Auto merge of rust-lang#143182 - xdoardo:more-addrspace, r=workingjubilee

Allow custom default address spaces and parse `p-` specifications in the datalayout string

Some targets, such as CHERI, use as default an address space different from the "normal" default address space `0` (in the case of CHERI, [200 is used](https://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-877.pdf)). Currently, `rustc` does not allow to specify custom address spaces and does not take into consideration [`p-` specifications in the datalayout string](https://llvm.org/docs/LangRef.html#langref-datalayout).

This patch tries to mitigate these problems by allowing targets to define a custom default address space (while keeping the default value to address space `0`) and adding the code to parse the `p-` specifications in `rustc_abi`. The main changes are that `TargetDataLayout` now uses functions to refer to pointer-related informations, instead of having specific fields for the size and alignment of pointers in the default address space; furthermore, the two `pointer_size` and `pointer_align` fields in `TargetDataLayout` are replaced with an `FxHashMap` that holds info for all the possible address spaces, as parsed by the `p-` specifications.

The potential performance drawbacks of not having ad-hoc fields for the default address space will be tested in this PR's CI run.

r? workingjubilee

Author: bors

clippy_lints/src/casts/fn_to_numeric_cast.rs

@@ -17,7 +17,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>,
         ty::FnDef(..) | ty::FnPtr(..) => {
             let mut applicability = Applicability::MaybeIncorrect;
 
-            if to_nbits >= cx.tcx.data_layout.pointer_size.bits() && !cast_to.is_usize() {
+            if to_nbits >= cx.tcx.data_layout.pointer_size().bits() && !cast_to.is_usize() {
                 let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
                 span_lint_and_sugg(
                     cx,

clippy_lints/src/casts/fn_to_numeric_cast_with_truncation.rs

@@ -17,7 +17,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>,
             let mut applicability = Applicability::MaybeIncorrect;
             let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
 
-            if to_nbits < cx.tcx.data_layout.pointer_size.bits() {
+            if to_nbits < cx.tcx.data_layout.pointer_size().bits() {
                 span_lint_and_sugg(
                     cx,
                     FN_TO_NUMERIC_CAST_WITH_TRUNCATION,

clippy_lints/src/casts/utils.rs

@@ -5,7 +5,7 @@ use rustc_middle::ty::{self, AdtDef, IntTy, Ty, TyCtxt, UintTy, VariantDiscr};
 /// integral type.
 pub(super) fn int_ty_to_nbits(tcx: TyCtxt<'_>, ty: Ty<'_>) -> Option<u64> {
     match ty.kind() {
-        ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => Some(tcx.data_layout.pointer_size.bits()),
+        ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => Some(tcx.data_layout.pointer_size().bits()),
         ty::Int(i) => i.bit_width(),
         ty::Uint(i) => i.bit_width(),
         _ => None,

clippy_lints/src/enum_clike.rs

@@ -35,7 +35,7 @@ declare_lint_pass!(UnportableVariant => [ENUM_CLIKE_UNPORTABLE_VARIANT]);
 impl<'tcx> LateLintPass<'tcx> for UnportableVariant {
     #[expect(clippy::cast_possible_wrap)]
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
-        if cx.tcx.data_layout.pointer_size.bits() != 64 {
+        if cx.tcx.data_layout.pointer_size().bits() != 64 {
             return;
         }
         if let ItemKind::Enum(_, _, def) = &item.kind {

clippy_utils/src/consts.rs

@@ -918,7 +918,7 @@ fn mir_is_empty<'tcx>(tcx: TyCtxt<'tcx>, result: mir::Const<'tcx>) -> Option<boo
                     // Get the length from the slice, using the same formula as
                     // [`ConstValue::try_get_slice_bytes_for_diagnostics`].
                     let a = tcx.global_alloc(alloc_id).unwrap_memory().inner();
-                    let ptr_size = tcx.data_layout.pointer_size;
+                    let ptr_size = tcx.data_layout.pointer_size();
                     if a.size() < offset + 2 * ptr_size {
                         // (partially) dangling reference
                         return None;