Pull in r201784 from upstream llvm trunk (by Benjamin Kramer):

  AsmParser: Disable Darwin-style macro argument expansion on non-darwin targets.

  There is code in the wild that relies on $0 not being expanded.

This fixes some cases of using $ signs in literals being incorrectly
assembled.

Reported by:	Richard Henderson
Upstream PR:	http://llvm.org/PR21500

Introduced here: http://svnweb.freebsd.org/changeset/base/274286

Index: lib/MC/MCParser/AsmParser.cpp
===================================================================
--- lib/MC/MCParser/AsmParser.cpp
+++ lib/MC/MCParser/AsmParser.cpp
@@ -1695,7 +1695,7 @@ bool AsmParser::expandMacro(raw_svector_ostream &O
                             const MCAsmMacroParameters &Parameters,
                             const MCAsmMacroArguments &A, const SMLoc &L) {
   unsigned NParameters = Parameters.size();
-  if (NParameters != 0 && NParameters != A.size())
+  if ((!IsDarwin || NParameters != 0) && NParameters != A.size())
     return Error(L, "Wrong number of arguments");
 
   // A macro without parameters is handled differently on Darwin:
@@ -1705,7 +1705,7 @@ bool AsmParser::expandMacro(raw_svector_ostream &O
     std::size_t End = Body.size(), Pos = 0;
     for (; Pos != End; ++Pos) {
       // Check for a substitution or escape.
-      if (!NParameters) {
+      if (IsDarwin && !NParameters) {
         // This macro has no parameters, look for $0, $1, etc.
         if (Body[Pos] != '$' || Pos + 1 == End)
           continue;
@@ -1728,7 +1728,7 @@ bool AsmParser::expandMacro(raw_svector_ostream &O
     if (Pos == End)
       break;
 
-    if (!NParameters) {
+    if (IsDarwin && !NParameters) {
       switch (Body[Pos + 1]) {
       // $$ => $
       case '$':
Index: test/MC/AsmParser/exprs.s
===================================================================
--- test/MC/AsmParser/exprs.s
+++ test/MC/AsmParser/exprs.s
@@ -1,4 +1,4 @@
-// RUN: llvm-mc -triple i386-unknown-unknown %s > %t
+// RUN: llvm-mc -triple i386-apple-darwin %s
 
 .macro check_expr
   .if ($0) != ($1)