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//===-- RISCVTargetTransformInfo.cpp - RISC-V specific TTI ----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "RISCVTargetTransformInfo.h"
#include "MCTargetDesc/RISCVMatInt.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/BasicTTIImpl.h"
#include "llvm/CodeGen/TargetLowering.h"
using namespace llvm;
#define DEBUG_TYPE "riscvtti"
int RISCVTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty,
TTI::TargetCostKind CostKind) {
assert(Ty->isIntegerTy() &&
"getIntImmCost can only estimate cost of materialising integers");
// We have a Zero register, so 0 is always free.
if (Imm == 0)
return TTI::TCC_Free;
// Otherwise, we check how many instructions it will take to materialise.
const DataLayout &DL = getDataLayout();
return RISCVMatInt::getIntMatCost(Imm, DL.getTypeSizeInBits(Ty),
getST()->is64Bit());
}
int RISCVTTIImpl::getIntImmCostInst(unsigned Opcode, unsigned Idx,
const APInt &Imm, Type *Ty,
TTI::TargetCostKind CostKind,
Instruction *Inst) {
assert(Ty->isIntegerTy() &&
"getIntImmCost can only estimate cost of materialising integers");
// We have a Zero register, so 0 is always free.
if (Imm == 0)
return TTI::TCC_Free;
// Some instructions in RISC-V can take a 12-bit immediate. Some of these are
// commutative, in others the immediate comes from a specific argument index.
bool Takes12BitImm = false;
unsigned ImmArgIdx = ~0U;
switch (Opcode) {
case Instruction::GetElementPtr:
// Never hoist any arguments to a GetElementPtr. CodeGenPrepare will
// split up large offsets in GEP into better parts than ConstantHoisting
// can.
return TTI::TCC_Free;
case Instruction::Add:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
case Instruction::Mul:
Takes12BitImm = true;
break;
case Instruction::Sub:
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
Takes12BitImm = true;
ImmArgIdx = 1;
break;
default:
break;
}
if (Takes12BitImm) {
// Check immediate is the correct argument...
if (Instruction::isCommutative(Opcode) || Idx == ImmArgIdx) {
// ... and fits into the 12-bit immediate.
if (Imm.getMinSignedBits() <= 64 &&
getTLI()->isLegalAddImmediate(Imm.getSExtValue())) {
return TTI::TCC_Free;
}
}
// Otherwise, use the full materialisation cost.
return getIntImmCost(Imm, Ty, CostKind);
}
// By default, prevent hoisting.
return TTI::TCC_Free;
}
int RISCVTTIImpl::getIntImmCostIntrin(Intrinsic::ID IID, unsigned Idx,
const APInt &Imm, Type *Ty,
TTI::TargetCostKind CostKind) {
// Prevent hoisting in unknown cases.
return TTI::TCC_Free;
}
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