14 // End module management, begin local code
18 use rustc_middle::{mir, ty};
19 use rustc_target::spec::abi::Abi;
22 use helpers::check_arg_count;
24 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
25 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
26 fn find_mir_or_eval_fn(
28 instance: ty::Instance<'tcx>,
30 args: &[OpTy<'tcx, Tag>],
31 dest: &PlaceTy<'tcx, Tag>,
32 ret: Option<mir::BasicBlock>,
33 unwind: StackPopUnwind,
34 ) -> InterpResult<'tcx, Option<(&'mir mir::Body<'tcx>, ty::Instance<'tcx>)>> {
35 let this = self.eval_context_mut();
36 trace!("eval_fn_call: {:#?}, {:?}", instance, dest);
38 // There are some more lang items we want to hook that CTFE does not hook (yet).
39 if this.tcx.lang_items().align_offset_fn() == Some(instance.def.def_id()) {
40 let [ptr, align] = check_arg_count(args)?;
41 if this.align_offset(ptr, align, dest, ret, unwind)? {
46 // Try to see if we can do something about foreign items.
47 if this.tcx.is_foreign_item(instance.def_id()) {
48 // An external function call that does not have a MIR body. We either find MIR elsewhere
49 // or emulate its effect.
50 // This will be Ok(None) if we're emulating the intrinsic entirely within Miri (no need
51 // to run extra MIR), and Ok(Some(body)) if we found MIR to run for the
53 // Any needed call to `goto_block` will be performed by `emulate_foreign_item`.
54 return this.emulate_foreign_item(instance.def_id(), abi, args, dest, ret, unwind);
57 // Otherwise, load the MIR.
58 Ok(Some((&*this.load_mir(instance.def, None)?, instance)))
61 /// Returns `true` if the computation was performed, and `false` if we should just evaluate
62 /// the actual MIR of `align_offset`.
65 ptr_op: &OpTy<'tcx, Tag>,
66 align_op: &OpTy<'tcx, Tag>,
67 dest: &PlaceTy<'tcx, Tag>,
68 ret: Option<mir::BasicBlock>,
69 unwind: StackPopUnwind,
70 ) -> InterpResult<'tcx, bool> {
71 let this = self.eval_context_mut();
72 let ret = ret.unwrap();
74 if this.machine.check_alignment != AlignmentCheck::Symbolic {
75 // Just use actual implementation.
79 let req_align = this.read_scalar(align_op)?.to_machine_usize(this)?;
81 // Stop if the alignment is not a power of two.
82 if !req_align.is_power_of_two() {
83 this.start_panic("align_offset: align is not a power-of-two", unwind)?;
84 return Ok(true); // nothing left to do
87 let ptr = this.read_pointer(ptr_op)?;
88 if let Ok((alloc_id, _offset, _)) = this.ptr_try_get_alloc_id(ptr) {
89 // Only do anything if we can identify the allocation this goes to.
90 let (_, cur_align) = this.get_alloc_size_and_align(alloc_id, AllocCheck::MaybeDead)?;
91 if cur_align.bytes() >= req_align {
92 // If the allocation alignment is at least the required alignment we use the
93 // real implementation.
98 // Return error result (usize::MAX), and jump to caller.
99 this.write_scalar(Scalar::from_machine_usize(this.machine_usize_max(), this), dest)?;
100 this.go_to_block(ret);