhahn

@huntergr-arm huntergr-arm Awaiting requested review from huntergr-arm

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@MacDue @sdesmalen-arm