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
This commit is contained in:
Daniel Dunbar 2010-05-17 17:46:23 +00:00
parent aa4b0159da
commit 525a3a67c1
3 changed files with 26 additions and 8 deletions

View File

@ -52,10 +52,15 @@ namespace llvm {
/// "Lfoo" or ".foo".
unsigned IsTemporary : 1;
/// IsUsedInExpr - True if this symbol has been used in an expression and
/// cannot be redefined.
unsigned IsUsedInExpr : 1;
private: // MCContext creates and uniques these.
friend class MCContext;
MCSymbol(StringRef name, bool isTemporary)
: Name(name), Section(0), Value(0), IsTemporary(isTemporary) {}
: Name(name), Section(0), Value(0),
IsTemporary(isTemporary), IsUsedInExpr(false) {}
MCSymbol(const MCSymbol&); // DO NOT IMPLEMENT
void operator=(const MCSymbol&); // DO NOT IMPLEMENT
@ -63,13 +68,15 @@ namespace llvm {
/// getName - Get the symbol name.
StringRef getName() const { return Name; }
/// @name Symbol Type
/// @name Accessors
/// @{
/// isTemporary - Check if this is an assembler temporary symbol.
bool isTemporary() const {
return IsTemporary;
}
bool isTemporary() const { return IsTemporary; }
/// isUsedInExpr - Check if this is an assembler temporary symbol.
bool isUsedInExpr() const { return IsUsedInExpr; }
void setUsedInExpr(bool Value) { IsUsedInExpr = Value; }
/// @}
/// @name Associated Sections

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@ -189,6 +189,9 @@ bool AsmParser::ParsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
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 @@ bool AsmParser::ParseAssignment(const StringRef &Name) {
//
// 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 @@ bool AsmParser::ParseAssignment(const StringRef &Name) {
// FIXME: Handle '.'.
Sym->setUsedInExpr(true);
// Do the assignment.
Out.EmitAssignment(Sym, Value);

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@ -2,6 +2,10 @@
# CHECK: TEST0:
# CHECK: a = 0
TEST0:
TEST0:
a = 0
# CHECK: .globl _f1
# CHECK: _f1 = 0
.globl _f1
_f1 = 0