autodiff: f128 support added for typetree

Author: KMJ-007

compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs

@@ -25,8 +25,8 @@ pub(crate) enum CConcreteType {
     DT_Half = 3,
     DT_Float = 4,
     DT_Double = 5,
-    // FIXME(KMJ-007): handle f128 using long double here(https://github.com/EnzymeAD/Enzyme/issues/1600)
     DT_Unknown = 6,
+    DT_FP128 = 9,
 }
 
 pub(crate) struct TypeTree {

compiler/rustc_codegen_llvm/src/typetree.rs

@@ -31,7 +31,7 @@ fn to_enzyme_typetree(
             rustc_ast::expand::typetree::Kind::Half => llvm::CConcreteType::DT_Half,
             rustc_ast::expand::typetree::Kind::Float => llvm::CConcreteType::DT_Float,
             rustc_ast::expand::typetree::Kind::Double => llvm::CConcreteType::DT_Double,
-            rustc_ast::expand::typetree::Kind::F128 => llvm::CConcreteType::DT_Unknown,
+            rustc_ast::expand::typetree::Kind::F128 => llvm::CConcreteType::DT_FP128,
             rustc_ast::expand::typetree::Kind::Unknown => llvm::CConcreteType::DT_Unknown,
         };