10 use std::convert::TryFrom;
16 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
17 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
18 fn find_mir_or_eval_fn(
20 instance: ty::Instance<'tcx>,
21 args: &[OpTy<'tcx, Tag>],
22 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
23 unwind: Option<mir::BasicBlock>,
24 ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
25 let this = self.eval_context_mut();
26 trace!("eval_fn_call: {:#?}, {:?}", instance, ret.map(|p| *p.0));
28 // There are some more lang items we want to hook that CTFE does not hook (yet).
29 if this.tcx.lang_items().align_offset_fn() == Some(instance.def.def_id()) {
30 this.align_offset(args[0], args[1], ret, unwind)?;
34 // Try to see if we can do something about foreign items.
35 if this.tcx.is_foreign_item(instance.def_id()) {
36 // An external function call that does not have a MIR body. We either find MIR elsewhere
37 // or emulate its effect.
38 // This will be Ok(None) if we're emulating the intrinsic entirely within Miri (no need
39 // to run extra MIR), and Ok(Some(body)) if we found MIR to run for the
41 // Any needed call to `goto_block` will be performed by `emulate_foreign_item`.
42 return this.emulate_foreign_item(instance.def_id(), args, ret, unwind);
45 // Otherwise, load the MIR.
46 Ok(Some(&*this.load_mir(instance.def, None)?))
51 ptr_op: OpTy<'tcx, Tag>,
52 align_op: OpTy<'tcx, Tag>,
53 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
54 unwind: Option<mir::BasicBlock>,
55 ) -> InterpResult<'tcx> {
56 let this = self.eval_context_mut();
57 let (dest, ret) = ret.unwrap();
60 .force_bits(this.read_scalar(align_op)?.not_undef()?, this.pointer_size())?;
62 // Stop if the alignment is not a power of two.
63 if !req_align.is_power_of_two() {
64 return this.start_panic("align_offset: align is not a power-of-two", unwind);
67 let ptr_scalar = this.read_scalar(ptr_op)?.not_undef()?;
69 // Default: no result.
70 let mut result = this.truncate(u128::MAX, dest.layout);
71 if let Ok(ptr) = this.force_ptr(ptr_scalar) {
72 // Only do anything if we can identify the allocation this goes to.
74 this.memory.get_size_and_align(ptr.alloc_id, AllocCheck::MaybeDead)?.1.bytes();
75 if u128::from(cur_align) >= req_align {
76 // If the allocation alignment is at least the required alignment we use the
77 // libcore implementation.
78 // FIXME: is this correct in case of truncation?
79 result = u128::try_from(
80 (this.force_bits(ptr_scalar, this.pointer_size())? as *const i8)
81 .align_offset(usize::try_from(req_align).unwrap())
86 // Return result, and jump to caller.
87 this.write_scalar(Scalar::from_uint(result, dest.layout.size), dest)?;
88 this.go_to_block(ret);