llvm-mc: Support reassignment of variables in one special case, when the
variable has not yet been used in an expression. This allows us to support a few
cases that show up in real code (mostly because gcc generates it for Objective-C
on Darwin), without giving up a reasonable semantic model for assignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103950 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index e5af357..0df839b 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -189,6 +189,9 @@
std::pair<StringRef, StringRef> Split = getTok().getIdentifier().split('@');
MCSymbol *Sym = CreateSymbol(Split.first);
+ // Mark the symbol as used in an expression.
+ Sym->setUsedInExpr(true);
+
// Lookup the symbol variant if used.
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
if (Split.first.size() != getTok().getIdentifier().size())
@@ -788,7 +791,9 @@
//
// FIXME: Diagnostics. Note the location of the definition as a label.
// FIXME: Diagnose assignment to protected identifier (e.g., register name).
- if (!Sym->isUndefined() && !Sym->isAbsolute())
+ if (Sym->isUndefined() && !Sym->isUsedInExpr())
+ ; // Allow redefinitions of undefined symbols only used in directives.
+ else if (!Sym->isUndefined() && !Sym->isAbsolute())
return Error(EqualLoc, "redefinition of '" + Name + "'");
else if (!Sym->isVariable())
return Error(EqualLoc, "invalid assignment to '" + Name + "'");
@@ -800,6 +805,8 @@
// FIXME: Handle '.'.
+ Sym->setUsedInExpr(true);
+
// Do the assignment.
Out.EmitAssignment(Sym, Value);