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interpret: don't rely on ScalarPair for overflowed arithmetic

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This commit is contained in:
Ralf Jung 2022-06-28 11:39:22 -04:00
parent baf382e63c
commit 595dd976bd
1 changed files with 16 additions and 2 deletions
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18
compiler/rustc_const_eval/src/interpret/operator.rs
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@ -5,6 +5,7 @@ use rustc_middle::mir;
use rustc_middle::mir::interpret::{InterpResult, Scalar};
use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
use rustc_middle::ty::{self, FloatTy, Ty};
use rustc_target::abi::Abi;
use super::{ImmTy, Immediate, InterpCx, Machine, PlaceTy};
@ -25,8 +26,21 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
"type mismatch for result of {:?}",
op,
);
let val = Immediate::ScalarPair(val.into(), Scalar::from_bool(overflowed).into());
self.write_immediate(val, dest)
if let Abi::ScalarPair(..) = dest.layout.abi {
// We can use the optimized path and avoid `place_field` (which might do
// `force_allocation`).
let pair = Immediate::ScalarPair(val.into(), Scalar::from_bool(overflowed).into());
self.write_immediate(pair, dest)?;
} else {
// With randomized layout, `(int, bool)` might cease to be a `ScalarPair`, so we have to
// do a component-wise write here. This code path is slower than the above because
// `place_field` will have to `force_allocate` locals here.
let val_field = self.place_field(&dest, 0)?;
self.write_scalar(val, &val_field)?;
let overflowed_field = self.place_field(&dest, 1)?;
self.write_scalar(Scalar::from_bool(overflowed), &overflowed_field)?;
}
Ok(())
}
/// Applies the binary operation `op` to the arguments and writes the result to the