Make the randomize feature of rustc_abi additive

Author: HKalbasi

compiler/rustc_abi/src/layout.rs

@@ -907,7 +907,7 @@ fn univariant<
                 // `ReprOptions.layout_seed` is a deterministic seed we can use to randomize field
                 // ordering.
                 let mut rng = rand_xoshiro::Xoshiro128StarStar::seed_from_u64(
-                    repr.field_shuffle_seed.as_u64(),
+                    repr.field_shuffle_seed,
                 );
 
                 // Shuffle the ordering of the fields.

compiler/rustc_abi/src/lib.rs

@@ -76,15 +76,14 @@ pub struct ReprOptions {
     pub align: Option<Align>,
     pub pack: Option<Align>,
     pub flags: ReprFlags,
-    #[cfg(feature = "randomize")]
     /// The seed to be used for randomizing a type's layout
     ///
-    /// Note: This could technically be a `Hash128` which would
+    /// Note: This could technically be a `u128` which would
     /// be the "most accurate" hash as it'd encompass the item and crate
     /// hash without loss, but it does pay the price of being larger.
     /// Everything's a tradeoff, a 64-bit seed should be sufficient for our
     /// purposes (primarily `-Z randomize-layout`)
-    pub field_shuffle_seed: rustc_data_structures::stable_hasher::Hash64,
+    pub field_shuffle_seed: u64,
 }
 
 impl ReprOptions {

compiler/rustc_middle/src/ty/mod.rs

@@ -2011,7 +2011,7 @@ impl<'tcx> TyCtxt<'tcx> {
 
         // Generate a deterministically-derived seed from the item's path hash
         // to allow for cross-crate compilation to actually work
-        let mut field_shuffle_seed = self.def_path_hash(did).0.to_smaller_hash();
+        let mut field_shuffle_seed = self.def_path_hash(did).0.to_smaller_hash().as_u64();
 
         // If the user defined a custom seed for layout randomization, xor the item's
         // path hash with the user defined seed, this will allowing determinism while

compiler/rustc_mir_transform/src/sroa.rs

@@ -7,7 +7,7 @@ use rustc_middle::mir::visit::*;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_mir_dataflow::value_analysis::{excluded_locals, iter_fields};
-use rustc_target::abi::{FieldIdx, ReprFlags, FIRST_VARIANT};
+use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
 
 pub struct ScalarReplacementOfAggregates;
 
@@ -66,7 +66,7 @@ fn escaping_locals<'tcx>(
             return true;
         }
         if let ty::Adt(def, _args) = ty.kind() {
-            if def.repr().flags.contains(ReprFlags::IS_SIMD) {
+            if def.repr().simd() {
                 // Exclude #[repr(simd)] types so that they are not de-optimized into an array
                 return true;
             }