[llvm-commits] [llvm] r103950 - in /llvm/trunk: include/llvm/MC/MCSymbol.h lib/MC/MCParser/AsmParser.cpp test/MC/AsmParser/assignment.s
Daniel Dunbar
daniel at zuster.org
Mon May 17 10:46:23 PDT 2010
Author: ddunbar
Date: Mon May 17 12:46:23 2010
New Revision: 103950
URL: http://llvm.org/viewvc/llvm-project?rev=103950&view=rev
Log:
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.
Modified:
llvm/trunk/include/llvm/MC/MCSymbol.h
llvm/trunk/lib/MC/MCParser/AsmParser.cpp
llvm/trunk/test/MC/AsmParser/assignment.s
Modified: llvm/trunk/include/llvm/MC/MCSymbol.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCSymbol.h?rev=103950&r1=103949&r2=103950&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCSymbol.h (original)
+++ llvm/trunk/include/llvm/MC/MCSymbol.h Mon May 17 12:46:23 2010
@@ -52,10 +52,15 @@
/// "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 @@
/// 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
Modified: llvm/trunk/lib/MC/MCParser/AsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCParser/AsmParser.cpp?rev=103950&r1=103949&r2=103950&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCParser/AsmParser.cpp (original)
+++ llvm/trunk/lib/MC/MCParser/AsmParser.cpp Mon May 17 12:46:23 2010
@@ -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);
Modified: llvm/trunk/test/MC/AsmParser/assignment.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/AsmParser/assignment.s?rev=103950&r1=103949&r2=103950&view=diff
==============================================================================
--- llvm/trunk/test/MC/AsmParser/assignment.s (original)
+++ llvm/trunk/test/MC/AsmParser/assignment.s Mon May 17 12:46:23 2010
@@ -2,6 +2,10 @@
# CHECK: TEST0:
# CHECK: a = 0
-TEST0:
+TEST0:
a = 0
-
+
+# CHECK: .globl _f1
+# CHECK: _f1 = 0
+ .globl _f1
+ _f1 = 0
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