Support float16

Author: sagudev

bindgen-tests/tests/expectations/tests/float16.rs

@@ -0,0 +1,36 @@
+// bindgen-flags: --with-derive-hash --with-derive-partialeq --with-derive-eq
+
+static __fp16 global;
+
+struct Test__Float16
+{
+    __fp16 f;
+};
+
+struct Test__Float16Ref
+{
+    __fp16 *f;
+};
+
+/*
+// This options are currently supported only on specific targets (eg. x86 with sse2)
+_Float16 returns_f16();
+
+void gets_f16(_Float16 arg);
+
+struct Test__Float16_Complex
+{
+    _Float16 _Complex mMember;
+};
+
+struct Test__Float16_ComplexPtr
+{
+    _Float16 _Complex *mMember;
+};
+
+_Float16 _Complex globalValueHalf;
+
+_Float16 _Complex returns_f16_complex();
+
+void gets_f16_complex(_Float16 _Complex arg);
+*/

bindgen-tests/tests/headers/float16.h

@@ -232,6 +232,15 @@ pub(crate) mod ast_ty {
         //
         // Also, maybe this one shouldn't be the default?
         match (fk, ctx.options().convert_floats) {
+            (FloatKind::Float16, _) => {
+                // TODO: do f16 when rust lands it
+                ctx.generated_bindgen_float16();
+                if ctx.options().enable_cxx_namespaces {
+                    syn::parse_quote! { root::__BindgenFloat16 }
+                } else {
+                    syn::parse_quote! { __BindgenFloat16 }
+                }
+            }
             (FloatKind::Float, true) => syn::parse_quote! { f32 },
             (FloatKind::Double, true) => syn::parse_quote! { f64 },
             (FloatKind::Float, false) => raw_type(ctx, "c_float"),

bindgen/codegen/helpers.rs

@@ -578,6 +578,9 @@ impl CodeGenerator for Module {
                 if result.saw_incomplete_array {
                     utils::prepend_incomplete_array_types(ctx, &mut *result);
                 }
+                if ctx.need_bindgen_float16_type() {
+                    utils::prepend_float16_type(&mut *result);
+                }
                 if ctx.need_bindgen_complex_type() {
                     utils::prepend_complex_type(&mut *result);
                 }
@@ -5136,6 +5139,20 @@ pub(crate) mod utils {
         result.extend(old_items);
     }
 
+    pub(crate) fn prepend_float16_type(
+        result: &mut Vec<proc_macro2::TokenStream>,
+    ) {
+        let float16_type = quote! {
+            #[derive(PartialEq, Copy, Clone, Hash, Debug, Default)]
+            #[repr(transparent)]
+            pub struct __BindgenFloat16(pub u16);
+        };
+
+        let items = vec![float16_type];
+        let old_items = mem::replace(result, items);
+        result.extend(old_items);
+    }
+
     pub(crate) fn prepend_complex_type(
         result: &mut Vec<proc_macro2::TokenStream>,
     ) {

bindgen/codegen/mod.rs

@@ -270,6 +270,7 @@ impl<'a> CSerialize<'a> for Type {
                     write!(writer, "const ")?;
                 }
                 match float_kind {
+                    FloatKind::Float16 => write!(writer, "_Float16")?,
                     FloatKind::Float => write!(writer, "float")?,
                     FloatKind::Double => write!(writer, "double")?,
                     FloatKind::LongDouble => write!(writer, "long double")?,
@@ -281,6 +282,7 @@ impl<'a> CSerialize<'a> for Type {
                     write!(writer, "const ")?;
                 }
                 match float_kind {
+                    FloatKind::Float16 => write!(writer, "_Float16 complex")?,
                     FloatKind::Float => write!(writer, "float complex")?,
                     FloatKind::Double => write!(writer, "double complex")?,
                     FloatKind::LongDouble => {

bindgen/codegen/serialize.rs

@@ -386,6 +386,9 @@ pub(crate) struct BindgenContext {
     /// Whether a bindgen complex was generated
     generated_bindgen_complex: Cell<bool>,
 
+    /// Whether a bindgen float16 was generated
+    generated_bindgen_float16: Cell<bool>,
+
     /// The set of `ItemId`s that are allowlisted. This the very first thing
     /// computed after parsing our IR, and before running any of our analyses.
     allowlisted: Option<ItemSet>,
@@ -585,6 +588,7 @@ If you encounter an error missing from this list, please file an issue or a PR!"
             target_info,
             options,
             generated_bindgen_complex: Cell::new(false),
+            generated_bindgen_float16: Cell::new(false),
             allowlisted: None,
             blocklisted_types_implement_traits: Default::default(),
             codegen_items: None,
@@ -2005,6 +2009,7 @@ If you encounter an error missing from this list, please file an issue or a PR!"
             CXType_ULongLong => TypeKind::Int(IntKind::ULongLong),
             CXType_Int128 => TypeKind::Int(IntKind::I128),
             CXType_UInt128 => TypeKind::Int(IntKind::U128),
+            CXType_Float16 | CXType_Half => TypeKind::Float(FloatKind::Float16),
             CXType_Float => TypeKind::Float(FloatKind::Float),
             CXType_Double => TypeKind::Float(FloatKind::Double),
             CXType_LongDouble => TypeKind::Float(FloatKind::LongDouble),
@@ -2013,6 +2018,7 @@ If you encounter an error missing from this list, please file an issue or a PR!"
                 let float_type =
                     ty.elem_type().expect("Not able to resolve complex type?");
                 let float_kind = match float_type.kind() {
+                    CXType_Float16 | CXType_Half => FloatKind::Float16,
                     CXType_Float => FloatKind::Float,
                     CXType_Double => FloatKind::Double,
                     CXType_LongDouble => FloatKind::LongDouble,
@@ -2528,6 +2534,16 @@ If you encounter an error missing from this list, please file an issue or a PR!"
         self.generated_bindgen_complex.get()
     }
 
+    /// Call if a bindgen float16 is generated
+    pub(crate) fn generated_bindgen_float16(&self) {
+        self.generated_bindgen_float16.set(true)
+    }
+
+    /// Whether we need to generate the bindgen float16 type
+    pub(crate) fn need_bindgen_float16_type(&self) -> bool {
+        self.generated_bindgen_float16.get()
+    }
+
     /// Compute which `enum`s have an associated `typedef` definition.
     fn compute_enum_typedef_combos(&mut self) {
         let _t = self.timer("compute_enum_typedef_combos");

bindgen/ir/context.rs

@@ -558,6 +558,8 @@ impl TemplateParameters for TypeKind {
 /// The kind of float this type represents.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub(crate) enum FloatKind {
+    /// A half (`_Float16` or `__fp16`)
+    Float16,
     /// A `float`.
     Float,
     /// A `double`.