[IR] Add a target extension type to LLVM.

Target-extension types represent types that need to be preserved through
optimization, but otherwise are not introspectable by target-independent
optimizations. This patch doesn't add any uses of these types by an existing
backend, it only provides basic infrastructure such that these types would work
correctly.

Reviewed By: nikic, barannikov88

Differential Revision: https://reviews.llvm.org/D135202

1 files changed, 22 insertions, 1 deletions

diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index b7126ad..9c8e299 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -87,7 +87,7 @@ bool Constant::isNullValue() const {
   // constant zero is zero for aggregates, cpnull is null for pointers, none for
   // tokens.
   return isa<ConstantAggregateZero>(this) || isa<ConstantPointerNull>(this) ||
-         isa<ConstantTokenNone>(this);
+         isa<ConstantTokenNone>(this) || isa<ConstantTargetNone>(this);
 }
 
 bool Constant::isAllOnesValue() const {
@@ -369,6 +369,8 @@ Constant *Constant::getNullValue(Type *Ty) {
     return ConstantAggregateZero::get(Ty);
   case Type::TokenTyID:
     return ConstantTokenNone::get(Ty->getContext());
+  case Type::TargetExtTyID:
+    return ConstantTargetNone::get(cast<TargetExtType>(Ty));
   default:
     // Function, Label, or Opaque type?
     llvm_unreachable("Cannot create a null constant of that type!");
@@ -1710,6 +1712,25 @@ void ConstantPointerNull::destroyConstantImpl() {
   getContext().pImpl->CPNConstants.erase(getType());
 }
 
+//---- ConstantTargetNone::get() implementation.
+//
+
+ConstantTargetNone *ConstantTargetNone::get(TargetExtType *Ty) {
+  assert(Ty->hasProperty(TargetExtType::HasZeroInit) &&
+         "Target extension type not allowed to have a zeroinitializer");
+  std::unique_ptr<ConstantTargetNone> &Entry =
+      Ty->getContext().pImpl->CTNConstants[Ty];
+  if (!Entry)
+    Entry.reset(new ConstantTargetNone(Ty));
+
+  return Entry.get();
+}
+
+/// Remove the constant from the constant table.
+void ConstantTargetNone::destroyConstantImpl() {
+  getContext().pImpl->CTNConstants.erase(getType());
+}
+
 UndefValue *UndefValue::get(Type *Ty) {
   std::unique_ptr<UndefValue> &Entry = Ty->getContext().pImpl->UVConstants[Ty];
   if (!Entry)