[Verifier] Verify scoped noalias metadata

Verify that !noalias, !alias.scope and llvm.experimental.noalias.scope
arguments have the format specified in
https://llvm.org/docs/LangRef.html#noalias-and-alias-scope-metadata.
I've fixed up a lot of broken metadata used by tests in advance.
Especially using a scope instead of the expected scope list is a
commonly made mistake.

Differential Revision: https://reviews.llvm.org/D110026

llvm/lib/IR/Verifier.cpp

@@ -461,6 +461,8 @@ private:
   void visitDereferenceableMetadata(Instruction &I, MDNode *MD);
   void visitProfMetadata(Instruction &I, MDNode *MD);
   void visitAnnotationMetadata(MDNode *Annotation);
+  void visitAliasScopeMetadata(const MDNode *MD);
+  void visitAliasScopeListMetadata(const MDNode *MD);
 
   template <class Ty> bool isValidMetadataArray(const MDTuple &N);
 #define HANDLE_SPECIALIZED_MDNODE_LEAF(CLASS) void visit##CLASS(const CLASS &N);
@@ -4343,6 +4345,38 @@ void Verifier::visitAnnotationMetadata(MDNode *Annotation) {
     Assert(isa<MDString>(Op.get()), "operands must be strings");
 }
 
+void Verifier::visitAliasScopeMetadata(const MDNode *MD) {
+  unsigned NumOps = MD->getNumOperands();
+  Assert(NumOps >= 2 && NumOps <= 3, "scope must have two or three operands",
+         MD);
+  Assert(MD->getOperand(0) == MD || isa<MDString>(MD->getOperand(0)),
+         "first scope operand must be self-referential or string", MD);
+  if (NumOps == 3)
+    Assert(isa<MDString>(MD->getOperand(2)),
+           "third scope operand must be string (if used)", MD);
+
+  MDNode *Domain = dyn_cast<MDNode>(MD->getOperand(1));
+  Assert(Domain != nullptr, "second scope operand must be MDNode", MD);
+
+  unsigned NumDomainOps = Domain->getNumOperands();
+  Assert(NumDomainOps >= 1 && NumDomainOps <= 2,
+         "domain must have one or two operands", Domain);
+  Assert(Domain->getOperand(0) == Domain ||
+             isa<MDString>(Domain->getOperand(0)),
+         "first domain operand must be self-referential or string", Domain);
+  if (NumDomainOps == 2)
+    Assert(isa<MDString>(Domain->getOperand(1)),
+           "second domain operand must be string (if used)", Domain);
+}
+
+void Verifier::visitAliasScopeListMetadata(const MDNode *MD) {
+  for (const MDOperand &Op : MD->operands()) {
+    const MDNode *OpMD = dyn_cast<MDNode>(Op);
+    Assert(OpMD != nullptr, "scope list must consist of MDNodes", MD);
+    visitAliasScopeMetadata(OpMD);
+  }
+}
+
 /// verifyInstruction - Verify that an instruction is well formed.
 ///
 void Verifier::visitInstruction(Instruction &I) {
@@ -4502,6 +4536,11 @@ void Verifier::visitInstruction(Instruction &I) {
   if (MDNode *TBAA = I.getMetadata(LLVMContext::MD_tbaa))
     TBAAVerifyHelper.visitTBAAMetadata(I, TBAA);
 
+  if (MDNode *MD = I.getMetadata(LLVMContext::MD_noalias))
+    visitAliasScopeListMetadata(MD);
+  if (MDNode *MD = I.getMetadata(LLVMContext::MD_alias_scope))
+    visitAliasScopeListMetadata(MD);
+
   if (MDNode *AlignMD = I.getMetadata(LLVMContext::MD_align)) {
     Assert(I.getType()->isPointerTy(), "align applies only to pointer types",
            &I);
@@ -5719,6 +5758,7 @@ void Verifier::verifyNoAliasScopeDecl() {
            II);
     Assert(ScopeListMD->getNumOperands() == 1,
            "!id.scope.list must point to a list with a single scope", II);
+    visitAliasScopeListMetadata(ScopeListMD);
   }
 
   // Only check the domination rule when requested. Once all passes have been

llvm/test/Verifier/alias-scope-metadata.ll

@@ -0,0 +1,61 @@
+; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+define void @test(i8* %p) {
+  load i8, i8* %p, !noalias !0
+  load i8, i8* %p, !noalias !1
+  load i8, i8* %p, !noalias !3
+  load i8, i8* %p, !noalias !5
+  load i8, i8* %p, !noalias !7
+  load i8, i8* %p, !noalias !9
+  load i8, i8* %p, !noalias !11
+  load i8, i8* %p, !noalias !14
+  load i8, i8* %p, !alias.scope !17
+  call void @llvm.experimental.noalias.scope.decl(metadata !20)
+  ret void
+}
+
+declare void @llvm.experimental.noalias.scope.decl(metadata)
+
+; CHECK: scope list must consist of MDNodes
+!0 = !{!"str"}
+
+; CHECK: scope must have two or three operands
+!1 = !{!2}
+!2 = !{!2}
+
+; CHECK: scope must have two or three operands
+!3 = !{!4}
+!4 = !{!4, !5, !6, !7}
+
+; CHECK: first scope operand must be self-referential or string
+!5 = !{!6}
+!6 = !{!7, !8}
+
+; CHECK: third scope operand must be string (if used)
+!7 = !{!8}
+!8 = !{!8, !9, !10}
+
+; CHECK: second scope operand must be MDNode
+!9 = !{!10}
+!10 = !{!10, !"str"}
+
+; CHECK: domain must have one or two operands
+!11 = !{!12}
+!12 = !{!12, !13}
+!13 = !{}
+
+; CHECK: domain must have one or two operands
+!14 = !{!15}
+!15 = !{!15, !16}
+!16 = !{!17, !18, !19}
+
+; CHECK: first domain operand must be self-referential or string
+!17 = !{!18}
+!18 = !{!18, !19}
+!19 = !{!20}
+
+; CHECK: second domain operand must be string (if used)
+!20 = !{!21}
+!21 = !{!21, !22}
+!22 = !{!22, !23}
+!23 = !{}