lower width info to enzyme

Author: ZuseZ4

compiler/rustc_codegen_llvm/src/builder/autodiff.rs

@@ -136,6 +136,13 @@ fn generate_enzyme_call<'ll>(
         let enzyme_dup = cx.create_metadata("enzyme_dup".to_string()).unwrap();
         let enzyme_dupnoneed = cx.create_metadata("enzyme_dupnoneed".to_string()).unwrap();
         let enzyme_primal_ret = cx.create_metadata("enzyme_primal_return".to_string()).unwrap();
+        let enzyme_width = cx.create_metadata("enzyme_width".to_string()).unwrap();
+
+        // FIXME(ZuseZ4): Find out, how enzyme_primal_ret and enzyme_width are combinable.
+        if attrs.width > 1 {
+            args.push(cx.get_metadata_value(enzyme_width));
+            args.push(cx.get_const_i64(attrs.width as u64));
+        }
 
         match output {
             DiffActivity::Dual => {

compiler/rustc_codegen_llvm/src/context.rs

@@ -637,6 +637,11 @@ impl<'ll> SimpleCx<'ll> {
         unsafe { llvm::LLVMMetadataAsValue(self.llcx, metadata) }
     }
 
+    pub(crate) fn get_const_i64(&self, n: u64) -> &'ll Value {
+        let ty = unsafe {llvm::LLVMInt64TypeInContext(self.llcx) };
+        unsafe { llvm::LLVMConstInt(ty, n, llvm::False) }
+    }
+
     pub(crate) fn get_function(&self, name: &str) -> Option<&'ll Value> {
         let name = SmallCStr::new(name);
         unsafe { llvm::LLVMGetNamedFunction(self.llmod, name.as_ptr()) }