bjoernager/rust
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Only check packed ADT.

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This commit is contained in:
Camille GILLOT 2023-08-24 15:42:55 +00:00
parent 1c5f1762b7
commit 15a68610dd
3 changed files with 8 additions and 6 deletions
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10
compiler/rustc_mir_transform/src/dead_store_elimination.rs
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@ -12,7 +12,7 @@
//! will still not cause any further changes.
//!
use crate::util::is_disaligned;
use crate::util::is_within_packed;
use rustc_index::bit_set::BitSet;
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::*;
@ -32,8 +32,6 @@ pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitS
.iterate_to_fixpoint()
.into_results_cursor(body);
let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
// For blocks with a call terminator, if an argument copy can be turned into a move,
// record it as (block, argument index).
let mut call_operands_to_move = Vec::new();
@ -52,7 +50,11 @@ pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitS
&& !place.is_indirect()
&& !borrowed.contains(place.local)
&& !state.contains(place.local)
&& !is_disaligned(tcx, body, param_env, place)
// If `place` is a projection of a disaligned field in a packed ADT,
// the move may be codegened as a pointer to that field.
// Using that disaligned pointer may trigger UB in the callee,
// so do nothing.
&& is_within_packed(tcx, body, place).is_none()
{
call_operands_to_move.push((bb, index));
}