[DebugInfo] Add verifier for DICompositeType vector

[mattd]

Summary

This patch adds verification logic for DICompositeType vectors, ensuring that they only have one element, and that element is of type subrange.

This patch complements https://reviews.llvm.org/D44048

[aprantl]

Thanks!

lib/IR/Verifier.cpp

            N.getRawBaseType());
 
   AssertDI(!N.getRawElements() || isa<MDTuple>(N.getRawElements()),
            "invalid composite elements", &N, N.getRawElements());
   AssertDI(isType(N.getRawVTableHolder()), "invalid vtable holder", &N,
            N.getRawVTableHolder());
   AssertDI(!hasConflictingReferenceFlags(N.getFlags()),
            "invalid reference flags", &N);
+
+  if (N.isVector()) {
+    const DINodeArray Elements = N.getElements();
+    AssertDI(Elements.size() == 1 &&
+             Elements[0]->getTag() == dwarf::DW_TAG_subrange_type,
+             "invalid vector, expected one element of type subrange", &N);
+  }
+
   if (auto *Params = N.getRawTemplateParams())
     visitTemplateParams(N, *Params);
 
   if (N.getTag() == dwarf::DW_TAG_class_type ||
       N.getTag() == dwarf::DW_TAG_union_type) {
     AssertDI(N.getFile() && !N.getFile()->getFilename().empty(),
              "class/union requires a filename", &N, N.getFile());
   }

test/Verifier/dbg-invalid-vector.ll

+; RUN: opt -verify -disable-output <%s 2>&1 | FileCheck %s
+;
+; This test creates an invalid vector by defining multiple elements for the
+; vector's DICompositeType definition.  A vector should only have one element
+; in its DICompositeType 'elements' array.
+;
+; CHECK: invalid vector
+
[e-mail] = private unnamed_addr constant <6 x float> zeroinitializer, align 32
+
+define void @f() {
+  %1 = alloca <6 x float>, align 32
+  call void @llvm.dbg.declare(metadata <6 x float>* %1, metadata !10, metadata !DIExpression()), !dbg !18
+  ret void
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "test.c", directory: "/dbg/info")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!7 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 3, type: !8, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null}
+!10 = !DILocalVariable(name: "foo", scope: !7, file: !1, line: 4, type: !12)
+!12 = !DICompositeType(tag: DW_TAG_array_type, baseType: !13, size: 256, flags: DIFlagVector, elements: !14)
+!13 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
+!14 = !{!15, !19}
+!15 = !DISubrange(count: 6)
+!18 = !DILocation(line: 4, column: 48, scope: !7)
+!19 = !DISubrange(count: 42)