Auto merge of #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

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/memory.rs b/compiler/rustc_const_eval/src/interpret/memory.rs
index c97d53a45de..524023b8104 100644
--- a/compiler/rustc_const_eval/src/interpret/memory.rs
+++ b/compiler/rustc_const_eval/src/interpret/memory.rs
@@ -1233,7 +1233,7 @@ impl<'a, 'tcx, Prov: Provenance, Extra, Bytes: AllocBytes>
 
     /// `offset` is relative to this allocation reference, not the base of the allocation.
     pub fn write_ptr_sized(&mut self, offset: Size, val: Scalar<Prov>) -> InterpResult<'tcx> {
-        self.write_scalar(alloc_range(offset, self.tcx.data_layout().pointer_size), val)
+        self.write_scalar(alloc_range(offset, self.tcx.data_layout().pointer_size()), val)
     }
 
     /// Mark the given sub-range (relative to this allocation reference) as uninitialized.
@@ -1285,7 +1285,7 @@ impl<'a, 'tcx, Prov: Provenance, Extra, Bytes: AllocBytes> AllocRef<'a, 'tcx, Pr
     /// `offset` is relative to this allocation reference, not the base of the allocation.
     pub fn read_pointer(&self, offset: Size) -> InterpResult<'tcx, Scalar<Prov>> {
         self.read_scalar(
-            alloc_range(offset, self.tcx.data_layout().pointer_size),
+            alloc_range(offset, self.tcx.data_layout().pointer_size()),
             /*read_provenance*/ true,
         )
     }