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[DAGCombiner] Add generic DAG combine for ISD::PARTIAL_REDUCE_MLA #127083

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Merged
merged 10 commits into from
Mar 4, 2025
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[DAGCombiner] Add generic DAG combine for ISD::PARTIAL_REDUCE_MLA #127083

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5053db6
[DAGCombiner] Add generic DAG combine for ISD::PARTIAL_REDUCE_MLA
JamesChesterman Feb 13, 2025
406041f
Split the DAG combine into two.
JamesChesterman Feb 19, 2025
bd7d333
Make DAG combine one function again
JamesChesterman Feb 20, 2025
793115a
Remove isLegalOrCustom check from DAG combine
JamesChesterman Feb 21, 2025
9908933
Remove unnecessary functions for getting PR operation action
JamesChesterman Feb 21, 2025
5ca85da
Rename variables and move a comment.
JamesChesterman Feb 28, 2025
ce0b098
Add an additional check into the DAG combine
JamesChesterman Feb 28, 2025
e694bcf
Rename variables to match those in the function
JamesChesterman Feb 28, 2025
7814fce
Simplify DAG combine
JamesChesterman Mar 3, 2025
ba150a4
Move comment
JamesChesterman Mar 3, 2025
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56 changes: 56 additions & 0 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -545,6 +545,7 @@ namespace {
SDValue visitMGATHER(SDNode *N);
SDValue visitMSCATTER(SDNode *N);
SDValue visitMHISTOGRAM(SDNode *N);
SDValue visitPARTIAL_REDUCE_MLA(SDNode *N);
SDValue visitVPGATHER(SDNode *N);
SDValue visitVPSCATTER(SDNode *N);
SDValue visitVP_STRIDED_LOAD(SDNode *N);
Expand Down Expand Up @@ -1972,6 +1973,9 @@ SDValue DAGCombiner::visit(SDNode *N) {
case ISD::MSCATTER: return visitMSCATTER(N);
case ISD::MSTORE: return visitMSTORE(N);
case ISD::EXPERIMENTAL_VECTOR_HISTOGRAM: return visitMHISTOGRAM(N);
case ISD::PARTIAL_REDUCE_SMLA:
case ISD::PARTIAL_REDUCE_UMLA:
return visitPARTIAL_REDUCE_MLA(N);
case ISD::VECTOR_COMPRESS: return visitVECTOR_COMPRESS(N);
case ISD::LIFETIME_END: return visitLIFETIME_END(N);
case ISD::FP_TO_FP16: return visitFP_TO_FP16(N);
Expand Down Expand Up @@ -12497,6 +12501,58 @@ SDValue DAGCombiner::visitMHISTOGRAM(SDNode *N) {
return SDValue();
}

// Makes PARTIAL_REDUCE_*MLA(Acc, MUL(ZEXT(LHSExtOp), ZEXT(RHSExtOp)),
// Splat(1)) into
// PARTIAL_REDUCE_UMLA(Acc, LHSExtOp, RHSExtOp).
// Makes PARTIAL_REDUCE_*MLA(Acc, MUL(SEXT(LHSExtOp), SEXT(RHSExtOp)),
// Splat(1)) into
// PARTIAL_REDUCE_SMLA(Acc, LHSExtOp, RHSExtOp).
SDValue DAGCombiner::visitPARTIAL_REDUCE_MLA(SDNode *N) {
SDLoc DL(N);

SDValue Acc = N->getOperand(0);
SDValue Op1 = N->getOperand(1);
SDValue Op2 = N->getOperand(2);

APInt ConstantOne;
if (Op1->getOpcode() != ISD::MUL ||
!ISD::isConstantSplatVector(Op2.getNode(), ConstantOne) ||
!ConstantOne.isOne())
return SDValue();

SDValue LHS = Op1->getOperand(0);
SDValue RHS = Op1->getOperand(1);
unsigned LHSOpcode = LHS->getOpcode();
unsigned RHSOpcode = RHS->getOpcode();
if (!ISD::isExtOpcode(LHSOpcode) || !ISD::isExtOpcode(RHSOpcode))
return SDValue();

SDValue LHSExtOp = LHS->getOperand(0);
SDValue RHSExtOp = RHS->getOperand(0);
EVT LHSExtOpVT = LHSExtOp.getValueType();
if (LHSExtOpVT != RHSExtOp.getValueType() || LHSOpcode != RHSOpcode)
return SDValue();

// FIXME: Add a check to only perform the DAG combine if there is lowering
// provided by the target

bool ExtIsSigned = LHSOpcode == ISD::SIGN_EXTEND;

// For a 2-stage extend the signedness of both of the extends must be the
// same. This is so the node can be folded into only a signed or unsigned
// node.
bool NodeIsSigned = N->getOpcode() == ISD::PARTIAL_REDUCE_SMLA;
EVT AccElemVT = Acc.getValueType().getVectorElementType();
if (ExtIsSigned != NodeIsSigned &&
Op1.getValueType().getVectorElementType() != AccElemVT)
return SDValue();

unsigned NewOpcode =
ExtIsSigned ? ISD::PARTIAL_REDUCE_SMLA : ISD::PARTIAL_REDUCE_UMLA;
return DAG.getNode(NewOpcode, DL, N->getValueType(0), Acc, LHSExtOp,
RHSExtOp);
}

SDValue DAGCombiner::visitVP_STRIDED_LOAD(SDNode *N) {
auto *SLD = cast<VPStridedLoadSDNode>(N);
EVT EltVT = SLD->getValueType(0).getVectorElementType();
Expand Down
139 changes: 82 additions & 57 deletions llvm/test/CodeGen/AArch64/neon-partial-reduce-dot-product.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -12,13 +12,15 @@ define <4 x i32> @udot(<4 x i32> %acc, <16 x i8> %u, <16 x i8> %s) {
;
; CHECK-NODOT-LABEL: udot:
; CHECK-NODOT: // %bb.0:
; CHECK-NODOT-NEXT: umull v3.8h, v2.8b, v1.8b
; CHECK-NODOT-NEXT: umull2 v1.8h, v2.16b, v1.16b
; CHECK-NODOT-NEXT: ushll v2.4s, v1.4h, #0
; CHECK-NODOT-NEXT: uaddw v0.4s, v0.4s, v3.4h
; CHECK-NODOT-NEXT: uaddw2 v2.4s, v2.4s, v3.8h
; CHECK-NODOT-NEXT: uaddw2 v0.4s, v0.4s, v1.8h
; CHECK-NODOT-NEXT: add v0.4s, v2.4s, v0.4s
; CHECK-NODOT-NEXT: ushll v3.8h, v1.8b, #0
; CHECK-NODOT-NEXT: ushll v4.8h, v2.8b, #0
; CHECK-NODOT-NEXT: ushll2 v1.8h, v1.16b, #0
; CHECK-NODOT-NEXT: ushll2 v2.8h, v2.16b, #0
; CHECK-NODOT-NEXT: umlal v0.4s, v4.4h, v3.4h
; CHECK-NODOT-NEXT: umull v5.4s, v2.4h, v1.4h
; CHECK-NODOT-NEXT: umlal2 v0.4s, v2.8h, v1.8h
; CHECK-NODOT-NEXT: umlal2 v5.4s, v4.8h, v3.8h
; CHECK-NODOT-NEXT: add v0.4s, v5.4s, v0.4s
; CHECK-NODOT-NEXT: ret
%u.wide = zext <16 x i8> %u to <16 x i32>
%s.wide = zext <16 x i8> %s to <16 x i32>
Expand All @@ -35,17 +37,19 @@ define <2 x i32> @udot_narrow(<2 x i32> %acc, <8 x i8> %u, <8 x i8> %s) {
;
; CHECK-NODOT-LABEL: udot_narrow:
; CHECK-NODOT: // %bb.0:
; CHECK-NODOT-NEXT: umull v1.8h, v2.8b, v1.8b
; CHECK-NODOT-NEXT: ushll v1.8h, v1.8b, #0
; CHECK-NODOT-NEXT: ushll v2.8h, v2.8b, #0
; CHECK-NODOT-NEXT: // kill: def $d0 killed $d0 def $q0
; CHECK-NODOT-NEXT: ushll v2.4s, v1.4h, #0
; CHECK-NODOT-NEXT: ushll2 v3.4s, v1.8h, #0
; CHECK-NODOT-NEXT: ext v4.16b, v1.16b, v1.16b, #8
; CHECK-NODOT-NEXT: uaddw v0.4s, v0.4s, v1.4h
; CHECK-NODOT-NEXT: umull v3.4s, v2.4h, v1.4h
; CHECK-NODOT-NEXT: umull2 v4.4s, v2.8h, v1.8h
; CHECK-NODOT-NEXT: ext v5.16b, v1.16b, v1.16b, #8
; CHECK-NODOT-NEXT: ext v6.16b, v2.16b, v2.16b, #8
; CHECK-NODOT-NEXT: umlal v0.4s, v2.4h, v1.4h
; CHECK-NODOT-NEXT: ext v3.16b, v3.16b, v3.16b, #8
; CHECK-NODOT-NEXT: ext v2.16b, v2.16b, v2.16b, #8
; CHECK-NODOT-NEXT: add v0.2s, v3.2s, v0.2s
; CHECK-NODOT-NEXT: uaddw v1.4s, v2.4s, v4.4h
; CHECK-NODOT-NEXT: ext v1.16b, v4.16b, v4.16b, #8
; CHECK-NODOT-NEXT: umlal v3.4s, v6.4h, v5.4h
; CHECK-NODOT-NEXT: add v0.2s, v1.2s, v0.2s
; CHECK-NODOT-NEXT: add v0.2s, v3.2s, v0.2s
; CHECK-NODOT-NEXT: ret
%u.wide = zext <8 x i8> %u to <8 x i32>
%s.wide = zext <8 x i8> %s to <8 x i32>
Expand All @@ -62,13 +66,15 @@ define <4 x i32> @sdot(<4 x i32> %acc, <16 x i8> %u, <16 x i8> %s) {
;
; CHECK-NODOT-LABEL: sdot:
; CHECK-NODOT: // %bb.0:
; CHECK-NODOT-NEXT: smull v3.8h, v2.8b, v1.8b
; CHECK-NODOT-NEXT: smull2 v1.8h, v2.16b, v1.16b
; CHECK-NODOT-NEXT: sshll v2.4s, v1.4h, #0
; CHECK-NODOT-NEXT: saddw v0.4s, v0.4s, v3.4h
; CHECK-NODOT-NEXT: saddw2 v2.4s, v2.4s, v3.8h
; CHECK-NODOT-NEXT: saddw2 v0.4s, v0.4s, v1.8h
; CHECK-NODOT-NEXT: add v0.4s, v2.4s, v0.4s
; CHECK-NODOT-NEXT: sshll v3.8h, v1.8b, #0
; CHECK-NODOT-NEXT: sshll v4.8h, v2.8b, #0
; CHECK-NODOT-NEXT: sshll2 v1.8h, v1.16b, #0
; CHECK-NODOT-NEXT: sshll2 v2.8h, v2.16b, #0
; CHECK-NODOT-NEXT: smlal v0.4s, v4.4h, v3.4h
; CHECK-NODOT-NEXT: smull v5.4s, v2.4h, v1.4h
; CHECK-NODOT-NEXT: smlal2 v0.4s, v2.8h, v1.8h
; CHECK-NODOT-NEXT: smlal2 v5.4s, v4.8h, v3.8h
; CHECK-NODOT-NEXT: add v0.4s, v5.4s, v0.4s
; CHECK-NODOT-NEXT: ret
%u.wide = sext <16 x i8> %u to <16 x i32>
%s.wide = sext <16 x i8> %s to <16 x i32>
Expand All @@ -85,17 +91,19 @@ define <2 x i32> @sdot_narrow(<2 x i32> %acc, <8 x i8> %u, <8 x i8> %s) {
;
; CHECK-NODOT-LABEL: sdot_narrow:
; CHECK-NODOT: // %bb.0:
; CHECK-NODOT-NEXT: smull v1.8h, v2.8b, v1.8b
; CHECK-NODOT-NEXT: sshll v1.8h, v1.8b, #0
; CHECK-NODOT-NEXT: sshll v2.8h, v2.8b, #0
; CHECK-NODOT-NEXT: // kill: def $d0 killed $d0 def $q0
; CHECK-NODOT-NEXT: sshll v2.4s, v1.4h, #0
; CHECK-NODOT-NEXT: sshll2 v3.4s, v1.8h, #0
; CHECK-NODOT-NEXT: ext v4.16b, v1.16b, v1.16b, #8
; CHECK-NODOT-NEXT: saddw v0.4s, v0.4s, v1.4h
; CHECK-NODOT-NEXT: smull v3.4s, v2.4h, v1.4h
; CHECK-NODOT-NEXT: smull2 v4.4s, v2.8h, v1.8h
; CHECK-NODOT-NEXT: ext v5.16b, v1.16b, v1.16b, #8
; CHECK-NODOT-NEXT: ext v6.16b, v2.16b, v2.16b, #8
; CHECK-NODOT-NEXT: smlal v0.4s, v2.4h, v1.4h
; CHECK-NODOT-NEXT: ext v3.16b, v3.16b, v3.16b, #8
; CHECK-NODOT-NEXT: ext v2.16b, v2.16b, v2.16b, #8
; CHECK-NODOT-NEXT: add v0.2s, v3.2s, v0.2s
; CHECK-NODOT-NEXT: saddw v1.4s, v2.4s, v4.4h
; CHECK-NODOT-NEXT: ext v1.16b, v4.16b, v4.16b, #8
; CHECK-NODOT-NEXT: smlal v3.4s, v6.4h, v5.4h
; CHECK-NODOT-NEXT: add v0.2s, v1.2s, v0.2s
; CHECK-NODOT-NEXT: add v0.2s, v3.2s, v0.2s
; CHECK-NODOT-NEXT: ret
%u.wide = sext <8 x i8> %u to <8 x i32>
%s.wide = sext <8 x i8> %s to <8 x i32>
Expand Down Expand Up @@ -223,19 +231,27 @@ define <4 x i64> @udot_8to64(<4 x i64> %acc, <16 x i8> %a, <16 x i8> %b) {
;
; CHECK-NODOT-LABEL: udot_8to64:
; CHECK-NODOT: // %bb.0: // %entry
; CHECK-NODOT-NEXT: umull v4.8h, v2.8b, v3.8b
; CHECK-NODOT-NEXT: umull2 v2.8h, v2.16b, v3.16b
; CHECK-NODOT-NEXT: ushll v3.4s, v4.4h, #0
; CHECK-NODOT-NEXT: ushll v5.4s, v2.4h, #0
; CHECK-NODOT-NEXT: ushll v4.8h, v3.8b, #0
; CHECK-NODOT-NEXT: ushll v5.8h, v2.8b, #0
; CHECK-NODOT-NEXT: ushll2 v3.8h, v3.16b, #0
; CHECK-NODOT-NEXT: ushll2 v2.8h, v2.16b, #0
; CHECK-NODOT-NEXT: ushll v6.4s, v4.4h, #0
; CHECK-NODOT-NEXT: ushll v7.4s, v5.4h, #0
; CHECK-NODOT-NEXT: ushll2 v4.4s, v4.8h, #0
; CHECK-NODOT-NEXT: ushll2 v2.4s, v2.8h, #0
; CHECK-NODOT-NEXT: uaddw2 v1.2d, v1.2d, v3.4s
; CHECK-NODOT-NEXT: uaddw v0.2d, v0.2d, v3.2s
; CHECK-NODOT-NEXT: uaddl2 v3.2d, v4.4s, v5.4s
; CHECK-NODOT-NEXT: uaddl v4.2d, v4.2s, v5.2s
; CHECK-NODOT-NEXT: uaddw2 v1.2d, v1.2d, v2.4s
; CHECK-NODOT-NEXT: uaddw v0.2d, v0.2d, v2.2s
; CHECK-NODOT-NEXT: add v1.2d, v3.2d, v1.2d
; CHECK-NODOT-NEXT: ushll2 v5.4s, v5.8h, #0
; CHECK-NODOT-NEXT: ushll2 v16.4s, v3.8h, #0
; CHECK-NODOT-NEXT: ushll2 v17.4s, v2.8h, #0
; CHECK-NODOT-NEXT: ushll v3.4s, v3.4h, #0
; CHECK-NODOT-NEXT: ushll v2.4s, v2.4h, #0
; CHECK-NODOT-NEXT: umlal2 v1.2d, v7.4s, v6.4s
; CHECK-NODOT-NEXT: umlal v0.2d, v7.2s, v6.2s
; CHECK-NODOT-NEXT: umull2 v18.2d, v5.4s, v4.4s
; CHECK-NODOT-NEXT: umull v4.2d, v5.2s, v4.2s
; CHECK-NODOT-NEXT: umlal2 v1.2d, v17.4s, v16.4s
; CHECK-NODOT-NEXT: umlal v0.2d, v17.2s, v16.2s
; CHECK-NODOT-NEXT: umlal2 v18.2d, v2.4s, v3.4s
; CHECK-NODOT-NEXT: umlal v4.2d, v2.2s, v3.2s
; CHECK-NODOT-NEXT: add v1.2d, v18.2d, v1.2d
; CHECK-NODOT-NEXT: add v0.2d, v4.2d, v0.2d
; CHECK-NODOT-NEXT: ret
entry:
Expand All @@ -258,19 +274,27 @@ define <4 x i64> @sdot_8to64(<4 x i64> %acc, <16 x i8> %a, <16 x i8> %b){
;
; CHECK-NODOT-LABEL: sdot_8to64:
; CHECK-NODOT: // %bb.0: // %entry
; CHECK-NODOT-NEXT: smull v4.8h, v2.8b, v3.8b
; CHECK-NODOT-NEXT: smull2 v2.8h, v2.16b, v3.16b
; CHECK-NODOT-NEXT: sshll v3.4s, v4.4h, #0
; CHECK-NODOT-NEXT: sshll v5.4s, v2.4h, #0
; CHECK-NODOT-NEXT: sshll v4.8h, v3.8b, #0
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I know these are regressions, but they'll be addressed by follow-up patches that further improve this code-gen.

; CHECK-NODOT-NEXT: sshll v5.8h, v2.8b, #0
; CHECK-NODOT-NEXT: sshll2 v3.8h, v3.16b, #0
; CHECK-NODOT-NEXT: sshll2 v2.8h, v2.16b, #0
; CHECK-NODOT-NEXT: sshll v6.4s, v4.4h, #0
; CHECK-NODOT-NEXT: sshll v7.4s, v5.4h, #0
; CHECK-NODOT-NEXT: sshll2 v4.4s, v4.8h, #0
; CHECK-NODOT-NEXT: sshll2 v2.4s, v2.8h, #0
; CHECK-NODOT-NEXT: saddw2 v1.2d, v1.2d, v3.4s
; CHECK-NODOT-NEXT: saddw v0.2d, v0.2d, v3.2s
; CHECK-NODOT-NEXT: saddl2 v3.2d, v4.4s, v5.4s
; CHECK-NODOT-NEXT: saddl v4.2d, v4.2s, v5.2s
; CHECK-NODOT-NEXT: saddw2 v1.2d, v1.2d, v2.4s
; CHECK-NODOT-NEXT: saddw v0.2d, v0.2d, v2.2s
; CHECK-NODOT-NEXT: add v1.2d, v3.2d, v1.2d
; CHECK-NODOT-NEXT: sshll2 v5.4s, v5.8h, #0
; CHECK-NODOT-NEXT: sshll2 v16.4s, v3.8h, #0
; CHECK-NODOT-NEXT: sshll2 v17.4s, v2.8h, #0
; CHECK-NODOT-NEXT: sshll v3.4s, v3.4h, #0
; CHECK-NODOT-NEXT: sshll v2.4s, v2.4h, #0
; CHECK-NODOT-NEXT: smlal2 v1.2d, v7.4s, v6.4s
; CHECK-NODOT-NEXT: smlal v0.2d, v7.2s, v6.2s
; CHECK-NODOT-NEXT: smull2 v18.2d, v5.4s, v4.4s
; CHECK-NODOT-NEXT: smull v4.2d, v5.2s, v4.2s
; CHECK-NODOT-NEXT: smlal2 v1.2d, v17.4s, v16.4s
; CHECK-NODOT-NEXT: smlal v0.2d, v17.2s, v16.2s
; CHECK-NODOT-NEXT: smlal2 v18.2d, v2.4s, v3.4s
; CHECK-NODOT-NEXT: smlal v4.2d, v2.2s, v3.2s
; CHECK-NODOT-NEXT: add v1.2d, v18.2d, v1.2d
; CHECK-NODOT-NEXT: add v0.2d, v4.2d, v0.2d
; CHECK-NODOT-NEXT: ret
entry:
Expand Down Expand Up @@ -531,9 +555,10 @@ define <4 x i64> @sdot_no_bin_op_8to64(<4 x i64> %acc, <16 x i8> %a){
define <4 x i32> @not_udot(<4 x i32> %acc, <8 x i8> %u, <8 x i8> %s) #0{
; CHECK-LABEL: not_udot:
; CHECK: // %bb.0:
; CHECK-NEXT: umull v1.8h, v2.8b, v1.8b
; CHECK-NEXT: uaddw v0.4s, v0.4s, v1.4h
; CHECK-NEXT: uaddw2 v0.4s, v0.4s, v1.8h
; CHECK-NEXT: ushll v1.8h, v1.8b, #0
; CHECK-NEXT: ushll v2.8h, v2.8b, #0
; CHECK-NEXT: umlal v0.4s, v2.4h, v1.4h
; CHECK-NEXT: umlal2 v0.4s, v2.8h, v1.8h
; CHECK-NEXT: ret
%u.wide = zext <8 x i8> %u to <8 x i32>
%s.wide = zext <8 x i8> %s to <8 x i32>
Expand Down
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