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[LV] Fix missing MetaData for histogram instructions #134241

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[LV] Fix missing MetaData for histogram instructions #134241

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2 changes: 2 additions & 0 deletions llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8642,6 +8642,8 @@ VPRecipeBuilder::tryToWidenHistogram(const HistogramInfo *HI,
HGramOps.push_back(Operands[1]);
// Increment value.
HGramOps.push_back(getVPValueOrAddLiveIn(HI->Update->getOperand(1)));
// Store Instruction.
HGramOps.push_back(getVPValueOrAddLiveIn(HI->Store));
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Adding a live-in for the store as operand, just to get the underlying instruction to retrieve the metadata seems like a bit of a workaround.

I think it would be good to improve the existing metadata handling first and model it explicit in VPlan: #135272

Then it should be easy to preserve the metadata directly without needing any artificial operands


// In case of predicated execution (due to tail-folding, or conditional
// execution, or both), pass the relevant mask.
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2 changes: 1 addition & 1 deletion llvm/lib/Transforms/Vectorize/VPlan.h
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Expand Up @@ -1466,7 +1466,7 @@ class VPHistogramRecipe : public VPRecipeBase {
/// Return the mask operand if one was provided, or a null pointer if all
/// lanes should be executed unconditionally.
VPValue *getMask() const {
return getNumOperands() == 3 ? getOperand(2) : nullptr;
return getNumOperands() == 4 ? getOperand(3) : nullptr;
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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8 changes: 5 additions & 3 deletions llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
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Expand Up @@ -1242,9 +1242,11 @@ void VPHistogramRecipe::execute(VPTransformState &State) {
else
assert(Opcode == Instruction::Add && "only add or sub supported for now");

State.Builder.CreateIntrinsic(Intrinsic::experimental_vector_histogram_add,
{VTy, IncAmt->getType()},
{Address, IncAmt, Mask});
auto *HistogramInst = State.Builder.CreateIntrinsic(
Intrinsic::experimental_vector_histogram_add, {VTy, IncAmt->getType()},
{Address, IncAmt, Mask});
State.addMetadata(HistogramInst,
cast<Instruction>(getOperand(2)->getUnderlyingValue()));
}

InstructionCost VPHistogramRecipe::computeCost(ElementCount VF,
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75 changes: 75 additions & 0 deletions llvm/test/Transforms/LoopVectorize/AArch64/sve2-histcnt.ll
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Expand Up @@ -927,6 +927,72 @@ for.exit:
ret void
}

define void @simple_histogram_metadata(ptr noalias %buckets, ptr readonly %indices, i64 %N) #0 {
; CHECK-LABEL: define void @simple_histogram_metadata(
; CHECK-SAME: ptr noalias [[BUCKETS:%.*]], ptr readonly [[INDICES:%.*]], i64 [[N:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP1:%.*]] = shl nuw nsw i64 [[TMP0]], 2
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[N]], [[TMP1]]
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[TMP2:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[DOTNEG:%.*]] = mul nsw i64 [[TMP2]], -4
; CHECK-NEXT: [[N_VEC:%.*]] = and i64 [[N]], [[DOTNEG]]
; CHECK-NEXT: [[TMP3:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP4:%.*]] = shl nuw nsw i64 [[TMP3]], 2
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP5:%.*]] = getelementptr inbounds i32, ptr [[INDICES]], i64 [[INDEX]]
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <vscale x 4 x i32>, ptr [[TMP5]], align 4, !alias.scope [[META26:![0-9]+]], !noalias [[META29:![0-9]+]]
; CHECK-NEXT: [[TMP6:%.*]] = zext <vscale x 4 x i32> [[WIDE_LOAD]] to <vscale x 4 x i64>
; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds i32, ptr [[BUCKETS]], <vscale x 4 x i64> [[TMP6]]
; CHECK-NEXT: call void @llvm.experimental.vector.histogram.add.nxv4p0.i32(<vscale x 4 x ptr> [[TMP7]], i32 1, <vscale x 4 x i1> splat (i1 true)), !alias.scope [[META31:![0-9]+]], !noalias [[META26]]
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], [[TMP4]]
; CHECK-NEXT: [[TMP8:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP34:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[N]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_EXIT:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], [[FOR_BODY]] ]
; CHECK-NEXT: [[GEP_INDICES:%.*]] = getelementptr inbounds i32, ptr [[INDICES]], i64 [[IV]]
; CHECK-NEXT: [[L_IDX:%.*]] = load i32, ptr [[GEP_INDICES]], align 4, !alias.scope [[META26]], !noalias [[META29]]
; CHECK-NEXT: [[IDXPROM1:%.*]] = zext i32 [[L_IDX]] to i64
; CHECK-NEXT: [[GEP_BUCKET:%.*]] = getelementptr inbounds nuw i32, ptr [[BUCKETS]], i64 [[IDXPROM1]]
; CHECK-NEXT: [[L_BUCKET:%.*]] = load i32, ptr [[GEP_BUCKET]], align 4, !alias.scope [[META31]], !noalias [[META26]]
; CHECK-NEXT: [[INC:%.*]] = add nsw i32 [[L_BUCKET]], 1
; CHECK-NEXT: store i32 [[INC]], ptr [[GEP_BUCKET]], align 4, !alias.scope [[META31]], !noalias [[META26]]
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], [[N]]
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_EXIT]], label [[FOR_BODY]], !llvm.loop [[LOOP35:![0-9]+]]
; CHECK: for.exit:
; CHECK-NEXT: ret void
;
entry:
br label %for.body

for.body:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %for.body ]
%gep.indices = getelementptr inbounds i32, ptr %indices, i64 %iv
%l.idx = load i32, ptr %gep.indices, align 4, !alias.scope !44, !noalias !47
%idxprom1 = zext i32 %l.idx to i64
%gep.bucket = getelementptr inbounds i32, ptr %buckets, i64 %idxprom1
%l.bucket = load i32, ptr %gep.bucket, align 4, !alias.scope !52, !noalias !44
%inc = add nsw i32 %l.bucket, 1
store i32 %inc, ptr %gep.bucket, align 4, !alias.scope !52, !noalias !44
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, %N
br i1 %exitcond, label %for.exit, label %for.body, !llvm.loop !4

for.exit:
ret void
}

attributes #0 = { "target-features"="+sve2" vscale_range(1,16) }

!0 = distinct !{!0, !1}
Expand All @@ -935,3 +1001,12 @@ attributes #0 = { "target-features"="+sve2" vscale_range(1,16) }
!3 = !{!"llvm.loop.vectorize.predicate.enable", i1 true}
!4 = distinct !{!4, !5}
!5 = !{!"llvm.loop.interleave.count", i32 1}

!44 = !{!45}
!45 = distinct !{!45, !46, !"scope-index-1"}
!46 = distinct !{!46, !"scopes-indices"}
!47 = !{!48}
!48 = distinct !{!48, !46, !"scope-bucket-1"}
!52 = !{!48, !53}
!53 = distinct !{!53, !54, !"scope-bucket-2"}
!54 = distinct !{!54, !"scopes-buckets"}