Better diagnostic for malformed .org assembly directive.

Provide source line number information.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149101 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 64d0dd8..1af7cd9 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -1970,6 +1970,7 @@
   CheckForValidSection();
 
   const MCExpr *Offset;
+  SMLoc Loc = getTok().getLoc();
   if (ParseExpression(Offset))
     return true;
 
@@ -1989,9 +1990,11 @@
 
   Lex();
 
-  // FIXME: Only limited forms of relocatable expressions are accepted here, it
-  // has to be relative to the current section.
-  getStreamer().EmitValueToOffset(Offset, FillExpr);
+  // Only limited forms of relocatable expressions are accepted here, it
+  // has to be relative to the current section. The streamer will return
+  // 'true' if the expression wasn't evaluatable.
+  if (getStreamer().EmitValueToOffset(Offset, FillExpr))
+    return Error(Loc, "expected assembly-time absolute expression");
 
   return false;
 }