Assembler should accept redefinitions of unused variable symbols.

rdar://11027851

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153137 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 41ad164..ab5ddaf 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -1629,6 +1629,8 @@
       return Error(EqualLoc, "Recursive use of '" + Name + "'");
     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.
     else if (!Sym->isUndefined() && (!Sym->isVariable() || !allow_redef))
       return Error(EqualLoc, "redefinition of '" + Name + "'");
     else if (!Sym->isVariable())
diff --git a/lib/MC/MCSymbol.cpp b/lib/MC/MCSymbol.cpp
index 87b58d7..e013e77 100644
--- a/lib/MC/MCSymbol.cpp
+++ b/lib/MC/MCSymbol.cpp
@@ -54,8 +54,6 @@
 void MCSymbol::setVariableValue(const MCExpr *Value) {
   assert(!IsUsed && "Cannot set a variable that has already been used.");
   assert(Value && "Invalid variable value!");
-  assert((isUndefined() || (isAbsolute() && isa<MCConstantExpr>(Value))) &&
-         "Invalid redefinition!");
   this->Value = Value;
 
   // Variables should always be marked as in the same "section" as the value.
diff --git a/test/MC/AsmParser/variables-invalid.s b/test/MC/AsmParser/variables-invalid.s
index 21758d2..c466d42 100644
--- a/test/MC/AsmParser/variables-invalid.s
+++ b/test/MC/AsmParser/variables-invalid.s
@@ -13,6 +13,7 @@
         t2_s0 = 2
 
         t3_s0 = t2_s0 + 1
+        .long t3_s0
 // CHECK: invalid reassignment of non-absolute variable 't3_s0'
         t3_s0 = 1