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 "ARMBaseRegisterInfo.h"
17 #include "llvm/GlobalValue.h"
18 #include "llvm/Target/TargetOptions.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/ADT/SmallVector.h"
24 ReserveR9("arm-reserve-r9", cl::Hidden,
25 cl::desc("Reserve R9, making it unavailable as GPR"));
28 DarwinUseMOVT("arm-darwin-use-movt", cl::init(true), cl::Hidden);
31 StrictAlign("arm-strict-align", cl::Hidden,
32 cl::desc("Disallow all unaligned memory accesses"));
34 ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
37 , ARMProcFamily(Others)
39 , UseNEONForSinglePrecisionFP(false)
41 , HasVMLxForwarding(false)
46 , PostRAScheduler(false)
47 , IsR9Reserved(ReserveR9)
51 , HasHardwareDivide(false)
52 , HasT2ExtractPack(false)
53 , HasDataBarrier(false)
54 , Pref32BitThumb(false)
55 , AvoidCPSRPartialUpdate(false)
56 , HasMPExtension(false)
58 , AllowsUnalignedMem(false)
60 , CPUString("generic")
62 , TargetABI(ARM_ABI_APCS) {
63 // Default to soft float ABI
64 if (FloatABIType == FloatABI::Default)
65 FloatABIType = FloatABI::Soft;
67 // Determine default and user specified characteristics
69 // When no arch is specified either by CPU or by attributes, make the default
71 const char *ARMArchFeature = "";
72 if (CPUString == "generic" && (FS.empty() || FS == "generic")) {
74 ARMArchFeature = ",+v4t";
77 // Set the boolean corresponding to the current target triple, or the default
78 // if one cannot be determined, to true.
79 unsigned Len = TT.length();
82 if (Len >= 5 && TT.substr(0, 4) == "armv")
84 else if (Len >= 6 && TT.substr(0, 5) == "thumb") {
86 if (Len >= 7 && TT[5] == 'v')
90 unsigned SubVer = TT[Idx];
91 if (SubVer >= '7' && SubVer <= '9') {
93 ARMArchFeature = ",+v7a";
94 if (Len >= Idx+2 && TT[Idx+1] == 'm') {
96 ARMArchFeature = ",+v7m";
98 } else if (SubVer == '6') {
100 ARMArchFeature = ",+v6";
101 if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2') {
102 ARMArchVersion = V6T2;
103 ARMArchFeature = ",+v6t2";
105 } else if (SubVer == '5') {
106 ARMArchVersion = V5T;
107 ARMArchFeature = ",+v5t";
108 if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == 'e') {
109 ARMArchVersion = V5TE;
110 ARMArchFeature = ",+v5te";
112 } else if (SubVer == '4') {
113 if (Len >= Idx+2 && TT[Idx+1] == 't') {
114 ARMArchVersion = V4T;
115 ARMArchFeature = ",+v4t";
123 if (TT.find("eabi") != std::string::npos)
124 TargetABI = ARM_ABI_AAPCS;
126 // Parse features string. If the first entry in FS (the CPU) is missing,
127 // insert the architecture feature derived from the target triple. This is
128 // important for setting features that are implied based on the architecture
130 std::string FSWithArch;
132 FSWithArch = std::string(ARMArchFeature);
133 else if (FS.find(',') == 0)
134 FSWithArch = std::string(ARMArchFeature) + FS;
137 CPUString = ParseSubtargetFeatures(FSWithArch, CPUString);
139 // After parsing Itineraries, set ItinData.IssueWidth.
142 // Thumb2 implies at least V6T2.
143 if (ARMArchVersion >= V6T2)
145 else if (ThumbMode >= Thumb2)
146 ARMArchVersion = V6T2;
151 if (!isTargetDarwin())
152 UseMovt = hasV6T2Ops();
154 IsR9Reserved = ReserveR9 | (ARMArchVersion < V6);
155 UseMovt = DarwinUseMOVT && hasV6T2Ops();
158 if (!isThumb() || hasThumb2())
159 PostRAScheduler = true;
161 // v6+ may or may not support unaligned mem access depending on the system
163 if (!StrictAlign && hasV6Ops() && isTargetDarwin())
164 AllowsUnalignedMem = true;
167 /// GVIsIndirectSymbol - true if the GV will be accessed via an indirect symbol.
169 ARMSubtarget::GVIsIndirectSymbol(const GlobalValue *GV,
170 Reloc::Model RelocM) const {
171 if (RelocM == Reloc::Static)
174 // Materializable GVs (in JIT lazy compilation mode) do not require an extra
176 bool isDecl = GV->hasAvailableExternallyLinkage();
177 if (GV->isDeclaration() && !GV->isMaterializable())
180 if (!isTargetDarwin()) {
181 // Extra load is needed for all externally visible.
182 if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
186 if (RelocM == Reloc::PIC_) {
187 // If this is a strong reference to a definition, it is definitely not
189 if (!isDecl && !GV->isWeakForLinker())
192 // Unless we have a symbol with hidden visibility, we have to go through a
193 // normal $non_lazy_ptr stub because this symbol might be resolved late.
194 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
197 // If symbol visibility is hidden, we have a stub for common symbol
198 // references and external declarations.
199 if (isDecl || GV->hasCommonLinkage())
200 // Hidden $non_lazy_ptr reference.
205 // If this is a strong reference to a definition, it is definitely not
207 if (!isDecl && !GV->isWeakForLinker())
210 // Unless we have a symbol with hidden visibility, we have to go through a
211 // normal $non_lazy_ptr stub because this symbol might be resolved late.
212 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
220 unsigned ARMSubtarget::getMispredictionPenalty() const {
221 // If we have a reasonable estimate of the pipeline depth, then we can
222 // estimate the penalty of a misprediction based on that.
225 else if (isCortexA9())
228 // Otherwise, just return a sensible default.
232 void ARMSubtarget::computeIssueWidth() {
233 unsigned allStage1Units = 0;
234 for (const InstrItinerary *itin = InstrItins.Itineraries;
235 itin->FirstStage != ~0U; ++itin) {
236 const InstrStage *IS = InstrItins.Stages + itin->FirstStage;
237 allStage1Units |= IS->getUnits();
239 InstrItins.IssueWidth = 0;
240 while (allStage1Units) {
241 ++InstrItins.IssueWidth;
242 // clear the lowest bit
243 allStage1Units ^= allStage1Units & ~(allStage1Units - 1);
245 assert(InstrItins.IssueWidth <= 2 && "itinerary bug, too many stage 1 units");
248 bool ARMSubtarget::enablePostRAScheduler(
249 CodeGenOpt::Level OptLevel,
250 TargetSubtarget::AntiDepBreakMode& Mode,
251 RegClassVector& CriticalPathRCs) const {
252 Mode = TargetSubtarget::ANTIDEP_CRITICAL;
253 CriticalPathRCs.clear();
254 CriticalPathRCs.push_back(&ARM::GPRRegClass);
255 return PostRAScheduler && OptLevel >= CodeGenOpt::Default;