bjoernager/rust
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Lower intrinsics::offset to mir::BinOp::Offset

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They're semantically the same, so this means the backends don't need to handle the intrinsic and means fewer MIR basic blocks in pointer arithmetic code.
This commit is contained in:
Scott McMurray 2023-04-25 12:10:55 -07:00
parent a7aa20517c
commit 05a665f21a
7 changed files with 66 additions and 20 deletions
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17
compiler/rustc_const_eval/src/const_eval/machine.rs
View file

@ -559,11 +559,20 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
}
fn binary_ptr_op(
_ecx: &InterpCx<'mir, 'tcx, Self>,
_bin_op: mir::BinOp,
_left: &ImmTy<'tcx>,
_right: &ImmTy<'tcx>,
ecx: &InterpCx<'mir, 'tcx, Self>,
bin_op: mir::BinOp,
left: &ImmTy<'tcx>,
right: &ImmTy<'tcx>,
) -> InterpResult<'tcx, (Scalar, bool, Ty<'tcx>)> {
if bin_op == mir::BinOp::Offset {
let ptr = left.to_scalar().to_pointer(ecx)?;
let offset_count = right.to_scalar().to_target_isize(ecx)?;
let pointee_ty = left.layout.ty.builtin_deref(true).unwrap().ty;
let offset_ptr = ecx.ptr_offset_inbounds(ptr, pointee_ty, offset_count)?;
return Ok((Scalar::from_maybe_pointer(offset_ptr, ecx), false, left.layout.ty));
}
throw_unsup_format!("pointer arithmetic or comparison is not supported at compile-time");
}

8
compiler/rustc_const_eval/src/interpret/intrinsics.rs
View file

@ -286,14 +286,6 @@ 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::offset => {
let ptr = self.read_pointer(&args[0])?;
let offset_count = self.read_target_isize(&args[1])?;
let pointee_ty = substs.type_at(0);
let offset_ptr = self.ptr_offset_inbounds(ptr, pointee_ty, offset_count)?;
self.write_pointer(offset_ptr, dest)?;
}
sym::arith_offset => {
let ptr = self.read_pointer(&args[0])?;
let offset_count = self.read_target_isize(&args[1])?;