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[RISCV] Optimize (add (mul x, c0), c1)
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Optimize (add (mul x, c0), c1) -> (ADDI (MUL (ADDI, c1/c0), c0), c1%c0),
if c1/c0 and c1%c0 are simm12, while c1 is not.

Optimize (add (mul x, c0), c1) -> (MUL (ADDI, c1/c0), c0),
if c1%c0 is zero, and c1/c0 is simm12 while c1 is not.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D108607
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@benshi001
benshi001 committed Sep 21, 2021
1 parent 32b994b commit b305201
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Showing 2 changed files with 70 additions and 45 deletions.
45 changes: 45 additions & 0 deletions llvm/lib/Target/RISCV/RISCVISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6216,8 +6216,53 @@ static SDValue combineSelectAndUseCommutative(SDNode *N, SelectionDAG &DAG,
return SDValue();
}

// Transform (add (mul x, c0), c1) ->
// (add (mul (add x, c1/c0), c0), c1%c0).
// if c1/c0 and c1%c0 are simm12, while c1 is not.
// Or transform (add (mul x, c0), c1) ->
// (mul (add x, c1/c0), c0).
// if c1%c0 is zero, and c1/c0 is simm12 while c1 is not.
static SDValue transformAddImmMulImm(SDNode *N, SelectionDAG &DAG,
const RISCVSubtarget &Subtarget) {
// Skip for vector types and larger types.
EVT VT = N->getValueType(0);
if (VT.isVector() || VT.getSizeInBits() > Subtarget.getXLen())
return SDValue();
// The first operand node must be a MUL and has no other use.
SDValue N0 = N->getOperand(0);
if (!N0->hasOneUse() || N0->getOpcode() != ISD::MUL)
return SDValue();
// Check if c0 and c1 match above conditions.
auto *N0C = dyn_cast<ConstantSDNode>(N0->getOperand(1));
auto *N1C = dyn_cast<ConstantSDNode>(N->getOperand(1));
if (!N0C || !N1C)
return SDValue();
int64_t C0 = N0C->getSExtValue();
int64_t C1 = N1C->getSExtValue();
if (C0 == -1 || C0 == 0 || C0 == 1 || (C1 / C0) == 0 || isInt<12>(C1) ||
!isInt<12>(C1 % C0) || !isInt<12>(C1 / C0))
return SDValue();
// Build new nodes (add (mul (add x, c1/c0), c0), c1%c0).
SDLoc DL(N);
SDValue New0 = DAG.getNode(ISD::ADD, DL, VT, N0->getOperand(0),
DAG.getConstant(C1 / C0, DL, VT));
SDValue New1 =
DAG.getNode(ISD::MUL, DL, VT, New0, DAG.getConstant(C0, DL, VT));
if ((C1 % C0) == 0)
return New1;
return DAG.getNode(ISD::ADD, DL, VT, New1, DAG.getConstant(C1 % C0, DL, VT));
}

static SDValue performADDCombine(SDNode *N, SelectionDAG &DAG,
const RISCVSubtarget &Subtarget) {
// Transform (add (mul x, c0), c1) ->
// (add (mul (add x, c1/c0), c0), c1%c0).
// if c1/c0 and c1%c0 are simm12, while c1 is not.
// Or transform (add (mul x, c0), c1) ->
// (mul (add x, c1/c0), c0).
// if c1%c0 is zero, and c1/c0 is simm12 while c1 is not.
if (SDValue V = transformAddImmMulImm(N, DAG, Subtarget))
return V;
// Fold (add (shl x, c0), (shl y, c1)) ->
// (SLLI (SH*ADD x, y), c0), if c1-c0 equals to [1|2|3].
if (SDValue V = transformAddShlImm(N, DAG, Subtarget))
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70 changes: 25 additions & 45 deletions llvm/test/CodeGen/RISCV/addimm-mulimm.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -342,20 +342,16 @@ define i64 @add_mul_combine_reject_d3(i64 %x) {
define i32 @add_mul_combine_reject_e1(i32 %x) {
; RV32IMB-LABEL: add_mul_combine_reject_e1:
; RV32IMB: # %bb.0:
; RV32IMB-NEXT: addi a0, a0, 1971
; RV32IMB-NEXT: addi a1, zero, 29
; RV32IMB-NEXT: mul a0, a0, a1
; RV32IMB-NEXT: lui a1, 14
; RV32IMB-NEXT: addi a1, a1, -185
; RV32IMB-NEXT: add a0, a0, a1
; RV32IMB-NEXT: ret
;
; RV64IMB-LABEL: add_mul_combine_reject_e1:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addiw a0, a0, 1971
; RV64IMB-NEXT: addi a1, zero, 29
; RV64IMB-NEXT: mulw a0, a0, a1
; RV64IMB-NEXT: lui a1, 14
; RV64IMB-NEXT: addiw a1, a1, -185
; RV64IMB-NEXT: addw a0, a0, a1
; RV64IMB-NEXT: ret
%tmp0 = mul i32 %x, 29
%tmp1 = add i32 %tmp0, 57159
Expand All @@ -365,20 +361,16 @@ define i32 @add_mul_combine_reject_e1(i32 %x) {
define signext i32 @add_mul_combine_reject_e2(i32 signext %x) {
; RV32IMB-LABEL: add_mul_combine_reject_e2:
; RV32IMB: # %bb.0:
; RV32IMB-NEXT: addi a0, a0, 1971
; RV32IMB-NEXT: addi a1, zero, 29
; RV32IMB-NEXT: mul a0, a0, a1
; RV32IMB-NEXT: lui a1, 14
; RV32IMB-NEXT: addi a1, a1, -185
; RV32IMB-NEXT: add a0, a0, a1
; RV32IMB-NEXT: ret
;
; RV64IMB-LABEL: add_mul_combine_reject_e2:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addiw a0, a0, 1971
; RV64IMB-NEXT: addi a1, zero, 29
; RV64IMB-NEXT: mulw a0, a0, a1
; RV64IMB-NEXT: lui a1, 14
; RV64IMB-NEXT: addiw a1, a1, -185
; RV64IMB-NEXT: addw a0, a0, a1
; RV64IMB-NEXT: ret
%tmp0 = mul i32 %x, 29
%tmp1 = add i32 %tmp0, 57159
Expand All @@ -402,11 +394,9 @@ define i64 @add_mul_combine_reject_e3(i64 %x) {
;
; RV64IMB-LABEL: add_mul_combine_reject_e3:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addi a0, a0, 1971
; RV64IMB-NEXT: addi a1, zero, 29
; RV64IMB-NEXT: mul a0, a0, a1
; RV64IMB-NEXT: lui a1, 14
; RV64IMB-NEXT: addiw a1, a1, -185
; RV64IMB-NEXT: add a0, a0, a1
; RV64IMB-NEXT: ret
%tmp0 = mul i64 %x, 29
%tmp1 = add i64 %tmp0, 57159
Expand All @@ -416,20 +406,18 @@ define i64 @add_mul_combine_reject_e3(i64 %x) {
define i32 @add_mul_combine_reject_f1(i32 %x) {
; RV32IMB-LABEL: add_mul_combine_reject_f1:
; RV32IMB: # %bb.0:
; RV32IMB-NEXT: addi a0, a0, 1972
; RV32IMB-NEXT: addi a1, zero, 29
; RV32IMB-NEXT: mul a0, a0, a1
; RV32IMB-NEXT: lui a1, 14
; RV32IMB-NEXT: addi a1, a1, -145
; RV32IMB-NEXT: add a0, a0, a1
; RV32IMB-NEXT: addi a0, a0, 11
; RV32IMB-NEXT: ret
;
; RV64IMB-LABEL: add_mul_combine_reject_f1:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addiw a0, a0, 1972
; RV64IMB-NEXT: addi a1, zero, 29
; RV64IMB-NEXT: mulw a0, a0, a1
; RV64IMB-NEXT: lui a1, 14
; RV64IMB-NEXT: addiw a1, a1, -145
; RV64IMB-NEXT: addw a0, a0, a1
; RV64IMB-NEXT: addiw a0, a0, 11
; RV64IMB-NEXT: ret
%tmp0 = mul i32 %x, 29
%tmp1 = add i32 %tmp0, 57199
Expand All @@ -439,20 +427,18 @@ define i32 @add_mul_combine_reject_f1(i32 %x) {
define signext i32 @add_mul_combine_reject_f2(i32 signext %x) {
; RV32IMB-LABEL: add_mul_combine_reject_f2:
; RV32IMB: # %bb.0:
; RV32IMB-NEXT: addi a0, a0, 1972
; RV32IMB-NEXT: addi a1, zero, 29
; RV32IMB-NEXT: mul a0, a0, a1
; RV32IMB-NEXT: lui a1, 14
; RV32IMB-NEXT: addi a1, a1, -145
; RV32IMB-NEXT: add a0, a0, a1
; RV32IMB-NEXT: addi a0, a0, 11
; RV32IMB-NEXT: ret
;
; RV64IMB-LABEL: add_mul_combine_reject_f2:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addiw a0, a0, 1972
; RV64IMB-NEXT: addi a1, zero, 29
; RV64IMB-NEXT: mulw a0, a0, a1
; RV64IMB-NEXT: lui a1, 14
; RV64IMB-NEXT: addiw a1, a1, -145
; RV64IMB-NEXT: addw a0, a0, a1
; RV64IMB-NEXT: addiw a0, a0, 11
; RV64IMB-NEXT: ret
%tmp0 = mul i32 %x, 29
%tmp1 = add i32 %tmp0, 57199
Expand All @@ -476,11 +462,10 @@ define i64 @add_mul_combine_reject_f3(i64 %x) {
;
; RV64IMB-LABEL: add_mul_combine_reject_f3:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addi a0, a0, 1972
; RV64IMB-NEXT: addi a1, zero, 29
; RV64IMB-NEXT: mul a0, a0, a1
; RV64IMB-NEXT: lui a1, 14
; RV64IMB-NEXT: addiw a1, a1, -145
; RV64IMB-NEXT: add a0, a0, a1
; RV64IMB-NEXT: addi a0, a0, 11
; RV64IMB-NEXT: ret
%tmp0 = mul i64 %x, 29
%tmp1 = add i64 %tmp0, 57199
Expand All @@ -490,20 +475,18 @@ define i64 @add_mul_combine_reject_f3(i64 %x) {
define i32 @add_mul_combine_reject_g1(i32 %x) {
; RV32IMB-LABEL: add_mul_combine_reject_g1:
; RV32IMB: # %bb.0:
; RV32IMB-NEXT: addi a0, a0, 100
; RV32IMB-NEXT: sh3add a1, a0, a0
; RV32IMB-NEXT: sh3add a0, a1, a0
; RV32IMB-NEXT: lui a1, 2
; RV32IMB-NEXT: addi a1, a1, -882
; RV32IMB-NEXT: add a0, a0, a1
; RV32IMB-NEXT: addi a0, a0, 10
; RV32IMB-NEXT: ret
;
; RV64IMB-LABEL: add_mul_combine_reject_g1:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addi a0, a0, 100
; RV64IMB-NEXT: sh3add a1, a0, a0
; RV64IMB-NEXT: sh3add a0, a1, a0
; RV64IMB-NEXT: lui a1, 2
; RV64IMB-NEXT: addiw a1, a1, -882
; RV64IMB-NEXT: addw a0, a0, a1
; RV64IMB-NEXT: addiw a0, a0, 10
; RV64IMB-NEXT: ret
%tmp0 = mul i32 %x, 73
%tmp1 = add i32 %tmp0, 7310
Expand All @@ -513,20 +496,18 @@ define i32 @add_mul_combine_reject_g1(i32 %x) {
define signext i32 @add_mul_combine_reject_g2(i32 signext %x) {
; RV32IMB-LABEL: add_mul_combine_reject_g2:
; RV32IMB: # %bb.0:
; RV32IMB-NEXT: addi a0, a0, 100
; RV32IMB-NEXT: sh3add a1, a0, a0
; RV32IMB-NEXT: sh3add a0, a1, a0
; RV32IMB-NEXT: lui a1, 2
; RV32IMB-NEXT: addi a1, a1, -882
; RV32IMB-NEXT: add a0, a0, a1
; RV32IMB-NEXT: addi a0, a0, 10
; RV32IMB-NEXT: ret
;
; RV64IMB-LABEL: add_mul_combine_reject_g2:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addi a0, a0, 100
; RV64IMB-NEXT: sh3add a1, a0, a0
; RV64IMB-NEXT: sh3add a0, a1, a0
; RV64IMB-NEXT: lui a1, 2
; RV64IMB-NEXT: addiw a1, a1, -882
; RV64IMB-NEXT: addw a0, a0, a1
; RV64IMB-NEXT: addiw a0, a0, 10
; RV64IMB-NEXT: ret
%tmp0 = mul i32 %x, 73
%tmp1 = add i32 %tmp0, 7310
Expand All @@ -550,11 +531,10 @@ define i64 @add_mul_combine_reject_g3(i64 %x) {
;
; RV64IMB-LABEL: add_mul_combine_reject_g3:
; RV64IMB: # %bb.0:
; RV64IMB-NEXT: addi a0, a0, 100
; RV64IMB-NEXT: sh3add a1, a0, a0
; RV64IMB-NEXT: sh3add a0, a1, a0
; RV64IMB-NEXT: lui a1, 2
; RV64IMB-NEXT: addiw a1, a1, -882
; RV64IMB-NEXT: add a0, a0, a1
; RV64IMB-NEXT: addi a0, a0, 10
; RV64IMB-NEXT: ret
%tmp0 = mul i64 %x, 73
%tmp1 = add i64 %tmp0, 7310
Expand Down

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