[IR] Provide array with poison-generating metadata IDs.

Add Instruction::PoisonGeneratingMetadataIDs containing IDs of
poison-generating metadata to allow easier re-use.

Currently it is a static const array in Instruction, maybe here's a
better place?

Author: fhahn

llvm/include/llvm/IR/Instruction.h

@@ -503,6 +503,10 @@ class Instruction : public User,
   /// Determine whether the the nneg flag is set.
   bool hasNonNeg() const LLVM_READONLY;
 
+  /// Metadata IDs that may generate poison.
+  constexpr static const unsigned PoisonGeneratingMetadataIDs[] = {
+      LLVMContext::MD_range, LLVMContext::MD_nonnull, LLVMContext::MD_align};
+
   /// Return true if this operator has flags which may cause this instruction
   /// to evaluate to poison despite having non-poison inputs.
   bool hasPoisonGeneratingFlags() const LLVM_READONLY;

llvm/lib/IR/Instruction.cpp

@@ -458,9 +458,8 @@ void Instruction::dropPoisonGeneratingFlags() {
 }
 
 bool Instruction::hasPoisonGeneratingMetadata() const {
-  return hasMetadata(LLVMContext::MD_range) ||
-         hasMetadata(LLVMContext::MD_nonnull) ||
-         hasMetadata(LLVMContext::MD_align);
+  return any_of(PoisonGeneratingMetadataIDs,
+                [this](unsigned ID) { return hasMetadata(ID); });
 }
 
 bool Instruction::hasNonDebugLocLoopMetadata() const {
@@ -487,9 +486,8 @@ bool Instruction::hasNonDebugLocLoopMetadata() const {
 }
 
 void Instruction::dropPoisonGeneratingMetadata() {
-  eraseMetadata(LLVMContext::MD_range);
-  eraseMetadata(LLVMContext::MD_nonnull);
-  eraseMetadata(LLVMContext::MD_align);
+  for (unsigned ID : PoisonGeneratingMetadataIDs)
+    eraseMetadata(ID);
 }
 
 bool Instruction::hasPoisonGeneratingReturnAttributes() const {