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/MCAsmLexer.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 // Do not use assembler-level information for parsing inline assembly.
106 OutStreamer->setUseAssemblerInfoForParsing(false);
107
108 // We create a new MCInstrInfo here since we might be at the module level
109 // and not have a MachineFunction to initialize the TargetInstrInfo from and
110 // we only need MCInstrInfo for asm parsing. We create one unconditionally
111 // because it's not subtarget dependent.
112 std::unique_ptr<MCInstrInfo> MII(TM.getTarget().createMCInstrInfo());
113 assert(MII && "Failed to create instruction info");
114 std::unique_ptr<MCTargetAsmParser> TAP(TM.getTarget().createMCAsmParser(
115 STI, Parser&: *Parser, MII: *MII, Options: MCOptions));
116 if (!TAP)
117 report_fatal_error(reason: "Inline asm not supported by this streamer because"
118 " we don't have an asm parser for this target\n");
119 Parser->setAssemblerDialect(Dialect);
120 Parser->setTargetParser(*TAP);
121 // Enable lexing Masm binary and hex integer literals in intel inline
122 // assembly.
123 if (Dialect == InlineAsm::AD_Intel)
124 Parser->getLexer().setLexMasmIntegers(true);
125
126 emitInlineAsmStart();
127 // Don't implicitly switch to the text section before the asm.
128 (void)Parser->Run(/*NoInitialTextSection*/ true,
129 /*NoFinalize*/ true);
130 emitInlineAsmEnd(StartInfo: STI, EndInfo: &TAP->getSTI());
131}
132
133static void EmitInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
134 MachineModuleInfo *MMI, const MCAsmInfo *MAI,
135 AsmPrinter *AP, uint64_t LocCookie,
136 raw_ostream &OS) {
137 bool InputIsIntelDialect = MI->getInlineAsmDialect() == InlineAsm::AD_Intel;
138
139 if (InputIsIntelDialect) {
140 // Switch to the inline assembly variant.
141 OS << "\t.intel_syntax\n\t";
142 }
143
144 int CurVariant = -1; // The number of the {.|.|.} region we are in.
145 const char *LastEmitted = AsmStr; // One past the last character emitted.
146 unsigned NumOperands = MI->getNumOperands();
147
148 int AsmPrinterVariant;
149 if (InputIsIntelDialect)
150 AsmPrinterVariant = 1; // X86MCAsmInfo.cpp's AsmWriterFlavorTy::Intel.
151 else
152 AsmPrinterVariant = MMI->getTarget().unqualifiedInlineAsmVariant();
153
154 // FIXME: Should this happen for `asm inteldialect` as well?
155 if (!InputIsIntelDialect && MAI->getEmitGNUAsmStartIndentationMarker())
156 OS << '\t';
157
158 while (*LastEmitted) {
159 switch (*LastEmitted) {
160 default: {
161 // Not a special case, emit the string section literally.
162 const char *LiteralEnd = LastEmitted+1;
163 while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
164 *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
165 ++LiteralEnd;
166 if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
167 OS.write(Ptr: LastEmitted, Size: LiteralEnd - LastEmitted);
168 LastEmitted = LiteralEnd;
169 break;
170 }
171 case '\n':
172 ++LastEmitted; // Consume newline character.
173 OS << '\n'; // Indent code with newline.
174 break;
175 case '$': {
176 ++LastEmitted; // Consume '$' character.
177 bool Done = true;
178
179 // Handle escapes.
180 switch (*LastEmitted) {
181 default: Done = false; break;
182 case '$': // $$ -> $
183 if (!InputIsIntelDialect)
184 if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
185 OS << '$';
186 ++LastEmitted; // Consume second '$' character.
187 break;
188 case '(': // $( -> same as GCC's { character.
189 ++LastEmitted; // Consume '(' character.
190 if (CurVariant != -1)
191 report_fatal_error(reason: "Nested variants found in inline asm string: '" +
192 Twine(AsmStr) + "'");
193 CurVariant = 0; // We're in the first variant now.
194 break;
195 case '|':
196 ++LastEmitted; // Consume '|' character.
197 if (CurVariant == -1)
198 OS << '|'; // This is gcc's behavior for | outside a variant.
199 else
200 ++CurVariant; // We're in the next variant.
201 break;
202 case ')': // $) -> same as GCC's } char.
203 ++LastEmitted; // Consume ')' character.
204 if (CurVariant == -1)
205 OS << '}'; // This is gcc's behavior for } outside a variant.
206 else
207 CurVariant = -1;
208 break;
209 }
210 if (Done) break;
211
212 bool HasCurlyBraces = false;
213 if (*LastEmitted == '{') { // ${variable}
214 ++LastEmitted; // Consume '{' character.
215 HasCurlyBraces = true;
216 }
217
218 // If we have ${:foo}, then this is not a real operand reference, it is a
219 // "magic" string reference, just like in .td files. Arrange to call
220 // PrintSpecial.
221 if (HasCurlyBraces && *LastEmitted == ':') {
222 ++LastEmitted;
223 const char *StrStart = LastEmitted;
224 const char *StrEnd = strchr(s: StrStart, c: '}');
225 if (!StrEnd)
226 report_fatal_error(reason: "Unterminated ${:foo} operand in inline asm"
227 " string: '" + Twine(AsmStr) + "'");
228 if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
229 AP->PrintSpecial(MI, OS, Code: StringRef(StrStart, StrEnd - StrStart));
230 LastEmitted = StrEnd+1;
231 break;
232 }
233
234 const char *IDStart = LastEmitted;
235 const char *IDEnd = IDStart;
236 while (isDigit(C: *IDEnd))
237 ++IDEnd;
238
239 unsigned Val;
240 if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(Radix: 10, Result&: Val))
241 report_fatal_error(reason: "Bad $ operand number in inline asm string: '" +
242 Twine(AsmStr) + "'");
243 LastEmitted = IDEnd;
244
245 if (Val >= NumOperands - 1)
246 report_fatal_error(reason: "Invalid $ operand number in inline asm string: '" +
247 Twine(AsmStr) + "'");
248
249 char Modifier[2] = { 0, 0 };
250
251 if (HasCurlyBraces) {
252 // If we have curly braces, check for a modifier character. This
253 // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
254 if (*LastEmitted == ':') {
255 ++LastEmitted; // Consume ':' character.
256 if (*LastEmitted == 0)
257 report_fatal_error(reason: "Bad ${:} expression in inline asm string: '" +
258 Twine(AsmStr) + "'");
259
260 Modifier[0] = *LastEmitted;
261 ++LastEmitted; // Consume modifier character.
262 }
263
264 if (*LastEmitted != '}')
265 report_fatal_error(reason: "Bad ${} expression in inline asm string: '" +
266 Twine(AsmStr) + "'");
267 ++LastEmitted; // Consume '}' character.
268 }
269
270 // Okay, we finally have a value number. Ask the target to print this
271 // operand!
272 if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
273 unsigned OpNo = InlineAsm::MIOp_FirstOperand;
274
275 bool Error = false;
276
277 // Scan to find the machine operand number for the operand.
278 for (; Val; --Val) {
279 if (OpNo >= MI->getNumOperands())
280 break;
281 const InlineAsm::Flag F(MI->getOperand(i: OpNo).getImm());
282 OpNo += F.getNumOperandRegisters() + 1;
283 }
284
285 // We may have a location metadata attached to the end of the
286 // instruction, and at no point should see metadata at any
287 // other point while processing. It's an error if so.
288 if (OpNo >= MI->getNumOperands() || MI->getOperand(i: OpNo).isMetadata()) {
289 Error = true;
290 } else {
291 const InlineAsm::Flag F(MI->getOperand(i: OpNo).getImm());
292 ++OpNo; // Skip over the ID number.
293
294 // FIXME: Shouldn't arch-independent output template handling go into
295 // PrintAsmOperand?
296 // Labels are target independent.
297 if (MI->getOperand(i: OpNo).isBlockAddress()) {
298 const BlockAddress *BA = MI->getOperand(i: OpNo).getBlockAddress();
299 MCSymbol *Sym = AP->GetBlockAddressSymbol(BA);
300 Sym->print(OS, MAI: AP->MAI);
301 MMI->getContext().registerInlineAsmLabel(Sym);
302 } else if (MI->getOperand(i: OpNo).isMBB()) {
303 const MCSymbol *Sym = MI->getOperand(i: OpNo).getMBB()->getSymbol();
304 Sym->print(OS, MAI: AP->MAI);
305 } else if (F.isMemKind()) {
306 Error = AP->PrintAsmMemoryOperand(
307 MI, OpNo, ExtraCode: Modifier[0] ? Modifier : nullptr, OS);
308 } else {
309 Error = AP->PrintAsmOperand(MI, OpNo,
310 ExtraCode: Modifier[0] ? Modifier : nullptr, OS);
311 }
312 }
313 if (Error) {
314 std::string msg;
315 raw_string_ostream Msg(msg);
316 Msg << "invalid operand in inline asm: '" << AsmStr << "'";
317 MMI->getModule()->getContext().emitError(LocCookie, ErrorStr: Msg.str());
318 }
319 }
320 break;
321 }
322 }
323 }
324 if (InputIsIntelDialect)
325 OS << "\n\t.att_syntax";
326 OS << '\n' << (char)0; // null terminate string.
327}
328
329/// This method formats and emits the specified machine instruction that is an
330/// inline asm.
331void AsmPrinter::emitInlineAsm(const MachineInstr *MI) const {
332 assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
333
334 // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
335 const char *AsmStr = MI->getOperand(i: 0).getSymbolName();
336
337 // If this asmstr is empty, just print the #APP/#NOAPP markers.
338 // These are useful to see where empty asm's wound up.
339 if (AsmStr[0] == 0) {
340 OutStreamer->emitRawComment(T: MAI->getInlineAsmStart());
341 OutStreamer->emitRawComment(T: MAI->getInlineAsmEnd());
342 return;
343 }
344
345 // Emit the #APP start marker. This has to happen even if verbose-asm isn't
346 // enabled, so we use emitRawComment.
347 OutStreamer->emitRawComment(T: MAI->getInlineAsmStart());
348
349 // Get the !srcloc metadata node if we have it, and decode the loc cookie from
350 // it.
351 uint64_t LocCookie = 0;
352 const MDNode *LocMD = nullptr;
353 for (const MachineOperand &MO : llvm::reverse(C: MI->operands())) {
354 if (MO.isMetadata() && (LocMD = MO.getMetadata()) &&
355 LocMD->getNumOperands() != 0) {
356 if (const ConstantInt *CI =
357 mdconst::dyn_extract<ConstantInt>(MD: LocMD->getOperand(I: 0))) {
358 LocCookie = CI->getZExtValue();
359 break;
360 }
361 }
362 }
363
364 // Emit the inline asm to a temporary string so we can emit it through
365 // EmitInlineAsm.
366 SmallString<256> StringData;
367 raw_svector_ostream OS(StringData);
368
369 AsmPrinter *AP = const_cast<AsmPrinter*>(this);
370 EmitInlineAsmStr(AsmStr, MI, MMI, MAI, AP, LocCookie, OS);
371
372 // Emit warnings if we use reserved registers on the clobber list, as
373 // that might lead to undefined behaviour.
374 SmallVector<Register, 8> RestrRegs;
375 const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
376 // Start with the first operand descriptor, and iterate over them.
377 for (unsigned I = InlineAsm::MIOp_FirstOperand, NumOps = MI->getNumOperands();
378 I < NumOps; ++I) {
379 const MachineOperand &MO = MI->getOperand(i: I);
380 if (!MO.isImm())
381 continue;
382 const InlineAsm::Flag F(MO.getImm());
383 if (F.isClobberKind()) {
384 Register Reg = MI->getOperand(i: I + 1).getReg();
385 if (!TRI->isAsmClobberable(MF: *MF, PhysReg: Reg))
386 RestrRegs.push_back(Elt: Reg);
387 }
388 // Skip to one before the next operand descriptor, if it exists.
389 I += F.getNumOperandRegisters();
390 }
391
392 if (!RestrRegs.empty()) {
393 std::string Msg = "inline asm clobber list contains reserved registers: ";
394 ListSeparator LS;
395 for (const Register RR : RestrRegs) {
396 Msg += LS;
397 Msg += TRI->getRegAsmName(Reg: RR);
398 }
399 const char *Note =
400 "Reserved registers on the clobber list may not be "
401 "preserved across the asm statement, and clobbering them may "
402 "lead to undefined behaviour.";
403 MMI->getModule()->getContext().diagnose(DI: DiagnosticInfoInlineAsm(
404 LocCookie, Msg, DiagnosticSeverity::DS_Warning));
405 MMI->getModule()->getContext().diagnose(
406 DI: DiagnosticInfoInlineAsm(LocCookie, Note, DiagnosticSeverity::DS_Note));
407
408 for (const Register RR : RestrRegs) {
409 if (std::optional<std::string> reason =
410 TRI->explainReservedReg(MF: *MF, PhysReg: RR)) {
411 MMI->getModule()->getContext().diagnose(DI: DiagnosticInfoInlineAsm(
412 LocCookie, *reason, DiagnosticSeverity::DS_Note));
413 }
414 }
415 }
416
417 emitInlineAsm(Str: OS.str(), STI: getSubtargetInfo(), MCOptions: TM.Options.MCOptions, LocMDNode: LocMD,
418 Dialect: MI->getInlineAsmDialect());
419
420 // Emit the #NOAPP end marker. This has to happen even if verbose-asm isn't
421 // enabled, so we use emitRawComment.
422 OutStreamer->emitRawComment(T: MAI->getInlineAsmEnd());
423}
424
425/// PrintSpecial - Print information related to the specified machine instr
426/// that is independent of the operand, and may be independent of the instr
427/// itself. This can be useful for portably encoding the comment character
428/// or other bits of target-specific knowledge into the asmstrings. The
429/// syntax used is ${:comment}. Targets can override this to add support
430/// for their own strange codes.
431void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
432 StringRef Code) const {
433 if (Code == "private") {
434 const DataLayout &DL = MF->getDataLayout();
435 OS << DL.getPrivateGlobalPrefix();
436 } else if (Code == "comment") {
437 OS << MAI->getCommentString();
438 } else if (Code == "uid") {
439 // Comparing the address of MI isn't sufficient, because machineinstrs may
440 // be allocated to the same address across functions.
441
442 // If this is a new LastFn instruction, bump the counter.
443 if (LastMI != MI || LastFn != getFunctionNumber()) {
444 ++Counter;
445 LastMI = MI;
446 LastFn = getFunctionNumber();
447 }
448 OS << Counter;
449 } else {
450 std::string msg;
451 raw_string_ostream Msg(msg);
452 Msg << "Unknown special formatter '" << Code
453 << "' for machine instr: " << *MI;
454 report_fatal_error(reason: Twine(Msg.str()));
455 }
456}
457
458void AsmPrinter::PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS) {
459 assert(MO.isGlobal() && "caller should check MO.isGlobal");
460 getSymbolPreferLocal(GV: *MO.getGlobal())->print(OS, MAI);
461 printOffset(Offset: MO.getOffset(), OS);
462}
463
464/// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
465/// instruction, using the specified assembler variant. Targets should
466/// override this to format as appropriate for machine specific ExtraCodes
467/// or when the arch-independent handling would be too complex otherwise.
468bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
469 const char *ExtraCode, raw_ostream &O) {
470 // Does this asm operand have a single letter operand modifier?
471 if (ExtraCode && ExtraCode[0]) {
472 if (ExtraCode[1] != 0) return true; // Unknown modifier.
473
474 // https://gcc.gnu.org/onlinedocs/gccint/Output-Template.html
475 const MachineOperand &MO = MI->getOperand(i: OpNo);
476 switch (ExtraCode[0]) {
477 default:
478 return true; // Unknown modifier.
479 case 'a': // Print as memory address.
480 if (MO.isReg()) {
481 PrintAsmMemoryOperand(MI, OpNo, ExtraCode: nullptr, OS&: O);
482 return false;
483 }
484 [[fallthrough]]; // GCC allows '%a' to behave like '%c' with immediates.
485 case 'c': // Substitute immediate value without immediate syntax
486 if (MO.isImm()) {
487 O << MO.getImm();
488 return false;
489 }
490 if (MO.isGlobal()) {
491 PrintSymbolOperand(MO, OS&: O);
492 return false;
493 }
494 return true;
495 case 'n': // Negate the immediate constant.
496 if (!MO.isImm())
497 return true;
498 O << -MO.getImm();
499 return false;
500 case 's': // The GCC deprecated s modifier
501 if (!MO.isImm())
502 return true;
503 O << ((32 - MO.getImm()) & 31);
504 return false;
505 }
506 }
507 return true;
508}
509
510bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
511 const char *ExtraCode, raw_ostream &O) {
512 // Target doesn't support this yet!
513 return true;
514}
515
516void AsmPrinter::emitInlineAsmStart() const {}
517
518void AsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
519 const MCSubtargetInfo *EndInfo) const {}
520

source code of llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp