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/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"));
27 DarwinUseMOVT("arm-darwin-use-movt", cl::init(true), cl::Hidden);
30 StrictAlign("arm-strict-align", cl::Hidden,
31 cl::desc("Disallow all unaligned memory accesses"));
33 ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
36 , ARMProcFamily(Others)
38 , UseNEONForSinglePrecisionFP(false)
40 , HasVMLxForwarding(false)
45 , PostRAScheduler(false)
46 , IsR9Reserved(ReserveR9)
50 , HasHardwareDivide(false)
51 , HasT2ExtractPack(false)
52 , HasDataBarrier(false)
53 , Pref32BitThumb(false)
54 , AvoidCPSRPartialUpdate(false)
55 , HasMPExtension(false)
57 , AllowsUnalignedMem(false)
59 , CPUString("generic")
61 , TargetABI(ARM_ABI_APCS) {
62 // Determine default and user specified characteristics
64 // When no arch is specified either by CPU or by attributes, make the default
66 const char *ARMArchFeature = "";
67 if (CPUString == "generic" && (FS.empty() || FS == "generic")) {
69 ARMArchFeature = ",+v4t";
72 // Set the boolean corresponding to the current target triple, or the default
73 // if one cannot be determined, to true.
74 unsigned Len = TT.length();
77 if (Len >= 5 && TT.substr(0, 4) == "armv")
79 else if (Len >= 6 && TT.substr(0, 5) == "thumb") {
81 if (Len >= 7 && TT[5] == 'v')
85 unsigned SubVer = TT[Idx];
86 if (SubVer >= '7' && SubVer <= '9') {
88 ARMArchFeature = ",+v7a";
89 if (Len >= Idx+2 && TT[Idx+1] == 'm') {
91 ARMArchFeature = ",+v7m";
93 } else if (SubVer == '6') {
95 ARMArchFeature = ",+v6";
96 if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2') {
97 ARMArchVersion = V6T2;
98 ARMArchFeature = ",+v6t2";
100 } else if (SubVer == '5') {
101 ARMArchVersion = V5T;
102 ARMArchFeature = ",+v5t";
103 if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == 'e') {
104 ARMArchVersion = V5TE;
105 ARMArchFeature = ",+v5te";
107 } else if (SubVer == '4') {
108 if (Len >= Idx+2 && TT[Idx+1] == 't') {
109 ARMArchVersion = V4T;
110 ARMArchFeature = ",+v4t";
118 if (TT.find("eabi") != std::string::npos)
119 TargetABI = ARM_ABI_AAPCS;
121 // Parse features string. If the first entry in FS (the CPU) is missing,
122 // insert the architecture feature derived from the target triple. This is
123 // important for setting features that are implied based on the architecture
125 std::string FSWithArch;
127 FSWithArch = std::string(ARMArchFeature);
128 else if (FS.find(',') == 0)
129 FSWithArch = std::string(ARMArchFeature) + FS;
132 CPUString = ParseSubtargetFeatures(FSWithArch, CPUString);
134 // After parsing Itineraries, set ItinData.IssueWidth.
137 // Thumb2 implies at least V6T2.
138 if (ARMArchVersion >= V6T2)
140 else if (ThumbMode >= Thumb2)
141 ARMArchVersion = V6T2;
146 if (!isTargetDarwin())
147 UseMovt = hasV6T2Ops();
149 IsR9Reserved = ReserveR9 | (ARMArchVersion < V6);
150 UseMovt = DarwinUseMOVT && hasV6T2Ops();
153 if (!isThumb() || hasThumb2())
154 PostRAScheduler = true;
156 // v6+ may or may not support unaligned mem access depending on the system
158 if (!StrictAlign && hasV6Ops() && isTargetDarwin())
159 AllowsUnalignedMem = true;
162 /// GVIsIndirectSymbol - true if the GV will be accessed via an indirect symbol.
164 ARMSubtarget::GVIsIndirectSymbol(const GlobalValue *GV,
165 Reloc::Model RelocM) const {
166 if (RelocM == Reloc::Static)
169 // Materializable GVs (in JIT lazy compilation mode) do not require an extra
171 bool isDecl = GV->hasAvailableExternallyLinkage();
172 if (GV->isDeclaration() && !GV->isMaterializable())
175 if (!isTargetDarwin()) {
176 // Extra load is needed for all externally visible.
177 if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
181 if (RelocM == Reloc::PIC_) {
182 // If this is a strong reference to a definition, it is definitely not
184 if (!isDecl && !GV->isWeakForLinker())
187 // Unless we have a symbol with hidden visibility, we have to go through a
188 // normal $non_lazy_ptr stub because this symbol might be resolved late.
189 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
192 // If symbol visibility is hidden, we have a stub for common symbol
193 // references and external declarations.
194 if (isDecl || GV->hasCommonLinkage())
195 // Hidden $non_lazy_ptr reference.
200 // If this is a strong reference to a definition, it is definitely not
202 if (!isDecl && !GV->isWeakForLinker())
205 // Unless we have a symbol with hidden visibility, we have to go through a
206 // normal $non_lazy_ptr stub because this symbol might be resolved late.
207 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
215 unsigned ARMSubtarget::getMispredictionPenalty() const {
216 // If we have a reasonable estimate of the pipeline depth, then we can
217 // estimate the penalty of a misprediction based on that.
220 else if (isCortexA9())
223 // Otherwise, just return a sensible default.
227 void ARMSubtarget::computeIssueWidth() {
228 unsigned allStage1Units = 0;
229 for (const InstrItinerary *itin = InstrItins.Itineraries;
230 itin->FirstStage != ~0U; ++itin) {
231 const InstrStage *IS = InstrItins.Stages + itin->FirstStage;
232 allStage1Units |= IS->getUnits();
234 InstrItins.IssueWidth = 0;
235 while (allStage1Units) {
236 ++InstrItins.IssueWidth;
237 // clear the lowest bit
238 allStage1Units ^= allStage1Units & ~(allStage1Units - 1);
240 assert(InstrItins.IssueWidth <= 2 && "itinerary bug, too many stage 1 units");
243 bool ARMSubtarget::enablePostRAScheduler(
244 CodeGenOpt::Level OptLevel,
245 TargetSubtarget::AntiDepBreakMode& Mode,
246 RegClassVector& CriticalPathRCs) const {
247 Mode = TargetSubtarget::ANTIDEP_CRITICAL;
248 CriticalPathRCs.clear();
249 CriticalPathRCs.push_back(&ARM::GPRRegClass);
250 return PostRAScheduler && OptLevel >= CodeGenOpt::Default;