AArch64Subtarget.cpp revision 37ed9c199ca639565f6ce88105f9e39e898d82d0
1//===-- AArch64Subtarget.cpp - AArch64 Subtarget Information ----*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the AArch64 specific subclass of TargetSubtarget. 11// 12//===----------------------------------------------------------------------===// 13 14#include "AArch64InstrInfo.h" 15#include "AArch64PBQPRegAlloc.h" 16#include "AArch64Subtarget.h" 17#include "llvm/ADT/SmallVector.h" 18#include "llvm/CodeGen/MachineScheduler.h" 19#include "llvm/IR/GlobalValue.h" 20#include "llvm/Support/TargetRegistry.h" 21 22using namespace llvm; 23 24#define DEBUG_TYPE "aarch64-subtarget" 25 26#define GET_SUBTARGETINFO_CTOR 27#define GET_SUBTARGETINFO_TARGET_DESC 28#include "AArch64GenSubtargetInfo.inc" 29 30static cl::opt<bool> 31EnableEarlyIfConvert("aarch64-early-ifcvt", cl::desc("Enable the early if " 32 "converter pass"), cl::init(true), cl::Hidden); 33 34AArch64Subtarget & 35AArch64Subtarget::initializeSubtargetDependencies(StringRef FS) { 36 // Determine default and user-specified characteristics 37 38 if (CPUString.empty()) 39 CPUString = "generic"; 40 41 ParseSubtargetFeatures(CPUString, FS); 42 return *this; 43} 44 45AArch64Subtarget::AArch64Subtarget(const std::string &TT, 46 const std::string &CPU, 47 const std::string &FS, 48 const TargetMachine &TM, bool LittleEndian) 49 : AArch64GenSubtargetInfo(TT, CPU, FS), ARMProcFamily(Others), 50 HasFPARMv8(false), HasNEON(false), HasCrypto(false), HasCRC(false), 51 HasZeroCycleRegMove(false), HasZeroCycleZeroing(false), CPUString(CPU), 52 TargetTriple(TT), 53 // This nested ternary is horrible, but DL needs to be properly 54 // initialized 55 // before TLInfo is constructed. 56 DL(isTargetMachO() 57 ? "e-m:o-i64:64-i128:128-n32:64-S128" 58 : (LittleEndian ? "e-m:e-i64:64-i128:128-n32:64-S128" 59 : "E-m:e-i64:64-i128:128-n32:64-S128")), 60 FrameLowering(), InstrInfo(initializeSubtargetDependencies(FS)), 61 TSInfo(&DL), TLInfo(TM) {} 62 63/// ClassifyGlobalReference - Find the target operand flags that describe 64/// how a global value should be referenced for the current subtarget. 65unsigned char 66AArch64Subtarget::ClassifyGlobalReference(const GlobalValue *GV, 67 const TargetMachine &TM) const { 68 bool isDecl = GV->isDeclarationForLinker(); 69 70 // MachO large model always goes via a GOT, simply to get a single 8-byte 71 // absolute relocation on all global addresses. 72 if (TM.getCodeModel() == CodeModel::Large && isTargetMachO()) 73 return AArch64II::MO_GOT; 74 75 // The small code mode's direct accesses use ADRP, which cannot necessarily 76 // produce the value 0 (if the code is above 4GB). 77 if (TM.getCodeModel() == CodeModel::Small && 78 GV->isWeakForLinker() && isDecl) { 79 // In PIC mode use the GOT, but in absolute mode use a constant pool load. 80 if (TM.getRelocationModel() == Reloc::Static) 81 return AArch64II::MO_CONSTPOOL; 82 else 83 return AArch64II::MO_GOT; 84 } 85 86 // If symbol visibility is hidden, the extra load is not needed if 87 // the symbol is definitely defined in the current translation unit. 88 89 // The handling of non-hidden symbols in PIC mode is rather target-dependent: 90 // + On MachO, if the symbol is defined in this module the GOT can be 91 // skipped. 92 // + On ELF, the R_AARCH64_COPY relocation means that even symbols actually 93 // defined could end up in unexpected places. Use a GOT. 94 if (TM.getRelocationModel() != Reloc::Static && GV->hasDefaultVisibility()) { 95 if (isTargetMachO()) 96 return (isDecl || GV->isWeakForLinker()) ? AArch64II::MO_GOT 97 : AArch64II::MO_NO_FLAG; 98 else 99 // No need to go through the GOT for local symbols on ELF. 100 return GV->hasLocalLinkage() ? AArch64II::MO_NO_FLAG : AArch64II::MO_GOT; 101 } 102 103 return AArch64II::MO_NO_FLAG; 104} 105 106/// This function returns the name of a function which has an interface 107/// like the non-standard bzero function, if such a function exists on 108/// the current subtarget and it is considered prefereable over 109/// memset with zero passed as the second argument. Otherwise it 110/// returns null. 111const char *AArch64Subtarget::getBZeroEntry() const { 112 // Prefer bzero on Darwin only. 113 if(isTargetDarwin()) 114 return "bzero"; 115 116 return nullptr; 117} 118 119void AArch64Subtarget::overrideSchedPolicy(MachineSchedPolicy &Policy, 120 MachineInstr *begin, MachineInstr *end, 121 unsigned NumRegionInstrs) const { 122 // LNT run (at least on Cyclone) showed reasonably significant gains for 123 // bi-directional scheduling. 253.perlbmk. 124 Policy.OnlyTopDown = false; 125 Policy.OnlyBottomUp = false; 126} 127 128bool AArch64Subtarget::enableEarlyIfConversion() const { 129 return EnableEarlyIfConvert; 130} 131 132std::unique_ptr<PBQPRAConstraint> 133AArch64Subtarget::getCustomPBQPConstraints() const { 134 if (!isCortexA57()) 135 return nullptr; 136 137 return llvm::make_unique<A57ChainingConstraint>(); 138} 139