IR: Give 'DI' prefix to debug info metadata

Finish off PR23080 by renaming the debug info IR constructs from `MD*`
to `DI*`.  The last of the `DIDescriptor` classes were deleted in
r235356, and the last of the related typedefs removed in r235413, so
this has all baked for about a week.

Note: If you have out-of-tree code (like a frontend), I recommend that
you get everything compiling and tests passing with the *previous*
commit before updating to this one.  It'll be easier to keep track of
what code is using the `DIDescriptor` hierarchy and what you've already
updated, and I think you're extremely unlikely to insert bugs.  YMMV of
course.

Back to *this* commit: I did this using the rename-md-di-nodes.sh
upgrade script I've attached to PR23080 (both code and testcases) and
filtered through clang-format-diff.py.  I edited the tests for
test/Assembler/invalid-generic-debug-node-*.ll by hand since the columns
were off-by-three.  It should work on your out-of-tree testcases (and
code, if you've followed the advice in the previous paragraph).

Some of the tests are in badly named files now (e.g.,
test/Assembler/invalid-mdcompositetype-missing-tag.ll should be
'dicompositetype'); I'll come back and move the files in a follow-up
commit.

llvm-svn: 236120
diff --git a/llvm/test/Transforms/Inline/ignore-debug-info.ll b/llvm/test/Transforms/Inline/ignore-debug-info.ll
index 4cbd2fa..eb92bc5 100644
--- a/llvm/test/Transforms/Inline/ignore-debug-info.ll
+++ b/llvm/test/Transforms/Inline/ignore-debug-info.ll
@@ -12,11 +12,11 @@
 
 define <4 x float> @inner_vectors(<4 x float> %a, <4 x float> %b) {
 entry:
-  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !MDLocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !MDExpression()), !dbg !MDLocation(scope: !6)
+  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !DILocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !DIExpression()), !dbg !DILocation(scope: !6)
   %mul = fmul <4 x float> %a, <float 3.000000e+00, float 3.000000e+00, float 3.000000e+00, float 3.000000e+00>
-  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !MDLocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !MDExpression()), !dbg !MDLocation(scope: !6)
+  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !DILocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !DIExpression()), !dbg !DILocation(scope: !6)
   %mul1 = fmul <4 x float> %b, <float 5.000000e+00, float 5.000000e+00, float 5.000000e+00, float 5.000000e+00>
-  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !MDLocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !MDExpression()), !dbg !MDLocation(scope: !6)
+  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !DILocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !DIExpression()), !dbg !DILocation(scope: !6)
   %add = fadd <4 x float> %mul, %mul1
   ret <4 x float> %add
 }
@@ -27,10 +27,10 @@
 ; CHECK: ret float
 
 entry:
-  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !MDLocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !MDExpression()), !dbg !MDLocation(scope: !6)
-  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !MDLocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !MDExpression()), !dbg !MDLocation(scope: !6)
+  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !DILocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !DIExpression()), !dbg !DILocation(scope: !6)
+  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !DILocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !DIExpression()), !dbg !DILocation(scope: !6)
   %call = call <4 x float> @inner_vectors(<4 x float> %a, <4 x float> %b)
-  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !MDLocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !MDExpression()), !dbg !MDLocation(scope: !6)
+  call void @llvm.dbg.value(metadata i32 undef, i64 0, metadata !DILocalVariable(tag: DW_TAG_auto_variable, scope: !6), metadata !DIExpression()), !dbg !DILocation(scope: !6)
   %vecext = extractelement <4 x float> %call, i32 0
   %vecext1 = extractelement <4 x float> %call, i32 1
   %add = fadd float %vecext, %vecext1
@@ -47,10 +47,10 @@
 !llvm.module.flags = !{!3, !4}
 !llvm.ident = !{!5}
 
-!0 = !MDCompileUnit(language: DW_LANG_C_plus_plus, isOptimized: false, emissionKind: 0, file: !1, enums: !2, retainedTypes: !2, subprograms: !{!6}, globals: !2, imports: !2)
-!1 = !MDFile(filename: "test.c", directory: "")
+!0 = !DICompileUnit(language: DW_LANG_C_plus_plus, isOptimized: false, emissionKind: 0, file: !1, enums: !2, retainedTypes: !2, subprograms: !{!6}, globals: !2, imports: !2)
+!1 = !DIFile(filename: "test.c", directory: "")
 !2 = !{}
 !3 = !{i32 2, !"Dwarf Version", i32 4}
 !4 = !{i32 1, !"Debug Info Version", i32 3}
 !5 = !{!""}
-!6 = !MDSubprogram()
+!6 = !DISubprogram()