1 //===--- RISCV.cpp - RISCV 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 "RISCV.h"
10 #include "clang/Basic/CharInfo.h"
11 #include "clang/Driver/Driver.h"
12 #include "clang/Driver/DriverDiagnostic.h"
13 #include "clang/Driver/Options.h"
14 #include "llvm/Option/ArgList.h"
15 #include "llvm/ADT/Optional.h"
16 #include "llvm/Support/TargetParser.h"
17 #include "llvm/Support/raw_ostream.h"
18 #include "ToolChains/CommonArgs.h"
19
20 using namespace clang::driver;
21 using namespace clang::driver::tools;
22 using namespace clang;
23 using namespace llvm::opt;
24
25 namespace {
26 // Represents the major and version number components of a RISC-V extension
27 struct RISCVExtensionVersion {
28 StringRef Major;
29 StringRef Minor;
30 };
31 } // end anonymous namespace
32
getExtensionTypeDesc(StringRef Ext)33 static StringRef getExtensionTypeDesc(StringRef Ext) {
34 if (Ext.startswith("sx"))
35 return "non-standard supervisor-level extension";
36 if (Ext.startswith("s"))
37 return "standard supervisor-level extension";
38 if (Ext.startswith("x"))
39 return "non-standard user-level extension";
40 if (Ext.startswith("z"))
41 return "standard user-level extension";
42 return StringRef();
43 }
44
getExtensionType(StringRef Ext)45 static StringRef getExtensionType(StringRef Ext) {
46 if (Ext.startswith("sx"))
47 return "sx";
48 if (Ext.startswith("s"))
49 return "s";
50 if (Ext.startswith("x"))
51 return "x";
52 if (Ext.startswith("z"))
53 return "z";
54 return StringRef();
55 }
56
57 // If the extension is supported as experimental, return the version of that
58 // extension that the compiler currently supports.
59 static Optional<RISCVExtensionVersion>
isExperimentalExtension(StringRef Ext)60 isExperimentalExtension(StringRef Ext) {
61 if (Ext == "b" || Ext == "zbb" || Ext == "zbc" || Ext == "zbe" ||
62 Ext == "zbf" || Ext == "zbm" || Ext == "zbp" || Ext == "zbr" ||
63 Ext == "zbs" || Ext == "zbt" || Ext == "zbproposedc")
64 return RISCVExtensionVersion{"0", "92"};
65 if (Ext == "v")
66 return RISCVExtensionVersion{"0", "9"};
67 if (Ext == "zfh")
68 return RISCVExtensionVersion{"0", "1"};
69 return None;
70 }
71
isSupportedExtension(StringRef Ext)72 static bool isSupportedExtension(StringRef Ext) {
73 // LLVM supports "z" extensions which are marked as experimental.
74 if (isExperimentalExtension(Ext))
75 return true;
76
77 // LLVM does not support "sx", "s" nor "x" extensions.
78 return false;
79 }
80
81 // Extensions may have a version number, and may be separated by
82 // an underscore '_' e.g.: rv32i2_m2.
83 // Version number is divided into major and minor version numbers,
84 // separated by a 'p'. If the minor version is 0 then 'p0' can be
85 // omitted from the version string. E.g., rv32i2p0, rv32i2, rv32i2p1.
getExtensionVersion(const Driver & D,const ArgList & Args,StringRef MArch,StringRef Ext,StringRef In,std::string & Major,std::string & Minor)86 static bool getExtensionVersion(const Driver &D, const ArgList &Args,
87 StringRef MArch, StringRef Ext, StringRef In,
88 std::string &Major, std::string &Minor) {
89 Major = std::string(In.take_while(isDigit));
90 In = In.substr(Major.size());
91
92 if (Major.size() && In.consume_front("p")) {
93 Minor = std::string(In.take_while(isDigit));
94 In = In.substr(Major.size() + 1);
95
96 // Expected 'p' to be followed by minor version number.
97 if (Minor.empty()) {
98 std::string Error =
99 "minor version number missing after 'p' for extension";
100 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
101 << MArch << Error << Ext;
102 return false;
103 }
104 }
105
106 // Expected multi-character extension with version number to have no
107 // subsequent characters (i.e. must either end string or be followed by
108 // an underscore).
109 if (Ext.size() > 1 && In.size()) {
110 std::string Error =
111 "multi-character extensions must be separated by underscores";
112 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name) << MArch << Error << In;
113 return false;
114 }
115
116 // If experimental extension, require use of current version number number
117 if (auto ExperimentalExtension = isExperimentalExtension(Ext)) {
118 if (!Args.hasArg(options::OPT_menable_experimental_extensions)) {
119 std::string Error =
120 "requires '-menable-experimental-extensions' for experimental extension";
121 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
122 << MArch << Error << Ext;
123 return false;
124 } else if (Major.empty() && Minor.empty()) {
125 std::string Error =
126 "experimental extension requires explicit version number";
127 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
128 << MArch << Error << Ext;
129 return false;
130 }
131 auto SupportedVers = *ExperimentalExtension;
132 if (Major != SupportedVers.Major || Minor != SupportedVers.Minor) {
133 std::string Error =
134 "unsupported version number " + Major;
135 if (!Minor.empty())
136 Error += "." + Minor;
137 Error += " for experimental extension (this compiler supports "
138 + SupportedVers.Major.str() + "."
139 + SupportedVers.Minor.str() + ")";
140
141 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
142 << MArch << Error << Ext;
143 return false;
144 }
145 return true;
146 }
147
148 // Allow extensions to declare no version number
149 if (Major.empty() && Minor.empty())
150 return true;
151
152 // TODO: Handle supported extensions with version number.
153 std::string Error = "unsupported version number " + Major;
154 if (!Minor.empty())
155 Error += "." + Minor;
156 Error += " for extension";
157 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name) << MArch << Error << Ext;
158
159 return false;
160 }
161
162 // Handle other types of extensions other than the standard
163 // general purpose and standard user-level extensions.
164 // Parse the ISA string containing non-standard user-level
165 // extensions, standard supervisor-level extensions and
166 // non-standard supervisor-level extensions.
167 // These extensions start with 'z', 'x', 's', 'sx' prefixes, follow a
168 // canonical order, might have a version number (major, minor)
169 // and are separated by a single underscore '_'.
170 // Set the hardware features for the extensions that are supported.
getExtensionFeatures(const Driver & D,const ArgList & Args,std::vector<StringRef> & Features,StringRef & MArch,StringRef & Exts)171 static void getExtensionFeatures(const Driver &D,
172 const ArgList &Args,
173 std::vector<StringRef> &Features,
174 StringRef &MArch, StringRef &Exts) {
175 if (Exts.empty())
176 return;
177
178 // Multi-letter extensions are seperated by a single underscore
179 // as described in RISC-V User-Level ISA V2.2.
180 SmallVector<StringRef, 8> Split;
181 Exts.split(Split, StringRef("_"));
182
183 SmallVector<StringRef, 4> Prefix{"z", "x", "s", "sx"};
184 auto I = Prefix.begin();
185 auto E = Prefix.end();
186
187 SmallVector<StringRef, 8> AllExts;
188
189 for (StringRef Ext : Split) {
190 if (Ext.empty()) {
191 D.Diag(diag::err_drv_invalid_riscv_arch_name) << MArch
192 << "extension name missing after separator '_'";
193 return;
194 }
195
196 StringRef Type = getExtensionType(Ext);
197 StringRef Desc = getExtensionTypeDesc(Ext);
198 auto Pos = Ext.find_if(isDigit);
199 StringRef Name(Ext.substr(0, Pos));
200 StringRef Vers(Ext.substr(Pos));
201
202 if (Type.empty()) {
203 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
204 << MArch << "invalid extension prefix" << Ext;
205 return;
206 }
207
208 // Check ISA extensions are specified in the canonical order.
209 while (I != E && *I != Type)
210 ++I;
211
212 if (I == E) {
213 std::string Error = std::string(Desc);
214 Error += " not given in canonical order";
215 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
216 << MArch << Error << Ext;
217 return;
218 }
219
220 // The order is OK, do not advance I to the next prefix
221 // to allow repeated extension type, e.g.: rv32ixabc_xdef.
222
223 if (Name.size() == Type.size()) {
224 std::string Error = std::string(Desc);
225 Error += " name missing after";
226 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
227 << MArch << Error << Type;
228 return;
229 }
230
231 std::string Major, Minor;
232 if (!getExtensionVersion(D, Args, MArch, Name, Vers, Major, Minor))
233 return;
234
235 // Check if duplicated extension.
236 if (llvm::is_contained(AllExts, Name)) {
237 std::string Error = "duplicated ";
238 Error += Desc;
239 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
240 << MArch << Error << Name;
241 return;
242 }
243
244 // Extension format is correct, keep parsing the extensions.
245 // TODO: Save Type, Name, Major, Minor to avoid parsing them later.
246 AllExts.push_back(Name);
247 }
248
249 // Set target features.
250 // TODO: Hardware features to be handled in Support/TargetParser.cpp.
251 // TODO: Use version number when setting target features.
252 for (auto Ext : AllExts) {
253 if (!isSupportedExtension(Ext)) {
254 StringRef Desc = getExtensionTypeDesc(getExtensionType(Ext));
255 std::string Error = "unsupported ";
256 Error += Desc;
257 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
258 << MArch << Error << Ext;
259 return;
260 }
261 if (isExperimentalExtension(Ext))
262 Features.push_back(Args.MakeArgString("+experimental-" + Ext));
263 else
264 Features.push_back(Args.MakeArgString("+" + Ext));
265 }
266 }
267
268 // Returns false if an error is diagnosed.
getArchFeatures(const Driver & D,StringRef MArch,std::vector<StringRef> & Features,const ArgList & Args)269 static bool getArchFeatures(const Driver &D, StringRef MArch,
270 std::vector<StringRef> &Features,
271 const ArgList &Args) {
272 // RISC-V ISA strings must be lowercase.
273 if (llvm::any_of(MArch, [](char c) { return isupper(c); })) {
274 D.Diag(diag::err_drv_invalid_riscv_arch_name)
275 << MArch << "string must be lowercase";
276 return false;
277 }
278
279 // ISA string must begin with rv32 or rv64.
280 if (!(MArch.startswith("rv32") || MArch.startswith("rv64")) ||
281 (MArch.size() < 5)) {
282 D.Diag(diag::err_drv_invalid_riscv_arch_name)
283 << MArch << "string must begin with rv32{i,e,g} or rv64{i,g}";
284 return false;
285 }
286
287 bool HasRV64 = MArch.startswith("rv64");
288
289 // The canonical order specified in ISA manual.
290 // Ref: Table 22.1 in RISC-V User-Level ISA V2.2
291 StringRef StdExts = "mafdqlcbjtpvn";
292 bool HasF = false, HasD = false;
293 char Baseline = MArch[4];
294
295 // First letter should be 'e', 'i' or 'g'.
296 switch (Baseline) {
297 default:
298 D.Diag(diag::err_drv_invalid_riscv_arch_name)
299 << MArch << "first letter should be 'e', 'i' or 'g'";
300 return false;
301 case 'e': {
302 StringRef Error;
303 // Currently LLVM does not support 'e'.
304 // Extension 'e' is not allowed in rv64.
305 if (HasRV64)
306 Error = "standard user-level extension 'e' requires 'rv32'";
307 else
308 Error = "unsupported standard user-level extension 'e'";
309 D.Diag(diag::err_drv_invalid_riscv_arch_name) << MArch << Error;
310 return false;
311 }
312 case 'i':
313 break;
314 case 'g':
315 // g = imafd
316 StdExts = StdExts.drop_front(4);
317 Features.push_back("+m");
318 Features.push_back("+a");
319 Features.push_back("+f");
320 Features.push_back("+d");
321 HasF = true;
322 HasD = true;
323 break;
324 }
325
326 // Skip rvxxx
327 StringRef Exts = MArch.substr(5);
328
329 // Remove multi-letter standard extensions, non-standard extensions and
330 // supervisor-level extensions. They have 'z', 'x', 's', 'sx' prefixes.
331 // Parse them at the end.
332 // Find the very first occurrence of 's', 'x' or 'z'.
333 StringRef OtherExts;
334 size_t Pos = Exts.find_first_of("zsx");
335 if (Pos != StringRef::npos) {
336 OtherExts = Exts.substr(Pos);
337 Exts = Exts.substr(0, Pos);
338 }
339
340 std::string Major, Minor;
341 if (!getExtensionVersion(D, Args, MArch, std::string(1, Baseline), Exts,
342 Major, Minor))
343 return false;
344
345 // Consume the base ISA version number and any '_' between rvxxx and the
346 // first extension
347 Exts = Exts.drop_front(Major.size());
348 if (!Minor.empty())
349 Exts = Exts.drop_front(Minor.size() + 1 /*'p'*/);
350 Exts.consume_front("_");
351
352 // TODO: Use version number when setting target features
353
354 auto StdExtsItr = StdExts.begin();
355 auto StdExtsEnd = StdExts.end();
356
357 for (auto I = Exts.begin(), E = Exts.end(); I != E; ) {
358 char c = *I;
359
360 // Check ISA extensions are specified in the canonical order.
361 while (StdExtsItr != StdExtsEnd && *StdExtsItr != c)
362 ++StdExtsItr;
363
364 if (StdExtsItr == StdExtsEnd) {
365 // Either c contains a valid extension but it was not given in
366 // canonical order or it is an invalid extension.
367 StringRef Error;
368 if (StdExts.contains(c))
369 Error = "standard user-level extension not given in canonical order";
370 else
371 Error = "invalid standard user-level extension";
372 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
373 << MArch << Error << std::string(1, c);
374 return false;
375 }
376
377 // Move to next char to prevent repeated letter.
378 ++StdExtsItr;
379
380 std::string Next, Major, Minor;
381 if (std::next(I) != E)
382 Next = std::string(std::next(I), E);
383 if (!getExtensionVersion(D, Args, MArch, std::string(1, c), Next, Major,
384 Minor))
385 return false;
386
387 // The order is OK, then push it into features.
388 // TODO: Use version number when setting target features
389 switch (c) {
390 default:
391 // Currently LLVM supports only "mafdc".
392 D.Diag(diag::err_drv_invalid_riscv_ext_arch_name)
393 << MArch << "unsupported standard user-level extension"
394 << std::string(1, c);
395 return false;
396 case 'm':
397 Features.push_back("+m");
398 break;
399 case 'a':
400 Features.push_back("+a");
401 break;
402 case 'f':
403 Features.push_back("+f");
404 HasF = true;
405 break;
406 case 'd':
407 Features.push_back("+d");
408 HasD = true;
409 break;
410 case 'c':
411 Features.push_back("+c");
412 break;
413 case 'b':
414 Features.push_back("+experimental-b");
415 break;
416 case 'v':
417 Features.push_back("+experimental-v");
418 break;
419 }
420
421 // Consume full extension name and version, including any optional '_'
422 // between this extension and the next
423 ++I;
424 I += Major.size();
425 if (Minor.size())
426 I += Minor.size() + 1 /*'p'*/;
427 if (*I == '_')
428 ++I;
429 }
430
431 // Dependency check.
432 // It's illegal to specify the 'd' (double-precision floating point)
433 // extension without also specifying the 'f' (single precision
434 // floating-point) extension.
435 if (HasD && !HasF) {
436 D.Diag(diag::err_drv_invalid_riscv_arch_name)
437 << MArch << "d requires f extension to also be specified";
438 return false;
439 }
440
441 // Additional dependency checks.
442 // TODO: The 'q' extension requires rv64.
443 // TODO: It is illegal to specify 'e' extensions with 'f' and 'd'.
444
445 // Handle all other types of extensions.
446 getExtensionFeatures(D, Args, Features, MArch, OtherExts);
447
448 return true;
449 }
450
451 // Get features except standard extension feature
getRISCFeaturesFromMcpu(const Driver & D,const llvm::Triple & Triple,const llvm::opt::ArgList & Args,const llvm::opt::Arg * A,StringRef Mcpu,std::vector<StringRef> & Features)452 static void getRISCFeaturesFromMcpu(const Driver &D, const llvm::Triple &Triple,
453 const llvm::opt::ArgList &Args,
454 const llvm::opt::Arg *A, StringRef Mcpu,
455 std::vector<StringRef> &Features) {
456 bool Is64Bit = (Triple.getArch() == llvm::Triple::riscv64);
457 llvm::RISCV::CPUKind CPUKind = llvm::RISCV::parseCPUKind(Mcpu);
458 if (!llvm::RISCV::checkCPUKind(CPUKind, Is64Bit) ||
459 !llvm::RISCV::getCPUFeaturesExceptStdExt(CPUKind, Features)) {
460 D.Diag(clang::diag::err_drv_clang_unsupported) << A->getAsString(Args);
461 }
462 }
463
getRISCVTargetFeatures(const Driver & D,const llvm::Triple & Triple,const ArgList & Args,std::vector<StringRef> & Features)464 void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
465 const ArgList &Args,
466 std::vector<StringRef> &Features) {
467 StringRef MArch = getRISCVArch(Args, Triple);
468
469 if (!getArchFeatures(D, MArch, Features, Args))
470 return;
471
472 // If users give march and mcpu, get std extension feature from MArch
473 // and other features (ex. mirco architecture feature) from mcpu
474 if (Arg *A = Args.getLastArg(options::OPT_mcpu_EQ))
475 getRISCFeaturesFromMcpu(D, Triple, Args, A, A->getValue(), Features);
476
477 // Handle features corresponding to "-ffixed-X" options
478 if (Args.hasArg(options::OPT_ffixed_x1))
479 Features.push_back("+reserve-x1");
480 if (Args.hasArg(options::OPT_ffixed_x2))
481 Features.push_back("+reserve-x2");
482 if (Args.hasArg(options::OPT_ffixed_x3))
483 Features.push_back("+reserve-x3");
484 if (Args.hasArg(options::OPT_ffixed_x4))
485 Features.push_back("+reserve-x4");
486 if (Args.hasArg(options::OPT_ffixed_x5))
487 Features.push_back("+reserve-x5");
488 if (Args.hasArg(options::OPT_ffixed_x6))
489 Features.push_back("+reserve-x6");
490 if (Args.hasArg(options::OPT_ffixed_x7))
491 Features.push_back("+reserve-x7");
492 if (Args.hasArg(options::OPT_ffixed_x8))
493 Features.push_back("+reserve-x8");
494 if (Args.hasArg(options::OPT_ffixed_x9))
495 Features.push_back("+reserve-x9");
496 if (Args.hasArg(options::OPT_ffixed_x10))
497 Features.push_back("+reserve-x10");
498 if (Args.hasArg(options::OPT_ffixed_x11))
499 Features.push_back("+reserve-x11");
500 if (Args.hasArg(options::OPT_ffixed_x12))
501 Features.push_back("+reserve-x12");
502 if (Args.hasArg(options::OPT_ffixed_x13))
503 Features.push_back("+reserve-x13");
504 if (Args.hasArg(options::OPT_ffixed_x14))
505 Features.push_back("+reserve-x14");
506 if (Args.hasArg(options::OPT_ffixed_x15))
507 Features.push_back("+reserve-x15");
508 if (Args.hasArg(options::OPT_ffixed_x16))
509 Features.push_back("+reserve-x16");
510 if (Args.hasArg(options::OPT_ffixed_x17))
511 Features.push_back("+reserve-x17");
512 if (Args.hasArg(options::OPT_ffixed_x18))
513 Features.push_back("+reserve-x18");
514 if (Args.hasArg(options::OPT_ffixed_x19))
515 Features.push_back("+reserve-x19");
516 if (Args.hasArg(options::OPT_ffixed_x20))
517 Features.push_back("+reserve-x20");
518 if (Args.hasArg(options::OPT_ffixed_x21))
519 Features.push_back("+reserve-x21");
520 if (Args.hasArg(options::OPT_ffixed_x22))
521 Features.push_back("+reserve-x22");
522 if (Args.hasArg(options::OPT_ffixed_x23))
523 Features.push_back("+reserve-x23");
524 if (Args.hasArg(options::OPT_ffixed_x24))
525 Features.push_back("+reserve-x24");
526 if (Args.hasArg(options::OPT_ffixed_x25))
527 Features.push_back("+reserve-x25");
528 if (Args.hasArg(options::OPT_ffixed_x26))
529 Features.push_back("+reserve-x26");
530 if (Args.hasArg(options::OPT_ffixed_x27))
531 Features.push_back("+reserve-x27");
532 if (Args.hasArg(options::OPT_ffixed_x28))
533 Features.push_back("+reserve-x28");
534 if (Args.hasArg(options::OPT_ffixed_x29))
535 Features.push_back("+reserve-x29");
536 if (Args.hasArg(options::OPT_ffixed_x30))
537 Features.push_back("+reserve-x30");
538 if (Args.hasArg(options::OPT_ffixed_x31))
539 Features.push_back("+reserve-x31");
540
541 // -mrelax is default, unless -mno-relax is specified.
542 if (Args.hasFlag(options::OPT_mrelax, options::OPT_mno_relax, true))
543 Features.push_back("+relax");
544 else
545 Features.push_back("-relax");
546
547 // GCC Compatibility: -mno-save-restore is default, unless -msave-restore is
548 // specified.
549 if (Args.hasFlag(options::OPT_msave_restore, options::OPT_mno_save_restore, false))
550 Features.push_back("+save-restore");
551 else
552 Features.push_back("-save-restore");
553
554 // Now add any that the user explicitly requested on the command line,
555 // which may override the defaults.
556 handleTargetFeaturesGroup(Args, Features, options::OPT_m_riscv_Features_Group);
557 }
558
getRISCVABI(const ArgList & Args,const llvm::Triple & Triple)559 StringRef riscv::getRISCVABI(const ArgList &Args, const llvm::Triple &Triple) {
560 assert((Triple.getArch() == llvm::Triple::riscv32 ||
561 Triple.getArch() == llvm::Triple::riscv64) &&
562 "Unexpected triple");
563
564 // GCC's logic around choosing a default `-mabi=` is complex. If GCC is not
565 // configured using `--with-abi=`, then the logic for the default choice is
566 // defined in config.gcc. This function is based on the logic in GCC 9.2.0.
567 //
568 // The logic used in GCC 9.2.0 is the following, in order:
569 // 1. Explicit choices using `--with-abi=`
570 // 2. A default based on `--with-arch=`, if provided
571 // 3. A default based on the target triple's arch
572 //
573 // The logic in config.gcc is a little circular but it is not inconsistent.
574 //
575 // Clang does not have `--with-arch=` or `--with-abi=`, so we use `-march=`
576 // and `-mabi=` respectively instead.
577 //
578 // In order to make chosing logic more clear, Clang uses the following logic,
579 // in order:
580 // 1. Explicit choices using `-mabi=`
581 // 2. A default based on the architecture as determined by getRISCVArch
582 // 3. Choose a default based on the triple
583
584 // 1. If `-mabi=` is specified, use it.
585 if (const Arg *A = Args.getLastArg(options::OPT_mabi_EQ))
586 return A->getValue();
587
588 // 2. Choose a default based on the target architecture.
589 //
590 // rv32g | rv32*d -> ilp32d
591 // rv32e -> ilp32e
592 // rv32* -> ilp32
593 // rv64g | rv64*d -> lp64d
594 // rv64* -> lp64
595 StringRef MArch = getRISCVArch(Args, Triple);
596
597 if (MArch.startswith_lower("rv32")) {
598 // FIXME: parse `March` to find `D` extension properly
599 if (MArch.substr(4).contains_lower("d") || MArch.startswith_lower("rv32g"))
600 return "ilp32d";
601 else if (MArch.startswith_lower("rv32e"))
602 return "ilp32e";
603 else
604 return "ilp32";
605 } else if (MArch.startswith_lower("rv64")) {
606 // FIXME: parse `March` to find `D` extension properly
607 if (MArch.substr(4).contains_lower("d") || MArch.startswith_lower("rv64g"))
608 return "lp64d";
609 else
610 return "lp64";
611 }
612
613 // 3. Choose a default based on the triple
614 //
615 // We deviate from GCC's defaults here:
616 // - On `riscv{XLEN}-unknown-elf` we use the integer calling convention only.
617 // - On all other OSs we use the double floating point calling convention.
618 if (Triple.getArch() == llvm::Triple::riscv32) {
619 if (Triple.getOS() == llvm::Triple::UnknownOS)
620 return "ilp32";
621 else
622 return "ilp32d";
623 } else {
624 if (Triple.getOS() == llvm::Triple::UnknownOS)
625 return "lp64";
626 else
627 return "lp64d";
628 }
629 }
630
getRISCVArch(const llvm::opt::ArgList & Args,const llvm::Triple & Triple)631 StringRef riscv::getRISCVArch(const llvm::opt::ArgList &Args,
632 const llvm::Triple &Triple) {
633 assert((Triple.getArch() == llvm::Triple::riscv32 ||
634 Triple.getArch() == llvm::Triple::riscv64) &&
635 "Unexpected triple");
636
637 // GCC's logic around choosing a default `-march=` is complex. If GCC is not
638 // configured using `--with-arch=`, then the logic for the default choice is
639 // defined in config.gcc. This function is based on the logic in GCC 9.2.0. We
640 // deviate from GCC's default on additional `-mcpu` option (GCC does not
641 // support `-mcpu`) and baremetal targets (UnknownOS) where neither `-march`
642 // nor `-mabi` is specified.
643 //
644 // The logic used in GCC 9.2.0 is the following, in order:
645 // 1. Explicit choices using `--with-arch=`
646 // 2. A default based on `--with-abi=`, if provided
647 // 3. A default based on the target triple's arch
648 //
649 // The logic in config.gcc is a little circular but it is not inconsistent.
650 //
651 // Clang does not have `--with-arch=` or `--with-abi=`, so we use `-march=`
652 // and `-mabi=` respectively instead.
653 //
654 // Clang uses the following logic, in order:
655 // 1. Explicit choices using `-march=`
656 // 2. Based on `-mcpu` if the target CPU has a default ISA string
657 // 3. A default based on `-mabi`, if provided
658 // 4. A default based on the target triple's arch
659 //
660 // Clang does not yet support MULTILIB_REUSE, so we use `rv{XLEN}imafdc`
661 // instead of `rv{XLEN}gc` though they are (currently) equivalent.
662
663 // 1. If `-march=` is specified, use it.
664 if (const Arg *A = Args.getLastArg(options::OPT_march_EQ))
665 return A->getValue();
666
667 // 2. Get march (isa string) based on `-mcpu=`
668 if (const Arg *A = Args.getLastArg(options::OPT_mcpu_EQ)) {
669 StringRef MArch = llvm::RISCV::getMArchFromMcpu(A->getValue());
670 // Bypass if target cpu's default march is empty.
671 if (MArch != "")
672 return MArch;
673 }
674
675 // 3. Choose a default based on `-mabi=`
676 //
677 // ilp32e -> rv32e
678 // ilp32 | ilp32f | ilp32d -> rv32imafdc
679 // lp64 | lp64f | lp64d -> rv64imafdc
680 if (const Arg *A = Args.getLastArg(options::OPT_mabi_EQ)) {
681 StringRef MABI = A->getValue();
682
683 if (MABI.equals_lower("ilp32e"))
684 return "rv32e";
685 else if (MABI.startswith_lower("ilp32"))
686 return "rv32imafdc";
687 else if (MABI.startswith_lower("lp64"))
688 return "rv64imafdc";
689 }
690
691 // 4. Choose a default based on the triple
692 //
693 // We deviate from GCC's defaults here:
694 // - On `riscv{XLEN}-unknown-elf` we default to `rv{XLEN}imac`
695 // - On all other OSs we use `rv{XLEN}imafdc` (equivalent to `rv{XLEN}gc`)
696 if (Triple.getArch() == llvm::Triple::riscv32) {
697 if (Triple.getOS() == llvm::Triple::UnknownOS)
698 return "rv32imac";
699 else
700 return "rv32imafdc";
701 } else {
702 if (Triple.getOS() == llvm::Triple::UnknownOS)
703 return "rv64imac";
704 else
705 return "rv64imafdc";
706 }
707 }
708