Add support for NonNull function attribute

Author: GuillaumeGomez

src/abi.rs

@@ -1,4 +1,4 @@
-use gccjit::{ToLValue, ToRValue, Type};
+use gccjit::{FnAttribute, ToLValue, ToRValue, Type};
 use rustc_codegen_ssa::traits::{AbiBuilderMethods, BaseTypeMethods};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_middle::bug;
@@ -97,12 +97,12 @@ impl GccType for Reg {
 
 pub trait FnAbiGccExt<'gcc, 'tcx> {
     // TODO(antoyo): return a function pointer type instead?
-    fn gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> (Type<'gcc>, Vec<Type<'gcc>>, bool, FxHashSet<usize>);
+    fn gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> (Type<'gcc>, Vec<Type<'gcc>>, bool, FxHashSet<usize>, Vec<FnAttribute<'gcc>>);
     fn ptr_to_gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc>;
 }
 
 impl<'gcc, 'tcx> FnAbiGccExt<'gcc, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
-    fn gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> (Type<'gcc>, Vec<Type<'gcc>>, bool, FxHashSet<usize>) {
+    fn gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> (Type<'gcc>, Vec<Type<'gcc>>, bool, FxHashSet<usize>, Vec<FnAttribute<'gcc>>) {
         let mut on_stack_param_indices = FxHashSet::default();
 
         // This capacity calculation is approximate.
@@ -120,28 +120,33 @@ impl<'gcc, 'tcx> FnAbiGccExt<'gcc, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
                     cx.type_void()
                 }
             };
+        let mut non_null_args = Vec::new();
 
         #[cfg(feature = "master")]
-        let apply_attrs = |ty: Type<'gcc>, attrs: &ArgAttributes| {
-            if cx.sess().opts.optimize != config::OptLevel::No
-                && attrs.regular.contains(rustc_target::abi::call::ArgAttribute::NoAlias)
-            {
-                ty.make_restrict()
-            } else {
-                ty
+        let mut apply_attrs = |mut ty: Type<'gcc>, attrs: &ArgAttributes, arg_index: usize| {
+            if cx.sess().opts.optimize == config::OptLevel::No {
+                return ty;
             }
+            if attrs.regular.contains(rustc_target::abi::call::ArgAttribute::NoAlias) {
+                ty = ty.make_restrict()
+            }
+            if attrs.regular.contains(rustc_target::abi::call::ArgAttribute::NonNull) {
+                non_null_args.push(arg_index as i32 + 1);
+            }
+            ty
         };
         #[cfg(not(feature = "master"))]
-        let apply_attrs = |ty: Type<'gcc>, _attrs: &ArgAttributes| {
+        let apply_attrs = |ty: Type<'gcc>, _attrs: &ArgAttributes, _arg_index: usize| {
             ty
         };
 
         for arg in self.args.iter() {
             let arg_ty = match arg.mode {
                 PassMode::Ignore => continue,
                 PassMode::Pair(a, b) => {
-                    argument_tys.push(apply_attrs(arg.layout.scalar_pair_element_gcc_type(cx, 0, true), &a));
-                    argument_tys.push(apply_attrs(arg.layout.scalar_pair_element_gcc_type(cx, 1, true), &b));
+                    let arg_pos = argument_tys.len();
+                    argument_tys.push(apply_attrs(arg.layout.scalar_pair_element_gcc_type(cx, 0, true), &a, arg_pos));
+                    argument_tys.push(apply_attrs(arg.layout.scalar_pair_element_gcc_type(cx, 1, true), &b, arg_pos + 1));
                     continue;
                 }
                 PassMode::Cast(ref cast, pad_i32) => {
@@ -150,30 +155,41 @@ impl<'gcc, 'tcx> FnAbiGccExt<'gcc, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
                         argument_tys.push(Reg::i32().gcc_type(cx));
                     }
                     let ty = cast.gcc_type(cx);
-                    apply_attrs(ty, &cast.attrs)
+                    apply_attrs(ty, &cast.attrs, argument_tys.len())
                 }
                 PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: true } => {
                     // This is a "byval" argument, so we don't apply the `restrict` attribute on it.
                     on_stack_param_indices.insert(argument_tys.len());
                     arg.memory_ty(cx)
                 },
-                PassMode::Direct(attrs) => apply_attrs(arg.layout.immediate_gcc_type(cx), &attrs),
+                PassMode::Direct(attrs) => apply_attrs(arg.layout.immediate_gcc_type(cx), &attrs, argument_tys.len()),
                 PassMode::Indirect { attrs, extra_attrs: None, on_stack: false } => {
-                    apply_attrs(cx.type_ptr_to(arg.memory_ty(cx)), &attrs)
+                    apply_attrs(cx.type_ptr_to(arg.memory_ty(cx)), &attrs, argument_tys.len())
                 }
                 PassMode::Indirect { attrs, extra_attrs: Some(extra_attrs), on_stack } => {
                     assert!(!on_stack);
-                    apply_attrs(apply_attrs(cx.type_ptr_to(arg.memory_ty(cx)), &attrs), &extra_attrs)
+                    let ty = apply_attrs(cx.type_ptr_to(arg.memory_ty(cx)), &attrs, argument_tys.len());
+                    apply_attrs(ty, &extra_attrs, argument_tys.len())
                 }
             };
             argument_tys.push(arg_ty);
         }
 
-        (return_ty, argument_tys, self.c_variadic, on_stack_param_indices)
+        #[cfg(feature = "master")]
+        let fn_attrs = if non_null_args.is_empty() {
+            Vec::new()
+        } else {
+            vec![FnAttribute::NonNull(non_null_args)]
+        };
+        #[cfg(not(feature = "master"))]
+        let fn_attrs = Vec::new();
+
+        (return_ty, argument_tys, self.c_variadic, on_stack_param_indices, fn_attrs)
     }
 
     fn ptr_to_gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc> {
-        let (return_type, params, variadic, on_stack_param_indices) = self.gcc_type(cx);
+        // FIXME: Should we do something with `fn_attrs`?
+        let (return_type, params, variadic, on_stack_param_indices, _fn_attrs) = self.gcc_type(cx);
         let pointer_type = cx.context.new_function_pointer_type(None, return_type, &params, variadic);
         cx.on_stack_params.borrow_mut().insert(pointer_type.dyncast_function_ptr_type().expect("function ptr type"), on_stack_param_indices);
         pointer_type

src/declare.rs

@@ -80,9 +80,13 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
     }
 
     pub fn declare_fn(&self, name: &str, fn_abi: &FnAbi<'tcx, Ty<'tcx>>) -> Function<'gcc> {
-        let (return_type, params, variadic, on_stack_param_indices) = fn_abi.gcc_type(self);
+        let (return_type, params, variadic, on_stack_param_indices, fn_attrs) = fn_abi.gcc_type(self);
         let func = declare_raw_fn(self, name, () /*fn_abi.llvm_cconv()*/, return_type, &params, variadic);
         self.on_stack_function_params.borrow_mut().insert(func, on_stack_param_indices);
+        // We need to handle `nonnull` here where we still have access to function args.
+        for fn_attr in fn_attrs {
+            func.add_attribute(fn_attr);
+        }
         func
     }
 

src/intrinsic/mod.rs

@@ -1197,7 +1197,7 @@ fn get_rust_try_fn<'a, 'gcc, 'tcx>(cx: &'a CodegenCx<'gcc, 'tcx>, codegen: &mut
 #[cfg(feature="master")]
 fn gen_fn<'a, 'gcc, 'tcx>(cx: &'a CodegenCx<'gcc, 'tcx>, name: &str, rust_fn_sig: ty::PolyFnSig<'tcx>, codegen: &mut dyn FnMut(Builder<'a, 'gcc, 'tcx>)) -> (Type<'gcc>, Function<'gcc>) {
     let fn_abi = cx.fn_abi_of_fn_ptr(rust_fn_sig, ty::List::empty());
-    let (typ, _, _, _) = fn_abi.gcc_type(cx);
+    let (typ, _, _, _, _) = fn_abi.gcc_type(cx);
     // FIXME(eddyb) find a nicer way to do this.
     cx.linkage.set(FunctionType::Internal);
     let func = cx.declare_fn(name, fn_abi);

src/type_of.rs

@@ -384,7 +384,8 @@ impl<'gcc, 'tcx> LayoutTypeMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
     }
 
     fn fn_decl_backend_type(&self, fn_abi: &FnAbi<'tcx, Ty<'tcx>>) -> Type<'gcc> {
-        let (return_type, param_types, variadic, _) = fn_abi.gcc_type(self);
+        // // FIXME: Should we do something with `fn_attrs`?
+        let (return_type, param_types, variadic, _, _fn_attrs) = fn_abi.gcc_type(self);
         self.context.new_function_pointer_type(None, return_type, &param_types, variadic)
     }
 }