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[RISCV][GISel] Port AddiPair optimization (llvm#120463)
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Check if (add r, imm) can be optimized to (ADDI (ADDI r, imm0), imm1),
in which imm = imm0 + imml and both imm0 and imm1 are simm12. We make
imm0 as large as possible and imm1 as small as possible so that we might
be able to use c.addi for the small immediate.
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@lquinn2015
lquinn2015 authored Dec 20, 2024
1 parent c7451ff commit 6ab8401
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24 changes: 24 additions & 0 deletions llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -137,6 +137,11 @@ class RISCVInstructionSelector : public InstructionSelector {
void renderXLenSubTrailingOnes(MachineInstrBuilder &MIB,
const MachineInstr &MI, int OpIdx) const;

void renderAddiPairImmLarge(MachineInstrBuilder &MIB, const MachineInstr &MI,
int OpIdx) const;
void renderAddiPairImmSmall(MachineInstrBuilder &MIB, const MachineInstr &MI,
int OpIdx) const;

const RISCVSubtarget &STI;
const RISCVInstrInfo &TII;
const RISCVRegisterInfo &TRI;
Expand Down Expand Up @@ -871,6 +876,25 @@ void RISCVInstructionSelector::renderXLenSubTrailingOnes(
MIB.addImm(Subtarget->getXLen() - llvm::countr_one(C));
}

void RISCVInstructionSelector::renderAddiPairImmSmall(MachineInstrBuilder &MIB,
const MachineInstr &MI,
int OpIdx) const {
assert(MI.getOpcode() == TargetOpcode::G_CONSTANT && OpIdx == -1 &&
"Expected G_CONSTANT");
int64_t Imm = MI.getOperand(1).getCImm()->getSExtValue();
int64_t Adj = Imm < 0 ? -2048 : 2047;
MIB.addImm(Imm - Adj);
}

void RISCVInstructionSelector::renderAddiPairImmLarge(MachineInstrBuilder &MIB,
const MachineInstr &MI,
int OpIdx) const {
assert(MI.getOpcode() == TargetOpcode::G_CONSTANT && OpIdx == -1 &&
"Expected G_CONSTANT");
int64_t Imm = MI.getOperand(1).getCImm()->getSExtValue() < 0 ? -2048 : 2047;
MIB.addImm(Imm);
}

const TargetRegisterClass *RISCVInstructionSelector::getRegClassForTypeOnBank(
LLT Ty, const RegisterBank &RB) const {
if (RB.getID() == RISCV::GPRBRegBankID) {
Expand Down
14 changes: 12 additions & 2 deletions llvm/lib/Target/RISCV/RISCVInstrInfo.td
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Original file line number Diff line number Diff line change
Expand Up @@ -454,7 +454,14 @@ def AddiPair : PatLeaf<(imm), [{
// The immediate operand must be in range [-4096,-2049] or [2048,4094].
int64_t Imm = N->getSExtValue();
return (-4096 <= Imm && Imm <= -2049) || (2048 <= Imm && Imm <= 4094);
}]>;
}]> {
let GISelPredicateCode = [{
if (!MRI.hasOneNonDBGUse(MI.getOperand(0).getReg()))
return false;
int64_t Imm = MI.getOperand(1).getCImm()->getSExtValue();
return (-4096 <= Imm && Imm <= -2049) || (2048 <= Imm && Imm <= 4094);
}];
}

// Return imm - (imm < 0 ? -2048 : 2047).
def AddiPairImmSmall : SDNodeXForm<imm, [{
Expand All @@ -463,13 +470,17 @@ def AddiPairImmSmall : SDNodeXForm<imm, [{
return CurDAG->getSignedTargetConstant(Imm - Adj, SDLoc(N),
N->getValueType(0));
}]>;
def GIAddiPairImmSmall : GICustomOperandRenderer<"renderAddiPairImmSmall">,
GISDNodeXFormEquiv<AddiPairImmSmall>;

// Return -2048 if immediate is negative or 2047 if positive. These are the
// largest simm12 values.
def AddiPairImmLarge : SDNodeXForm<imm, [{
int64_t Imm = N->getSExtValue() < 0 ? -2048 : 2047;
return CurDAG->getSignedTargetConstant(Imm, SDLoc(N), N->getValueType(0));
}]>;
def GIAddiPairImmLarge : GICustomOperandRenderer<"renderAddiPairImmLarge">,
GISDNodeXFormEquiv<AddiPairImmLarge>;

def TrailingZeros : SDNodeXForm<imm, [{
return CurDAG->getTargetConstant(llvm::countr_zero(N->getZExtValue()),
Expand Down Expand Up @@ -537,7 +548,6 @@ def LeadingOnesWMask : PatLeaf<(imm), [{
return !isInt<32>(Imm) && isUInt<32>(Imm) && isShiftedMask_64(Imm) &&
Imm != UINT64_C(0xffffffff);
}];

}

//===----------------------------------------------------------------------===//
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247 changes: 247 additions & 0 deletions llvm/test/CodeGen/RISCV/GlobalISel/add-imm.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,247 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=riscv32 -global-isel < %s \
; RUN: | FileCheck %s -check-prefix=RV32I
; RUN: llc -mtriple=riscv64 -global-isel < %s \
; RUN: | FileCheck %s -check-prefix=RV64I

; These test how the immediate in an addition is materialized.

define i32 @add_positive_low_bound_reject(i32 %a) nounwind {
; RV32I-LABEL: add_positive_low_bound_reject:
; RV32I: # %bb.0:
; RV32I-NEXT: addi a0, a0, 2047
; RV32I-NEXT: ret
;
; RV64I-LABEL: add_positive_low_bound_reject:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, 2047
; RV64I-NEXT: ret
%1 = add i32 %a, 2047
ret i32 %1
}

define i32 @add_positive_low_bound_accept(i32 %a) nounwind {
; RV32I-LABEL: add_positive_low_bound_accept:
; RV32I: # %bb.0:
; RV32I-NEXT: addi a0, a0, 2047
; RV32I-NEXT: addi a0, a0, 1
; RV32I-NEXT: ret
;
; RV64I-LABEL: add_positive_low_bound_accept:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, 2047
; RV64I-NEXT: addi a0, a0, 1
; RV64I-NEXT: ret
%1 = add i32 %a, 2048
ret i32 %1
}

define i32 @add_positive_high_bound_accept(i32 %a) nounwind {
; RV32I-LABEL: add_positive_high_bound_accept:
; RV32I: # %bb.0:
; RV32I-NEXT: addi a0, a0, 2047
; RV32I-NEXT: addi a0, a0, 2047
; RV32I-NEXT: ret
;
; RV64I-LABEL: add_positive_high_bound_accept:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, 2047
; RV64I-NEXT: addi a0, a0, 2047
; RV64I-NEXT: ret
%1 = add i32 %a, 4094
ret i32 %1
}

define i32 @add_positive_high_bound_reject(i32 %a) nounwind {
; RV32I-LABEL: add_positive_high_bound_reject:
; RV32I: # %bb.0:
; RV32I-NEXT: lui a1, 1
; RV32I-NEXT: addi a1, a1, -1
; RV32I-NEXT: add a0, a0, a1
; RV32I-NEXT: ret
;
; RV64I-LABEL: add_positive_high_bound_reject:
; RV64I: # %bb.0:
; RV64I-NEXT: lui a1, 1
; RV64I-NEXT: addiw a1, a1, -1
; RV64I-NEXT: add a0, a0, a1
; RV64I-NEXT: ret
%1 = add i32 %a, 4095
ret i32 %1
}

define i32 @add_negative_high_bound_reject(i32 %a) nounwind {
; RV32I-LABEL: add_negative_high_bound_reject:
; RV32I: # %bb.0:
; RV32I-NEXT: addi a0, a0, -2048
; RV32I-NEXT: ret
;
; RV64I-LABEL: add_negative_high_bound_reject:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, -2048
; RV64I-NEXT: ret
%1 = add i32 %a, -2048
ret i32 %1
}

define i32 @add_negative_high_bound_accept(i32 %a) nounwind {
; RV32I-LABEL: add_negative_high_bound_accept:
; RV32I: # %bb.0:
; RV32I-NEXT: addi a0, a0, -2048
; RV32I-NEXT: addi a0, a0, -1
; RV32I-NEXT: ret
;
; RV64I-LABEL: add_negative_high_bound_accept:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, -2048
; RV64I-NEXT: addi a0, a0, -1
; RV64I-NEXT: ret
%1 = add i32 %a, -2049
ret i32 %1
}

define i32 @add_negative_low_bound_accept(i32 %a) nounwind {
; RV32I-LABEL: add_negative_low_bound_accept:
; RV32I: # %bb.0:
; RV32I-NEXT: addi a0, a0, -2048
; RV32I-NEXT: addi a0, a0, -2048
; RV32I-NEXT: ret
;
; RV64I-LABEL: add_negative_low_bound_accept:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, -2048
; RV64I-NEXT: addi a0, a0, -2048
; RV64I-NEXT: ret
%1 = add i32 %a, -4096
ret i32 %1
}

define i32 @add_negative_low_bound_reject(i32 %a) nounwind {
; RV32I-LABEL: add_negative_low_bound_reject:
; RV32I: # %bb.0:
; RV32I-NEXT: lui a1, 1048575
; RV32I-NEXT: addi a1, a1, -1
; RV32I-NEXT: add a0, a0, a1
; RV32I-NEXT: ret
;
; RV64I-LABEL: add_negative_low_bound_reject:
; RV64I: # %bb.0:
; RV64I-NEXT: lui a1, 1048575
; RV64I-NEXT: addiw a1, a1, -1
; RV64I-NEXT: add a0, a0, a1
; RV64I-NEXT: ret
%1 = add i32 %a, -4097
ret i32 %1
}

define i32 @add32_accept(i32 %a) nounwind {
; RV32I-LABEL: add32_accept:
; RV32I: # %bb.0:
; RV32I-NEXT: addi a0, a0, 2047
; RV32I-NEXT: addi a0, a0, 952
; RV32I-NEXT: ret
;
; RV64I-LABEL: add32_accept:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, 2047
; RV64I-NEXT: addi a0, a0, 952
; RV64I-NEXT: ret
%1 = add i32 %a, 2999
ret i32 %1
}

define signext i32 @add32_sext_accept(i32 signext %a) nounwind {
; RV32I-LABEL: add32_sext_accept:
; RV32I: # %bb.0:
; RV32I-NEXT: addi a0, a0, 2047
; RV32I-NEXT: addi a0, a0, 952
; RV32I-NEXT: ret
;
; RV64I-LABEL: add32_sext_accept:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, 2047
; RV64I-NEXT: addiw a0, a0, 952
; RV64I-NEXT: ret
%1 = add i32 %a, 2999
ret i32 %1
}

@gv0 = global i32 0, align 4
define signext i32 @add32_sext_reject_on_rv64(i32 signext %a) nounwind {
; RV32I-LABEL: add32_sext_reject_on_rv64:
; RV32I: # %bb.0:
; RV32I-NEXT: lui a1, %hi(gv0)
; RV32I-NEXT: addi a0, a0, 2047
; RV32I-NEXT: addi a0, a0, 953
; RV32I-NEXT: sw a0, %lo(gv0)(a1)
; RV32I-NEXT: ret
;
; RV64I-LABEL: add32_sext_reject_on_rv64:
; RV64I: # %bb.0:
; RV64I-NEXT: lui a1, %hi(gv0)
; RV64I-NEXT: addi a0, a0, 2047
; RV64I-NEXT: addiw a0, a0, 953
; RV64I-NEXT: sw a0, %lo(gv0)(a1)
; RV64I-NEXT: ret
%b = add nsw i32 %a, 3000
store i32 %b, ptr @gv0, align 4
ret i32 %b
}

define i64 @add64_accept(i64 %a) nounwind {
; RV32I-LABEL: add64_accept:
; RV32I: # %bb.0:
; RV32I-NEXT: lui a2, 1
; RV32I-NEXT: addi a2, a2, -1097
; RV32I-NEXT: add a0, a0, a2
; RV32I-NEXT: sltu a2, a0, a2
; RV32I-NEXT: add a1, a1, a2
; RV32I-NEXT: ret
;
; RV64I-LABEL: add64_accept:
; RV64I: # %bb.0:
; RV64I-NEXT: addi a0, a0, 2047
; RV64I-NEXT: addi a0, a0, 952
; RV64I-NEXT: ret
%1 = add i64 %a, 2999
ret i64 %1
}

@ga = global i32 0, align 4
@gb = global i32 0, align 4
define void @add32_reject() nounwind {
; RV32I-LABEL: add32_reject:
; RV32I: # %bb.0:
; RV32I-NEXT: lui a0, %hi(ga)
; RV32I-NEXT: lui a1, %hi(gb)
; RV32I-NEXT: lw a2, %lo(ga)(a0)
; RV32I-NEXT: lw a3, %lo(gb)(a1)
; RV32I-NEXT: lui a4, 1
; RV32I-NEXT: addi a4, a4, -1096
; RV32I-NEXT: add a2, a2, a4
; RV32I-NEXT: add a3, a3, a4
; RV32I-NEXT: sw a2, %lo(ga)(a0)
; RV32I-NEXT: sw a3, %lo(gb)(a1)
; RV32I-NEXT: ret
;
; RV64I-LABEL: add32_reject:
; RV64I: # %bb.0:
; RV64I-NEXT: lui a0, %hi(ga)
; RV64I-NEXT: lui a1, %hi(gb)
; RV64I-NEXT: lw a2, %lo(ga)(a0)
; RV64I-NEXT: lw a3, %lo(gb)(a1)
; RV64I-NEXT: lui a4, 1
; RV64I-NEXT: addi a4, a4, -1096
; RV64I-NEXT: add a2, a2, a4
; RV64I-NEXT: add a3, a3, a4
; RV64I-NEXT: sw a2, %lo(ga)(a0)
; RV64I-NEXT: sw a3, %lo(gb)(a1)
; RV64I-NEXT: ret
%1 = load i32, ptr @ga, align 4
%2 = load i32, ptr @gb, align 4
%3 = add i32 %1, 3000
%4 = add i32 %2, 3000
store i32 %3, ptr @ga, align 4
store i32 %4, ptr @gb, align 4
ret void
}

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