1 //===-- AArch64Subtarget.cpp - AArch64 Subtarget Information ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the AArch64 specific subclass of TargetSubtarget.
12 //===----------------------------------------------------------------------===//
14 #include "AArch64InstrInfo.h"
15 #include "AArch64Subtarget.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/CodeGen/MachineScheduler.h"
18 #include "llvm/IR/GlobalValue.h"
19 #include "llvm/Support/TargetRegistry.h"
23 #define DEBUG_TYPE "aarch64-subtarget"
25 #define GET_SUBTARGETINFO_CTOR
26 #define GET_SUBTARGETINFO_TARGET_DESC
27 #include "AArch64GenSubtargetInfo.inc"
30 EnableEarlyIfConvert("aarch64-early-ifcvt", cl::desc("Enable the early if "
31 "converter pass"), cl::init(true), cl::Hidden);
33 AArch64Subtarget::AArch64Subtarget(const std::string &TT,
34 const std::string &CPU,
35 const std::string &FS, bool LittleEndian)
36 : AArch64GenSubtargetInfo(TT, CPU, FS), ARMProcFamily(Others),
37 HasFPARMv8(false), HasNEON(false), HasCrypto(false), HasCRC(false),
38 HasZeroCycleRegMove(false), HasZeroCycleZeroing(false), CPUString(CPU),
40 // This nested ternary is horrible, but DL needs to be properly
42 // before TLInfo is constructed.
44 ? "e-m:o-i64:64-i128:128-n32:64-S128"
45 : (LittleEndian ? "e-m:e-i64:64-i128:128-n32:64-S128"
46 : "E-m:e-i64:64-i128:128-n32:64-S128")),
47 FrameLowering(), InstrInfo(*this), TSInfo(&DL) {
48 // Determine default and user-specified characteristics
50 if (CPUString.empty())
51 CPUString = "generic";
53 ParseSubtargetFeatures(CPUString, FS);
56 /// ClassifyGlobalReference - Find the target operand flags that describe
57 /// how a global value should be referenced for the current subtarget.
59 AArch64Subtarget::ClassifyGlobalReference(const GlobalValue *GV,
60 const TargetMachine &TM) const {
62 // Determine whether this is a reference to a definition or a declaration.
63 // Materializable GVs (in JIT lazy compilation mode) do not require an extra
65 bool isDecl = GV->hasAvailableExternallyLinkage();
66 if (GV->isDeclaration() && !GV->isMaterializable())
69 // MachO large model always goes via a GOT, simply to get a single 8-byte
70 // absolute relocation on all global addresses.
71 if (TM.getCodeModel() == CodeModel::Large && isTargetMachO())
72 return AArch64II::MO_GOT;
74 // The small code mode's direct accesses use ADRP, which cannot necessarily
75 // produce the value 0 (if the code is above 4GB). Therefore they must use the
77 if (TM.getCodeModel() == CodeModel::Small && GV->isWeakForLinker() && isDecl)
78 return AArch64II::MO_GOT;
80 // If symbol visibility is hidden, the extra load is not needed if
81 // the symbol is definitely defined in the current translation unit.
83 // The handling of non-hidden symbols in PIC mode is rather target-dependent:
84 // + On MachO, if the symbol is defined in this module the GOT can be
86 // + On ELF, the R_AARCH64_COPY relocation means that even symbols actually
87 // defined could end up in unexpected places. Use a GOT.
88 if (TM.getRelocationModel() != Reloc::Static && GV->hasDefaultVisibility()) {
90 return (isDecl || GV->isWeakForLinker()) ? AArch64II::MO_GOT
91 : AArch64II::MO_NO_FLAG;
93 // No need to go through the GOT for local symbols on ELF.
94 return GV->hasLocalLinkage() ? AArch64II::MO_NO_FLAG : AArch64II::MO_GOT;
97 return AArch64II::MO_NO_FLAG;
100 /// This function returns the name of a function which has an interface
101 /// like the non-standard bzero function, if such a function exists on
102 /// the current subtarget and it is considered prefereable over
103 /// memset with zero passed as the second argument. Otherwise it
105 const char *AArch64Subtarget::getBZeroEntry() const {
106 // Prefer bzero on Darwin only.
113 void AArch64Subtarget::overrideSchedPolicy(MachineSchedPolicy &Policy,
114 MachineInstr *begin, MachineInstr *end,
115 unsigned NumRegionInstrs) const {
116 // LNT run (at least on Cyclone) showed reasonably significant gains for
117 // bi-directional scheduling. 253.perlbmk.
118 Policy.OnlyTopDown = false;
119 Policy.OnlyBottomUp = false;
122 bool AArch64Subtarget::enableEarlyIfConversion() const {
123 return EnableEarlyIfConvert;