cg_ssa: remove pointee types and pointercast/bitcast-of-ptr

Author: erikdesjardins

compiler/rustc_codegen_gcc/src/builder.rs

@@ -27,7 +27,6 @@ use rustc_codegen_ssa::traits::{
     BaseTypeMethods,
     BuilderMethods,
     ConstMethods,
-    DerivedTypeMethods,
     LayoutTypeMethods,
     HasCodegen,
     OverflowOp,

compiler/rustc_codegen_gcc/src/common.rs

@@ -16,6 +16,10 @@ use crate::context::CodegenCx;
 use crate::type_of::LayoutGccExt;
 
 impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    pub fn const_ptrcast(&self, val: RValue<'gcc>, ty: Type<'gcc>) -> RValue<'gcc> {
+        self.context.new_cast(None, val, ty)
+    }
+
     pub fn const_bytes(&self, bytes: &[u8]) -> RValue<'gcc> {
         bytes_in_context(self, bytes)
     }
@@ -242,10 +246,6 @@ impl<'gcc, 'tcx> ConstMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         const_alloc_to_gcc(self, alloc)
     }
 
-    fn const_ptrcast(&self, val: RValue<'gcc>, ty: Type<'gcc>) -> RValue<'gcc> {
-        self.context.new_cast(None, val, ty)
-    }
-
     fn const_bitcast(&self, value: RValue<'gcc>, typ: Type<'gcc>) -> RValue<'gcc> {
         if value.get_type() == self.bool_type.make_pointer() {
             if let Some(pointee) = typ.get_pointee() {

compiler/rustc_codegen_gcc/src/intrinsic/mod.rs

@@ -12,7 +12,7 @@ use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::traits::{ArgAbiMethods, BaseTypeMethods, BuilderMethods, ConstMethods, IntrinsicCallMethods};
 #[cfg(feature="master")]
-use rustc_codegen_ssa::traits::{DerivedTypeMethods, MiscMethods};
+use rustc_codegen_ssa::traits::MiscMethods;
 use rustc_codegen_ssa::errors::InvalidMonomorphization;
 use rustc_middle::bug;
 use rustc_middle::ty::{self, Instance, Ty};

compiler/rustc_codegen_gcc/src/type_.rs

@@ -54,6 +54,23 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
         self.u128_type
     }
 
+    pub fn type_ptr_to(&self, ty: Type<'gcc>) -> Type<'gcc> {
+        ty.make_pointer()
+    }
+
+    pub fn type_ptr_to_ext(&self, ty: Type<'gcc>, _address_space: AddressSpace) -> Type<'gcc> {
+        // TODO(antoyo): use address_space, perhaps with TYPE_ADDR_SPACE?
+        ty.make_pointer()
+    }
+
+    pub fn type_i8p(&self) -> Type<'gcc> {
+        self.type_ptr_to(self.type_i8())
+    }
+
+    pub fn type_i8p_ext(&self, address_space: AddressSpace) -> Type<'gcc> {
+        self.type_ptr_to_ext(self.type_i8(), address_space)
+    }
+
     pub fn type_pointee_for_align(&self, align: Align) -> Type<'gcc> {
         // FIXME(eddyb) We could find a better approximation if ity.align < align.
         let ity = Integer::approximate_align(self, align);
@@ -149,13 +166,12 @@ impl<'gcc, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         }
     }
 
-    fn type_ptr_to(&self, ty: Type<'gcc>) -> Type<'gcc> {
-        ty.make_pointer()
+    fn type_ptr(&self) -> Type<'gcc> {
+        self.type_ptr_to(self.type_void())
     }
 
-    fn type_ptr_to_ext(&self, ty: Type<'gcc>, _address_space: AddressSpace) -> Type<'gcc> {
-        // TODO(antoyo): use address_space, perhaps with TYPE_ADDR_SPACE?
-        ty.make_pointer()
+    fn type_ptr_ext(&self, address_space: AddressSpace) -> Type<'gcc> {
+        self.type_ptr_to_ext(self.type_void(), address_space)
     }
 
     fn element_type(&self, ty: Type<'gcc>) -> Type<'gcc> {

compiler/rustc_codegen_llvm/src/common.rs

@@ -1,6 +1,6 @@
 //! Code that is useful in various codegen modules.
 
-use crate::consts::{self, const_alloc_to_llvm};
+use crate::consts::const_alloc_to_llvm;
 pub use crate::context::CodegenCx;
 use crate::llvm::{self, BasicBlock, Bool, ConstantInt, False, OperandBundleDef, True};
 use crate::type_::Type;
@@ -304,10 +304,6 @@ impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         const_alloc_to_llvm(self, alloc)
     }
 
-    fn const_ptrcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
-        consts::ptrcast(val, ty)
-    }
-
     fn const_bitcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
         self.const_bitcast(val, ty)
     }

compiler/rustc_codegen_llvm/src/consts.rs

@@ -193,10 +193,6 @@ fn check_and_apply_linkage<'ll, 'tcx>(
     }
 }
 
-pub fn ptrcast<'ll>(val: &'ll Value, ty: &'ll Type) -> &'ll Value {
-    unsafe { llvm::LLVMConstPointerCast(val, ty) }
-}
-
 impl<'ll> CodegenCx<'ll, '_> {
     pub(crate) fn const_bitcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
         unsafe { llvm::LLVMConstBitCast(val, ty) }

compiler/rustc_codegen_llvm/src/type_.rs

@@ -69,14 +69,6 @@ impl<'ll> CodegenCx<'ll, '_> {
         unsafe { llvm::LLVMVectorType(ty, len as c_uint) }
     }
 
-    pub(crate) fn type_ptr(&self) -> &'ll Type {
-        self.type_ptr_ext(AddressSpace::DATA)
-    }
-
-    pub(crate) fn type_ptr_ext(&self, address_space: AddressSpace) -> &'ll Type {
-        unsafe { llvm::LLVMPointerTypeInContext(self.llcx, address_space.0) }
-    }
-
     pub(crate) fn func_params_types(&self, ty: &'ll Type) -> Vec<&'ll Type> {
         unsafe {
             let n_args = llvm::LLVMCountParamTypes(ty) as usize;
@@ -191,12 +183,12 @@ impl<'ll, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         unsafe { llvm::LLVMRustGetTypeKind(ty).to_generic() }
     }
 
-    fn type_ptr_to(&self, _ty: &'ll Type) -> &'ll Type {
-        self.type_ptr()
+    fn type_ptr(&self) -> &'ll Type {
+        self.type_ptr_ext(AddressSpace::DATA)
     }
 
-    fn type_ptr_to_ext(&self, _ty: &'ll Type, address_space: AddressSpace) -> &'ll Type {
-        self.type_ptr_ext(address_space)
+    fn type_ptr_ext(&self, address_space: AddressSpace) -> &'ll Type {
+        unsafe { llvm::LLVMPointerTypeInContext(self.llcx, address_space.0) }
     }
 
     fn element_type(&self, ty: &'ll Type) -> &'ll Type {

compiler/rustc_codegen_ssa/src/base.rs

@@ -165,50 +165,27 @@ pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                 cx.tcx().vtable_trait_upcasting_coercion_new_vptr_slot((source, target));
 
             if let Some(entry_idx) = vptr_entry_idx {
-                let ptr_ty = cx.type_i8p();
+                let ptr_ty = cx.type_ptr();
                 let ptr_align = cx.tcx().data_layout.pointer_align.abi;
-                let vtable_ptr_ty = vtable_ptr_ty(cx, target, target_dyn_kind);
-                let llvtable = bx.pointercast(old_info, bx.type_ptr_to(ptr_ty));
                 let gep = bx.inbounds_gep(
                     ptr_ty,
-                    llvtable,
+                    old_info,
                     &[bx.const_usize(u64::try_from(entry_idx).unwrap())],
                 );
                 let new_vptr = bx.load(ptr_ty, gep, ptr_align);
                 bx.nonnull_metadata(new_vptr);
                 // VTable loads are invariant.
                 bx.set_invariant_load(new_vptr);
-                bx.pointercast(new_vptr, vtable_ptr_ty)
+                new_vptr
             } else {
                 old_info
             }
         }
-        (_, &ty::Dynamic(ref data, _, target_dyn_kind)) => {
-            let vtable_ptr_ty = vtable_ptr_ty(cx, target, target_dyn_kind);
-            cx.const_ptrcast(meth::get_vtable(cx, source, data.principal()), vtable_ptr_ty)
-        }
+        (_, &ty::Dynamic(ref data, _, _)) => meth::get_vtable(cx, source, data.principal()),
         _ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target),
     }
 }
 
-// Returns the vtable pointer type of a `dyn` or `dyn*` type
-fn vtable_ptr_ty<'tcx, Cx: CodegenMethods<'tcx>>(
-    cx: &Cx,
-    target: Ty<'tcx>,
-    kind: ty::DynKind,
-) -> <Cx as BackendTypes>::Type {
-    cx.scalar_pair_element_backend_type(
-        cx.layout_of(match kind {
-            // vtable is the second field of `*mut dyn Trait`
-            ty::Dyn => Ty::new_mut_ptr(cx.tcx(), target),
-            // vtable is the second field of `dyn* Trait`
-            ty::DynStar => target,
-        }),
-        1,
-        true,
-    )
-}
-
 /// Coerces `src` to `dst_ty`. `src_ty` must be a pointer.
 pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     bx: &mut Bx,
@@ -222,8 +199,7 @@ pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         (&ty::Ref(_, a, _), &ty::Ref(_, b, _) | &ty::RawPtr(ty::TypeAndMut { ty: b, .. }))
         | (&ty::RawPtr(ty::TypeAndMut { ty: a, .. }), &ty::RawPtr(ty::TypeAndMut { ty: b, .. })) => {
             assert_eq!(bx.cx().type_is_sized(a), old_info.is_none());
-            let ptr_ty = bx.cx().type_ptr_to(bx.cx().backend_type(bx.cx().layout_of(b)));
-            (bx.pointercast(src, ptr_ty), unsized_info(bx, a, b, old_info))
+            (src, unsized_info(bx, a, b, old_info))
         }
         (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
             assert_eq!(def_a, def_b);
@@ -248,11 +224,7 @@ pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                 assert_eq!(result, None);
                 result = Some(unsize_ptr(bx, src, src_f.ty, dst_f.ty, old_info));
             }
-            let (lldata, llextra) = result.unwrap();
-            let lldata_ty = bx.cx().scalar_pair_element_backend_type(dst_layout, 0, true);
-            let llextra_ty = bx.cx().scalar_pair_element_backend_type(dst_layout, 1, true);
-            // HACK(eddyb) have to bitcast pointers until LLVM removes pointee types.
-            (bx.bitcast(lldata, lldata_ty), bx.bitcast(llextra, llextra_ty))
+            result.unwrap()
         }
         _ => bug!("unsize_ptr: called on bad types"),
     }
@@ -271,11 +243,9 @@ pub fn cast_to_dyn_star<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         matches!(dst_ty.kind(), ty::Dynamic(_, _, ty::DynStar)),
         "destination type must be a dyn*"
     );
-    // FIXME(dyn-star): We can remove this when all supported LLVMs use opaque ptrs only.
-    let unit_ptr = bx.cx().type_ptr_to(bx.cx().type_struct(&[], false));
     let src = match bx.cx().type_kind(bx.cx().backend_type(src_ty_and_layout)) {
-        TypeKind::Pointer => bx.pointercast(src, unit_ptr),
-        TypeKind::Integer => bx.inttoptr(src, unit_ptr),
+        TypeKind::Pointer => src,
+        TypeKind::Integer => bx.inttoptr(src, bx.type_ptr()),
         // FIXME(dyn-star): We probably have to do a bitcast first, then inttoptr.
         kind => bug!("unexpected TypeKind for left-hand side of `dyn*` cast: {kind:?}"),
     };
@@ -398,11 +368,6 @@ pub fn memcpy_ty<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     if flags == MemFlags::empty()
         && let Some(bty) = bx.cx().scalar_copy_backend_type(layout)
     {
-        // I look forward to only supporting opaque pointers
-        let pty = bx.type_ptr_to(bty);
-        let src = bx.pointercast(src, pty);
-        let dst = bx.pointercast(dst, pty);
-
         let temp = bx.load(bty, src, src_align);
         bx.store(temp, dst, dst_align);
     } else {
@@ -456,7 +421,7 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         // The entry function is either `int main(void)` or `int main(int argc, char **argv)`,
         // depending on whether the target needs `argc` and `argv` to be passed in.
         let llfty = if cx.sess().target.main_needs_argc_argv {
-            cx.type_func(&[cx.type_int(), cx.type_ptr_to(cx.type_i8p())], cx.type_int())
+            cx.type_func(&[cx.type_int(), cx.type_ptr()], cx.type_int())
         } else {
             cx.type_func(&[], cx.type_int())
         };
@@ -490,7 +455,7 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         bx.insert_reference_to_gdb_debug_scripts_section_global();
 
         let isize_ty = cx.type_isize();
-        let i8pp_ty = cx.type_ptr_to(cx.type_i8p());
+        let ptr_ty = cx.type_ptr();
         let (arg_argc, arg_argv) = get_argc_argv(cx, &mut bx);
 
         let (start_fn, start_ty, args) = if let EntryFnType::Main { sigpipe } = entry_type {
@@ -509,12 +474,11 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             let i8_ty = cx.type_i8();
             let arg_sigpipe = bx.const_u8(sigpipe);
 
-            let start_ty =
-                cx.type_func(&[cx.val_ty(rust_main), isize_ty, i8pp_ty, i8_ty], isize_ty);
+            let start_ty = cx.type_func(&[cx.val_ty(rust_main), isize_ty, ptr_ty, i8_ty], isize_ty);
             (start_fn, start_ty, vec![rust_main, arg_argc, arg_argv, arg_sigpipe])
         } else {
             debug!("using user-defined start fn");
-            let start_ty = cx.type_func(&[isize_ty, i8pp_ty], isize_ty);
+            let start_ty = cx.type_func(&[isize_ty, ptr_ty], isize_ty);
             (rust_main, start_ty, vec![arg_argc, arg_argv])
         };
 
@@ -541,7 +505,7 @@ fn get_argc_argv<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     } else {
         // The Rust start function doesn't need `argc` and `argv`, so just pass zeros.
         let arg_argc = bx.const_int(cx.type_int(), 0);
-        let arg_argv = bx.const_null(cx.type_ptr_to(cx.type_i8p()));
+        let arg_argv = bx.const_null(cx.type_ptr());
         (arg_argc, arg_argv)
     }
 }

compiler/rustc_codegen_ssa/src/meth.rs

@@ -23,7 +23,6 @@ impl<'a, 'tcx> VirtualIndex {
         // Load the data pointer from the object.
         debug!("get_fn({llvtable:?}, {ty:?}, {self:?})");
         let llty = bx.fn_ptr_backend_type(fn_abi);
-        let llvtable = bx.pointercast(llvtable, bx.type_ptr_to(llty));
 
         if bx.cx().sess().opts.unstable_opts.virtual_function_elimination
             && bx.cx().sess().lto() == Lto::Fat
@@ -33,7 +32,7 @@ impl<'a, 'tcx> VirtualIndex {
                 .unwrap();
             let vtable_byte_offset = self.0 * bx.data_layout().pointer_size.bytes();
             let func = bx.type_checked_load(llvtable, vtable_byte_offset, typeid);
-            bx.pointercast(func, llty)
+            func
         } else {
             let ptr_align = bx.tcx().data_layout.pointer_align.abi;
             let gep = bx.inbounds_gep(llty, llvtable, &[bx.const_usize(self.0)]);
@@ -54,7 +53,6 @@ impl<'a, 'tcx> VirtualIndex {
         debug!("get_int({:?}, {:?})", llvtable, self);
 
         let llty = bx.type_isize();
-        let llvtable = bx.pointercast(llvtable, bx.type_ptr_to(llty));
         let usize_align = bx.tcx().data_layout.pointer_align.abi;
         let gep = bx.inbounds_gep(llty, llvtable, &[bx.const_usize(self.0)]);
         let ptr = bx.load(llty, gep, usize_align);

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -439,8 +439,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     ZeroSized => bug!("ZST return value shouldn't be in PassMode::Cast"),
                 };
                 let ty = bx.cast_backend_type(cast_ty);
-                let addr = bx.pointercast(llslot, bx.type_ptr_to(ty));
-                bx.load(ty, addr, self.fn_abi.ret.layout.align.abi)
+                bx.load(ty, llslot, self.fn_abi.ret.layout.align.abi)
             }
         };
         bx.ret(llval);
@@ -853,9 +852,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             Some(intrinsic) => {
                 let dest = match ret_dest {
                     _ if fn_abi.ret.is_indirect() => llargs[0],
-                    ReturnDest::Nothing => {
-                        bx.const_undef(bx.type_ptr_to(bx.arg_memory_ty(&fn_abi.ret)))
-                    }
+                    ReturnDest::Nothing => bx.const_undef(bx.type_ptr()),
                     ReturnDest::IndirectOperand(dst, _) | ReturnDest::Store(dst) => dst.llval,
                     ReturnDest::DirectOperand(_) => {
                         bug!("Cannot use direct operand with an intrinsic call")
@@ -1428,8 +1425,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             // Have to load the argument, maybe while casting it.
             if let PassMode::Cast(ty, _) = &arg.mode {
                 let llty = bx.cast_backend_type(ty);
-                let addr = bx.pointercast(llval, bx.type_ptr_to(llty));
-                llval = bx.load(llty, addr, align.min(arg.layout.align.abi));
+                llval = bx.load(llty, llval, align.min(arg.layout.align.abi));
             } else {
                 // We can't use `PlaceRef::load` here because the argument
                 // may have a type we don't treat as immediate, but the ABI
@@ -1634,7 +1630,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 // represents that this is a catch-all block.
                 bx = Bx::build(self.cx, cp_llbb);
                 let null =
-                    bx.const_null(bx.type_i8p_ext(bx.cx().data_layout().instruction_address_space));
+                    bx.const_null(bx.type_ptr_ext(bx.cx().data_layout().instruction_address_space));
                 let sixty_four = bx.const_i32(64);
                 funclet = Some(bx.catch_pad(cs, &[null, sixty_four, null]));
             } else {