Reapply "Verifier: Add check for DICompositeType elements being null"

This remove some erroneous debug info from tests that should address the
test failures that showed up when the this was previously committed.

This reverts commit 6716ce8.

Author: dwblaikie

llvm/lib/IR/Verifier.cpp

@@ -1319,6 +1319,8 @@ void Verifier::visitDICompositeType(const DICompositeType &N) {
   unsigned DIBlockByRefStruct = 1 << 4;
   CheckDI((N.getFlags() & DIBlockByRefStruct) == 0,
           "DIBlockByRefStruct on DICompositeType is no longer supported", &N);
+  CheckDI(llvm::all_of(N.getElements(), [](const DINode *N) { return N; }),
+          "DISubprogram contains null entry in `elements` field", &N);
 
   if (N.isVector()) {
     const DINodeArray Elements = N.getElements();

llvm/test/DebugInfo/X86/set.ll

@@ -109,7 +109,7 @@ attributes #1 = { nofree nosync nounwind readnone speculatable willreturn }
 !31 = !DISubroutineType(types: !32)
 !32 = !{!33, !35}
 !33 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "ADDR", baseType: !34, size: 64, align: 64)
-!34 = !DICompositeType(tag: DW_TAG_class_type, name: "ADDR__HeapObject", scope: !5, file: !2, line: 22, size: 64, align: 64, elements: !7, identifier: "AJWxb1")
+!34 = !DICompositeType(tag: DW_TAG_class_type, name: "ADDR__HeapObject", scope: !5, file: !2, line: 22, size: 64, align: 64, identifier: "AJWxb1")
 !35 = !DIBasicType(name: "INTEGER", size: 64, encoding: DW_ATE_signed)
 !36 = !DILocation(line: 23, scope: !30)
 !37 = !DILocalVariable(name: "mode", arg: 1, scope: !30, file: !2, line: 22, type: !35)

llvm/test/Transforms/LoopVectorize/dbg.value.ll

@@ -51,10 +51,8 @@ attributes #1 = { nounwind readnone }
 !0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
 !1 = !DIGlobalVariable(name: "A", scope: null, file: !2, line: 1, type: !3, isLocal: false, isDefinition: true)
 !2 = !DIFile(filename: "test", directory: "/path/to/somewhere")
-!3 = !DICompositeType(tag: DW_TAG_array_type, baseType: !4, size: 32768, align: 32, elements: !5)
+!3 = !DICompositeType(tag: DW_TAG_array_type, baseType: !4, size: 32768, align: 32)
 !4 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
-!5 = !{!6}
-!6 = !{i32 786465, i64 0, i64 1024}
 !7 = !DIGlobalVariableExpression(var: !8, expr: !DIExpression())
 !8 = !DIGlobalVariable(name: "B", scope: null, file: !2, line: 2, type: !3, isLocal: false, isDefinition: true)
 !9 = !DIGlobalVariableExpression(var: !10, expr: !DIExpression())

llvm/test/Verifier/dicompositetype-elements-null.ll

@@ -0,0 +1,6 @@
+; RUN: not opt -S < %s 2>&1 | FileCheck %s
+
+!named = !{!0}
+; CHECK: DISubprogram contains null entry in `elements` field
+!0 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t1", elements: !1)
+!1 = !{null}