Add 'notail' marker for call instructions.

This marker prevents optimization passes from adding 'tail' or
'musttail' markers to a call. Is is used to prevent tail call
optimization from being performed on the call.

rdar://problem/22667622

Differential Revision: http://reviews.llvm.org/D12923


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252368 91177308-0d34-0410-b5e6-96231b3b80d8

test/Bitcode/compatibility.ll

@@ -1144,6 +1144,13 @@ define void @instructions.call_musttail(i8* inalloca %val) {
   ret void
 }
 
+define void @instructions.call_notail() {
+  notail call void @f1()
+  ; CHECK: notail call void @f1()
+
+  ret void
+}
+
 define void @instructions.landingpad() personality i32 -2 {
   invoke void @llvm.donothing() to label %proceed unwind label %catch1
   invoke void @llvm.donothing() to label %proceed unwind label %catch2