14 // End module management, begin local code
16 use std::convert::TryFrom;
20 use rustc_middle::{mir, ty};
23 use helpers::check_arg_count;
25 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
26 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
27 fn find_mir_or_eval_fn(
29 instance: ty::Instance<'tcx>,
30 args: &[OpTy<'tcx, Tag>],
31 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
32 unwind: Option<mir::BasicBlock>,
33 ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
34 let this = self.eval_context_mut();
35 trace!("eval_fn_call: {:#?}, {:?}", instance, ret.map(|p| *p.0));
37 // There are some more lang items we want to hook that CTFE does not hook (yet).
38 if this.tcx.lang_items().align_offset_fn() == Some(instance.def.def_id()) {
39 let &[ptr, align] = check_arg_count(args)?;
40 this.align_offset(ptr, align, ret, unwind)?;
44 // Try to see if we can do something about foreign items.
45 if this.tcx.is_foreign_item(instance.def_id()) {
46 // An external function call that does not have a MIR body. We either find MIR elsewhere
47 // or emulate its effect.
48 // This will be Ok(None) if we're emulating the intrinsic entirely within Miri (no need
49 // to run extra MIR), and Ok(Some(body)) if we found MIR to run for the
51 // Any needed call to `goto_block` will be performed by `emulate_foreign_item`.
52 return this.emulate_foreign_item(instance.def_id(), args, ret, unwind);
55 // Otherwise, load the MIR.
56 Ok(Some(&*this.load_mir(instance.def, None)?))
61 ptr_op: OpTy<'tcx, Tag>,
62 align_op: OpTy<'tcx, Tag>,
63 ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
64 unwind: Option<mir::BasicBlock>,
65 ) -> InterpResult<'tcx> {
66 let this = self.eval_context_mut();
67 let (dest, ret) = ret.unwrap();
70 .force_bits(this.read_scalar(align_op)?.not_undef()?, this.pointer_size())?;
72 // Stop if the alignment is not a power of two.
73 if !req_align.is_power_of_two() {
74 return this.start_panic("align_offset: align is not a power-of-two", unwind);
77 let ptr_scalar = this.read_scalar(ptr_op)?.not_undef()?;
79 // Default: no result.
80 let mut result = this.machine_usize_max();
81 if let Ok(ptr) = this.force_ptr(ptr_scalar) {
82 // Only do anything if we can identify the allocation this goes to.
84 this.memory.get_size_and_align(ptr.alloc_id, AllocCheck::MaybeDead)?.1.bytes();
85 if u128::from(cur_align) >= req_align {
86 // If the allocation alignment is at least the required alignment we use the
87 // libcore implementation.
88 // FIXME: is this correct in case of truncation?
89 result = u64::try_from(
90 (this.force_bits(ptr_scalar, this.pointer_size())? as *const i8)
91 .align_offset(usize::try_from(req_align).unwrap())
96 // Return result, and jump to caller.
97 this.write_scalar(Scalar::from_machine_usize(result, this), dest)?;
98 this.go_to_block(ret);