Auto merge of #105545 - erikdesjardins:ptrclean, r=bjorn3

cleanup: remove pointee types

This can't be merged until the oldest LLVM version we support uses opaque pointers, which will be the case after #114148. (Also note `-Cllvm-args="-opaque-pointers=0"` can technically be used in LLVM 15, though I don't think we should support that configuration.)

I initially hoped this would provide some minor perf win, but in #105412 (comment) it had very little impact, so this is only valuable as a cleanup.

As a followup, this will enable #96242 to be resolved.

r? `@ghost`

`@rustbot` label S-blocked

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/abi.rs

@@ -216,9 +216,7 @@ impl<'ll, 'tcx> ArgAbiExt<'ll, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
             // uses it for i16 -> {i8, i8}, but not for i24 -> {i8, i8, i8}.
             let can_store_through_cast_ptr = false;
             if can_store_through_cast_ptr {
-                let cast_ptr_llty = bx.type_ptr_to(cast.llvm_type(bx));
-                let cast_dst = bx.pointercast(dst.llval, cast_ptr_llty);
-                bx.store(val, cast_dst, self.layout.align.abi);
+                bx.store(val, dst.llval, self.layout.align.abi);
             } else {
                 // The actual return type is a struct, but the ABI
                 // adaptation code has cast it into some scalar type. The
@@ -336,7 +334,7 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
             PassMode::Direct(_) | PassMode::Pair(..) => self.ret.layout.immediate_llvm_type(cx),
             PassMode::Cast(cast, _) => cast.llvm_type(cx),
             PassMode::Indirect { .. } => {
-                llargument_tys.push(cx.type_ptr_to(self.ret.memory_ty(cx)));
+                llargument_tys.push(cx.type_ptr());
                 cx.type_void()
             }
         };
@@ -364,9 +362,7 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
                     }
                     cast.llvm_type(cx)
                 }
-                PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
-                    cx.type_ptr_to(arg.memory_ty(cx))
-                }
+                PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => cx.type_ptr(),
             };
             llargument_tys.push(llarg_ty);
         }
@@ -379,12 +375,7 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
     }
 
     fn ptr_to_llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
-        unsafe {
-            llvm::LLVMPointerType(
-                self.llvm_type(cx),
-                cx.data_layout().instruction_address_space.0 as c_uint,
-            )
-        }
+        cx.type_ptr_ext(cx.data_layout().instruction_address_space)
     }
 
     fn llvm_cconv(&self) -> llvm::CallConv {

compiler/rustc_codegen_llvm/src/allocator.rs

@@ -28,7 +28,7 @@ pub(crate) unsafe fn codegen(
         tws => bug!("Unsupported target word size for int: {}", tws),
     };
     let i8 = llvm::LLVMInt8TypeInContext(llcx);
-    let i8p = llvm::LLVMPointerType(i8, 0);
+    let i8p = llvm::LLVMPointerTypeInContext(llcx, 0);
     let void = llvm::LLVMVoidTypeInContext(llcx);
 
     if kind == AllocatorKind::Default {

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -4,7 +4,6 @@ use crate::back::profiling::{
 };
 use crate::base;
 use crate::common;
-use crate::consts;
 use crate::errors::{
     CopyBitcode, FromLlvmDiag, FromLlvmOptimizationDiag, LlvmError, WithLlvmError, WriteBytecode,
 };
@@ -992,7 +991,7 @@ fn create_msvc_imps(
     let prefix = if cgcx.target_arch == "x86" { "\x01__imp__" } else { "\x01__imp_" };
 
     unsafe {
-        let i8p_ty = Type::i8p_llcx(llcx);
+        let ptr_ty = Type::ptr_llcx(llcx);
         let globals = base::iter_globals(llmod)
             .filter(|&val| {
                 llvm::LLVMRustGetLinkage(val) == llvm::Linkage::ExternalLinkage
@@ -1012,8 +1011,8 @@ fn create_msvc_imps(
             .collect::<Vec<_>>();
 
         for (imp_name, val) in globals {
-            let imp = llvm::LLVMAddGlobal(llmod, i8p_ty, imp_name.as_ptr().cast());
-            llvm::LLVMSetInitializer(imp, consts::ptrcast(val, i8p_ty));
+            let imp = llvm::LLVMAddGlobal(llmod, ptr_ty, imp_name.as_ptr().cast());
+            llvm::LLVMSetInitializer(imp, val);
             llvm::LLVMRustSetLinkage(imp, llvm::Linkage::ExternalLinkage);
         }
     }

compiler/rustc_codegen_llvm/src/base.rs

@@ -123,8 +123,7 @@ pub fn compile_codegen_unit(tcx: TyCtxt<'_>, cgu_name: Symbol) -> (ModuleCodegen
             // happen after the llvm.used variables are created.
             for &(old_g, new_g) in cx.statics_to_rauw().borrow().iter() {
                 unsafe {
-                    let bitcast = llvm::LLVMConstPointerCast(new_g, cx.val_ty(old_g));
-                    llvm::LLVMReplaceAllUsesWith(old_g, bitcast);
+                    llvm::LLVMReplaceAllUsesWith(old_g, new_g);
                     llvm::LLVMDeleteGlobal(old_g);
                 }
             }

compiler/rustc_codegen_llvm/src/builder.rs

@@ -652,7 +652,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         flags: MemFlags,
     ) -> &'ll Value {
         debug!("Store {:?} -> {:?} ({:?})", val, ptr, flags);
-        let ptr = self.check_store(val, ptr);
+        assert_eq!(self.cx.type_kind(self.cx.val_ty(ptr)), TypeKind::Pointer);
         unsafe {
             let store = llvm::LLVMBuildStore(self.llbuilder, val, ptr);
             let align =
@@ -682,7 +682,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         size: Size,
     ) {
         debug!("Store {:?} -> {:?}", val, ptr);
-        let ptr = self.check_store(val, ptr);
+        assert_eq!(self.cx.type_kind(self.cx.val_ty(ptr)), TypeKind::Pointer);
         unsafe {
             let store = llvm::LLVMRustBuildAtomicStore(
                 self.llbuilder,
@@ -873,8 +873,6 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         assert!(!flags.contains(MemFlags::NONTEMPORAL), "non-temporal memcpy not supported");
         let size = self.intcast(size, self.type_isize(), false);
         let is_volatile = flags.contains(MemFlags::VOLATILE);
-        let dst = self.pointercast(dst, self.type_i8p());
-        let src = self.pointercast(src, self.type_i8p());
         unsafe {
             llvm::LLVMRustBuildMemCpy(
                 self.llbuilder,
@@ -900,8 +898,6 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         assert!(!flags.contains(MemFlags::NONTEMPORAL), "non-temporal memmove not supported");
         let size = self.intcast(size, self.type_isize(), false);
         let is_volatile = flags.contains(MemFlags::VOLATILE);
-        let dst = self.pointercast(dst, self.type_i8p());
-        let src = self.pointercast(src, self.type_i8p());
         unsafe {
             llvm::LLVMRustBuildMemMove(
                 self.llbuilder,
@@ -924,7 +920,6 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         flags: MemFlags,
     ) {
         let is_volatile = flags.contains(MemFlags::VOLATILE);
-        let ptr = self.pointercast(ptr, self.type_i8p());
         unsafe {
             llvm::LLVMRustBuildMemSet(
                 self.llbuilder,
@@ -981,7 +976,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn cleanup_landing_pad(&mut self, pers_fn: &'ll Value) -> (&'ll Value, &'ll Value) {
-        let ty = self.type_struct(&[self.type_i8p(), self.type_i32()], false);
+        let ty = self.type_struct(&[self.type_ptr(), self.type_i32()], false);
         let landing_pad = self.landing_pad(ty, pers_fn, 0);
         unsafe {
             llvm::LLVMSetCleanup(landing_pad, llvm::True);
@@ -990,14 +985,14 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn filter_landing_pad(&mut self, pers_fn: &'ll Value) -> (&'ll Value, &'ll Value) {
-        let ty = self.type_struct(&[self.type_i8p(), self.type_i32()], false);
+        let ty = self.type_struct(&[self.type_ptr(), self.type_i32()], false);
         let landing_pad = self.landing_pad(ty, pers_fn, 1);
-        self.add_clause(landing_pad, self.const_array(self.type_i8p(), &[]));
+        self.add_clause(landing_pad, self.const_array(self.type_ptr(), &[]));
         (self.extract_value(landing_pad, 0), self.extract_value(landing_pad, 1))
     }
 
     fn resume(&mut self, exn0: &'ll Value, exn1: &'ll Value) {
-        let ty = self.type_struct(&[self.type_i8p(), self.type_i32()], false);
+        let ty = self.type_struct(&[self.type_ptr(), self.type_i32()], false);
         let mut exn = self.const_poison(ty);
         exn = self.insert_value(exn, exn0, 0);
         exn = self.insert_value(exn, exn1, 1);
@@ -1161,7 +1156,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
         let llfn = unsafe { llvm::LLVMRustGetInstrProfIncrementIntrinsic(self.cx().llmod) };
         let llty = self.cx.type_func(
-            &[self.cx.type_i8p(), self.cx.type_i64(), self.cx.type_i32(), self.cx.type_i32()],
+            &[self.cx.type_ptr(), self.cx.type_i64(), self.cx.type_i32(), self.cx.type_i32()],
             self.cx.type_void(),
         );
         let args = &[fn_name, hash, num_counters, index];
@@ -1387,25 +1382,6 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
         ret.expect("LLVM does not have support for catchret")
     }
 
-    fn check_store(&mut self, val: &'ll Value, ptr: &'ll Value) -> &'ll Value {
-        let dest_ptr_ty = self.cx.val_ty(ptr);
-        let stored_ty = self.cx.val_ty(val);
-        let stored_ptr_ty = self.cx.type_ptr_to(stored_ty);
-
-        assert_eq!(self.cx.type_kind(dest_ptr_ty), TypeKind::Pointer);
-
-        if dest_ptr_ty == stored_ptr_ty {
-            ptr
-        } else {
-            debug!(
-                "type mismatch in store. \
-                    Expected {:?}, got {:?}; inserting bitcast",
-                dest_ptr_ty, stored_ptr_ty
-            );
-            self.bitcast(ptr, stored_ptr_ty)
-        }
-    }
-
     fn check_call<'b>(
         &mut self,
         typ: &str,
@@ -1466,7 +1442,6 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
             return;
         }
 
-        let ptr = self.pointercast(ptr, self.cx.type_i8p());
         self.call_intrinsic(intrinsic, &[self.cx.const_u64(size), ptr]);
     }
 

compiler/rustc_codegen_llvm/src/callee.rs

@@ -4,13 +4,11 @@
 //! and methods are represented as just a fn ptr and not a full
 //! closure.
 
-use crate::abi::FnAbiLlvmExt;
 use crate::attributes;
 use crate::common;
 use crate::context::CodegenCx;
 use crate::llvm;
 use crate::value::Value;
-use rustc_codegen_ssa::traits::*;
 
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt};
 use rustc_middle::ty::{self, Instance, TypeVisitableExt};
@@ -45,39 +43,7 @@ pub fn get_fn<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'tcx>) ->
     let fn_abi = cx.fn_abi_of_instance(instance, ty::List::empty());
 
     let llfn = if let Some(llfn) = cx.get_declared_value(sym) {
-        // Create a fn pointer with the new signature.
-        let llptrty = fn_abi.ptr_to_llvm_type(cx);
-
-        // This is subtle and surprising, but sometimes we have to bitcast
-        // the resulting fn pointer. The reason has to do with external
-        // functions. If you have two crates that both bind the same C
-        // library, they may not use precisely the same types: for
-        // example, they will probably each declare their own structs,
-        // which are distinct types from LLVM's point of view (nominal
-        // types).
-        //
-        // Now, if those two crates are linked into an application, and
-        // they contain inlined code, you can wind up with a situation
-        // where both of those functions wind up being loaded into this
-        // application simultaneously. In that case, the same function
-        // (from LLVM's point of view) requires two types. But of course
-        // LLVM won't allow one function to have two types.
-        //
-        // What we currently do, therefore, is declare the function with
-        // one of the two types (whichever happens to come first) and then
-        // bitcast as needed when the function is referenced to make sure
-        // it has the type we expect.
-        //
-        // This can occur on either a crate-local or crate-external
-        // reference. It also occurs when testing libcore and in some
-        // other weird situations. Annoying.
-        if cx.val_ty(llfn) != llptrty {
-            debug!("get_fn: casting {:?} to {:?}", llfn, llptrty);
-            cx.const_ptrcast(llfn, llptrty)
-        } else {
-            debug!("get_fn: not casting pointer!");
-            llfn
-        }
+        llfn
     } else {
         let instance_def_id = instance.def_id();
         let llfn = if tcx.sess.target.arch == "x86" &&