Rollup merge of #133088 - the8472:randomize-me-harder, r=workingjubilee

`-Zrandomize-layout` harder. `Foo<T> != Foo<U>`

Tracking issue: #106764

Previously randomize-layout only used a deterministic shuffle based on the seed stored in an Adt's ReprOptions, meaning that `Foo<T>`  and `Foo<U>` were shuffled by the same seed. This change adds a similar seed to each calculated LayoutData so that a struct can be randomized both based on the layout of its fields and its per-type seed.
Primitives start with simple seed derived from some of their properties. Though some types can no longer be distinguished at that point, e.g. usize and u64 will still be treated the same.

compiler/rustc_ty_utils/src/layout.rs

@@ -347,6 +347,7 @@ fn layout_of_uncached<'tcx>(
                 size,
                 max_repr_align: None,
                 unadjusted_abi_align: element.align.abi,
+                randomization_seed: element.randomization_seed.wrapping_add(count),
             })
         }
         ty::Slice(element) => {
@@ -360,6 +361,8 @@ fn layout_of_uncached<'tcx>(
                 size: Size::ZERO,
                 max_repr_align: None,
                 unadjusted_abi_align: element.align.abi,
+                // adding a randomly chosen value to distinguish slices
+                randomization_seed: element.randomization_seed.wrapping_add(0x2dcba99c39784102),
             })
         }
         ty::Str => tcx.mk_layout(LayoutData {
@@ -371,6 +374,8 @@ fn layout_of_uncached<'tcx>(
             size: Size::ZERO,
             max_repr_align: None,
             unadjusted_abi_align: dl.i8_align.abi,
+            // another random value
+            randomization_seed: 0xc1325f37d127be22,
         }),
 
         // Odd unit types.
@@ -542,6 +547,7 @@ fn layout_of_uncached<'tcx>(
                 align,
                 max_repr_align: None,
                 unadjusted_abi_align: align.abi,
+                randomization_seed: e_ly.randomization_seed.wrapping_add(e_len),
             })
         }
 
@@ -999,6 +1005,9 @@ fn coroutine_layout<'tcx>(
         BackendRepr::Memory { sized: true }
     };
 
+    // this is similar to how ReprOptions populates its field_shuffle_seed
+    let def_hash = tcx.def_path_hash(def_id).0.to_smaller_hash().as_u64();
+
     let layout = tcx.mk_layout(LayoutData {
         variants: Variants::Multiple {
             tag,
@@ -1019,6 +1028,7 @@ fn coroutine_layout<'tcx>(
         align,
         max_repr_align: None,
         unadjusted_abi_align: align.abi,
+        randomization_seed: def_hash,
     });
     debug!("coroutine layout ({:?}): {:#?}", ty, layout);
     Ok(layout)