rust/src/shims/mod.rs
2021-12-24 12:02:22 +01:00

103 lines
3.7 KiB
Rust

mod backtrace;
pub mod foreign_items;
pub mod intrinsics;
pub mod posix;
pub mod windows;
pub mod dlsym;
pub mod env;
pub mod os_str;
pub mod panic;
pub mod time;
pub mod tls;
// End module management, begin local code
use log::trace;
use rustc_middle::{mir, ty};
use rustc_target::spec::abi::Abi;
use crate::*;
use helpers::check_arg_count;
impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
fn find_mir_or_eval_fn(
&mut self,
instance: ty::Instance<'tcx>,
abi: Abi,
args: &[OpTy<'tcx, Tag>],
ret: Option<(&PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
unwind: StackPopUnwind,
) -> InterpResult<'tcx, Option<(&'mir mir::Body<'tcx>, ty::Instance<'tcx>)>> {
let this = self.eval_context_mut();
trace!("eval_fn_call: {:#?}, {:?}", instance, ret.map(|p| p.0));
// There are some more lang items we want to hook that CTFE does not hook (yet).
if this.tcx.lang_items().align_offset_fn() == Some(instance.def.def_id()) {
let &[ref ptr, ref align] = check_arg_count(args)?;
if this.align_offset(ptr, align, ret, unwind)? {
return Ok(None);
}
}
// Try to see if we can do something about foreign items.
if this.tcx.is_foreign_item(instance.def_id()) {
// An external function call that does not have a MIR body. We either find MIR elsewhere
// or emulate its effect.
// This will be Ok(None) if we're emulating the intrinsic entirely within Miri (no need
// to run extra MIR), and Ok(Some(body)) if we found MIR to run for the
// foreign function
// Any needed call to `goto_block` will be performed by `emulate_foreign_item`.
return this.emulate_foreign_item(instance.def_id(), abi, args, ret, unwind);
}
// Otherwise, load the MIR.
Ok(Some((&*this.load_mir(instance.def, None)?, instance)))
}
/// Returns `true` if the computation was performed, and `false` if we should just evaluate
/// the actual MIR of `align_offset`.
fn align_offset(
&mut self,
ptr_op: &OpTy<'tcx, Tag>,
align_op: &OpTy<'tcx, Tag>,
ret: Option<(&PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
unwind: StackPopUnwind,
) -> InterpResult<'tcx, bool> {
let this = self.eval_context_mut();
let (dest, ret) = ret.unwrap();
if this.memory.extra.check_alignment != AlignmentCheck::Symbolic {
// Just use actual implementation.
return Ok(false);
}
let req_align = this.read_scalar(align_op)?.to_machine_usize(this)?;
// Stop if the alignment is not a power of two.
if !req_align.is_power_of_two() {
this.start_panic("align_offset: align is not a power-of-two", unwind)?;
return Ok(true); // nothing left to do
}
let ptr = this.read_pointer(ptr_op)?;
if let Ok(ptr) = ptr.into_pointer_or_addr() {
// Only do anything if we can identify the allocation this goes to.
let (_, cur_align) =
this.memory.get_size_and_align(ptr.provenance.alloc_id, AllocCheck::MaybeDead)?;
if cur_align.bytes() >= req_align {
// If the allocation alignment is at least the required alignment we use the
// real implementation.
return Ok(false);
}
}
// Return error result (usize::MAX), and jump to caller.
this.write_scalar(Scalar::from_machine_usize(this.machine_usize_max(), this), dest)?;
this.go_to_block(ret);
Ok(true)
}
}