bjoernager/rust
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Add a new compare_bytes intrinsic instead of calling memcmp directly

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This commit is contained in:
Scott McMurray 2023-08-02 12:45:52 -07:00
parent 85fbb57149
commit 502af03445
17 changed files with 267 additions and 22 deletions
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22
compiler/rustc_const_eval/src/interpret/intrinsics.rs
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@ -261,6 +261,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
sym::write_bytes => {
self.write_bytes_intrinsic(&args[0], &args[1], &args[2])?;
}
sym::compare_bytes => {
let result = self.compare_bytes_intrinsic(&args[0], &args[1], &args[2])?;
self.write_scalar(result, dest)?;
}
sym::arith_offset => {
let ptr = self.read_pointer(&args[0])?;
let offset_count = self.read_target_isize(&args[1])?;
@ -643,6 +647,24 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
self.write_bytes_ptr(dst, bytes)
}
pub(crate) fn compare_bytes_intrinsic(
&mut self,
left: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>,
right: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>,
byte_count: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>,
) -> InterpResult<'tcx, Scalar<M::Provenance>> {
let left = self.read_pointer(left)?;
let right = self.read_pointer(right)?;
let n = Size::from_bytes(self.read_target_usize(byte_count)?);
let left_bytes = self.read_bytes_ptr_strip_provenance(left, n)?;
let right_bytes = self.read_bytes_ptr_strip_provenance(right, n)?;
// `Ordering`'s discriminants are -1/0/+1, so casting does the right thing.
let result = Ord::cmp(left_bytes, right_bytes) as i32;
Ok(Scalar::from_i32(result))
}
pub(crate) fn raw_eq_intrinsic(
&mut self,
lhs: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>,