1 //===-- ARMSubtarget.cpp - ARM 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 ARM specific subclass of TargetSubtarget.
12 //===----------------------------------------------------------------------===//
14 #include "ARMSubtarget.h"
15 #include "ARMGenSubtarget.inc"
16 #include "llvm/GlobalValue.h"
17 #include "llvm/Target/TargetOptions.h"
18 #include "llvm/Support/CommandLine.h"
19 #include "llvm/ADT/SmallVector.h"
23 ReserveR9("arm-reserve-r9", cl::Hidden,
24 cl::desc("Reserve R9, making it unavailable as GPR"));
26 UseNEONFP("arm-use-neon-fp",
27 cl::desc("Use NEON for single-precision FP"),
28 cl::init(false), cl::Hidden);
31 UseMOVT("arm-use-movt",
32 cl::init(true), cl::Hidden);
34 ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
38 , UseNEONForSinglePrecisionFP(UseNEONFP)
41 , PostRAScheduler(false)
42 , IsR9Reserved(ReserveR9)
45 , CPUString("generic")
46 , TargetType(isELF) // Default to ELF unless otherwise specified.
47 , TargetABI(ARM_ABI_APCS) {
48 // default to soft float ABI
49 if (FloatABIType == FloatABI::Default)
50 FloatABIType = FloatABI::Soft;
52 // Determine default and user specified characteristics
54 // Parse features string.
55 CPUString = ParseSubtargetFeatures(FS, CPUString);
57 // Set the boolean corresponding to the current target triple, or the default
58 // if one cannot be determined, to true.
59 unsigned Len = TT.length();
62 if (Len >= 5 && TT.substr(0, 4) == "armv")
64 else if (Len >= 6 && TT.substr(0, 5) == "thumb") {
66 if (Len >= 7 && TT[5] == 'v')
70 unsigned SubVer = TT[Idx];
71 if (SubVer > '4' && SubVer <= '9') {
74 } else if (SubVer == '6') {
76 if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2')
77 ARMArchVersion = V6T2;
78 } else if (SubVer == '5') {
80 if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == 'e')
81 ARMArchVersion = V5TE;
83 if (ARMArchVersion >= V6T2)
88 // Thumb2 implies at least V6T2.
89 if (ARMArchVersion < V6T2 && ThumbMode >= Thumb2)
90 ARMArchVersion = V6T2;
93 if (TT.find("-darwin") != std::string::npos)
95 TargetType = isDarwin;
98 if (TT.find("eabi") != std::string::npos)
99 TargetABI = ARM_ABI_AAPCS;
104 if (isTargetDarwin())
105 IsR9Reserved = ReserveR9 | (ARMArchVersion < V6);
107 if (!isThumb() || hasThumb2())
108 PostRAScheduler = true;
110 // Set CPU specific features.
111 if (CPUString == "cortex-a8") {
112 // On Cortex-a8, it's faster to perform some single-precision FP
113 // operations with NEON instructions.
114 if (UseNEONFP.getPosition() == 0)
115 UseNEONForSinglePrecisionFP = true;
119 /// GVIsIndirectSymbol - true if the GV will be accessed via an indirect symbol.
121 ARMSubtarget::GVIsIndirectSymbol(GlobalValue *GV, Reloc::Model RelocM) const {
122 if (RelocM == Reloc::Static)
125 // GV with ghost linkage (in JIT lazy compilation mode) do not require an
126 // extra load from stub.
127 bool isDecl = GV->isDeclaration() && !GV->hasNotBeenReadFromBitcode();
129 if (!isTargetDarwin()) {
130 // Extra load is needed for all externally visible.
131 if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
135 if (RelocM == Reloc::PIC_) {
136 // If this is a strong reference to a definition, it is definitely not
138 if (!isDecl && !GV->isWeakForLinker())
141 // Unless we have a symbol with hidden visibility, we have to go through a
142 // normal $non_lazy_ptr stub because this symbol might be resolved late.
143 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
146 // If symbol visibility is hidden, we have a stub for common symbol
147 // references and external declarations.
148 if (isDecl || GV->hasCommonLinkage())
149 // Hidden $non_lazy_ptr reference.
154 // If this is a strong reference to a definition, it is definitely not
156 if (!isDecl && !GV->isWeakForLinker())
159 // Unless we have a symbol with hidden visibility, we have to go through a
160 // normal $non_lazy_ptr stub because this symbol might be resolved late.
161 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
169 bool ARMSubtarget::enablePostRAScheduler(
170 CodeGenOpt::Level OptLevel,
171 TargetSubtarget::AntiDepBreakMode& Mode,
172 RegClassVector& CriticalPathRCs) const {
173 Mode = TargetSubtarget::ANTIDEP_CRITICAL;
174 CriticalPathRCs.clear();
175 CriticalPathRCs.push_back(&ARM::GPRRegClass);
176 return PostRAScheduler && OptLevel >= CodeGenOpt::Default;