[llvm] [IR] Check parameters of target extension types on construction (PR #107268)

[Jay Foad via llvm-commits]

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@@ -792,28 +793,51 @@ TargetExtType::TargetExtType(LLVMContext &C, StringRef Name,
 TargetExtType *TargetExtType::get(LLVMContext &C, StringRef Name,
                                   ArrayRef<Type *> Types,
                                   ArrayRef<unsigned> Ints) {
+  return cantFail(getOrError(C, Name, Types, Ints));
+}
+
+Expected<TargetExtType *> TargetExtType::getOrError(LLVMContext &C,
+                                                    StringRef Name,
+                                                    ArrayRef<Type *> Types,
+                                                    ArrayRef<unsigned> Ints) {
   const TargetExtTypeKeyInfo::KeyTy Key(Name, Types, Ints);
   TargetExtType *TT;
   // Since we only want to allocate a fresh target type in case none is found
   // and we don't want to perform two lookups (one for checking if existent and
   // one for inserting the newly allocated one), here we instead lookup based on
   // Key and update the reference to the target type in-place to a newly
   // allocated one if not found.
-  auto Insertion = C.pImpl->TargetExtTypes.insert_as(nullptr, Key);
-  if (Insertion.second) {
+  auto [Iter, Inserted] = C.pImpl->TargetExtTypes.insert_as(nullptr, Key);
+  if (Inserted) {
     // The target type was not found. Allocate one and update TargetExtTypes
     // in-place.
     TT = (TargetExtType *)C.pImpl->Alloc.Allocate(
         sizeof(TargetExtType) + sizeof(Type *) * Types.size() +
             sizeof(unsigned) * Ints.size(),
         alignof(TargetExtType));
     new (TT) TargetExtType(C, Name, Types, Ints);
-    *Insertion.first = TT;
-  } else {
-    // The target type was found. Just return it.
-    TT = *Insertion.first;
+    *Iter = TT;
+    return checkParams(TT);
   }
-  return TT;
+
+  // The target type was found. Just return it.
+  return *Iter;
+}
+
+Expected<TargetExtType *> TargetExtType::checkParams(TargetExtType *TTy) {
+  // Opaque types in the AArch64 name space.
+  if (TTy->Name == "aarch64.svcount" &&
+      (TTy->getNumTypeParameters() != 0 || TTy->getNumIntParameters() != 0))
+    return createStringError(
+        "Target type aarch64.svcount should have no parameters");
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jayfoad wrote:

Maybe "Target _extension_ type ..." would be more correct, though I see "target type" is already reasonably common in the code base.

https://github.com/llvm/llvm-project/pull/107268