1//===-- AsmPrinterInlineAsm.cpp - AsmPrinter Inline Asm Handling ----------===//
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// This file implements the inline assembler pieces of the AsmPrinter class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/ADT/SmallString.h"
14#include "llvm/ADT/SmallVector.h"
15#include "llvm/ADT/StringExtras.h"
16#include "llvm/ADT/Twine.h"
17#include "llvm/CodeGen/AsmPrinter.h"
18#include "llvm/CodeGen/MachineBasicBlock.h"
19#include "llvm/CodeGen/MachineFunction.h"
20#include "llvm/CodeGen/MachineModuleInfo.h"
21#include "llvm/CodeGen/TargetRegisterInfo.h"
22#include "llvm/CodeGen/TargetSubtargetInfo.h"
23#include "llvm/IR/Constants.h"
24#include "llvm/IR/DataLayout.h"
25#include "llvm/IR/DiagnosticInfo.h"
26#include "llvm/IR/InlineAsm.h"
27#include "llvm/IR/LLVMContext.h"
28#include "llvm/IR/Module.h"
29#include "llvm/MC/MCAsmInfo.h"
30#include "llvm/MC/MCInstrInfo.h"
31#include "llvm/MC/MCParser/AsmLexer.h"
32#include "llvm/MC/MCParser/MCTargetAsmParser.h"
33#include "llvm/MC/MCStreamer.h"
34#include "llvm/MC/MCSymbol.h"
35#include "llvm/MC/TargetRegistry.h"
36#include "llvm/Support/ErrorHandling.h"
37#include "llvm/Support/MemoryBuffer.h"
38#include "llvm/Support/SourceMgr.h"
39#include "llvm/Support/raw_ostream.h"
40#include "llvm/Target/TargetMachine.h"
41using namespace llvm;
42
43#define DEBUG_TYPE "asm-printer"
44
45unsigned AsmPrinter::addInlineAsmDiagBuffer(StringRef AsmStr,
46 const MDNode *LocMDNode) const {
47 MCContext &Context = MMI->getContext();
48 Context.initInlineSourceManager();
49 SourceMgr &SrcMgr = *Context.getInlineSourceManager();
50 std::vector<const MDNode *> &LocInfos = Context.getLocInfos();
51
52 std::unique_ptr<MemoryBuffer> Buffer;
53 // The inline asm source manager will outlive AsmStr, so make a copy of the
54 // string for SourceMgr to own.
55 Buffer = MemoryBuffer::getMemBufferCopy(InputData: AsmStr, BufferName: "<inline asm>");
56
57 // Tell SrcMgr about this buffer, it takes ownership of the buffer.
58 unsigned BufNum = SrcMgr.AddNewSourceBuffer(F: std::move(Buffer), IncludeLoc: SMLoc());
59
60 // Store LocMDNode in DiagInfo, using BufNum as an identifier.
61 if (LocMDNode) {
62 LocInfos.resize(new_size: BufNum);
63 LocInfos[BufNum - 1] = LocMDNode;
64 }
65
66 return BufNum;
67}
68
69
70/// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
71void AsmPrinter::emitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
72 const MCTargetOptions &MCOptions,
73 const MDNode *LocMDNode,
74 InlineAsm::AsmDialect Dialect) const {
75 assert(!Str.empty() && "Can't emit empty inline asm block");
76
77 // Remember if the buffer is nul terminated or not so we can avoid a copy.
78 bool isNullTerminated = Str.back() == 0;
79 if (isNullTerminated)
80 Str = Str.substr(Start: 0, N: Str.size()-1);
81
82 // If the output streamer does not have mature MC support or the integrated
83 // assembler has been disabled or not required, just emit the blob textually.
84 // Otherwise parse the asm and emit it via MC support.
85 // This is useful in case the asm parser doesn't handle something but the
86 // system assembler does.
87 const MCAsmInfo *MCAI = TM.getMCAsmInfo();
88 assert(MCAI && "No MCAsmInfo");
89 if (!MCAI->useIntegratedAssembler() &&
90 !MCAI->parseInlineAsmUsingAsmParser() &&
91 !OutStreamer->isIntegratedAssemblerRequired()) {
92 emitInlineAsmStart();
93 OutStreamer->emitRawText(String: Str);
94 emitInlineAsmEnd(StartInfo: STI, EndInfo: nullptr);
95 return;
96 }
97
98 unsigned BufNum = addInlineAsmDiagBuffer(AsmStr: Str, LocMDNode);
99 SourceMgr &SrcMgr = *MMI->getContext().getInlineSourceManager();
100 SrcMgr.setIncludeDirs(MCOptions.IASSearchPaths);
101
102 std::unique_ptr<MCAsmParser> Parser(
103 createMCAsmParser(SrcMgr, OutContext, *OutStreamer, *MAI, CB: BufNum));
104
105 // We create a new MCInstrInfo here since we might be at the module level
106 // and not have a MachineFunction to initialize the TargetInstrInfo from and
107 // we only need MCInstrInfo for asm parsing. We create one unconditionally
108 // because it's not subtarget dependent.
109 std::unique_ptr<MCInstrInfo> MII(TM.getTarget().createMCInstrInfo());
110 assert(MII && "Failed to create instruction info");
111 std::unique_ptr<MCTargetAsmParser> TAP(TM.getTarget().createMCAsmParser(
112 STI, Parser&: *Parser, MII: *MII, Options: MCOptions));
113 if (!TAP)
114 report_fatal_error(reason: "Inline asm not supported by this streamer because"
115 " we don't have an asm parser for this target\n");
116
117 // Respect inlineasm dialect on X86 targets only
118 if (TM.getTargetTriple().isX86()) {
119 Parser->setAssemblerDialect(Dialect);
120 // Enable lexing Masm binary and hex integer literals in intel inline
121 // assembly.
122 if (Dialect == InlineAsm::AD_Intel)
123 Parser->getLexer().setLexMasmIntegers(true);
124 }
125 Parser->setTargetParser(*TAP);
126
127 emitInlineAsmStart();
128 // Don't implicitly switch to the text section before the asm.
129 (void)Parser->Run(/*NoInitialTextSection*/ true,
130 /*NoFinalize*/ true);
131 emitInlineAsmEnd(StartInfo: STI, EndInfo: &TAP->getSTI());
132}
133
134static void EmitInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
135 MachineModuleInfo *MMI, const MCAsmInfo *MAI,
136 AsmPrinter *AP, uint64_t LocCookie,
137 raw_ostream &OS) {
138 bool InputIsIntelDialect = MI->getInlineAsmDialect() == InlineAsm::AD_Intel;
139
140 if (InputIsIntelDialect) {
141 // Switch to the inline assembly variant.
142 OS << "\t.intel_syntax\n\t";
143 }
144
145 int CurVariant = -1; // The number of the {.|.|.} region we are in.
146 const char *LastEmitted = AsmStr; // One past the last character emitted.
147 unsigned NumOperands = MI->getNumOperands();
148
149 int AsmPrinterVariant;
150 if (InputIsIntelDialect)
151 AsmPrinterVariant = 1; // X86MCAsmInfo.cpp's AsmWriterFlavorTy::Intel.
152 else
153 AsmPrinterVariant = MMI->getTarget().unqualifiedInlineAsmVariant();
154
155 // FIXME: Should this happen for `asm inteldialect` as well?
156 if (!InputIsIntelDialect && !MAI->isHLASM())
157 OS << '\t';
158
159 while (*LastEmitted) {
160 switch (*LastEmitted) {
161 default: {
162 // Not a special case, emit the string section literally.
163 const char *LiteralEnd = LastEmitted+1;
164 while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
165 *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
166 ++LiteralEnd;
167 if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
168 OS.write(Ptr: LastEmitted, Size: LiteralEnd - LastEmitted);
169 LastEmitted = LiteralEnd;
170 break;
171 }
172 case '\n':
173 ++LastEmitted; // Consume newline character.
174 OS << '\n'; // Indent code with newline.
175 break;
176 case '$': {
177 ++LastEmitted; // Consume '$' character.
178 bool Done = true;
179
180 // Handle escapes.
181 switch (*LastEmitted) {
182 default: Done = false; break;
183 case '$': // $$ -> $
184 if (!InputIsIntelDialect)
185 if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
186 OS << '$';
187 ++LastEmitted; // Consume second '$' character.
188 break;
189 case '(': // $( -> same as GCC's { character.
190 ++LastEmitted; // Consume '(' character.
191 if (CurVariant != -1)
192 report_fatal_error(reason: "Nested variants found in inline asm string: '" +
193 Twine(AsmStr) + "'");
194 CurVariant = 0; // We're in the first variant now.
195 break;
196 case '|':
197 ++LastEmitted; // Consume '|' character.
198 if (CurVariant == -1)
199 OS << '|'; // This is gcc's behavior for | outside a variant.
200 else
201 ++CurVariant; // We're in the next variant.
202 break;
203 case ')': // $) -> same as GCC's } char.
204 ++LastEmitted; // Consume ')' character.
205 if (CurVariant == -1)
206 OS << '}'; // This is gcc's behavior for } outside a variant.
207 else
208 CurVariant = -1;
209 break;
210 }
211 if (Done) break;
212
213 bool HasCurlyBraces = false;
214 if (*LastEmitted == '{') { // ${variable}
215 ++LastEmitted; // Consume '{' character.
216 HasCurlyBraces = true;
217 }
218
219 // If we have ${:foo}, then this is not a real operand reference, it is a
220 // "magic" string reference, just like in .td files. Arrange to call
221 // PrintSpecial.
222 if (HasCurlyBraces && *LastEmitted == ':') {
223 ++LastEmitted;
224 const char *StrStart = LastEmitted;
225 const char *StrEnd = strchr(s: StrStart, c: '}');
226 if (!StrEnd)
227 report_fatal_error(reason: "Unterminated ${:foo} operand in inline asm"
228 " string: '" + Twine(AsmStr) + "'");
229 if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
230 AP->PrintSpecial(MI, OS, Code: StringRef(StrStart, StrEnd - StrStart));
231 LastEmitted = StrEnd+1;
232 break;
233 }
234
235 const char *IDStart = LastEmitted;
236 const char *IDEnd = IDStart;
237 while (isDigit(C: *IDEnd))
238 ++IDEnd;
239
240 unsigned Val;
241 if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(Radix: 10, Result&: Val))
242 report_fatal_error(reason: "Bad $ operand number in inline asm string: '" +
243 Twine(AsmStr) + "'");
244 LastEmitted = IDEnd;
245
246 if (Val >= NumOperands - 1)
247 report_fatal_error(reason: "Invalid $ operand number in inline asm string: '" +
248 Twine(AsmStr) + "'");
249
250 char Modifier[2] = { 0, 0 };
251
252 if (HasCurlyBraces) {
253 // If we have curly braces, check for a modifier character. This
254 // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
255 if (*LastEmitted == ':') {
256 ++LastEmitted; // Consume ':' character.
257 if (*LastEmitted == 0)
258 report_fatal_error(reason: "Bad ${:} expression in inline asm string: '" +
259 Twine(AsmStr) + "'");
260
261 Modifier[0] = *LastEmitted;
262 ++LastEmitted; // Consume modifier character.
263 }
264
265 if (*LastEmitted != '}')
266 report_fatal_error(reason: "Bad ${} expression in inline asm string: '" +
267 Twine(AsmStr) + "'");
268 ++LastEmitted; // Consume '}' character.
269 }
270
271 // Okay, we finally have a value number. Ask the target to print this
272 // operand!
273 if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
274 unsigned OpNo = InlineAsm::MIOp_FirstOperand;
275
276 bool Error = false;
277
278 // Scan to find the machine operand number for the operand.
279 for (; Val; --Val) {
280 if (OpNo >= MI->getNumOperands())
281 break;
282 const InlineAsm::Flag F(MI->getOperand(i: OpNo).getImm());
283 OpNo += F.getNumOperandRegisters() + 1;
284 }
285
286 // We may have a location metadata attached to the end of the
287 // instruction, and at no point should see metadata at any
288 // other point while processing. It's an error if so.
289 if (OpNo >= MI->getNumOperands() || MI->getOperand(i: OpNo).isMetadata()) {
290 Error = true;
291 } else {
292 const InlineAsm::Flag F(MI->getOperand(i: OpNo).getImm());
293 ++OpNo; // Skip over the ID number.
294
295 // FIXME: Shouldn't arch-independent output template handling go into
296 // PrintAsmOperand?
297 // Labels are target independent.
298 if (MI->getOperand(i: OpNo).isBlockAddress()) {
299 const BlockAddress *BA = MI->getOperand(i: OpNo).getBlockAddress();
300 MCSymbol *Sym = AP->GetBlockAddressSymbol(BA);
301 Sym->print(OS, MAI: AP->MAI);
302 MMI->getContext().registerInlineAsmLabel(Sym);
303 } else if (MI->getOperand(i: OpNo).isMBB()) {
304 const MCSymbol *Sym = MI->getOperand(i: OpNo).getMBB()->getSymbol();
305 Sym->print(OS, MAI: AP->MAI);
306 } else if (F.isMemKind()) {
307 Error = AP->PrintAsmMemoryOperand(
308 MI, OpNo, ExtraCode: Modifier[0] ? Modifier : nullptr, OS);
309 } else {
310 Error = AP->PrintAsmOperand(MI, OpNo,
311 ExtraCode: Modifier[0] ? Modifier : nullptr, OS);
312 }
313 }
314 if (Error) {
315 const Function &Fn = MI->getMF()->getFunction();
316 Fn.getContext().diagnose(DI: DiagnosticInfoInlineAsm(
317 LocCookie,
318 "invalid operand in inline asm: '" + Twine(AsmStr) + "'"));
319 }
320 }
321 break;
322 }
323 }
324 }
325 if (InputIsIntelDialect)
326 OS << "\n\t.att_syntax";
327 OS << '\n' << (char)0; // null terminate string.
328}
329
330/// This method formats and emits the specified machine instruction that is an
331/// inline asm.
332void AsmPrinter::emitInlineAsm(const MachineInstr *MI) const {
333 assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
334
335 // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
336 const char *AsmStr = MI->getOperand(i: 0).getSymbolName();
337
338 // If this asmstr is empty, just print the #APP/#NOAPP markers.
339 // These are useful to see where empty asm's wound up.
340 if (AsmStr[0] == 0) {
341 OutStreamer->emitRawComment(T: MAI->getInlineAsmStart());
342 OutStreamer->emitRawComment(T: MAI->getInlineAsmEnd());
343 return;
344 }
345
346 // Emit the #APP start marker. This has to happen even if verbose-asm isn't
347 // enabled, so we use emitRawComment.
348 OutStreamer->emitRawComment(T: MAI->getInlineAsmStart());
349
350 const MDNode *LocMD = MI->getLocCookieMD();
351 uint64_t LocCookie =
352 LocMD
353 ? mdconst::extract<ConstantInt>(MD: LocMD->getOperand(I: 0))->getZExtValue()
354 : 0;
355
356 // Emit the inline asm to a temporary string so we can emit it through
357 // EmitInlineAsm.
358 SmallString<256> StringData;
359 raw_svector_ostream OS(StringData);
360
361 AsmPrinter *AP = const_cast<AsmPrinter*>(this);
362 EmitInlineAsmStr(AsmStr, MI, MMI, MAI, AP, LocCookie, OS);
363
364 // Emit warnings if we use reserved registers on the clobber list, as
365 // that might lead to undefined behaviour.
366 SmallVector<Register, 8> RestrRegs;
367 const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
368 // Start with the first operand descriptor, and iterate over them.
369 for (unsigned I = InlineAsm::MIOp_FirstOperand, NumOps = MI->getNumOperands();
370 I < NumOps; ++I) {
371 const MachineOperand &MO = MI->getOperand(i: I);
372 if (!MO.isImm())
373 continue;
374 const InlineAsm::Flag F(MO.getImm());
375 if (F.isClobberKind()) {
376 Register Reg = MI->getOperand(i: I + 1).getReg();
377 if (!TRI->isAsmClobberable(MF: *MF, PhysReg: Reg))
378 RestrRegs.push_back(Elt: Reg);
379 }
380 // Skip to one before the next operand descriptor, if it exists.
381 I += F.getNumOperandRegisters();
382 }
383
384 if (!RestrRegs.empty()) {
385 std::string Msg = "inline asm clobber list contains reserved registers: ";
386 ListSeparator LS;
387 for (const Register RR : RestrRegs) {
388 Msg += LS;
389 Msg += TRI->getRegAsmName(Reg: RR);
390 }
391
392 const Function &Fn = MF->getFunction();
393 const char *Note =
394 "Reserved registers on the clobber list may not be "
395 "preserved across the asm statement, and clobbering them may "
396 "lead to undefined behaviour.";
397 LLVMContext &Ctx = Fn.getContext();
398 Ctx.diagnose(DI: DiagnosticInfoInlineAsm(LocCookie, Msg,
399 DiagnosticSeverity::DS_Warning));
400 Ctx.diagnose(
401 DI: DiagnosticInfoInlineAsm(LocCookie, Note, DiagnosticSeverity::DS_Note));
402
403 for (const Register RR : RestrRegs) {
404 if (std::optional<std::string> reason =
405 TRI->explainReservedReg(MF: *MF, PhysReg: RR)) {
406 Ctx.diagnose(DI: DiagnosticInfoInlineAsm(LocCookie, *reason,
407 DiagnosticSeverity::DS_Note));
408 }
409 }
410 }
411
412 emitInlineAsm(Str: StringData, STI: getSubtargetInfo(), MCOptions: TM.Options.MCOptions, LocMDNode: LocMD,
413 Dialect: MI->getInlineAsmDialect());
414
415 // Emit the #NOAPP end marker. This has to happen even if verbose-asm isn't
416 // enabled, so we use emitRawComment.
417 OutStreamer->emitRawComment(T: MAI->getInlineAsmEnd());
418}
419
420/// PrintSpecial - Print information related to the specified machine instr
421/// that is independent of the operand, and may be independent of the instr
422/// itself. This can be useful for portably encoding the comment character
423/// or other bits of target-specific knowledge into the asmstrings. The
424/// syntax used is ${:comment}. Targets can override this to add support
425/// for their own strange codes.
426void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
427 StringRef Code) const {
428 if (Code == "private") {
429 const DataLayout &DL = MF->getDataLayout();
430 OS << DL.getPrivateGlobalPrefix();
431 } else if (Code == "comment") {
432 OS << MAI->getCommentString();
433 } else if (Code == "uid") {
434 // Comparing the address of MI isn't sufficient, because machineinstrs may
435 // be allocated to the same address across functions.
436
437 // If this is a new LastFn instruction, bump the counter.
438 if (LastMI != MI || LastFn != getFunctionNumber()) {
439 ++Counter;
440 LastMI = MI;
441 LastFn = getFunctionNumber();
442 }
443 OS << Counter;
444 } else {
445 std::string msg;
446 raw_string_ostream Msg(msg);
447 Msg << "Unknown special formatter '" << Code
448 << "' for machine instr: " << *MI;
449 report_fatal_error(reason: Twine(Msg.str()));
450 }
451}
452
453void AsmPrinter::PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS) {
454 assert(MO.isGlobal() && "caller should check MO.isGlobal");
455 getSymbolPreferLocal(GV: *MO.getGlobal())->print(OS, MAI);
456 printOffset(Offset: MO.getOffset(), OS);
457}
458
459/// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
460/// instruction, using the specified assembler variant. Targets should
461/// override this to format as appropriate for machine specific ExtraCodes
462/// or when the arch-independent handling would be too complex otherwise.
463bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
464 const char *ExtraCode, raw_ostream &O) {
465 // Does this asm operand have a single letter operand modifier?
466 if (ExtraCode && ExtraCode[0]) {
467 if (ExtraCode[1] != 0) return true; // Unknown modifier.
468
469 // https://gcc.gnu.org/onlinedocs/gccint/Output-Template.html
470 const MachineOperand &MO = MI->getOperand(i: OpNo);
471 switch (ExtraCode[0]) {
472 default:
473 return true; // Unknown modifier.
474 case 'a': // Print as memory address.
475 if (MO.isReg()) {
476 PrintAsmMemoryOperand(MI, OpNo, ExtraCode: nullptr, OS&: O);
477 return false;
478 }
479 [[fallthrough]]; // GCC allows '%a' to behave like '%c' with immediates.
480 case 'c': // Substitute immediate value without immediate syntax
481 if (MO.isImm()) {
482 O << MO.getImm();
483 return false;
484 }
485 if (MO.isGlobal()) {
486 PrintSymbolOperand(MO, OS&: O);
487 return false;
488 }
489 return true;
490 case 'n': // Negate the immediate constant.
491 if (!MO.isImm())
492 return true;
493 O << -MO.getImm();
494 return false;
495 case 's': // The GCC deprecated s modifier
496 if (!MO.isImm())
497 return true;
498 O << ((32 - MO.getImm()) & 31);
499 return false;
500 }
501 }
502 return true;
503}
504
505bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
506 const char *ExtraCode, raw_ostream &O) {
507 // Target doesn't support this yet!
508 return true;
509}
510
511void AsmPrinter::emitInlineAsmStart() const {}
512
513void AsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
514 const MCSubtargetInfo *EndInfo) const {}
515