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llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp

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//===-- AsmPrinterInlineAsm.cpp - AsmPrinter Inline Asm Handling ----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the inline assembler pieces of the AsmPrinter class.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCParser/MCTargetAsmParser.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
using namespace llvm;
#define DEBUG_TYPE "asm-printer"
unsigned AsmPrinter::addInlineAsmDiagBuffer(StringRef AsmStr,
const MDNode *LocMDNode) const {
MCContext &Context = MMI->getContext();
Context.initInlineSourceManager();
SourceMgr &SrcMgr = *Context.getInlineSourceManager();
std::vector<const MDNode *> &LocInfos = Context.getLocInfos();
std::unique_ptr<MemoryBuffer> Buffer;
// The inline asm source manager will outlive AsmStr, so make a copy of the
// string for SourceMgr to own.
Buffer = MemoryBuffer::getMemBufferCopy(AsmStr, "<inline asm>");
// Tell SrcMgr about this buffer, it takes ownership of the buffer.
unsigned BufNum = SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
// Store LocMDNode in DiagInfo, using BufNum as an identifier.
if (LocMDNode) {
LocInfos.resize(BufNum);
LocInfos[BufNum - 1] = LocMDNode;
}
return BufNum;
}
/// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
void AsmPrinter::emitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
const MCTargetOptions &MCOptions,
const MDNode *LocMDNode,
InlineAsm::AsmDialect Dialect) const {
assert(!Str.empty() && "Can't emit empty inline asm block");
// Remember if the buffer is nul terminated or not so we can avoid a copy.
bool isNullTerminated = Str.back() == 0;
if (isNullTerminated)
Str = Str.substr(0, Str.size()-1);
// If the output streamer does not have mature MC support or the integrated
// assembler has been disabled or not required, just emit the blob textually.
// Otherwise parse the asm and emit it via MC support.
// This is useful in case the asm parser doesn't handle something but the
// system assembler does.
const MCAsmInfo *MCAI = TM.getMCAsmInfo();
assert(MCAI && "No MCAsmInfo");
if (!MCAI->useIntegratedAssembler() &&
!MCAI->parseInlineAsmUsingAsmParser() &&
!OutStreamer->isIntegratedAssemblerRequired()) {
emitInlineAsmStart();
OutStreamer->emitRawText(Str);
emitInlineAsmEnd(STI, nullptr);
return;
}
unsigned BufNum = addInlineAsmDiagBuffer(Str, LocMDNode);
SourceMgr &SrcMgr = *MMI->getContext().getInlineSourceManager();
SrcMgr.setIncludeDirs(MCOptions.IASSearchPaths);
std::unique_ptr<MCAsmParser> Parser(
createMCAsmParser(SrcMgr, OutContext, *OutStreamer, *MAI, BufNum));
// Do not use assembler-level information for parsing inline assembly.
OutStreamer->setUseAssemblerInfoForParsing(false);
// We create a new MCInstrInfo here since we might be at the module level
// and not have a MachineFunction to initialize the TargetInstrInfo from and
// we only need MCInstrInfo for asm parsing. We create one unconditionally
// because it's not subtarget dependent.
std::unique_ptr<MCInstrInfo> MII(TM.getTarget().createMCInstrInfo());
assert(MII && "Failed to create instruction info");
std::unique_ptr<MCTargetAsmParser> TAP(TM.getTarget().createMCAsmParser(
STI, *Parser, *MII, MCOptions));
if (!TAP)
report_fatal_error("Inline asm not supported by this streamer because"
" we don't have an asm parser for this target\n");
Parser->setAssemblerDialect(Dialect);
Parser->setTargetParser(*TAP.get());
// Enable lexing Masm binary and hex integer literals in intel inline
// assembly.
if (Dialect == InlineAsm::AD_Intel)
Parser->getLexer().setLexMasmIntegers(true);
emitInlineAsmStart();
// Don't implicitly switch to the text section before the asm.
(void)Parser->Run(/*NoInitialTextSection*/ true,
/*NoFinalize*/ true);
emitInlineAsmEnd(STI, &TAP->getSTI());
}
static void EmitInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
MachineModuleInfo *MMI, const MCAsmInfo *MAI,
AsmPrinter *AP, uint64_t LocCookie,
raw_ostream &OS) {
bool InputIsIntelDialect = MI->getInlineAsmDialect() == InlineAsm::AD_Intel;
if (InputIsIntelDialect) {
// Switch to the inline assembly variant.
OS << "\t.intel_syntax\n\t";
}
int CurVariant = -1; // The number of the {.|.|.} region we are in.
const char *LastEmitted = AsmStr; // One past the last character emitted.
unsigned NumOperands = MI->getNumOperands();
int AsmPrinterVariant;
if (InputIsIntelDialect)
AsmPrinterVariant = 1; // X86MCAsmInfo.cpp's AsmWriterFlavorTy::Intel.
else
AsmPrinterVariant = MMI->getTarget().unqualifiedInlineAsmVariant();
// FIXME: Should this happen for `asm inteldialect` as well?
if (!InputIsIntelDialect && MAI->getEmitGNUAsmStartIndentationMarker())
OS << '\t';
while (*LastEmitted) {
switch (*LastEmitted) {
default: {
// Not a special case, emit the string section literally.
const char *LiteralEnd = LastEmitted+1;
while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
*LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
++LiteralEnd;
if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
OS.write(LastEmitted, LiteralEnd - LastEmitted);
LastEmitted = LiteralEnd;
break;
}
case '\n':
++LastEmitted; // Consume newline character.
OS << '\n'; // Indent code with newline.
break;
case '$': {
++LastEmitted; // Consume '$' character.
bool Done = true;
// Handle escapes.
switch (*LastEmitted) {
default: Done = false; break;
case '$': // $$ -> $
if (!InputIsIntelDialect)
if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
OS << '$';
++LastEmitted; // Consume second '$' character.
break;
case '(': // $( -> same as GCC's { character.
++LastEmitted; // Consume '(' character.
if (CurVariant != -1)
report_fatal_error("Nested variants found in inline asm string: '" +
Twine(AsmStr) + "'");
CurVariant = 0; // We're in the first variant now.
break;
case '|':
++LastEmitted; // Consume '|' character.
if (CurVariant == -1)
OS << '|'; // This is gcc's behavior for | outside a variant.
else
++CurVariant; // We're in the next variant.
break;
case ')': // $) -> same as GCC's } char.
++LastEmitted; // Consume ')' character.
if (CurVariant == -1)
OS << '}'; // This is gcc's behavior for } outside a variant.
else
CurVariant = -1;
break;
}
if (Done) break;
bool HasCurlyBraces = false;
if (*LastEmitted == '{') { // ${variable}
++LastEmitted; // Consume '{' character.
HasCurlyBraces = true;
}
// If we have ${:foo}, then this is not a real operand reference, it is a
// "magic" string reference, just like in .td files. Arrange to call
// PrintSpecial.
if (HasCurlyBraces && *LastEmitted == ':') {
++LastEmitted;
const char *StrStart = LastEmitted;
const char *StrEnd = strchr(StrStart, '}');
if (!StrEnd)
report_fatal_error("Unterminated ${:foo} operand in inline asm"
" string: '" + Twine(AsmStr) + "'");
if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
AP->PrintSpecial(MI, OS, StringRef(StrStart, StrEnd - StrStart));
LastEmitted = StrEnd+1;
break;
}
const char *IDStart = LastEmitted;
const char *IDEnd = IDStart;
while (isDigit(*IDEnd))
++IDEnd;
unsigned Val;
if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
report_fatal_error("Bad $ operand number in inline asm string: '" +
Twine(AsmStr) + "'");
LastEmitted = IDEnd;
if (Val >= NumOperands - 1)
report_fatal_error("Invalid $ operand number in inline asm string: '" +
Twine(AsmStr) + "'");
char Modifier[2] = { 0, 0 };
if (HasCurlyBraces) {
// If we have curly braces, check for a modifier character. This
// supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
if (*LastEmitted == ':') {
++LastEmitted; // Consume ':' character.
if (*LastEmitted == 0)
report_fatal_error("Bad ${:} expression in inline asm string: '" +
Twine(AsmStr) + "'");
Modifier[0] = *LastEmitted;
++LastEmitted; // Consume modifier character.
}
if (*LastEmitted != '}')
report_fatal_error("Bad ${} expression in inline asm string: '" +
Twine(AsmStr) + "'");
++LastEmitted; // Consume '}' character.
}
// Okay, we finally have a value number. Ask the target to print this
// operand!
if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
unsigned OpNo = InlineAsm::MIOp_FirstOperand;
bool Error = false;
// Scan to find the machine operand number for the operand.
for (; Val; --Val) {
if (OpNo >= MI->getNumOperands())
break;
unsigned OpFlags = MI->getOperand(OpNo).getImm();
OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
}
// We may have a location metadata attached to the end of the
// instruction, and at no point should see metadata at any
// other point while processing. It's an error if so.
if (OpNo >= MI->getNumOperands() || MI->getOperand(OpNo).isMetadata()) {
Error = true;
} else {
unsigned OpFlags = MI->getOperand(OpNo).getImm();
++OpNo; // Skip over the ID number.
// FIXME: Shouldn't arch-independent output template handling go into
// PrintAsmOperand?
// Labels are target independent.
if (MI->getOperand(OpNo).isBlockAddress()) {
const BlockAddress *BA = MI->getOperand(OpNo).getBlockAddress();
MCSymbol *Sym = AP->GetBlockAddressSymbol(BA);
Sym->print(OS, AP->MAI);
MMI->getContext().registerInlineAsmLabel(Sym);
} else if (MI->getOperand(OpNo).isMBB()) {
const MCSymbol *Sym = MI->getOperand(OpNo).getMBB()->getSymbol();
Sym->print(OS, AP->MAI);
} else if (InlineAsm::isMemKind(OpFlags)) {
Error = AP->PrintAsmMemoryOperand(
MI, OpNo, Modifier[0] ? Modifier : nullptr, OS);
} else {
Error = AP->PrintAsmOperand(MI, OpNo,
Modifier[0] ? Modifier : nullptr, OS);
}
}
if (Error) {
std::string msg;
raw_string_ostream Msg(msg);
Msg << "invalid operand in inline asm: '" << AsmStr << "'";
MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
}
}
break;
}
}
}
if (InputIsIntelDialect)
OS << "\n\t.att_syntax";
OS << '\n' << (char)0; // null terminate string.
}
/// This method formats and emits the specified machine instruction that is an
/// inline asm.
void AsmPrinter::emitInlineAsm(const MachineInstr *MI) const {
assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
// Count the number of register definitions to find the asm string.
unsigned NumDefs = 0;
for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
++NumDefs)
assert(NumDefs != MI->getNumOperands()-2 && "No asm string?");
assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
// Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
// If this asmstr is empty, just print the #APP/#NOAPP markers.
// These are useful to see where empty asm's wound up.
if (AsmStr[0] == 0) {
OutStreamer->emitRawComment(MAI->getInlineAsmStart());
OutStreamer->emitRawComment(MAI->getInlineAsmEnd());
return;
}
// Emit the #APP start marker. This has to happen even if verbose-asm isn't
// enabled, so we use emitRawComment.
OutStreamer->emitRawComment(MAI->getInlineAsmStart());
// Get the !srcloc metadata node if we have it, and decode the loc cookie from
// it.
uint64_t LocCookie = 0;
const MDNode *LocMD = nullptr;
for (const MachineOperand &MO : llvm::reverse(MI->operands())) {
if (MO.isMetadata() && (LocMD = MO.getMetadata()) &&
LocMD->getNumOperands() != 0) {
if (const ConstantInt *CI =
mdconst::dyn_extract<ConstantInt>(LocMD->getOperand(0))) {
LocCookie = CI->getZExtValue();
break;
}
}
}
// Emit the inline asm to a temporary string so we can emit it through
// EmitInlineAsm.
SmallString<256> StringData;
raw_svector_ostream OS(StringData);
AsmPrinter *AP = const_cast<AsmPrinter*>(this);
EmitInlineAsmStr(AsmStr, MI, MMI, MAI, AP, LocCookie, OS);
// Emit warnings if we use reserved registers on the clobber list, as
// that might lead to undefined behaviour.
SmallVector<Register, 8> RestrRegs;
const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
// Start with the first operand descriptor, and iterate over them.
for (unsigned I = InlineAsm::MIOp_FirstOperand, NumOps = MI->getNumOperands();
I < NumOps; ++I) {
const MachineOperand &MO = MI->getOperand(I);
if (!MO.isImm())
continue;
unsigned Flags = MO.getImm();
if (InlineAsm::getKind(Flags) == InlineAsm::Kind_Clobber) {
Register Reg = MI->getOperand(I + 1).getReg();
if (!TRI->isAsmClobberable(*MF, Reg))
RestrRegs.push_back(Reg);
}
// Skip to one before the next operand descriptor, if it exists.
I += InlineAsm::getNumOperandRegisters(Flags);
}
if (!RestrRegs.empty()) {
std::string Msg = "inline asm clobber list contains reserved registers: ";
ListSeparator LS;
for (const Register &RR : RestrRegs) {
Msg += LS;
Msg += TRI->getName(RR);
}
const char *Note =
"Reserved registers on the clobber list may not be "
"preserved across the asm statement, and clobbering them may "
"lead to undefined behaviour.";
MMI->getModule()->getContext().diagnose(DiagnosticInfoInlineAsm(
LocCookie, Msg, DiagnosticSeverity::DS_Warning));
MMI->getModule()->getContext().diagnose(
DiagnosticInfoInlineAsm(LocCookie, Note, DiagnosticSeverity::DS_Note));
}
emitInlineAsm(OS.str(), getSubtargetInfo(), TM.Options.MCOptions, LocMD,
MI->getInlineAsmDialect());
// Emit the #NOAPP end marker. This has to happen even if verbose-asm isn't
// enabled, so we use emitRawComment.
OutStreamer->emitRawComment(MAI->getInlineAsmEnd());
}
/// PrintSpecial - Print information related to the specified machine instr
/// that is independent of the operand, and may be independent of the instr
/// itself. This can be useful for portably encoding the comment character
/// or other bits of target-specific knowledge into the asmstrings. The
/// syntax used is ${:comment}. Targets can override this to add support
/// for their own strange codes.
void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
StringRef Code) const {
if (Code == "private") {
const DataLayout &DL = MF->getDataLayout();
OS << DL.getPrivateGlobalPrefix();
} else if (Code == "comment") {
OS << MAI->getCommentString();
} else if (Code == "uid") {
// Comparing the address of MI isn't sufficient, because machineinstrs may
// be allocated to the same address across functions.
// If this is a new LastFn instruction, bump the counter.
if (LastMI != MI || LastFn != getFunctionNumber()) {
++Counter;
LastMI = MI;
LastFn = getFunctionNumber();
}
OS << Counter;
} else {
std::string msg;
raw_string_ostream Msg(msg);
Msg << "Unknown special formatter '" << Code
<< "' for machine instr: " << *MI;
report_fatal_error(Twine(Msg.str()));
}
}
void AsmPrinter::PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS) {
assert(MO.isGlobal() && "caller should check MO.isGlobal");
getSymbolPreferLocal(*MO.getGlobal())->print(OS, MAI);
printOffset(MO.getOffset(), OS);
}
/// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
/// instruction, using the specified assembler variant. Targets should
/// override this to format as appropriate for machine specific ExtraCodes
/// or when the arch-independent handling would be too complex otherwise.
bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
const char *ExtraCode, raw_ostream &O) {
// Does this asm operand have a single letter operand modifier?
if (ExtraCode && ExtraCode[0]) {
if (ExtraCode[1] != 0) return true; // Unknown modifier.
// https://gcc.gnu.org/onlinedocs/gccint/Output-Template.html
const MachineOperand &MO = MI->getOperand(OpNo);
switch (ExtraCode[0]) {
default:
return true; // Unknown modifier.
case 'a': // Print as memory address.
if (MO.isReg()) {
PrintAsmMemoryOperand(MI, OpNo, nullptr, O);
return false;
}
LLVM_FALLTHROUGH; // GCC allows '%a' to behave like '%c' with immediates.
case 'c': // Substitute immediate value without immediate syntax
if (MO.isImm()) {
O << MO.getImm();
return false;
}
if (MO.isGlobal()) {
PrintSymbolOperand(MO, O);
return false;
}
return true;
case 'n': // Negate the immediate constant.
if (!MO.isImm())
return true;
O << -MO.getImm();
return false;
case 's': // The GCC deprecated s modifier
if (!MO.isImm())
return true;
O << ((32 - MO.getImm()) & 31);
return false;
}
}
return true;
}
bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
const char *ExtraCode, raw_ostream &O) {
// Target doesn't support this yet!
return true;
}
void AsmPrinter::emitInlineAsmStart() const {}
void AsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
const MCSubtargetInfo *EndInfo) const {}
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