Merge pull request #726 from rust-lang/fix/const_undef

Fix const_undef

Author: antoyo

src/builder.rs

@@ -538,11 +538,6 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
     }
 
     fn ret(&mut self, mut value: RValue<'gcc>) {
-        if self.structs_as_pointer.borrow().contains(&value) {
-            // NOTE: hack to workaround a limitation of the rustc API: see comment on
-            // CodegenCx.structs_as_pointer
-            value = value.dereference(self.location).to_rvalue();
-        }
         let expected_return_type = self.current_func().get_return_type();
         if !expected_return_type.is_compatible_with(value.get_type()) {
             // NOTE: due to opaque pointers now being used, we need to cast here.
@@ -1119,13 +1114,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         // TODO(antoyo)
     }
 
-    fn store(&mut self, mut val: RValue<'gcc>, ptr: RValue<'gcc>, align: Align) -> RValue<'gcc> {
-        if self.structs_as_pointer.borrow().contains(&val) {
-            // NOTE: hack to workaround a limitation of the rustc API: see comment on
-            // CodegenCx.structs_as_pointer
-            val = val.dereference(self.location).to_rvalue();
-        }
-
+    fn store(&mut self, val: RValue<'gcc>, ptr: RValue<'gcc>, align: Align) -> RValue<'gcc> {
         self.store_with_flags(val, ptr, align, MemFlags::empty())
     }
 
@@ -1508,16 +1497,6 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
             element.get_address(self.location)
         } else if value_type.dyncast_vector().is_some() {
             panic!();
-        } else if let Some(pointer_type) = value_type.get_pointee() {
-            if let Some(struct_type) = pointer_type.is_struct() {
-                // NOTE: hack to workaround a limitation of the rustc API: see comment on
-                // CodegenCx.structs_as_pointer
-                aggregate_value
-                    .dereference_field(self.location, struct_type.get_field(idx as i32))
-                    .to_rvalue()
-            } else {
-                panic!("Unexpected type {:?}", value_type);
-            }
         } else if let Some(struct_type) = value_type.is_struct() {
             aggregate_value
                 .access_field(self.location, struct_type.get_field(idx as i32))
@@ -1537,21 +1516,18 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         assert_eq!(idx as usize as u64, idx);
         let value_type = aggregate_value.get_type();
 
+        let new_val = self.current_func().new_local(None, value_type, "aggregate_value");
+        self.block.add_assignment(None, new_val, aggregate_value);
+
         let lvalue = if value_type.dyncast_array().is_some() {
             let index = self
                 .context
                 .new_rvalue_from_long(self.u64_type, i64::try_from(idx).expect("i64::try_from"));
-            self.context.new_array_access(self.location, aggregate_value, index)
+            self.context.new_array_access(self.location, new_val, index)
         } else if value_type.dyncast_vector().is_some() {
             panic!();
-        } else if let Some(pointer_type) = value_type.get_pointee() {
-            if let Some(struct_type) = pointer_type.is_struct() {
-                // NOTE: hack to workaround a limitation of the rustc API: see comment on
-                // CodegenCx.structs_as_pointer
-                aggregate_value.dereference_field(self.location, struct_type.get_field(idx as i32))
-            } else {
-                panic!("Unexpected type {:?}", value_type);
-            }
+        } else if let Some(struct_type) = value_type.is_struct() {
+            new_val.access_field(None, struct_type.get_field(idx as i32))
         } else {
             panic!("Unexpected type {:?}", value_type);
         };
@@ -1568,7 +1544,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
 
         self.llbb().add_assignment(self.location, lvalue, value);
 
-        aggregate_value
+        new_val.to_rvalue()
     }
 
     fn set_personality_fn(&mut self, _personality: Function<'gcc>) {

src/common.rs

@@ -117,15 +117,7 @@ impl<'gcc, 'tcx> ConstCodegenMethods for CodegenCx<'gcc, 'tcx> {
 
     fn const_undef(&self, typ: Type<'gcc>) -> RValue<'gcc> {
         let local = self.current_func.borrow().expect("func").new_local(None, typ, "undefined");
-        if typ.is_struct().is_some() {
-            // NOTE: hack to workaround a limitation of the rustc API: see comment on
-            // CodegenCx.structs_as_pointer
-            let pointer = local.get_address(None);
-            self.structs_as_pointer.borrow_mut().insert(pointer);
-            pointer
-        } else {
-            local.to_rvalue()
-        }
+        local.to_rvalue()
     }
 
     fn const_poison(&self, typ: Type<'gcc>) -> RValue<'gcc> {

src/context.rs

@@ -124,14 +124,6 @@ pub struct CodegenCx<'gcc, 'tcx> {
 
     pub pointee_infos: RefCell<FxHashMap<(Ty<'tcx>, Size), Option<PointeeInfo>>>,
 
-    /// NOTE: a hack is used because the rustc API is not suitable to libgccjit and as such,
-    /// `const_undef()` returns struct as pointer so that they can later be assigned a value (in
-    /// e.g. Builder::insert_value).
-    /// As such, this set remembers which of these pointers were returned by this function so that
-    /// they can be dereferenced later.
-    /// FIXME(antoyo): fix the rustc API to avoid having this hack.
-    pub structs_as_pointer: RefCell<FxHashSet<RValue<'gcc>>>,
-
     #[cfg(feature = "master")]
     pub cleanup_blocks: RefCell<FxHashSet<Block<'gcc>>>,
     /// The alignment of a u128/i128 type.
@@ -304,7 +296,6 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
             #[cfg(feature = "master")]
             rust_try_fn: Cell::new(None),
             pointee_infos: Default::default(),
-            structs_as_pointer: Default::default(),
             #[cfg(feature = "master")]
             cleanup_blocks: Default::default(),
         };