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[DAG] Fold add(mul(add(A, CA), CM), CB) -> add(mul(A, CM), CM*CA+CB) (l…
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…lvm#90860)

This is useful when the inner add has multiple uses, and so cannot be
canonicalized by pushing the constants down through the mul. This patch
adds patterns for both `add(mul(add(A, CA), CM), CB)` and with an extra add
`add(add(mul(add(A, CA), CM), B) CB)` as the second can come up when
lowering geps.
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@davemgreen
davemgreen authored May 8, 2024
1 parent 965f3ca commit fcf945f
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Showing 2 changed files with 91 additions and 36 deletions.
60 changes: 60 additions & 0 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2838,6 +2838,66 @@ SDValue DAGCombiner::visitADDLike(SDNode *N) {
return DAG.getNode(ISD::ADD, DL, VT, Not, N0.getOperand(0));
}

// Fold add(mul(add(A, CA), CM), CB) -> add(mul(A, CM), CM*CA+CB).
// This can help if the inner add has multiple uses.
APInt CM, CA;
if (ConstantSDNode *CB = dyn_cast<ConstantSDNode>(N1)) {
if (VT.getScalarSizeInBits() <= 64) {
if (sd_match(N0, m_OneUse(m_Mul(m_Add(m_Value(A), m_ConstInt(CA)),
m_ConstInt(CM)))) &&
TLI.isLegalAddImmediate(
(CA * CM + CB->getAPIntValue()).getSExtValue())) {
SDNodeFlags Flags;
// If all the inputs are nuw, the outputs can be nuw. If all the input
// are _also_ nsw the outputs can be too.
if (N->getFlags().hasNoUnsignedWrap() &&
N0->getFlags().hasNoUnsignedWrap() &&
N0.getOperand(0)->getFlags().hasNoUnsignedWrap()) {
Flags.setNoUnsignedWrap(true);
if (N->getFlags().hasNoSignedWrap() &&
N0->getFlags().hasNoSignedWrap() &&
N0.getOperand(0)->getFlags().hasNoSignedWrap())
Flags.setNoSignedWrap(true);
}
SDValue Mul = DAG.getNode(ISD::MUL, SDLoc(N1), VT, A,
DAG.getConstant(CM, DL, VT), Flags);
return DAG.getNode(
ISD::ADD, DL, VT, Mul,
DAG.getConstant(CA * CM + CB->getAPIntValue(), DL, VT), Flags);
}
// Also look in case there is an intermediate add.
if (sd_match(N0, m_OneUse(m_Add(
m_OneUse(m_Mul(m_Add(m_Value(A), m_ConstInt(CA)),
m_ConstInt(CM))),
m_Value(B)))) &&
TLI.isLegalAddImmediate(
(CA * CM + CB->getAPIntValue()).getSExtValue())) {
SDNodeFlags Flags;
// If all the inputs are nuw, the outputs can be nuw. If all the input
// are _also_ nsw the outputs can be too.
SDValue OMul =
N0.getOperand(0) == B ? N0.getOperand(1) : N0.getOperand(0);
if (N->getFlags().hasNoUnsignedWrap() &&
N0->getFlags().hasNoUnsignedWrap() &&
OMul->getFlags().hasNoUnsignedWrap() &&
OMul.getOperand(0)->getFlags().hasNoUnsignedWrap()) {
Flags.setNoUnsignedWrap(true);
if (N->getFlags().hasNoSignedWrap() &&
N0->getFlags().hasNoSignedWrap() &&
OMul->getFlags().hasNoSignedWrap() &&
OMul.getOperand(0)->getFlags().hasNoSignedWrap())
Flags.setNoSignedWrap(true);
}
SDValue Mul = DAG.getNode(ISD::MUL, SDLoc(N1), VT, A,
DAG.getConstant(CM, DL, VT), Flags);
SDValue Add = DAG.getNode(ISD::ADD, SDLoc(N1), VT, Mul, B, Flags);
return DAG.getNode(
ISD::ADD, DL, VT, Add,
DAG.getConstant(CA * CM + CB->getAPIntValue(), DL, VT), Flags);
}
}
}

if (SDValue Combined = visitADDLikeCommutative(N0, N1, N))
return Combined;

Expand Down
67 changes: 31 additions & 36 deletions llvm/test/CodeGen/AArch64/addimm-mulimm.ll
View file
Original file line number Diff line number Diff line change
Expand Up @@ -166,9 +166,9 @@ define signext i32 @addmuladd_multiuse(i32 signext %a) {
; CHECK-LABEL: addmuladd_multiuse:
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #324 // =0x144
; CHECK-NEXT: mov w9, #1300 // =0x514
; CHECK-NEXT: madd w8, w0, w8, w9
; CHECK-NEXT: add w9, w0, #4
; CHECK-NEXT: mov w10, #4 // =0x4
; CHECK-NEXT: madd w8, w9, w8, w10
; CHECK-NEXT: eor w0, w9, w8
; CHECK-NEXT: ret
%tmp0 = add i32 %a, 4
Expand Down Expand Up @@ -198,11 +198,10 @@ define signext i32 @addmuladd_multiuse2(i32 signext %a) {
; CHECK-LABEL: addmuladd_multiuse2:
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #324 // =0x144
; CHECK-NEXT: add w9, w0, #4
; CHECK-NEXT: mov w11, #4 // =0x4
; CHECK-NEXT: lsl w10, w9, #2
; CHECK-NEXT: madd w8, w9, w8, w11
; CHECK-NEXT: add w9, w10, #4
; CHECK-NEXT: lsl w9, w0, #2
; CHECK-NEXT: mov w10, #1300 // =0x514
; CHECK-NEXT: madd w8, w0, w8, w10
; CHECK-NEXT: add w9, w9, #20
; CHECK-NEXT: eor w0, w8, w9
; CHECK-NEXT: ret
%tmp0 = add i32 %a, 4
Expand Down Expand Up @@ -233,8 +232,8 @@ define signext i32 @addaddmuladd_multiuse(i32 signext %a, i32 %b) {
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #324 // =0x144
; CHECK-NEXT: add w9, w0, #4
; CHECK-NEXT: madd w8, w9, w8, w1
; CHECK-NEXT: add w8, w8, #4
; CHECK-NEXT: madd w8, w0, w8, w1
; CHECK-NEXT: add w8, w8, #1300
; CHECK-NEXT: eor w0, w9, w8
; CHECK-NEXT: ret
%tmp0 = add i32 %a, 4
Expand All @@ -249,12 +248,11 @@ define signext i32 @addaddmuladd_multiuse2(i32 signext %a, i32 %b) {
; CHECK-LABEL: addaddmuladd_multiuse2:
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #324 // =0x144
; CHECK-NEXT: add w9, w0, #4
; CHECK-NEXT: mov w10, #162 // =0xa2
; CHECK-NEXT: madd w8, w9, w8, w1
; CHECK-NEXT: madd w9, w9, w10, w1
; CHECK-NEXT: add w8, w8, #4
; CHECK-NEXT: add w9, w9, #4
; CHECK-NEXT: mov w9, #162 // =0xa2
; CHECK-NEXT: madd w8, w0, w8, w1
; CHECK-NEXT: madd w9, w0, w9, w1
; CHECK-NEXT: add w8, w8, #1300
; CHECK-NEXT: add w9, w9, #652
; CHECK-NEXT: eor w0, w9, w8
; CHECK-NEXT: ret
%tmp0 = add i32 %a, 4
Expand Down Expand Up @@ -319,17 +317,17 @@ define void @addmuladd_gep(ptr %p, i64 %a) {
define i32 @addmuladd_gep2(ptr %p, i32 %a) {
; CHECK-LABEL: addmuladd_gep2:
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #3240 // =0xca8
; CHECK-NEXT: // kill: def $w1 killed $w1 def $x1
; CHECK-NEXT: sxtw x8, w1
; CHECK-NEXT: mov w9, #3240 // =0xca8
; CHECK-NEXT: add x8, x8, #1
; CHECK-NEXT: madd x9, x8, x9, x0
; CHECK-NEXT: ldr w9, [x9, #20]
; CHECK-NEXT: tbnz w9, #31, .LBB22_2
; CHECK-NEXT: smaddl x8, w1, w8, x0
; CHECK-NEXT: ldr w8, [x8, #3260]
; CHECK-NEXT: tbnz w8, #31, .LBB22_2
; CHECK-NEXT: // %bb.1:
; CHECK-NEXT: mov w0, wzr
; CHECK-NEXT: ret
; CHECK-NEXT: .LBB22_2: // %then
; CHECK-NEXT: sxtw x8, w1
; CHECK-NEXT: add x8, x8, #1
; CHECK-NEXT: str x8, [x0]
; CHECK-NEXT: mov w0, #1 // =0x1
; CHECK-NEXT: ret
Expand All @@ -351,11 +349,10 @@ define signext i32 @addmuladd_multiuse2_nsw(i32 signext %a) {
; CHECK-LABEL: addmuladd_multiuse2_nsw:
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #324 // =0x144
; CHECK-NEXT: add w9, w0, #4
; CHECK-NEXT: mov w11, #4 // =0x4
; CHECK-NEXT: lsl w10, w9, #2
; CHECK-NEXT: madd w8, w9, w8, w11
; CHECK-NEXT: add w9, w10, #4
; CHECK-NEXT: lsl w9, w0, #2
; CHECK-NEXT: mov w10, #1300 // =0x514
; CHECK-NEXT: madd w8, w0, w8, w10
; CHECK-NEXT: add w9, w9, #20
; CHECK-NEXT: eor w0, w8, w9
; CHECK-NEXT: ret
%tmp0 = add nsw i32 %a, 4
Expand All @@ -371,11 +368,10 @@ define signext i32 @addmuladd_multiuse2_nuw(i32 signext %a) {
; CHECK-LABEL: addmuladd_multiuse2_nuw:
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #324 // =0x144
; CHECK-NEXT: add w9, w0, #4
; CHECK-NEXT: mov w11, #4 // =0x4
; CHECK-NEXT: lsl w10, w9, #2
; CHECK-NEXT: madd w8, w9, w8, w11
; CHECK-NEXT: add w9, w10, #4
; CHECK-NEXT: lsl w9, w0, #2
; CHECK-NEXT: mov w10, #1300 // =0x514
; CHECK-NEXT: madd w8, w0, w8, w10
; CHECK-NEXT: add w9, w9, #20
; CHECK-NEXT: eor w0, w8, w9
; CHECK-NEXT: ret
%tmp0 = add nuw i32 %a, 4
Expand All @@ -391,11 +387,10 @@ define signext i32 @addmuladd_multiuse2_nswnuw(i32 signext %a) {
; CHECK-LABEL: addmuladd_multiuse2_nswnuw:
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #324 // =0x144
; CHECK-NEXT: add w9, w0, #4
; CHECK-NEXT: mov w11, #4 // =0x4
; CHECK-NEXT: lsl w10, w9, #2
; CHECK-NEXT: madd w8, w9, w8, w11
; CHECK-NEXT: add w9, w10, #4
; CHECK-NEXT: lsl w9, w0, #2
; CHECK-NEXT: mov w10, #1300 // =0x514
; CHECK-NEXT: madd w8, w0, w8, w10
; CHECK-NEXT: add w9, w9, #20
; CHECK-NEXT: eor w0, w8, w9
; CHECK-NEXT: ret
%tmp0 = add nsw nuw i32 %a, 4
Expand Down

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