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[MC] Remove SetUsed on isUndefined and getFragment

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Due to the known limitations of .set reassignment (see
https://sourceware.org/PR288), we use diagnostics to reject patterns
that could lead to errors (ae7ac010594f693fdf7b3ab879e196428d961e75 2009-06)).

This code gets refined multiple times, see:

* 9b4a824217f1fe23f83045afe7521acb791bc2d0 (2010-05) `IsUsedInExpr`
* 46c79ef1132607aead144dfda0f26aa8b065214f (2010-11) renamed `IsUsedInExpr` to `IsUsed`

The related `SetUsed` bit seems unnecessary nowadays.
This commit is contained in:
Fangrui Song 2025-04-13 00:53:29 -07:00
parent 1c5ce2d74f
commit ca5b3a0f51
3 changed files with 8 additions and 11 deletions
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6
llvm/include/llvm/MC/MCSymbol.h
View File

@ -257,9 +257,7 @@ public:
}
/// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
bool isUndefined(bool SetUsed = true) const {
return getFragment(SetUsed) == nullptr;
}
bool isUndefined() const { return getFragment() == nullptr; }
/// isAbsolute - Check if this is an absolute symbol.
bool isAbsolute() const {
@ -395,7 +393,7 @@ public:
return SymbolContents == SymContentsTargetCommon;
}
MCFragment *getFragment(bool SetUsed = true) const {
MCFragment *getFragment(bool SetUsed = false) const {
if (Fragment || !isVariable() || isWeakExternal())
return Fragment;
// If the symbol is a non-weak alias, get information about

7
llvm/lib/MC/MCParser/AsmParser.cpp
View File

@ -5284,9 +5284,9 @@ bool AsmParser::parseDirectiveIfdef(SMLoc DirectiveLoc, bool expect_defined) {
MCSymbol *Sym = getContext().lookupSymbol(Name);
if (expect_defined)
TheCondState.CondMet = (Sym && !Sym->isUndefined(false));
TheCondState.CondMet = (Sym && !Sym->isUndefined());
else
TheCondState.CondMet = (!Sym || Sym->isUndefined(false));
TheCondState.CondMet = (!Sym || Sym->isUndefined());
TheCondState.Ignore = !TheCondState.CondMet;
}
@ -6362,8 +6362,7 @@ bool parseAssignmentExpression(StringRef Name, bool allow_redef,
// FIXME: Diagnose assignment to protected identifier (e.g., register name).
if (Value->isSymbolUsedInExpression(Sym))
return Parser.Error(EqualLoc, "Recursive use of '" + Name + "'");
else if (Sym->isUndefined(/*SetUsed*/ false) && !Sym->isUsed() &&
!Sym->isVariable())
else if (Sym->isUndefined() && !Sym->isUsed() && !Sym->isVariable())
; // Allow redefinitions of undefined symbols only used in directives.
else if (Sym->isVariable() && !Sym->isUsed() && allow_redef)
; // Allow redefinitions of variables that haven't yet been used.

6
llvm/lib/MC/MCParser/MasmParser.cpp
View File

@ -4761,7 +4761,7 @@ bool MasmParser::parseDirectiveIfdef(SMLoc DirectiveLoc, bool expect_defined) {
is_defined = true;
} else {
MCSymbol *Sym = getContext().lookupSymbol(Name.lower());
is_defined = (Sym && !Sym->isUndefined(false));
is_defined = (Sym && !Sym->isUndefined());
}
}
@ -4882,7 +4882,7 @@ bool MasmParser::parseDirectiveElseIfdef(SMLoc DirectiveLoc,
is_defined = true;
} else {
MCSymbol *Sym = getContext().lookupSymbol(Name);
is_defined = (Sym && !Sym->isUndefined(false));
is_defined = (Sym && !Sym->isUndefined());
}
}
@ -5052,7 +5052,7 @@ bool MasmParser::parseDirectiveErrorIfdef(SMLoc DirectiveLoc,
IsDefined = true;
} else {
MCSymbol *Sym = getContext().lookupSymbol(Name);
IsDefined = (Sym && !Sym->isUndefined(false));
IsDefined = (Sym && !Sym->isUndefined());
}
}