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699846f1a5
Changes TTI function getIntImmCostInst to take an additional Instruction parameter, which enables us to be able to check it is part of a min(max())/max(min()) pattern that will match SSAT. We can then mark the constant used as free to prevent it being hoisted so SSAT can still be generated. Required minor changes in some non-ARM backends to allow for the optional parameter to be included. Differential Revision: https://reviews.llvm.org/D87457
97 lines
3.2 KiB
C++
97 lines
3.2 KiB
C++
//===-- RISCVTargetTransformInfo.cpp - RISC-V specific TTI ----------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "RISCVTargetTransformInfo.h"
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#include "Utils/RISCVMatInt.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/CodeGen/BasicTTIImpl.h"
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#include "llvm/CodeGen/TargetLowering.h"
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using namespace llvm;
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#define DEBUG_TYPE "riscvtti"
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int RISCVTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty,
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TTI::TargetCostKind CostKind) {
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assert(Ty->isIntegerTy() &&
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"getIntImmCost can only estimate cost of materialising integers");
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// We have a Zero register, so 0 is always free.
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if (Imm == 0)
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return TTI::TCC_Free;
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// Otherwise, we check how many instructions it will take to materialise.
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const DataLayout &DL = getDataLayout();
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return RISCVMatInt::getIntMatCost(Imm, DL.getTypeSizeInBits(Ty),
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getST()->is64Bit());
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}
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int RISCVTTIImpl::getIntImmCostInst(unsigned Opcode, unsigned Idx,
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const APInt &Imm, Type *Ty,
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TTI::TargetCostKind CostKind,
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Instruction *Inst) {
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assert(Ty->isIntegerTy() &&
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"getIntImmCost can only estimate cost of materialising integers");
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// We have a Zero register, so 0 is always free.
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if (Imm == 0)
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return TTI::TCC_Free;
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// Some instructions in RISC-V can take a 12-bit immediate. Some of these are
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// commutative, in others the immediate comes from a specific argument index.
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bool Takes12BitImm = false;
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unsigned ImmArgIdx = ~0U;
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switch (Opcode) {
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case Instruction::GetElementPtr:
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// Never hoist any arguments to a GetElementPtr. CodeGenPrepare will
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// split up large offsets in GEP into better parts than ConstantHoisting
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// can.
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return TTI::TCC_Free;
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case Instruction::Add:
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case Instruction::And:
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case Instruction::Or:
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case Instruction::Xor:
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case Instruction::Mul:
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Takes12BitImm = true;
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break;
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case Instruction::Sub:
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case Instruction::Shl:
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case Instruction::LShr:
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case Instruction::AShr:
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Takes12BitImm = true;
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ImmArgIdx = 1;
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break;
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default:
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break;
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}
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if (Takes12BitImm) {
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// Check immediate is the correct argument...
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if (Instruction::isCommutative(Opcode) || Idx == ImmArgIdx) {
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// ... and fits into the 12-bit immediate.
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if (Imm.getMinSignedBits() <= 64 &&
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getTLI()->isLegalAddImmediate(Imm.getSExtValue())) {
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return TTI::TCC_Free;
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}
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}
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// Otherwise, use the full materialisation cost.
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return getIntImmCost(Imm, Ty, CostKind);
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}
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// By default, prevent hoisting.
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return TTI::TCC_Free;
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}
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int RISCVTTIImpl::getIntImmCostIntrin(Intrinsic::ID IID, unsigned Idx,
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const APInt &Imm, Type *Ty,
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TTI::TargetCostKind CostKind) {
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// Prevent hoisting in unknown cases.
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return TTI::TCC_Free;
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}
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