Rollup merge of rust-lang#101101 - RalfJung:read-pointer-as-bytes, r=…

…oli-obk

interpret: make read-pointer-as-bytes a CTFE-only error with extra information

Next step in the reaction to rust-lang#99923. Also teaches Miri to implicitly strip provenance in more situations when transmuting pointers to integers, which fixes rust-lang/miri#2456.

Pointer-to-int transmutation during CTFE now produces a message like this:
```
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
```

r? ``@oli-obk``

src/constant.rs

@@ -430,7 +430,7 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut dyn Module, cx: &mut Constant
         let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len()).to_vec();
         data_ctx.define(bytes.into_boxed_slice());
 
-        for &(offset, alloc_id) in alloc.relocations().iter() {
+        for &(offset, alloc_id) in alloc.provenance().iter() {
             let addend = {
                 let endianness = tcx.data_layout.endian;
                 let offset = offset.bytes() as usize;

src/intrinsics/simd.rs

@@ -186,7 +186,10 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
                         let size = Size::from_bytes(
                             4 * ret_lane_count, /* size_of([u32; ret_lane_count]) */
                         );
-                        alloc.inner().get_bytes(fx, alloc_range(offset, size)).unwrap()
+                        alloc
+                            .inner()
+                            .get_bytes_strip_provenance(fx, alloc_range(offset, size))
+                            .unwrap()
                     }
                     _ => unreachable!("{:?}", idx_const),
                 };