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[SLPVectorizer] Test -1 stride loads. #158358

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Merged
merged 2 commits into from
Sep 14, 2025
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Merged

[SLPVectorizer] Test -1 stride loads. #158358

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d951054
[SLPVectorizer] Test -1 stride loads.
Sep 12, 2025
2f8c6a9
Merge branch 'main' into test_reversed_strided_load
mgudim Sep 14, 2025
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15 changes: 14 additions & 1 deletion llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -198,6 +198,16 @@ static cl::opt<unsigned> MaxProfitableLoadStride(
"slp-max-stride", cl::init(8), cl::Hidden,
cl::desc("The maximum stride, considered to be profitable."));

static cl::opt<bool>
DisableTreeReorder("slp-disable-tree-reorder", cl::init(false), cl::Hidden,
cl::desc("Disable tree reordering even if it is "
"profitable. Used for testing only."));

static cl::opt<bool>
ForceStridedLoads("slp-force-strided-loads", cl::init(false), cl::Hidden,
cl::desc("Generate strided loads even if they are not "
"profitable. Used for testing only."));

static cl::opt<bool>
ViewSLPTree("view-slp-tree", cl::Hidden,
cl::desc("Display the SLP trees with Graphviz"));
Expand Down Expand Up @@ -7770,6 +7780,9 @@ static void combineOrders(MutableArrayRef<unsigned> Order,
}

bool BoUpSLP::isProfitableToReorder() const {
if (DisableTreeReorder)
return false;

constexpr unsigned TinyVF = 2;
constexpr unsigned TinyTree = 10;
constexpr unsigned PhiOpsLimit = 12;
Expand Down Expand Up @@ -13027,7 +13040,7 @@ void BoUpSLP::transformNodes() {
InstructionCost StridedCost = TTI->getStridedMemoryOpCost(
Instruction::Load, VecTy, BaseLI->getPointerOperand(),
/*VariableMask=*/false, CommonAlignment, CostKind, BaseLI);
if (StridedCost < OriginalVecCost)
if (StridedCost < OriginalVecCost || ForceStridedLoads)
// Strided load is more profitable than consecutive load + reverse -
// transform the node to strided load.
E.State = TreeEntry::StridedVectorize;
Expand Down
85 changes: 85 additions & 0 deletions llvm/test/Transforms/SLPVectorizer/RISCV/reversed-strided-load.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,85 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -mtriple=riscv64 -mattr=+m,+v \
; RUN: -passes=slp-vectorizer \
; RUN: -slp-disable-tree-reorder=true -slp-force-strided-loads=true \
; RUN: -S < %s | FileCheck %s

define void @const_stride_reversed(ptr %pl, ptr %ps) {
; CHECK-LABEL: define void @const_stride_reversed(
; CHECK-SAME: ptr [[PL:%.*]], ptr [[PS:%.*]]) #[[ATTR0:[0-9]+]] {
; CHECK-NEXT: [[GEP_L15:%.*]] = getelementptr inbounds i8, ptr [[PL]], i64 15
; CHECK-NEXT: [[GEP_S0:%.*]] = getelementptr inbounds i8, ptr [[PS]], i64 0
; CHECK-NEXT: [[TMP2:%.*]] = call <16 x i8> @llvm.experimental.vp.strided.load.v16i8.p0.i64(ptr align 16 [[GEP_L15]], i64 -1, <16 x i1> splat (i1 true), i32 16)
; CHECK-NEXT: store <16 x i8> [[TMP2]], ptr [[GEP_S0]], align 16
; CHECK-NEXT: ret void
;
%gep_l0 = getelementptr inbounds i8, ptr %pl, i64 0
%gep_l1 = getelementptr inbounds i8, ptr %pl, i64 1
%gep_l2 = getelementptr inbounds i8, ptr %pl, i64 2
%gep_l3 = getelementptr inbounds i8, ptr %pl, i64 3
%gep_l4 = getelementptr inbounds i8, ptr %pl, i64 4
%gep_l5 = getelementptr inbounds i8, ptr %pl, i64 5
%gep_l6 = getelementptr inbounds i8, ptr %pl, i64 6
%gep_l7 = getelementptr inbounds i8, ptr %pl, i64 7
%gep_l8 = getelementptr inbounds i8, ptr %pl, i64 8
%gep_l9 = getelementptr inbounds i8, ptr %pl, i64 9
%gep_l10 = getelementptr inbounds i8, ptr %pl, i64 10
%gep_l11 = getelementptr inbounds i8, ptr %pl, i64 11
%gep_l12 = getelementptr inbounds i8, ptr %pl, i64 12
%gep_l13 = getelementptr inbounds i8, ptr %pl, i64 13
%gep_l14 = getelementptr inbounds i8, ptr %pl, i64 14
%gep_l15 = getelementptr inbounds i8, ptr %pl, i64 15

%load0 = load i8, ptr %gep_l0 , align 16
%load1 = load i8, ptr %gep_l1 , align 16
%load2 = load i8, ptr %gep_l2 , align 16
%load3 = load i8, ptr %gep_l3 , align 16
%load4 = load i8, ptr %gep_l4 , align 16
%load5 = load i8, ptr %gep_l5 , align 16
%load6 = load i8, ptr %gep_l6 , align 16
%load7 = load i8, ptr %gep_l7 , align 16
%load8 = load i8, ptr %gep_l8 , align 16
%load9 = load i8, ptr %gep_l9 , align 16
%load10 = load i8, ptr %gep_l10, align 16
%load11 = load i8, ptr %gep_l11, align 16
%load12 = load i8, ptr %gep_l12, align 16
%load13 = load i8, ptr %gep_l13, align 16
%load14 = load i8, ptr %gep_l14, align 16
%load15 = load i8, ptr %gep_l15, align 16

%gep_s0 = getelementptr inbounds i8, ptr %ps, i64 0
%gep_s1 = getelementptr inbounds i8, ptr %ps, i64 1
%gep_s2 = getelementptr inbounds i8, ptr %ps, i64 2
%gep_s3 = getelementptr inbounds i8, ptr %ps, i64 3
%gep_s4 = getelementptr inbounds i8, ptr %ps, i64 4
%gep_s5 = getelementptr inbounds i8, ptr %ps, i64 5
%gep_s6 = getelementptr inbounds i8, ptr %ps, i64 6
%gep_s7 = getelementptr inbounds i8, ptr %ps, i64 7
%gep_s8 = getelementptr inbounds i8, ptr %ps, i64 8
%gep_s9 = getelementptr inbounds i8, ptr %ps, i64 9
%gep_s10 = getelementptr inbounds i8, ptr %ps, i64 10
%gep_s11 = getelementptr inbounds i8, ptr %ps, i64 11
%gep_s12 = getelementptr inbounds i8, ptr %ps, i64 12
%gep_s13 = getelementptr inbounds i8, ptr %ps, i64 13
%gep_s14 = getelementptr inbounds i8, ptr %ps, i64 14
%gep_s15 = getelementptr inbounds i8, ptr %ps, i64 15

store i8 %load0, ptr %gep_s15, align 16
store i8 %load1, ptr %gep_s14, align 16
store i8 %load2, ptr %gep_s13, align 16
store i8 %load3, ptr %gep_s12, align 16
store i8 %load4, ptr %gep_s11, align 16
store i8 %load5, ptr %gep_s10, align 16
store i8 %load6, ptr %gep_s9, align 16
store i8 %load7, ptr %gep_s8, align 16
store i8 %load8, ptr %gep_s7, align 16
store i8 %load9, ptr %gep_s6, align 16
store i8 %load10, ptr %gep_s5, align 16
store i8 %load11, ptr %gep_s4, align 16
store i8 %load12, ptr %gep_s3, align 16
store i8 %load13, ptr %gep_s2, align 16
store i8 %load14, ptr %gep_s1, align 16
store i8 %load15, ptr %gep_s0, align 16

ret void
}
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