Redesign `DeclRef` and systematic `Val` deduplication (#3049)

* Redesign DeclRef + Deduplicate Val.

* Update project files

* Fix warning.

* Fix.

* Fix.

* Remove `Val::_equalsImplOverride`.

* Rmove `Val::_getHashCodeOverride`.

* Remove `semanticVisitor` param from `resolve`.

* Cleanups.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/source/slang/slang-check-resolve-val.cpp b/source/slang/slang-check-resolve-val.cpp
new file mode 100644
index 000000000..91722f82c
--- /dev/null
+++ b/source/slang/slang-check-resolve-val.cpp
@@ -0,0 +1,48 @@
+// slang-check-resolve-val.cpp
+
+// Logic for resolving/simplifying Types and DeclRefs.
+
+#include "slang-check-impl.h"
+
+#include "slang-lookup.h"
+#include "slang-syntax.h"
+#include "slang-ast-synthesis.h"
+#include "slang-ast-reflect.h"
+
+namespace Slang
+{
+
+Type* Type::createCanonicalType()
+{
+    SLANG_AST_NODE_VIRTUAL_CALL(Type, createCanonicalType, ());
+}
+
+Val* Type::_resolveImplOverride()
+{
+    Val* resolvedVal = createCanonicalType();
+    return resolvedVal;
+}
+
+DeclRefBase* _resolveAsDeclRef(DeclRefBase* declRefToResolve);
+
+Type* DeclRefType::_createCanonicalTypeOverride()
+{
+    auto astBuilder = getCurrentASTBuilder();
+
+    // A declaration reference is already canonical
+    auto resolvedDeclRef = getDeclRef();
+    resolvedDeclRef = _resolveAsDeclRef(getDeclRef().declRefBase);
+    if (auto satisfyingVal = _tryLookupConcreteAssociatedTypeFromThisTypeSubst(astBuilder, resolvedDeclRef))
+        return as<Type>(satisfyingVal);
+    if (resolvedDeclRef != getDeclRef())
+        return DeclRefType::create(astBuilder, resolvedDeclRef);
+    return this;
+}
+
+
+Val* SubtypeWitness::_resolveImplOverride()
+{
+    return as<SubtypeWitness>(defaultResolveImpl());
+}
+
+}