Implement function prefix data as an IR feature.

Previous discussion:
http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-July/063909.html

Differential Revision: http://llvm-reviews.chandlerc.com/D1191

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190773 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/X86/prefixdata.ll

@@ -0,0 +1,15 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
+
+@i = linkonce_odr global i32 1
+
+; CHECK: f:
+; CHECK-NEXT: .long	1
+define void @f() prefix i32 1 {
+  ret void
+}
+
+; CHECK: g:
+; CHECK-NEXT: .quad	i
+define void @g() prefix i32* @i {
+  ret void
+}