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merged 2 commits into from
Sep 16, 2025
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MC: Better handle backslash-escaped symbols #158780

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MC: Better handle backslash-escaped symbols
MaskRay Sep 16, 2025
fc41691
Add CodeGen test
MaskRay Sep 16, 2025
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4 changes: 4 additions & 0 deletions llvm/include/llvm/MC/MCContext.h
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Expand Up @@ -484,6 +484,10 @@ class MCContext {
/// \param Name - The symbol name, which must be unique across all symbols.
LLVM_ABI MCSymbol *getOrCreateSymbol(const Twine &Name);

/// Variant of getOrCreateSymbol that handles backslash-escaped symbols.
/// For example, parse "a\"b\\" as a"\.
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Is there a typo? Where did 'b' go?

LLVM_ABI MCSymbol *parseSymbol(const Twine &Name);

/// Gets a symbol that will be defined to the final stack offset of a local
/// variable after codegen.
///
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49 changes: 28 additions & 21 deletions llvm/lib/MC/MCContext.cpp
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Expand Up @@ -203,27 +203,6 @@ MCInst *MCContext::createMCInst() {
MCSymbol *MCContext::getOrCreateSymbol(const Twine &Name) {
SmallString<128> NameSV;
StringRef NameRef = Name.toStringRef(NameSV);
if (NameRef.contains('\\')) {
NameSV = NameRef;
size_t S = 0;
// Support escaped \\ and \" as in GNU Assembler. GAS issues a warning for
// other characters following \\, which we do not implement due to code
// structure.
for (size_t I = 0, E = NameSV.size(); I != E; ++I) {
char C = NameSV[I];
if (C == '\\' && I + 1 != E) {
switch (NameSV[I + 1]) {
case '"':
case '\\':
C = NameSV[++I];
break;
}
}
NameSV[S++] = C;
}
NameSV.resize(S);
NameRef = NameSV;
}

assert(!NameRef.empty() && "Normal symbols cannot be unnamed!");

Expand All @@ -244,6 +223,34 @@ MCSymbol *MCContext::getOrCreateSymbol(const Twine &Name) {
return Entry.second.Symbol;
}

MCSymbol *MCContext::parseSymbol(const Twine &Name) {
SmallString<128> SV;
StringRef NameRef = Name.toStringRef(SV);
if (NameRef.contains('\\')) {
SV = NameRef;
size_t S = 0;
// Support escaped \\ and \" as in GNU Assembler. GAS issues a warning for
// other characters following \\, which we do not implement due to code
// structure.
for (size_t I = 0, E = SV.size(); I != E; ++I) {
char C = SV[I];
if (C == '\\' && I + 1 != E) {
switch (SV[I + 1]) {
case '"':
case '\\':
C = SV[++I];
break;
}
}
SV[S++] = C;
}
SV.resize(S);
NameRef = SV;
}

return getOrCreateSymbol(NameRef);
}

MCSymbol *MCContext::getOrCreateFrameAllocSymbol(const Twine &FuncName,
unsigned Idx) {
return getOrCreateSymbol(MAI->getPrivateGlobalPrefix() + FuncName +
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12 changes: 6 additions & 6 deletions llvm/lib/MC/MCParser/AsmParser.cpp
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Expand Up @@ -1213,8 +1213,8 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc,

MCSymbol *Sym = getContext().getInlineAsmLabel(SymbolName);
if (!Sym)
Sym = getContext().getOrCreateSymbol(MAI.isHLASM() ? SymbolName.upper()
: SymbolName);
Sym = getContext().parseSymbol(MAI.isHLASM() ? SymbolName.upper()
: SymbolName);

// If this is an absolute variable reference, substitute it now to preserve
// semantics in the face of reassignment.
Expand Down Expand Up @@ -1845,7 +1845,7 @@ bool AsmParser::parseStatement(ParseStatementInfo &Info,
RewrittenLabel);
IDVal = RewrittenLabel;
}
Sym = getContext().getOrCreateSymbol(IDVal);
Sym = getContext().parseSymbol(IDVal);
} else
Sym = Ctx.createDirectionalLocalSymbol(LocalLabelVal);
// End of Labels should be treated as end of line for lexing
Expand Down Expand Up @@ -4885,7 +4885,7 @@ bool AsmParser::parseDirectiveSymbolAttribute(MCSymbolAttr Attr) {
if (discardLTOSymbol(Name))
return false;

MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
MCSymbol *Sym = getContext().parseSymbol(Name);

// Assembler local symbols don't make any sense here, except for directives
// that the symbol should be tagged.
Expand Down Expand Up @@ -6142,7 +6142,7 @@ bool HLASMAsmParser::parseAsHLASMLabel(ParseStatementInfo &Info,
return Error(LabelLoc,
"Cannot have just a label for an HLASM inline asm statement");

MCSymbol *Sym = getContext().getOrCreateSymbol(
MCSymbol *Sym = getContext().parseSymbol(
getContext().getAsmInfo()->isHLASM() ? LabelVal.upper() : LabelVal);

// Emit the label.
Expand Down Expand Up @@ -6270,7 +6270,7 @@ bool parseAssignmentExpression(StringRef Name, bool allow_redef,
Parser.getStreamer().emitValueToOffset(Value, 0, EqualLoc);
return false;
} else
Sym = Parser.getContext().getOrCreateSymbol(Name);
Sym = Parser.getContext().parseSymbol(Name);

Sym->setRedefinable(allow_redef);

Expand Down
4 changes: 2 additions & 2 deletions llvm/lib/MC/MCParser/COFFMasmParser.cpp
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Expand Up @@ -510,8 +510,8 @@ bool COFFMasmParser::parseDirectiveAlias(StringRef Directive, SMLoc Loc) {
getParser().parseAngleBracketString(ActualName))
return Error(getTok().getLoc(), "expected <actualName>");

MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
MCSymbol *Actual = getContext().getOrCreateSymbol(ActualName);
MCSymbol *Alias = getContext().parseSymbol(AliasName);
MCSymbol *Actual = getContext().parseSymbol(ActualName);

getStreamer().emitWeakReference(Alias, Actual);

Expand Down
2 changes: 1 addition & 1 deletion llvm/lib/MC/MCParser/ELFAsmParser.cpp
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Expand Up @@ -163,7 +163,7 @@ bool ELFAsmParser::parseDirectiveSymbolAttribute(StringRef Directive, SMLoc) {
continue;
}

MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
MCSymbol *Sym = getContext().parseSymbol(Name);

getStreamer().emitSymbolAttribute(Sym, Attr);

Expand Down
2 changes: 1 addition & 1 deletion llvm/lib/MC/MCParser/MCAsmParser.cpp
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Expand Up @@ -168,7 +168,7 @@ bool MCAsmParser::parseSymbol(MCSymbol *&Res) {
if (parseIdentifier(Name))
return true;

Res = getContext().getOrCreateSymbol(Name);
Res = getContext().parseSymbol(Name);
return false;
}

Expand Down
4 changes: 2 additions & 2 deletions llvm/lib/MC/MCParser/MCAsmParserExtension.cpp
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Expand Up @@ -50,8 +50,8 @@ bool MCAsmParserExtension::parseDirectiveCGProfile(StringRef, SMLoc) {
if (getLexer().isNot(AsmToken::EndOfStatement))
return TokError("unexpected token in directive");

MCSymbol *FromSym = getContext().getOrCreateSymbol(From);
MCSymbol *ToSym = getContext().getOrCreateSymbol(To);
MCSymbol *FromSym = getContext().parseSymbol(From);
MCSymbol *ToSym = getContext().parseSymbol(To);

getStreamer().emitCGProfileEntry(
MCSymbolRefExpr::create(FromSym, getContext(), FromLoc),
Expand Down
13 changes: 6 additions & 7 deletions llvm/lib/MC/MCParser/MasmParser.cpp
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Expand Up @@ -1480,7 +1480,7 @@ bool MasmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc,
auto VarIt = Variables.find(SymbolName.lower());
if (VarIt != Variables.end())
SymbolName = VarIt->second.Name;
Sym = getContext().getOrCreateSymbol(SymbolName);
Sym = getContext().parseSymbol(SymbolName);
}

// If this is an absolute variable reference, substitute it now to preserve
Expand Down Expand Up @@ -1965,7 +1965,7 @@ bool MasmParser::parseStatement(ParseStatementInfo &Info,
if (IDVal == "@@") {
Sym = Ctx.createDirectionalLocalSymbol(0);
} else {
Sym = getContext().getOrCreateSymbol(IDVal);
Sym = getContext().parseSymbol(IDVal);
}

// End of Labels should be treated as end of line for lexing
Expand Down Expand Up @@ -3009,8 +3009,7 @@ bool MasmParser::parseDirectiveEquate(StringRef IDVal, StringRef Name,
return false;
}

auto *Sym =
static_cast<MCSymbolCOFF *>(getContext().getOrCreateSymbol(Var.Name));
auto *Sym = static_cast<MCSymbolCOFF *>(getContext().parseSymbol(Var.Name));
const MCConstantExpr *PrevValue =
Sym->isVariable()
? dyn_cast_or_null<MCConstantExpr>(Sym->getVariableValue())
Expand Down Expand Up @@ -3318,7 +3317,7 @@ bool MasmParser::parseDirectiveNamedValue(StringRef TypeName, unsigned Size,
StringRef Name, SMLoc NameLoc) {
if (StructInProgress.empty()) {
// Initialize named data value.
MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
MCSymbol *Sym = getContext().parseSymbol(Name);
getStreamer().emitLabel(Sym);
unsigned Count;
if (emitIntegralValues(Size, &Count))
Expand Down Expand Up @@ -3509,7 +3508,7 @@ bool MasmParser::parseDirectiveNamedRealValue(StringRef TypeName,
SMLoc NameLoc) {
if (StructInProgress.empty()) {
// Initialize named data value.
MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
MCSymbol *Sym = getContext().parseSymbol(Name);
getStreamer().emitLabel(Sym);
unsigned Count;
if (emitRealValues(Semantics, &Count))
Expand Down Expand Up @@ -4003,7 +4002,7 @@ bool MasmParser::parseDirectiveNamedStructValue(const StructInfo &Structure,
SMLoc DirLoc, StringRef Name) {
if (StructInProgress.empty()) {
// Initialize named data value.
MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
MCSymbol *Sym = getContext().parseSymbol(Name);
getStreamer().emitLabel(Sym);
unsigned Count;
if (emitStructValues(Structure, &Count))
Expand Down
3 changes: 1 addition & 2 deletions llvm/lib/MC/MCParser/WasmAsmParser.cpp
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Expand Up @@ -240,8 +240,7 @@ class WasmAsmParser : public MCAsmParserExtension {
return error("Expected label after .type directive, got: ",
Lexer->getTok());
auto *WasmSym = static_cast<MCSymbolWasm *>(
getStreamer().getContext().getOrCreateSymbol(
Lexer->getTok().getString()));
getStreamer().getContext().parseSymbol(Lexer->getTok().getString()));
Lex();
if (!(isNext(AsmToken::Comma) && isNext(AsmToken::At) &&
Lexer->is(AsmToken::Identifier)))
Expand Down
5 changes: 5 additions & 0 deletions llvm/test/CodeGen/X86/symbol-name.ll
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@@ -0,0 +1,5 @@
; RUN: llc < %s -mtriple=x86_64 -relocation-model=pic | FileCheck %s

; CHECK: .globl "\\\""
; CHECK-NEXT: "\\\"":
@"\\\22" = constant i8 0
10 changes: 5 additions & 5 deletions llvm/test/MC/ELF/cgprofile.s
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Expand Up @@ -5,11 +5,11 @@ a: .word b

.cg_profile a, b, 32
.cg_profile freq, a, 11
.cg_profile late, late2, 20
.cg_profile "late\\", late2, 20
.cg_profile .L.local, b, 42

.globl late
late:
.globl "late\\"
"late\\":
late2: .word 0
late3:
.L.local:
Expand All @@ -31,7 +31,7 @@ late3:
# CHECK-NEXT: 0010: 14000000 00000000 2A000000 00000000
# CHECK-NEXT: )

# CHECK: Name: .rel.llvm.call-graph-profile (28)
# CHECK: Name: .rel.llvm.call-graph-profile
# CHECK-NEXT: Type: SHT_REL (0x9)
# CHECK-NEXT: Flags [ (0x40)
# CHECK-NEXT: SHF_INFO_LINK
Expand Down Expand Up @@ -83,7 +83,7 @@ late3:
# CHECK-NEXT: Type:
# CHECK-NEXT: Other:
# CHECK-NEXT: Section: Undefined
# CHECK: Name: late
# CHECK: Name: late\ ([[#]])
# CHECK-NEXT: Value:
# CHECK-NEXT: Size:
# CHECK-NEXT: Binding: Global
Expand Down
3 changes: 3 additions & 0 deletions llvm/test/MC/ELF/symbol-names.s
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Expand Up @@ -5,6 +5,7 @@
// CHECK-LABEL:SYMBOL TABLE:
// CHECK-NEXT: 0000000000000001 l F .text 0000000000000000 a"b\{{$}}
// CHECK-NEXT: 0000000000000006 l .text 0000000000000000 a\{{$}}
// CHECK-NEXT: 000000000000000b l .text 0000000000000000 a\\{{$}}
// CHECK-NEXT: 0000000000000000 g F .text 0000000000000000 foo?bar
// CHECK-NEXT: 0000000000000000 *UND* 0000000000000000 a"b\q{{$}}
// CHECK-EMPTY:
Expand All @@ -26,3 +27,5 @@ ret
"a\\":
/// GAS emits a warning for \q
call "a\"b\q"

"a\\\\" = .