IR: Make metadata typeless in assembly

Now that `Metadata` is typeless, reflect that in the assembly.  These
are the matching assembly changes for the metadata/value split in
r223802.

  - Only use the `metadata` type when referencing metadata from a call
    intrinsic -- i.e., only when it's used as a `Value`.

  - Stop pretending that `ValueAsMetadata` is wrapped in an `MDNode`
    when referencing it from call intrinsics.

So, assembly like this:

    define @foo(i32 %v) {
      call void @llvm.foo(metadata !{i32 %v}, metadata !0)
      call void @llvm.foo(metadata !{i32 7}, metadata !0)
      call void @llvm.foo(metadata !1, metadata !0)
      call void @llvm.foo(metadata !3, metadata !0)
      call void @llvm.foo(metadata !{metadata !3}, metadata !0)
      ret void, !bar !2
    }
    !0 = metadata !{metadata !2}
    !1 = metadata !{i32* @global}
    !2 = metadata !{metadata !3}
    !3 = metadata !{}

turns into this:

    define @foo(i32 %v) {
      call void @llvm.foo(metadata i32 %v, metadata !0)
      call void @llvm.foo(metadata i32 7, metadata !0)
      call void @llvm.foo(metadata i32* @global, metadata !0)
      call void @llvm.foo(metadata !3, metadata !0)
      call void @llvm.foo(metadata !{!3}, metadata !0)
      ret void, !bar !2
    }
    !0 = !{!2}
    !1 = !{i32* @global}
    !2 = !{!3}
    !3 = !{}

I wrote an upgrade script that handled almost all of the tests in llvm
and many of the tests in cfe (even handling many `CHECK` lines).  I've
attached it (or will attach it in a moment if you're speedy) to PR21532
to help everyone update their out-of-tree testcases.

This is part of PR21532.

llvm-svn: 224257
diff --git a/llvm/test/DebugInfo/X86/vla.ll b/llvm/test/DebugInfo/X86/vla.ll
index be05c3b..da49a84 100644
--- a/llvm/test/DebugInfo/X86/vla.ll
+++ b/llvm/test/DebugInfo/X86/vla.ll
@@ -27,13 +27,13 @@
   %saved_stack = alloca i8*
   %cleanup.dest.slot = alloca i32
   store i32 %n, i32* %n.addr, align 4
-  call void @llvm.dbg.declare(metadata !{i32* %n.addr}, metadata !15, metadata !{metadata !"0x102"}), !dbg !16
+  call void @llvm.dbg.declare(metadata i32* %n.addr, metadata !15, metadata !{!"0x102"}), !dbg !16
   %0 = load i32* %n.addr, align 4, !dbg !17
   %1 = zext i32 %0 to i64, !dbg !17
   %2 = call i8* @llvm.stacksave(), !dbg !17
   store i8* %2, i8** %saved_stack, !dbg !17
   %vla = alloca i32, i64 %1, align 16, !dbg !17
-  call void @llvm.dbg.declare(metadata !{i32* %vla}, metadata !18, metadata !{metadata !"0x102"}), !dbg !17
+  call void @llvm.dbg.declare(metadata i32* %vla, metadata !18, metadata !{!"0x102"}), !dbg !17
   %arrayidx = getelementptr inbounds i32* %vla, i64 0, !dbg !22
   store i32 42, i32* %arrayidx, align 4, !dbg !22
   %3 = load i32* %n.addr, align 4, !dbg !23
@@ -64,9 +64,9 @@
   %argv.addr = alloca i8**, align 8
   store i32 0, i32* %retval
   store i32 %argc, i32* %argc.addr, align 4
-  call void @llvm.dbg.declare(metadata !{i32* %argc.addr}, metadata !25, metadata !{metadata !"0x102"}), !dbg !26
+  call void @llvm.dbg.declare(metadata i32* %argc.addr, metadata !25, metadata !{!"0x102"}), !dbg !26
   store i8** %argv, i8*** %argv.addr, align 8
-  call void @llvm.dbg.declare(metadata !{i8*** %argv.addr}, metadata !27, metadata !{metadata !"0x102"}), !dbg !26
+  call void @llvm.dbg.declare(metadata i8*** %argv.addr, metadata !27, metadata !{!"0x102"}), !dbg !26
   %0 = load i32* %argc.addr, align 4, !dbg !28
   %call = call i32 @vla(i32 %0), !dbg !28
   ret i32 %call, !dbg !28
@@ -75,33 +75,33 @@
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!29}
 
-!0 = metadata !{metadata !"0x11\0012\00clang version 3.3 \000\00\000\00\001", metadata !1, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2} ; [ DW_TAG_compile_unit ] [/vla.c] [DW_LANG_C99]
-!1 = metadata !{metadata !"vla.c", metadata !""}
-!2 = metadata !{}
-!3 = metadata !{metadata !4, metadata !9}
-!4 = metadata !{metadata !"0x2e\00vla\00vla\00\001\000\001\000\006\00256\000\001", metadata !1, metadata !5, metadata !6, null, i32 (i32)* @vla, null, null, metadata !2} ; [ DW_TAG_subprogram ] [line 1] [def] [vla]
-!5 = metadata !{metadata !"0x29", metadata !1}          ; [ DW_TAG_file_type ] [/vla.c]
-!6 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", i32 0, null, null, metadata !7, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
-!7 = metadata !{metadata !8, metadata !8}
-!8 = metadata !{metadata !"0x24\00int\000\0032\0032\000\000\005", null, null} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
-!9 = metadata !{metadata !"0x2e\00main\00main\00\007\000\001\000\006\00256\000\007", metadata !1, metadata !5, metadata !10, null, i32 (i32, i8**)* @main, null, null, metadata !2} ; [ DW_TAG_subprogram ] [line 7] [def] [main]
-!10 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", i32 0, null, null, metadata !11, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
-!11 = metadata !{metadata !8, metadata !8, metadata !12}
-!12 = metadata !{metadata !"0xf\00\000\0064\0064\000\000", null, null, metadata !13} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from ]
-!13 = metadata !{metadata !"0xf\00\000\0064\0064\000\000", null, null, metadata !14} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from char]
-!14 = metadata !{metadata !"0x24\00char\000\008\008\000\000\006", null, null} ; [ DW_TAG_base_type ] [char] [line 0, size 8, align 8, offset 0, enc DW_ATE_signed_char]
-!15 = metadata !{metadata !"0x101\00n\0016777217\000", metadata !4, metadata !5, metadata !8} ; [ DW_TAG_arg_variable ] [n] [line 1]
-!16 = metadata !{i32 1, i32 0, metadata !4, null}
-!17 = metadata !{i32 2, i32 0, metadata !4, null}
-!18 = metadata !{metadata !"0x100\00a\002\008192", metadata !4, metadata !5, metadata !19} ; [ DW_TAG_auto_variable ] [a] [line 2]
-!19 = metadata !{metadata !"0x1\00\000\000\0032\000\000", null, null, metadata !8, metadata !20, i32 0, null, null, null} ; [ DW_TAG_array_type ] [line 0, size 0, align 32, offset 0] [from int]
-!20 = metadata !{metadata !21}
-!21 = metadata !{metadata !"0x21\000\00-1"}       ; [ DW_TAG_subrange_type ] [unbounded]
-!22 = metadata !{i32 3, i32 0, metadata !4, null}
-!23 = metadata !{i32 4, i32 0, metadata !4, null}
-!24 = metadata !{i32 5, i32 0, metadata !4, null}
-!25 = metadata !{metadata !"0x101\00argc\0016777223\000", metadata !9, metadata !5, metadata !8} ; [ DW_TAG_arg_variable ] [argc] [line 7]
-!26 = metadata !{i32 7, i32 0, metadata !9, null}
-!27 = metadata !{metadata !"0x101\00argv\0033554439\000", metadata !9, metadata !5, metadata !12} ; [ DW_TAG_arg_variable ] [argv] [line 7]
-!28 = metadata !{i32 8, i32 0, metadata !9, null}
-!29 = metadata !{i32 1, metadata !"Debug Info Version", i32 2}
+!0 = !{!"0x11\0012\00clang version 3.3 \000\00\000\00\001", !1, !2, !2, !3, !2, !2} ; [ DW_TAG_compile_unit ] [/vla.c] [DW_LANG_C99]
+!1 = !{!"vla.c", !""}
+!2 = !{}
+!3 = !{!4, !9}
+!4 = !{!"0x2e\00vla\00vla\00\001\000\001\000\006\00256\000\001", !1, !5, !6, null, i32 (i32)* @vla, null, null, !2} ; [ DW_TAG_subprogram ] [line 1] [def] [vla]
+!5 = !{!"0x29", !1}          ; [ DW_TAG_file_type ] [/vla.c]
+!6 = !{!"0x15\00\000\000\000\000\000\000", i32 0, null, null, !7, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = !{!8, !8}
+!8 = !{!"0x24\00int\000\0032\0032\000\000\005", null, null} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!9 = !{!"0x2e\00main\00main\00\007\000\001\000\006\00256\000\007", !1, !5, !10, null, i32 (i32, i8**)* @main, null, null, !2} ; [ DW_TAG_subprogram ] [line 7] [def] [main]
+!10 = !{!"0x15\00\000\000\000\000\000\000", i32 0, null, null, !11, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!11 = !{!8, !8, !12}
+!12 = !{!"0xf\00\000\0064\0064\000\000", null, null, !13} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from ]
+!13 = !{!"0xf\00\000\0064\0064\000\000", null, null, !14} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from char]
+!14 = !{!"0x24\00char\000\008\008\000\000\006", null, null} ; [ DW_TAG_base_type ] [char] [line 0, size 8, align 8, offset 0, enc DW_ATE_signed_char]
+!15 = !{!"0x101\00n\0016777217\000", !4, !5, !8} ; [ DW_TAG_arg_variable ] [n] [line 1]
+!16 = !{i32 1, i32 0, !4, null}
+!17 = !{i32 2, i32 0, !4, null}
+!18 = !{!"0x100\00a\002\008192", !4, !5, !19} ; [ DW_TAG_auto_variable ] [a] [line 2]
+!19 = !{!"0x1\00\000\000\0032\000\000", null, null, !8, !20, i32 0, null, null, null} ; [ DW_TAG_array_type ] [line 0, size 0, align 32, offset 0] [from int]
+!20 = !{!21}
+!21 = !{!"0x21\000\00-1"}       ; [ DW_TAG_subrange_type ] [unbounded]
+!22 = !{i32 3, i32 0, !4, null}
+!23 = !{i32 4, i32 0, !4, null}
+!24 = !{i32 5, i32 0, !4, null}
+!25 = !{!"0x101\00argc\0016777223\000", !9, !5, !8} ; [ DW_TAG_arg_variable ] [argc] [line 7]
+!26 = !{i32 7, i32 0, !9, null}
+!27 = !{!"0x101\00argv\0033554439\000", !9, !5, !12} ; [ DW_TAG_arg_variable ] [argv] [line 7]
+!28 = !{i32 8, i32 0, !9, null}
+!29 = !{i32 1, !"Debug Info Version", i32 2}