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Make the randomize feature of rustc_abi additive
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HKalbasi committed Nov 5, 2023
1 parent a42d94e commit c8a25ed
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Showing 4 changed files with 7 additions and 9 deletions.
5 changes: 2 additions & 3 deletions compiler/rustc_abi/src/layout.rs
Original file line number Diff line number Diff line change
Expand Up @@ -906,9 +906,8 @@ fn univariant<
use rand::{seq::SliceRandom, SeedableRng};
// `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(),
);
let mut rng =
rand_xoshiro::Xoshiro128StarStar::seed_from_u64(repr.field_shuffle_seed);

// Shuffle the ordering of the fields.
optimizing.shuffle(&mut rng);
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5 changes: 2 additions & 3 deletions compiler/rustc_abi/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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 {
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2 changes: 1 addition & 1 deletion compiler/rustc_middle/src/ty/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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
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4 changes: 2 additions & 2 deletions compiler/rustc_mir_transform/src/sroa.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand Down Expand Up @@ -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;
}
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