xref: /freebsd/contrib/llvm-project/clang/lib/Driver/ToolChains/Arch/ARM.cpp (revision 780f28929782a104eefbc81f031836bf1febb6de)
1 //===--- ARM.cpp - ARM (not AArch64) Helpers for Tools ----------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "ARM.h"
10 #include "clang/Driver/Driver.h"
11 #include "clang/Driver/DriverDiagnostic.h"
12 #include "clang/Driver/Options.h"
13 #include "llvm/ADT/StringSwitch.h"
14 #include "llvm/Option/ArgList.h"
15 #include "llvm/TargetParser/ARMTargetParser.h"
16 #include "llvm/TargetParser/Host.h"
17 
18 using namespace clang::driver;
19 using namespace clang::driver::tools;
20 using namespace clang;
21 using namespace llvm::opt;
22 
23 // Get SubArch (vN).
24 int arm::getARMSubArchVersionNumber(const llvm::Triple &Triple) {
25   llvm::StringRef Arch = Triple.getArchName();
26   return llvm::ARM::parseArchVersion(Arch);
27 }
28 
29 // True if M-profile.
30 bool arm::isARMMProfile(const llvm::Triple &Triple) {
31   llvm::StringRef Arch = Triple.getArchName();
32   return llvm::ARM::parseArchProfile(Arch) == llvm::ARM::ProfileKind::M;
33 }
34 
35 // On Arm the endianness of the output file is determined by the target and
36 // can be overridden by the pseudo-target flags '-mlittle-endian'/'-EL' and
37 // '-mbig-endian'/'-EB'. Unlike other targets the flag does not result in a
38 // normalized triple so we must handle the flag here.
39 bool arm::isARMBigEndian(const llvm::Triple &Triple, const ArgList &Args) {
40   if (Arg *A = Args.getLastArg(options::OPT_mlittle_endian,
41                                options::OPT_mbig_endian)) {
42     return !A->getOption().matches(options::OPT_mlittle_endian);
43   }
44 
45   return Triple.getArch() == llvm::Triple::armeb ||
46          Triple.getArch() == llvm::Triple::thumbeb;
47 }
48 
49 // True if A-profile.
50 bool arm::isARMAProfile(const llvm::Triple &Triple) {
51   llvm::StringRef Arch = Triple.getArchName();
52   return llvm::ARM::parseArchProfile(Arch) == llvm::ARM::ProfileKind::A;
53 }
54 
55 // Get Arch/CPU from args.
56 void arm::getARMArchCPUFromArgs(const ArgList &Args, llvm::StringRef &Arch,
57                                 llvm::StringRef &CPU, bool FromAs) {
58   if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_mcpu_EQ))
59     CPU = A->getValue();
60   if (const Arg *A = Args.getLastArg(options::OPT_march_EQ))
61     Arch = A->getValue();
62   if (!FromAs)
63     return;
64 
65   for (const Arg *A :
66        Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler)) {
67     // Use getValues because -Wa can have multiple arguments
68     // e.g. -Wa,-mcpu=foo,-mcpu=bar
69     for (StringRef Value : A->getValues()) {
70       if (Value.starts_with("-mcpu="))
71         CPU = Value.substr(6);
72       if (Value.starts_with("-march="))
73         Arch = Value.substr(7);
74     }
75   }
76 }
77 
78 // Handle -mhwdiv=.
79 // FIXME: Use ARMTargetParser.
80 static void getARMHWDivFeatures(const Driver &D, const Arg *A,
81                                 const ArgList &Args, StringRef HWDiv,
82                                 std::vector<StringRef> &Features) {
83   uint64_t HWDivID = llvm::ARM::parseHWDiv(HWDiv);
84   if (!llvm::ARM::getHWDivFeatures(HWDivID, Features))
85     D.Diag(clang::diag::err_drv_clang_unsupported) << A->getAsString(Args);
86 }
87 
88 // Handle -mfpu=.
89 static llvm::ARM::FPUKind getARMFPUFeatures(const Driver &D, const Arg *A,
90                                             const ArgList &Args, StringRef FPU,
91                                             std::vector<StringRef> &Features) {
92   llvm::ARM::FPUKind FPUKind = llvm::ARM::parseFPU(FPU);
93   if (!llvm::ARM::getFPUFeatures(FPUKind, Features))
94     D.Diag(clang::diag::err_drv_clang_unsupported) << A->getAsString(Args);
95   return FPUKind;
96 }
97 
98 // Decode ARM features from string like +[no]featureA+[no]featureB+...
99 static bool DecodeARMFeatures(const Driver &D, StringRef text, StringRef CPU,
100                               llvm::ARM::ArchKind ArchKind,
101                               std::vector<StringRef> &Features,
102                               llvm::ARM::FPUKind &ArgFPUKind) {
103   SmallVector<StringRef, 8> Split;
104   text.split(Split, StringRef("+"), -1, false);
105 
106   for (StringRef Feature : Split) {
107     if (!appendArchExtFeatures(CPU, ArchKind, Feature, Features, ArgFPUKind))
108       return false;
109   }
110   return true;
111 }
112 
113 static void DecodeARMFeaturesFromCPU(const Driver &D, StringRef CPU,
114                                      std::vector<StringRef> &Features) {
115   CPU = CPU.split("+").first;
116   if (CPU != "generic") {
117     llvm::ARM::ArchKind ArchKind = llvm::ARM::parseCPUArch(CPU);
118     uint64_t Extension = llvm::ARM::getDefaultExtensions(CPU, ArchKind);
119     llvm::ARM::getExtensionFeatures(Extension, Features);
120   }
121 }
122 
123 // Check if -march is valid by checking if it can be canonicalised and parsed.
124 // getARMArch is used here instead of just checking the -march value in order
125 // to handle -march=native correctly.
126 static void checkARMArchName(const Driver &D, const Arg *A, const ArgList &Args,
127                              llvm::StringRef ArchName, llvm::StringRef CPUName,
128                              std::vector<StringRef> &Features,
129                              const llvm::Triple &Triple,
130                              llvm::ARM::FPUKind &ArgFPUKind) {
131   std::pair<StringRef, StringRef> Split = ArchName.split("+");
132 
133   std::string MArch = arm::getARMArch(ArchName, Triple);
134   llvm::ARM::ArchKind ArchKind = llvm::ARM::parseArch(MArch);
135   if (ArchKind == llvm::ARM::ArchKind::INVALID ||
136       (Split.second.size() &&
137        !DecodeARMFeatures(D, Split.second, CPUName, ArchKind, Features,
138                           ArgFPUKind)))
139     D.Diag(clang::diag::err_drv_unsupported_option_argument)
140         << A->getSpelling() << A->getValue();
141 }
142 
143 // Check -mcpu=. Needs ArchName to handle -mcpu=generic.
144 static void checkARMCPUName(const Driver &D, const Arg *A, const ArgList &Args,
145                             llvm::StringRef CPUName, llvm::StringRef ArchName,
146                             std::vector<StringRef> &Features,
147                             const llvm::Triple &Triple,
148                             llvm::ARM::FPUKind &ArgFPUKind) {
149   std::pair<StringRef, StringRef> Split = CPUName.split("+");
150 
151   std::string CPU = arm::getARMTargetCPU(CPUName, ArchName, Triple);
152   llvm::ARM::ArchKind ArchKind =
153     arm::getLLVMArchKindForARM(CPU, ArchName, Triple);
154   if (ArchKind == llvm::ARM::ArchKind::INVALID ||
155       (Split.second.size() && !DecodeARMFeatures(D, Split.second, CPU, ArchKind,
156                                                  Features, ArgFPUKind)))
157     D.Diag(clang::diag::err_drv_unsupported_option_argument)
158         << A->getSpelling() << A->getValue();
159 }
160 
161 // If -mfloat-abi=hard or -mhard-float are specified explicitly then check that
162 // floating point registers are available on the target CPU.
163 static void checkARMFloatABI(const Driver &D, const ArgList &Args,
164                              bool HasFPRegs) {
165   if (HasFPRegs)
166     return;
167   const Arg *A =
168       Args.getLastArg(options::OPT_msoft_float, options::OPT_mhard_float,
169                       options::OPT_mfloat_abi_EQ);
170   if (A && (A->getOption().matches(options::OPT_mhard_float) ||
171             (A->getOption().matches(options::OPT_mfloat_abi_EQ) &&
172              A->getValue() == StringRef("hard"))))
173     D.Diag(clang::diag::warn_drv_no_floating_point_registers)
174         << A->getAsString(Args);
175 }
176 
177 bool arm::useAAPCSForMachO(const llvm::Triple &T) {
178   // The backend is hardwired to assume AAPCS for M-class processors, ensure
179   // the frontend matches that.
180   return T.getEnvironment() == llvm::Triple::EABI ||
181          T.getEnvironment() == llvm::Triple::EABIHF ||
182          T.getOS() == llvm::Triple::UnknownOS || isARMMProfile(T);
183 }
184 
185 // We follow GCC and support when the backend has support for the MRC/MCR
186 // instructions that are used to set the hard thread pointer ("CP15 C13
187 // Thread id").
188 bool arm::isHardTPSupported(const llvm::Triple &Triple) {
189   int Ver = getARMSubArchVersionNumber(Triple);
190   llvm::ARM::ArchKind AK = llvm::ARM::parseArch(Triple.getArchName());
191   return Triple.isARM() || AK == llvm::ARM::ArchKind::ARMV6T2 ||
192          (Ver >= 7 && AK != llvm::ARM::ArchKind::ARMV8MBaseline);
193 }
194 
195 // Select mode for reading thread pointer (-mtp=soft/cp15).
196 arm::ReadTPMode arm::getReadTPMode(const Driver &D, const ArgList &Args,
197                                    const llvm::Triple &Triple, bool ForAS) {
198   if (Arg *A = Args.getLastArg(options::OPT_mtp_mode_EQ)) {
199     arm::ReadTPMode ThreadPointer =
200         llvm::StringSwitch<arm::ReadTPMode>(A->getValue())
201             .Case("cp15", ReadTPMode::TPIDRURO)
202             .Case("tpidrurw", ReadTPMode::TPIDRURW)
203             .Case("tpidruro", ReadTPMode::TPIDRURO)
204             .Case("tpidrprw", ReadTPMode::TPIDRPRW)
205             .Case("soft", ReadTPMode::Soft)
206             .Default(ReadTPMode::Invalid);
207     if ((ThreadPointer == ReadTPMode::TPIDRURW ||
208          ThreadPointer == ReadTPMode::TPIDRURO ||
209          ThreadPointer == ReadTPMode::TPIDRPRW) &&
210         !isHardTPSupported(Triple) && !ForAS) {
211       D.Diag(diag::err_target_unsupported_tp_hard) << Triple.getArchName();
212       return ReadTPMode::Invalid;
213     }
214     if (ThreadPointer != ReadTPMode::Invalid)
215       return ThreadPointer;
216     if (StringRef(A->getValue()).empty())
217       D.Diag(diag::err_drv_missing_arg_mtp) << A->getAsString(Args);
218     else
219       D.Diag(diag::err_drv_invalid_mtp) << A->getAsString(Args);
220     return ReadTPMode::Invalid;
221   }
222   return ReadTPMode::Soft;
223 }
224 
225 void arm::setArchNameInTriple(const Driver &D, const ArgList &Args,
226                               types::ID InputType, llvm::Triple &Triple) {
227   StringRef MCPU, MArch;
228   if (const Arg *A = Args.getLastArg(options::OPT_mcpu_EQ))
229     MCPU = A->getValue();
230   if (const Arg *A = Args.getLastArg(options::OPT_march_EQ))
231     MArch = A->getValue();
232 
233   std::string CPU = Triple.isOSBinFormatMachO()
234                         ? tools::arm::getARMCPUForMArch(MArch, Triple).str()
235                         : tools::arm::getARMTargetCPU(MCPU, MArch, Triple);
236   StringRef Suffix = tools::arm::getLLVMArchSuffixForARM(CPU, MArch, Triple);
237 
238   bool IsBigEndian = Triple.getArch() == llvm::Triple::armeb ||
239                      Triple.getArch() == llvm::Triple::thumbeb;
240   // Handle pseudo-target flags '-mlittle-endian'/'-EL' and
241   // '-mbig-endian'/'-EB'.
242   if (Arg *A = Args.getLastArg(options::OPT_mlittle_endian,
243                                options::OPT_mbig_endian)) {
244     IsBigEndian = !A->getOption().matches(options::OPT_mlittle_endian);
245   }
246   std::string ArchName = IsBigEndian ? "armeb" : "arm";
247 
248   // FIXME: Thumb should just be another -target-feaure, not in the triple.
249   bool IsMProfile =
250       llvm::ARM::parseArchProfile(Suffix) == llvm::ARM::ProfileKind::M;
251   bool ThumbDefault = IsMProfile ||
252                       // Thumb2 is the default for V7 on Darwin.
253                       (llvm::ARM::parseArchVersion(Suffix) == 7 &&
254                        Triple.isOSBinFormatMachO()) ||
255                       // FIXME: this is invalid for WindowsCE
256                       Triple.isOSWindows();
257 
258   // Check if ARM ISA was explicitly selected (using -mno-thumb or -marm) for
259   // M-Class CPUs/architecture variants, which is not supported.
260   bool ARMModeRequested =
261       !Args.hasFlag(options::OPT_mthumb, options::OPT_mno_thumb, ThumbDefault);
262   if (IsMProfile && ARMModeRequested) {
263     if (MCPU.size())
264       D.Diag(diag::err_cpu_unsupported_isa) << CPU << "ARM";
265     else
266       D.Diag(diag::err_arch_unsupported_isa)
267           << tools::arm::getARMArch(MArch, Triple) << "ARM";
268   }
269 
270   // Check to see if an explicit choice to use thumb has been made via
271   // -mthumb. For assembler files we must check for -mthumb in the options
272   // passed to the assembler via -Wa or -Xassembler.
273   bool IsThumb = false;
274   if (InputType != types::TY_PP_Asm)
275     IsThumb =
276         Args.hasFlag(options::OPT_mthumb, options::OPT_mno_thumb, ThumbDefault);
277   else {
278     // Ideally we would check for these flags in
279     // CollectArgsForIntegratedAssembler but we can't change the ArchName at
280     // that point.
281     llvm::StringRef WaMArch, WaMCPU;
282     for (const auto *A :
283          Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler)) {
284       for (StringRef Value : A->getValues()) {
285         // There is no assembler equivalent of -mno-thumb, -marm, or -mno-arm.
286         if (Value == "-mthumb")
287           IsThumb = true;
288         else if (Value.starts_with("-march="))
289           WaMArch = Value.substr(7);
290         else if (Value.starts_with("-mcpu="))
291           WaMCPU = Value.substr(6);
292       }
293     }
294 
295     if (WaMCPU.size() || WaMArch.size()) {
296       // The way this works means that we prefer -Wa,-mcpu's architecture
297       // over -Wa,-march. Which matches the compiler behaviour.
298       Suffix = tools::arm::getLLVMArchSuffixForARM(WaMCPU, WaMArch, Triple);
299     }
300   }
301 
302   // Assembly files should start in ARM mode, unless arch is M-profile, or
303   // -mthumb has been passed explicitly to the assembler. Windows is always
304   // thumb.
305   if (IsThumb || IsMProfile || Triple.isOSWindows()) {
306     if (IsBigEndian)
307       ArchName = "thumbeb";
308     else
309       ArchName = "thumb";
310   }
311   Triple.setArchName(ArchName + Suffix.str());
312 }
313 
314 void arm::setFloatABIInTriple(const Driver &D, const ArgList &Args,
315                               llvm::Triple &Triple) {
316   if (Triple.isOSLiteOS()) {
317     Triple.setEnvironment(llvm::Triple::OpenHOS);
318     return;
319   }
320 
321   bool isHardFloat =
322       (arm::getARMFloatABI(D, Triple, Args) == arm::FloatABI::Hard);
323 
324   switch (Triple.getEnvironment()) {
325   case llvm::Triple::GNUEABI:
326   case llvm::Triple::GNUEABIHF:
327     Triple.setEnvironment(isHardFloat ? llvm::Triple::GNUEABIHF
328                                       : llvm::Triple::GNUEABI);
329     break;
330   case llvm::Triple::GNUEABIT64:
331   case llvm::Triple::GNUEABIHFT64:
332     Triple.setEnvironment(isHardFloat ? llvm::Triple::GNUEABIHFT64
333                                       : llvm::Triple::GNUEABIT64);
334     break;
335   case llvm::Triple::EABI:
336   case llvm::Triple::EABIHF:
337     Triple.setEnvironment(isHardFloat ? llvm::Triple::EABIHF
338                                       : llvm::Triple::EABI);
339     break;
340   case llvm::Triple::MuslEABI:
341   case llvm::Triple::MuslEABIHF:
342     Triple.setEnvironment(isHardFloat ? llvm::Triple::MuslEABIHF
343                                       : llvm::Triple::MuslEABI);
344     break;
345   case llvm::Triple::OpenHOS:
346     break;
347   default: {
348     arm::FloatABI DefaultABI = arm::getDefaultFloatABI(Triple);
349     if (DefaultABI != arm::FloatABI::Invalid &&
350         isHardFloat != (DefaultABI == arm::FloatABI::Hard)) {
351       Arg *ABIArg =
352           Args.getLastArg(options::OPT_msoft_float, options::OPT_mhard_float,
353                           options::OPT_mfloat_abi_EQ);
354       assert(ABIArg && "Non-default float abi expected to be from arg");
355       D.Diag(diag::err_drv_unsupported_opt_for_target)
356           << ABIArg->getAsString(Args) << Triple.getTriple();
357     }
358     break;
359   }
360   }
361 }
362 
363 arm::FloatABI arm::getARMFloatABI(const ToolChain &TC, const ArgList &Args) {
364   return arm::getARMFloatABI(TC.getDriver(), TC.getEffectiveTriple(), Args);
365 }
366 
367 arm::FloatABI arm::getDefaultFloatABI(const llvm::Triple &Triple) {
368   auto SubArch = getARMSubArchVersionNumber(Triple);
369   switch (Triple.getOS()) {
370   case llvm::Triple::Darwin:
371   case llvm::Triple::MacOSX:
372   case llvm::Triple::IOS:
373   case llvm::Triple::TvOS:
374   case llvm::Triple::DriverKit:
375   case llvm::Triple::XROS:
376     // Darwin defaults to "softfp" for v6 and v7.
377     if (Triple.isWatchABI())
378       return FloatABI::Hard;
379     else
380       return (SubArch == 6 || SubArch == 7) ? FloatABI::SoftFP : FloatABI::Soft;
381 
382   case llvm::Triple::WatchOS:
383     return FloatABI::Hard;
384 
385   // FIXME: this is invalid for WindowsCE
386   case llvm::Triple::Win32:
387     // It is incorrect to select hard float ABI on MachO platforms if the ABI is
388     // "apcs-gnu".
389     if (Triple.isOSBinFormatMachO() && !useAAPCSForMachO(Triple))
390       return FloatABI::Soft;
391     return FloatABI::Hard;
392 
393   case llvm::Triple::NetBSD:
394     switch (Triple.getEnvironment()) {
395     case llvm::Triple::EABIHF:
396     case llvm::Triple::GNUEABIHF:
397       return FloatABI::Hard;
398     default:
399       return FloatABI::Soft;
400     }
401     break;
402 
403   case llvm::Triple::FreeBSD:
404     switch (Triple.getEnvironment()) {
405     case llvm::Triple::GNUEABIHF:
406       return FloatABI::Hard;
407     default:
408       // FreeBSD defaults to soft float
409       return FloatABI::Soft;
410     }
411     break;
412 
413   case llvm::Triple::Haiku:
414   case llvm::Triple::OpenBSD:
415     return FloatABI::SoftFP;
416 
417   default:
418     if (Triple.isOHOSFamily())
419       return FloatABI::Soft;
420     switch (Triple.getEnvironment()) {
421     case llvm::Triple::GNUEABIHF:
422     case llvm::Triple::GNUEABIHFT64:
423     case llvm::Triple::MuslEABIHF:
424     case llvm::Triple::EABIHF:
425       return FloatABI::Hard;
426     case llvm::Triple::GNUEABI:
427     case llvm::Triple::GNUEABIT64:
428     case llvm::Triple::MuslEABI:
429     case llvm::Triple::EABI:
430       // EABI is always AAPCS, and if it was not marked 'hard', it's softfp
431       return FloatABI::SoftFP;
432     case llvm::Triple::Android:
433       return (SubArch >= 7) ? FloatABI::SoftFP : FloatABI::Soft;
434     default:
435       return FloatABI::Invalid;
436     }
437   }
438   return FloatABI::Invalid;
439 }
440 
441 // Select the float ABI as determined by -msoft-float, -mhard-float, and
442 // -mfloat-abi=.
443 arm::FloatABI arm::getARMFloatABI(const Driver &D, const llvm::Triple &Triple,
444                                   const ArgList &Args) {
445   arm::FloatABI ABI = FloatABI::Invalid;
446   if (Arg *A =
447           Args.getLastArg(options::OPT_msoft_float, options::OPT_mhard_float,
448                           options::OPT_mfloat_abi_EQ)) {
449     if (A->getOption().matches(options::OPT_msoft_float)) {
450       ABI = FloatABI::Soft;
451     } else if (A->getOption().matches(options::OPT_mhard_float)) {
452       ABI = FloatABI::Hard;
453     } else {
454       ABI = llvm::StringSwitch<arm::FloatABI>(A->getValue())
455                 .Case("soft", FloatABI::Soft)
456                 .Case("softfp", FloatABI::SoftFP)
457                 .Case("hard", FloatABI::Hard)
458                 .Default(FloatABI::Invalid);
459       if (ABI == FloatABI::Invalid && !StringRef(A->getValue()).empty()) {
460         D.Diag(diag::err_drv_invalid_mfloat_abi) << A->getAsString(Args);
461         ABI = FloatABI::Soft;
462       }
463     }
464   }
465 
466   // If unspecified, choose the default based on the platform.
467   if (ABI == FloatABI::Invalid)
468     ABI = arm::getDefaultFloatABI(Triple);
469 
470   if (ABI == FloatABI::Invalid) {
471     // Assume "soft", but warn the user we are guessing.
472     if (Triple.isOSBinFormatMachO() &&
473         Triple.getSubArch() == llvm::Triple::ARMSubArch_v7em)
474       ABI = FloatABI::Hard;
475     else
476       ABI = FloatABI::Soft;
477 
478     if (Triple.getOS() != llvm::Triple::UnknownOS ||
479         !Triple.isOSBinFormatMachO())
480       D.Diag(diag::warn_drv_assuming_mfloat_abi_is) << "soft";
481   }
482 
483   assert(ABI != FloatABI::Invalid && "must select an ABI");
484   return ABI;
485 }
486 
487 static bool hasIntegerMVE(const std::vector<StringRef> &F) {
488   auto MVE = llvm::find(llvm::reverse(F), "+mve");
489   auto NoMVE = llvm::find(llvm::reverse(F), "-mve");
490   return MVE != F.rend() &&
491          (NoMVE == F.rend() || std::distance(MVE, NoMVE) > 0);
492 }
493 
494 llvm::ARM::FPUKind arm::getARMTargetFeatures(const Driver &D,
495                                              const llvm::Triple &Triple,
496                                              const ArgList &Args,
497                                              std::vector<StringRef> &Features,
498                                              bool ForAS, bool ForMultilib) {
499   bool KernelOrKext =
500       Args.hasArg(options::OPT_mkernel, options::OPT_fapple_kext);
501   arm::FloatABI ABI = arm::getARMFloatABI(D, Triple, Args);
502   std::optional<std::pair<const Arg *, StringRef>> WaCPU, WaFPU, WaHDiv, WaArch;
503 
504   // This vector will accumulate features from the architecture
505   // extension suffixes on -mcpu and -march (e.g. the 'bar' in
506   // -mcpu=foo+bar). We want to apply those after the features derived
507   // from the FPU, in case -mfpu generates a negative feature which
508   // the +bar is supposed to override.
509   std::vector<StringRef> ExtensionFeatures;
510 
511   if (!ForAS) {
512     // FIXME: Note, this is a hack, the LLVM backend doesn't actually use these
513     // yet (it uses the -mfloat-abi and -msoft-float options), and it is
514     // stripped out by the ARM target. We should probably pass this a new
515     // -target-option, which is handled by the -cc1/-cc1as invocation.
516     //
517     // FIXME2:  For consistency, it would be ideal if we set up the target
518     // machine state the same when using the frontend or the assembler. We don't
519     // currently do that for the assembler, we pass the options directly to the
520     // backend and never even instantiate the frontend TargetInfo. If we did,
521     // and used its handleTargetFeatures hook, then we could ensure the
522     // assembler and the frontend behave the same.
523 
524     // Use software floating point operations?
525     if (ABI == arm::FloatABI::Soft)
526       Features.push_back("+soft-float");
527 
528     // Use software floating point argument passing?
529     if (ABI != arm::FloatABI::Hard)
530       Features.push_back("+soft-float-abi");
531   } else {
532     // Here, we make sure that -Wa,-mfpu/cpu/arch/hwdiv will be passed down
533     // to the assembler correctly.
534     for (const Arg *A :
535          Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler)) {
536       // We use getValues here because you can have many options per -Wa
537       // We will keep the last one we find for each of these
538       for (StringRef Value : A->getValues()) {
539         if (Value.starts_with("-mfpu=")) {
540           WaFPU = std::make_pair(A, Value.substr(6));
541         } else if (Value.starts_with("-mcpu=")) {
542           WaCPU = std::make_pair(A, Value.substr(6));
543         } else if (Value.starts_with("-mhwdiv=")) {
544           WaHDiv = std::make_pair(A, Value.substr(8));
545         } else if (Value.starts_with("-march=")) {
546           WaArch = std::make_pair(A, Value.substr(7));
547         }
548       }
549     }
550 
551     // The integrated assembler doesn't implement e_flags setting behavior for
552     // -meabi=gnu (gcc -mabi={apcs-gnu,atpcs} passes -meabi=gnu to gas). For
553     // compatibility we accept but warn.
554     if (Arg *A = Args.getLastArgNoClaim(options::OPT_mabi_EQ))
555       A->ignoreTargetSpecific();
556   }
557 
558   if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::TPIDRURW)
559     Features.push_back("+read-tp-tpidrurw");
560   if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::TPIDRURO)
561     Features.push_back("+read-tp-tpidruro");
562   if (getReadTPMode(D, Args, Triple, ForAS) == ReadTPMode::TPIDRPRW)
563     Features.push_back("+read-tp-tpidrprw");
564 
565   const Arg *ArchArg = Args.getLastArg(options::OPT_march_EQ);
566   const Arg *CPUArg = Args.getLastArg(options::OPT_mcpu_EQ);
567   StringRef ArchName;
568   StringRef CPUName;
569   llvm::ARM::FPUKind ArchArgFPUKind = llvm::ARM::FK_INVALID;
570   llvm::ARM::FPUKind CPUArgFPUKind = llvm::ARM::FK_INVALID;
571 
572   // Check -mcpu. ClangAs gives preference to -Wa,-mcpu=.
573   if (WaCPU) {
574     if (CPUArg)
575       D.Diag(clang::diag::warn_drv_unused_argument)
576           << CPUArg->getAsString(Args);
577     CPUName = WaCPU->second;
578     CPUArg = WaCPU->first;
579   } else if (CPUArg)
580     CPUName = CPUArg->getValue();
581 
582   // Check -march. ClangAs gives preference to -Wa,-march=.
583   if (WaArch) {
584     if (ArchArg)
585       D.Diag(clang::diag::warn_drv_unused_argument)
586           << ArchArg->getAsString(Args);
587     ArchName = WaArch->second;
588     // This will set any features after the base architecture.
589     checkARMArchName(D, WaArch->first, Args, ArchName, CPUName,
590                      ExtensionFeatures, Triple, ArchArgFPUKind);
591     // The base architecture was handled in ToolChain::ComputeLLVMTriple because
592     // triple is read only by this point.
593   } else if (ArchArg) {
594     ArchName = ArchArg->getValue();
595     checkARMArchName(D, ArchArg, Args, ArchName, CPUName, ExtensionFeatures,
596                      Triple, ArchArgFPUKind);
597   }
598 
599   // Add CPU features for generic CPUs
600   if (CPUName == "native") {
601     for (auto &F : llvm::sys::getHostCPUFeatures())
602       Features.push_back(
603           Args.MakeArgString((F.second ? "+" : "-") + F.first()));
604   } else if (!CPUName.empty()) {
605     // This sets the default features for the specified CPU. We certainly don't
606     // want to override the features that have been explicitly specified on the
607     // command line. Therefore, process them directly instead of appending them
608     // at the end later.
609     DecodeARMFeaturesFromCPU(D, CPUName, Features);
610   }
611 
612   if (CPUArg)
613     checkARMCPUName(D, CPUArg, Args, CPUName, ArchName, ExtensionFeatures,
614                     Triple, CPUArgFPUKind);
615 
616   // TODO Handle -mtune=. Suppress -Wunused-command-line-argument as a
617   // longstanding behavior.
618   (void)Args.getLastArg(options::OPT_mtune_EQ);
619 
620   // Honor -mfpu=. ClangAs gives preference to -Wa,-mfpu=.
621   llvm::ARM::FPUKind FPUKind = llvm::ARM::FK_INVALID;
622   const Arg *FPUArg = Args.getLastArg(options::OPT_mfpu_EQ);
623   if (WaFPU) {
624     if (FPUArg)
625       D.Diag(clang::diag::warn_drv_unused_argument)
626           << FPUArg->getAsString(Args);
627     (void)getARMFPUFeatures(D, WaFPU->first, Args, WaFPU->second, Features);
628   } else if (FPUArg) {
629     FPUKind = getARMFPUFeatures(D, FPUArg, Args, FPUArg->getValue(), Features);
630   } else if (Triple.isAndroid() && getARMSubArchVersionNumber(Triple) >= 7) {
631     const char *AndroidFPU = "neon";
632     FPUKind = llvm::ARM::parseFPU(AndroidFPU);
633     if (!llvm::ARM::getFPUFeatures(FPUKind, Features))
634       D.Diag(clang::diag::err_drv_clang_unsupported)
635           << std::string("-mfpu=") + AndroidFPU;
636   } else if (ArchArgFPUKind != llvm::ARM::FK_INVALID ||
637              CPUArgFPUKind != llvm::ARM::FK_INVALID) {
638     FPUKind =
639         CPUArgFPUKind != llvm::ARM::FK_INVALID ? CPUArgFPUKind : ArchArgFPUKind;
640     (void)llvm::ARM::getFPUFeatures(FPUKind, Features);
641   } else {
642     if (!ForAS) {
643       std::string CPU = arm::getARMTargetCPU(CPUName, ArchName, Triple);
644       llvm::ARM::ArchKind ArchKind =
645           arm::getLLVMArchKindForARM(CPU, ArchName, Triple);
646       FPUKind = llvm::ARM::getDefaultFPU(CPU, ArchKind);
647       (void)llvm::ARM::getFPUFeatures(FPUKind, Features);
648     }
649   }
650 
651   // Now we've finished accumulating features from arch, cpu and fpu,
652   // we can append the ones for architecture extensions that we
653   // collected separately.
654   Features.insert(std::end(Features),
655                   std::begin(ExtensionFeatures), std::end(ExtensionFeatures));
656 
657   // Honor -mhwdiv=. ClangAs gives preference to -Wa,-mhwdiv=.
658   const Arg *HDivArg = Args.getLastArg(options::OPT_mhwdiv_EQ);
659   if (WaHDiv) {
660     if (HDivArg)
661       D.Diag(clang::diag::warn_drv_unused_argument)
662           << HDivArg->getAsString(Args);
663     getARMHWDivFeatures(D, WaHDiv->first, Args, WaHDiv->second, Features);
664   } else if (HDivArg)
665     getARMHWDivFeatures(D, HDivArg, Args, HDivArg->getValue(), Features);
666 
667   // Handle (arch-dependent) fp16fml/fullfp16 relationship.
668   // Must happen before any features are disabled due to soft-float.
669   // FIXME: this fp16fml option handling will be reimplemented after the
670   // TargetParser rewrite.
671   const auto ItRNoFullFP16 = std::find(Features.rbegin(), Features.rend(), "-fullfp16");
672   const auto ItRFP16FML = std::find(Features.rbegin(), Features.rend(), "+fp16fml");
673   if (Triple.getSubArch() == llvm::Triple::SubArchType::ARMSubArch_v8_4a) {
674     const auto ItRFullFP16  = std::find(Features.rbegin(), Features.rend(), "+fullfp16");
675     if (ItRFullFP16 < ItRNoFullFP16 && ItRFullFP16 < ItRFP16FML) {
676       // Only entangled feature that can be to the right of this +fullfp16 is -fp16fml.
677       // Only append the +fp16fml if there is no -fp16fml after the +fullfp16.
678       if (std::find(Features.rbegin(), ItRFullFP16, "-fp16fml") == ItRFullFP16)
679         Features.push_back("+fp16fml");
680     }
681     else
682       goto fp16_fml_fallthrough;
683   }
684   else {
685 fp16_fml_fallthrough:
686     // In both of these cases, putting the 'other' feature on the end of the vector will
687     // result in the same effect as placing it immediately after the current feature.
688     if (ItRNoFullFP16 < ItRFP16FML)
689       Features.push_back("-fp16fml");
690     else if (ItRNoFullFP16 > ItRFP16FML)
691       Features.push_back("+fullfp16");
692   }
693 
694   // Setting -msoft-float/-mfloat-abi=soft, -mfpu=none, or adding +nofp to
695   // -march/-mcpu effectively disables the FPU (GCC ignores the -mfpu options in
696   // this case). Note that the ABI can also be set implicitly by the target
697   // selected.
698   bool HasFPRegs = true;
699   if (ABI == arm::FloatABI::Soft) {
700     llvm::ARM::getFPUFeatures(llvm::ARM::FK_NONE, Features);
701 
702     // Disable all features relating to hardware FP, not already disabled by the
703     // above call.
704     Features.insert(Features.end(),
705                     {"-dotprod", "-fp16fml", "-bf16", "-mve", "-mve.fp"});
706     HasFPRegs = false;
707     FPUKind = llvm::ARM::FK_NONE;
708   } else if (FPUKind == llvm::ARM::FK_NONE ||
709              ArchArgFPUKind == llvm::ARM::FK_NONE ||
710              CPUArgFPUKind == llvm::ARM::FK_NONE) {
711     // -mfpu=none, -march=armvX+nofp or -mcpu=X+nofp is *very* similar to
712     // -mfloat-abi=soft, only that it should not disable MVE-I. They disable the
713     // FPU, but not the FPU registers, thus MVE-I, which depends only on the
714     // latter, is still supported.
715     Features.insert(Features.end(),
716                     {"-dotprod", "-fp16fml", "-bf16", "-mve.fp"});
717     HasFPRegs = hasIntegerMVE(Features);
718     FPUKind = llvm::ARM::FK_NONE;
719   }
720   if (!HasFPRegs)
721     Features.emplace_back("-fpregs");
722 
723   // En/disable crc code generation.
724   if (Arg *A = Args.getLastArg(options::OPT_mcrc, options::OPT_mnocrc)) {
725     if (A->getOption().matches(options::OPT_mcrc))
726       Features.push_back("+crc");
727     else
728       Features.push_back("-crc");
729   }
730 
731   // For Arch >= ARMv8.0 && A or R profile:  crypto = sha2 + aes
732   // Rather than replace within the feature vector, determine whether each
733   // algorithm is enabled and append this to the end of the vector.
734   // The algorithms can be controlled by their specific feature or the crypto
735   // feature, so their status can be determined by the last occurance of
736   // either in the vector. This allows one to supercede the other.
737   // e.g. +crypto+noaes in -march/-mcpu should enable sha2, but not aes
738   // FIXME: this needs reimplementation after the TargetParser rewrite
739   bool HasSHA2 = false;
740   bool HasAES = false;
741   const auto ItCrypto =
742       llvm::find_if(llvm::reverse(Features), [](const StringRef F) {
743         return F.contains("crypto");
744       });
745   const auto ItSHA2 =
746       llvm::find_if(llvm::reverse(Features), [](const StringRef F) {
747         return F.contains("crypto") || F.contains("sha2");
748       });
749   const auto ItAES =
750       llvm::find_if(llvm::reverse(Features), [](const StringRef F) {
751         return F.contains("crypto") || F.contains("aes");
752       });
753   const bool FoundSHA2 = ItSHA2 != Features.rend();
754   const bool FoundAES = ItAES != Features.rend();
755   if (FoundSHA2)
756     HasSHA2 = ItSHA2->take_front() == "+";
757   if (FoundAES)
758     HasAES = ItAES->take_front() == "+";
759   if (ItCrypto != Features.rend()) {
760     if (HasSHA2 && HasAES)
761       Features.push_back("+crypto");
762     else
763       Features.push_back("-crypto");
764     if (HasSHA2)
765       Features.push_back("+sha2");
766     else
767       Features.push_back("-sha2");
768     if (HasAES)
769       Features.push_back("+aes");
770     else
771       Features.push_back("-aes");
772   }
773 
774   if (HasSHA2 || HasAES) {
775     StringRef ArchSuffix = arm::getLLVMArchSuffixForARM(
776         arm::getARMTargetCPU(CPUName, ArchName, Triple), ArchName, Triple);
777     llvm::ARM::ProfileKind ArchProfile =
778         llvm::ARM::parseArchProfile(ArchSuffix);
779     if (!((llvm::ARM::parseArchVersion(ArchSuffix) >= 8) &&
780           (ArchProfile == llvm::ARM::ProfileKind::A ||
781            ArchProfile == llvm::ARM::ProfileKind::R))) {
782       if (HasSHA2)
783         D.Diag(clang::diag::warn_target_unsupported_extension)
784             << "sha2"
785             << llvm::ARM::getArchName(llvm::ARM::parseArch(ArchSuffix));
786       if (HasAES)
787         D.Diag(clang::diag::warn_target_unsupported_extension)
788             << "aes"
789             << llvm::ARM::getArchName(llvm::ARM::parseArch(ArchSuffix));
790       // With -fno-integrated-as -mfpu=crypto-neon-fp-armv8 some assemblers such
791       // as the GNU assembler will permit the use of crypto instructions as the
792       // fpu will override the architecture. We keep the crypto feature in this
793       // case to preserve compatibility. In all other cases we remove the crypto
794       // feature.
795       if (!Args.hasArg(options::OPT_fno_integrated_as)) {
796         Features.push_back("-sha2");
797         Features.push_back("-aes");
798       }
799     }
800   }
801 
802   // Propagate frame-chain model selection
803   if (Arg *A = Args.getLastArg(options::OPT_mframe_chain)) {
804     StringRef FrameChainOption = A->getValue();
805     if (FrameChainOption.starts_with("aapcs"))
806       Features.push_back("+aapcs-frame-chain");
807   }
808 
809   // CMSE: Check for target 8M (for -mcmse to be applicable) is performed later.
810   if (Args.getLastArg(options::OPT_mcmse))
811     Features.push_back("+8msecext");
812 
813   if (Arg *A = Args.getLastArg(options::OPT_mfix_cmse_cve_2021_35465,
814                                options::OPT_mno_fix_cmse_cve_2021_35465)) {
815     if (!Args.getLastArg(options::OPT_mcmse))
816       D.Diag(diag::err_opt_not_valid_without_opt)
817           << A->getOption().getName() << "-mcmse";
818 
819     if (A->getOption().matches(options::OPT_mfix_cmse_cve_2021_35465))
820       Features.push_back("+fix-cmse-cve-2021-35465");
821     else
822       Features.push_back("-fix-cmse-cve-2021-35465");
823   }
824 
825   // This also handles the -m(no-)fix-cortex-a72-1655431 arguments via aliases.
826   if (Arg *A = Args.getLastArg(options::OPT_mfix_cortex_a57_aes_1742098,
827                                options::OPT_mno_fix_cortex_a57_aes_1742098)) {
828     if (A->getOption().matches(options::OPT_mfix_cortex_a57_aes_1742098)) {
829       Features.push_back("+fix-cortex-a57-aes-1742098");
830     } else {
831       Features.push_back("-fix-cortex-a57-aes-1742098");
832     }
833   }
834 
835   // Look for the last occurrence of -mlong-calls or -mno-long-calls. If
836   // neither options are specified, see if we are compiling for kernel/kext and
837   // decide whether to pass "+long-calls" based on the OS and its version.
838   if (Arg *A = Args.getLastArg(options::OPT_mlong_calls,
839                                options::OPT_mno_long_calls)) {
840     if (A->getOption().matches(options::OPT_mlong_calls))
841       Features.push_back("+long-calls");
842   } else if (KernelOrKext && (!Triple.isiOS() || Triple.isOSVersionLT(6)) &&
843              !Triple.isWatchOS() && !Triple.isXROS()) {
844     Features.push_back("+long-calls");
845   }
846 
847   // Generate execute-only output (no data access to code sections).
848   // This only makes sense for the compiler, not for the assembler.
849   // It's not needed for multilib selection and may hide an unused
850   // argument diagnostic if the code is always run.
851   if (!ForAS && !ForMultilib) {
852     // Supported only on ARMv6T2 and ARMv7 and above.
853     // Cannot be combined with -mno-movt.
854     if (Arg *A = Args.getLastArg(options::OPT_mexecute_only, options::OPT_mno_execute_only)) {
855       if (A->getOption().matches(options::OPT_mexecute_only)) {
856         if (getARMSubArchVersionNumber(Triple) < 7 &&
857             llvm::ARM::parseArch(Triple.getArchName()) != llvm::ARM::ArchKind::ARMV6T2 &&
858             llvm::ARM::parseArch(Triple.getArchName()) != llvm::ARM::ArchKind::ARMV6M)
859               D.Diag(diag::err_target_unsupported_execute_only) << Triple.getArchName();
860         else if (llvm::ARM::parseArch(Triple.getArchName()) == llvm::ARM::ArchKind::ARMV6M) {
861           if (Arg *PIArg = Args.getLastArg(options::OPT_fropi, options::OPT_frwpi,
862                                            options::OPT_fpic, options::OPT_fpie,
863                                            options::OPT_fPIC, options::OPT_fPIE))
864             D.Diag(diag::err_opt_not_valid_with_opt_on_target)
865                 << A->getAsString(Args) << PIArg->getAsString(Args) << Triple.getArchName();
866         } else if (Arg *B = Args.getLastArg(options::OPT_mno_movt))
867           D.Diag(diag::err_opt_not_valid_with_opt)
868               << A->getAsString(Args) << B->getAsString(Args);
869         Features.push_back("+execute-only");
870       }
871     }
872   }
873 
874   if (Arg *A = Args.getLastArg(options::OPT_mno_unaligned_access,
875                                       options::OPT_munaligned_access,
876                                       options::OPT_mstrict_align,
877                                       options::OPT_mno_strict_align)) {
878     // Kernel code has more strict alignment requirements.
879     if (KernelOrKext ||
880         A->getOption().matches(options::OPT_mno_unaligned_access) ||
881         A->getOption().matches(options::OPT_mstrict_align)) {
882       Features.push_back("+strict-align");
883     } else {
884       // No v6M core supports unaligned memory access (v6M ARM ARM A3.2).
885       if (Triple.getSubArch() == llvm::Triple::SubArchType::ARMSubArch_v6m)
886         D.Diag(diag::err_target_unsupported_unaligned) << "v6m";
887       // v8M Baseline follows on from v6M, so doesn't support unaligned memory
888       // access either.
889       else if (Triple.getSubArch() == llvm::Triple::SubArchType::ARMSubArch_v8m_baseline)
890         D.Diag(diag::err_target_unsupported_unaligned) << "v8m.base";
891     }
892   } else {
893     // Assume pre-ARMv6 doesn't support unaligned accesses.
894     //
895     // ARMv6 may or may not support unaligned accesses depending on the
896     // SCTLR.U bit, which is architecture-specific. We assume ARMv6
897     // Darwin and NetBSD targets support unaligned accesses, and others don't.
898     //
899     // ARMv7 always has SCTLR.U set to 1, but it has a new SCTLR.A bit which
900     // raises an alignment fault on unaligned accesses. Assume ARMv7+ supports
901     // unaligned accesses, except ARMv6-M, and ARMv8-M without the Main
902     // Extension. This aligns with the default behavior of ARM's downstream
903     // versions of GCC and Clang.
904     //
905     // Users can change the default behavior via -m[no-]unaliged-access.
906     int VersionNum = getARMSubArchVersionNumber(Triple);
907     if (Triple.isOSDarwin() || Triple.isOSNetBSD()) {
908       if (VersionNum < 6 ||
909           Triple.getSubArch() == llvm::Triple::SubArchType::ARMSubArch_v6m)
910         Features.push_back("+strict-align");
911     } else if (VersionNum < 7 ||
912                Triple.getSubArch() ==
913                    llvm::Triple::SubArchType::ARMSubArch_v6m ||
914                Triple.getSubArch() ==
915                    llvm::Triple::SubArchType::ARMSubArch_v8m_baseline) {
916       Features.push_back("+strict-align");
917     }
918   }
919 
920   // llvm does not support reserving registers in general. There is support
921   // for reserving r9 on ARM though (defined as a platform-specific register
922   // in ARM EABI).
923   if (Args.hasArg(options::OPT_ffixed_r9))
924     Features.push_back("+reserve-r9");
925 
926   // The kext linker doesn't know how to deal with movw/movt.
927   if (KernelOrKext || Args.hasArg(options::OPT_mno_movt))
928     Features.push_back("+no-movt");
929 
930   if (Args.hasArg(options::OPT_mno_neg_immediates))
931     Features.push_back("+no-neg-immediates");
932 
933   // Enable/disable straight line speculation hardening.
934   if (Arg *A = Args.getLastArg(options::OPT_mharden_sls_EQ)) {
935     StringRef Scope = A->getValue();
936     bool EnableRetBr = false;
937     bool EnableBlr = false;
938     bool DisableComdat = false;
939     if (Scope != "none") {
940       SmallVector<StringRef, 4> Opts;
941       Scope.split(Opts, ",");
942       for (auto Opt : Opts) {
943         Opt = Opt.trim();
944         if (Opt == "all") {
945           EnableBlr = true;
946           EnableRetBr = true;
947           continue;
948         }
949         if (Opt == "retbr") {
950           EnableRetBr = true;
951           continue;
952         }
953         if (Opt == "blr") {
954           EnableBlr = true;
955           continue;
956         }
957         if (Opt == "comdat") {
958           DisableComdat = false;
959           continue;
960         }
961         if (Opt == "nocomdat") {
962           DisableComdat = true;
963           continue;
964         }
965         D.Diag(diag::err_drv_unsupported_option_argument)
966             << A->getSpelling() << Scope;
967         break;
968       }
969     }
970 
971     if (EnableRetBr || EnableBlr)
972       if (!(isARMAProfile(Triple) && getARMSubArchVersionNumber(Triple) >= 7))
973         D.Diag(diag::err_sls_hardening_arm_not_supported)
974             << Scope << A->getAsString(Args);
975 
976     if (EnableRetBr)
977       Features.push_back("+harden-sls-retbr");
978     if (EnableBlr)
979       Features.push_back("+harden-sls-blr");
980     if (DisableComdat) {
981       Features.push_back("+harden-sls-nocomdat");
982     }
983   }
984 
985   if (Args.getLastArg(options::OPT_mno_bti_at_return_twice))
986     Features.push_back("+no-bti-at-return-twice");
987 
988   checkARMFloatABI(D, Args, HasFPRegs);
989 
990   return FPUKind;
991 }
992 
993 std::string arm::getARMArch(StringRef Arch, const llvm::Triple &Triple) {
994   std::string MArch;
995   if (!Arch.empty())
996     MArch = std::string(Arch);
997   else
998     MArch = std::string(Triple.getArchName());
999   MArch = StringRef(MArch).split("+").first.lower();
1000 
1001   // Handle -march=native.
1002   if (MArch == "native") {
1003     std::string CPU = std::string(llvm::sys::getHostCPUName());
1004     if (CPU != "generic") {
1005       // Translate the native cpu into the architecture suffix for that CPU.
1006       StringRef Suffix = arm::getLLVMArchSuffixForARM(CPU, MArch, Triple);
1007       // If there is no valid architecture suffix for this CPU we don't know how
1008       // to handle it, so return no architecture.
1009       if (Suffix.empty())
1010         MArch = "";
1011       else
1012         MArch = std::string("arm") + Suffix.str();
1013     }
1014   }
1015 
1016   return MArch;
1017 }
1018 
1019 /// Get the (LLVM) name of the minimum ARM CPU for the arch we are targeting.
1020 StringRef arm::getARMCPUForMArch(StringRef Arch, const llvm::Triple &Triple) {
1021   std::string MArch = getARMArch(Arch, Triple);
1022   // getARMCPUForArch defaults to the triple if MArch is empty, but empty MArch
1023   // here means an -march=native that we can't handle, so instead return no CPU.
1024   if (MArch.empty())
1025     return StringRef();
1026 
1027   // We need to return an empty string here on invalid MArch values as the
1028   // various places that call this function can't cope with a null result.
1029   return llvm::ARM::getARMCPUForArch(Triple, MArch);
1030 }
1031 
1032 /// getARMTargetCPU - Get the (LLVM) name of the ARM cpu we are targeting.
1033 std::string arm::getARMTargetCPU(StringRef CPU, StringRef Arch,
1034                                  const llvm::Triple &Triple) {
1035   // FIXME: Warn on inconsistent use of -mcpu and -march.
1036   // If we have -mcpu=, use that.
1037   if (!CPU.empty()) {
1038     std::string MCPU = StringRef(CPU).split("+").first.lower();
1039     // Handle -mcpu=native.
1040     if (MCPU == "native")
1041       return std::string(llvm::sys::getHostCPUName());
1042     else
1043       return MCPU;
1044   }
1045 
1046   return std::string(getARMCPUForMArch(Arch, Triple));
1047 }
1048 
1049 /// getLLVMArchSuffixForARM - Get the LLVM ArchKind value to use for a
1050 /// particular CPU (or Arch, if CPU is generic). This is needed to
1051 /// pass to functions like llvm::ARM::getDefaultFPU which need an
1052 /// ArchKind as well as a CPU name.
1053 llvm::ARM::ArchKind arm::getLLVMArchKindForARM(StringRef CPU, StringRef Arch,
1054                                                const llvm::Triple &Triple) {
1055   llvm::ARM::ArchKind ArchKind;
1056   if (CPU == "generic" || CPU.empty()) {
1057     std::string ARMArch = tools::arm::getARMArch(Arch, Triple);
1058     ArchKind = llvm::ARM::parseArch(ARMArch);
1059     if (ArchKind == llvm::ARM::ArchKind::INVALID)
1060       // In case of generic Arch, i.e. "arm",
1061       // extract arch from default cpu of the Triple
1062       ArchKind =
1063           llvm::ARM::parseCPUArch(llvm::ARM::getARMCPUForArch(Triple, ARMArch));
1064   } else {
1065     // FIXME: horrible hack to get around the fact that Cortex-A7 is only an
1066     // armv7k triple if it's actually been specified via "-arch armv7k".
1067     ArchKind = (Arch == "armv7k" || Arch == "thumbv7k")
1068                           ? llvm::ARM::ArchKind::ARMV7K
1069                           : llvm::ARM::parseCPUArch(CPU);
1070   }
1071   return ArchKind;
1072 }
1073 
1074 /// getLLVMArchSuffixForARM - Get the LLVM arch name to use for a particular
1075 /// CPU  (or Arch, if CPU is generic).
1076 // FIXME: This is redundant with -mcpu, why does LLVM use this.
1077 StringRef arm::getLLVMArchSuffixForARM(StringRef CPU, StringRef Arch,
1078                                        const llvm::Triple &Triple) {
1079   llvm::ARM::ArchKind ArchKind = getLLVMArchKindForARM(CPU, Arch, Triple);
1080   if (ArchKind == llvm::ARM::ArchKind::INVALID)
1081     return "";
1082   return llvm::ARM::getSubArch(ArchKind);
1083 }
1084 
1085 void arm::appendBE8LinkFlag(const ArgList &Args, ArgStringList &CmdArgs,
1086                             const llvm::Triple &Triple) {
1087   if (Args.hasArg(options::OPT_r))
1088     return;
1089 
1090   // ARMv7 (and later) and ARMv6-M do not support BE-32, so instruct the linker
1091   // to generate BE-8 executables.
1092   if (arm::getARMSubArchVersionNumber(Triple) >= 7 || arm::isARMMProfile(Triple))
1093     CmdArgs.push_back("--be8");
1094 }
1095