[ARM] Enable changing instprinter's behavior based on the per-function
subtarget.

llvm-svn: 233451
diff --git a/llvm/lib/Target/ARM/ARM.td b/llvm/lib/Target/ARM/ARM.td
index 97c9a28..9babf4b 100644
--- a/llvm/lib/Target/ARM/ARM.td
+++ b/llvm/lib/Target/ARM/ARM.td
@@ -480,7 +480,15 @@
 // Declare the target which we are implementing
 //===----------------------------------------------------------------------===//
 
+def ARMAsmWriter : AsmWriter {
+  string AsmWriterClassName  = "InstPrinter";
+  int PassSubtarget = 1;
+  int Variant = 0;
+  bit isMCAsmWriter = 1;
+}
+
 def ARM : Target {
   // Pull in Instruction Info:
   let InstructionSet = ARMInstrInfo;
+  let AssemblyWriters = [ARMAsmWriter];
 }