447 lines
19 KiB
Rust
447 lines
19 KiB
Rust
//! Intrinsics and other functions that the miri engine executes without
|
|
//! looking at their MIR. Intrinsics/functions supported here are shared by CTFE
|
|
//! and miri.
|
|
|
|
use syntax::symbol::Symbol;
|
|
use syntax_pos::Span;
|
|
use rustc::ty;
|
|
use rustc::ty::layout::{LayoutOf, Primitive, Size};
|
|
use rustc::ty::subst::SubstsRef;
|
|
use rustc::hir::def_id::DefId;
|
|
use rustc::ty::TyCtxt;
|
|
use rustc::mir::{
|
|
self, BinOp,
|
|
interpret::{InterpResult, Scalar, GlobalId, ConstValue}
|
|
};
|
|
|
|
use super::{
|
|
Machine, PlaceTy, OpTy, InterpCx, ImmTy,
|
|
};
|
|
|
|
mod caller_location;
|
|
mod type_name;
|
|
|
|
fn numeric_intrinsic<'tcx, Tag>(
|
|
name: &str,
|
|
bits: u128,
|
|
kind: Primitive,
|
|
) -> InterpResult<'tcx, Scalar<Tag>> {
|
|
let size = match kind {
|
|
Primitive::Int(integer, _) => integer.size(),
|
|
_ => bug!("invalid `{}` argument: {:?}", name, bits),
|
|
};
|
|
let extra = 128 - size.bits() as u128;
|
|
let bits_out = match name {
|
|
"ctpop" => bits.count_ones() as u128,
|
|
"ctlz" => bits.leading_zeros() as u128 - extra,
|
|
"cttz" => (bits << extra).trailing_zeros() as u128 - extra,
|
|
"bswap" => (bits << extra).swap_bytes(),
|
|
"bitreverse" => (bits << extra).reverse_bits(),
|
|
_ => bug!("not a numeric intrinsic: {}", name),
|
|
};
|
|
Ok(Scalar::from_uint(bits_out, size))
|
|
}
|
|
|
|
/// The logic for all nullary intrinsics is implemented here. These intrinsics don't get evaluated
|
|
/// inside an `InterpCx` and instead have their value computed directly from rustc internal info.
|
|
crate fn eval_nullary_intrinsic<'tcx>(
|
|
tcx: TyCtxt<'tcx>,
|
|
param_env: ty::ParamEnv<'tcx>,
|
|
def_id: DefId,
|
|
substs: SubstsRef<'tcx>,
|
|
) -> InterpResult<'tcx, &'tcx ty::Const<'tcx>> {
|
|
let tp_ty = substs.type_at(0);
|
|
let name = &*tcx.item_name(def_id).as_str();
|
|
Ok(match name {
|
|
"type_name" => {
|
|
let alloc = type_name::alloc_type_name(tcx, tp_ty);
|
|
tcx.mk_const(ty::Const {
|
|
val: ty::ConstKind::Value(ConstValue::Slice {
|
|
data: alloc,
|
|
start: 0,
|
|
end: alloc.len(),
|
|
}),
|
|
ty: tcx.mk_static_str(),
|
|
})
|
|
},
|
|
"needs_drop" => ty::Const::from_bool(tcx, tp_ty.needs_drop(tcx, param_env)),
|
|
"size_of" |
|
|
"min_align_of" |
|
|
"pref_align_of" => {
|
|
let layout = tcx.layout_of(param_env.and(tp_ty)).map_err(|e| err_inval!(Layout(e)))?;
|
|
let n = match name {
|
|
"pref_align_of" => layout.align.pref.bytes(),
|
|
"min_align_of" => layout.align.abi.bytes(),
|
|
"size_of" => layout.size.bytes(),
|
|
_ => bug!(),
|
|
};
|
|
ty::Const::from_usize(tcx, n)
|
|
},
|
|
"type_id" => ty::Const::from_bits(
|
|
tcx,
|
|
tcx.type_id_hash(tp_ty).into(),
|
|
param_env.and(tcx.types.u64),
|
|
),
|
|
other => bug!("`{}` is not a zero arg intrinsic", other),
|
|
})
|
|
}
|
|
|
|
impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
|
|
/// Returns `true` if emulation happened.
|
|
pub fn emulate_intrinsic(
|
|
&mut self,
|
|
span: Span,
|
|
instance: ty::Instance<'tcx>,
|
|
args: &[OpTy<'tcx, M::PointerTag>],
|
|
ret: Option<(PlaceTy<'tcx, M::PointerTag>, mir::BasicBlock)>,
|
|
) -> InterpResult<'tcx, bool> {
|
|
let substs = instance.substs;
|
|
let intrinsic_name = &*self.tcx.item_name(instance.def_id()).as_str();
|
|
|
|
// We currently do not handle any intrinsics that are *allowed* to diverge,
|
|
// but `transmute` could lack a return place in case of UB.
|
|
let (dest, ret) = match ret {
|
|
Some(p) => p,
|
|
None => match intrinsic_name {
|
|
"transmute" => throw_ub!(Unreachable),
|
|
_ => return Ok(false),
|
|
}
|
|
};
|
|
|
|
match intrinsic_name {
|
|
"caller_location" => {
|
|
let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
|
|
let caller = self.tcx.sess.source_map().lookup_char_pos(topmost.lo());
|
|
let location = self.alloc_caller_location(
|
|
Symbol::intern(&caller.file.name.to_string()),
|
|
caller.line as u32,
|
|
caller.col_display as u32 + 1,
|
|
)?;
|
|
self.write_scalar(location.ptr, dest)?;
|
|
}
|
|
|
|
"min_align_of" |
|
|
"pref_align_of" |
|
|
"needs_drop" |
|
|
"size_of" |
|
|
"type_id" |
|
|
"type_name" => {
|
|
let gid = GlobalId {
|
|
instance,
|
|
promoted: None,
|
|
};
|
|
let val = self.tcx.const_eval(self.param_env.and(gid))?;
|
|
let val = self.eval_const_to_op(val, None)?;
|
|
self.copy_op(val, dest)?;
|
|
}
|
|
|
|
| "ctpop"
|
|
| "cttz"
|
|
| "cttz_nonzero"
|
|
| "ctlz"
|
|
| "ctlz_nonzero"
|
|
| "bswap"
|
|
| "bitreverse" => {
|
|
let ty = substs.type_at(0);
|
|
let layout_of = self.layout_of(ty)?;
|
|
let val = self.read_scalar(args[0])?.not_undef()?;
|
|
let bits = self.force_bits(val, layout_of.size)?;
|
|
let kind = match layout_of.abi {
|
|
ty::layout::Abi::Scalar(ref scalar) => scalar.value,
|
|
_ => throw_unsup!(TypeNotPrimitive(ty)),
|
|
};
|
|
let out_val = if intrinsic_name.ends_with("_nonzero") {
|
|
if bits == 0 {
|
|
throw_ub_format!("`{}` called on 0", intrinsic_name);
|
|
}
|
|
numeric_intrinsic(intrinsic_name.trim_end_matches("_nonzero"), bits, kind)?
|
|
} else {
|
|
numeric_intrinsic(intrinsic_name, bits, kind)?
|
|
};
|
|
self.write_scalar(out_val, dest)?;
|
|
}
|
|
| "wrapping_add"
|
|
| "wrapping_sub"
|
|
| "wrapping_mul"
|
|
| "add_with_overflow"
|
|
| "sub_with_overflow"
|
|
| "mul_with_overflow" => {
|
|
let lhs = self.read_immediate(args[0])?;
|
|
let rhs = self.read_immediate(args[1])?;
|
|
let (bin_op, ignore_overflow) = match intrinsic_name {
|
|
"wrapping_add" => (BinOp::Add, true),
|
|
"wrapping_sub" => (BinOp::Sub, true),
|
|
"wrapping_mul" => (BinOp::Mul, true),
|
|
"add_with_overflow" => (BinOp::Add, false),
|
|
"sub_with_overflow" => (BinOp::Sub, false),
|
|
"mul_with_overflow" => (BinOp::Mul, false),
|
|
_ => bug!("Already checked for int ops")
|
|
};
|
|
if ignore_overflow {
|
|
self.binop_ignore_overflow(bin_op, lhs, rhs, dest)?;
|
|
} else {
|
|
self.binop_with_overflow(bin_op, lhs, rhs, dest)?;
|
|
}
|
|
}
|
|
"saturating_add" | "saturating_sub" => {
|
|
let l = self.read_immediate(args[0])?;
|
|
let r = self.read_immediate(args[1])?;
|
|
let is_add = intrinsic_name == "saturating_add";
|
|
let (val, overflowed, _ty) = self.overflowing_binary_op(if is_add {
|
|
BinOp::Add
|
|
} else {
|
|
BinOp::Sub
|
|
}, l, r)?;
|
|
let val = if overflowed {
|
|
let num_bits = l.layout.size.bits();
|
|
if l.layout.abi.is_signed() {
|
|
// For signed ints the saturated value depends on the sign of the first
|
|
// term since the sign of the second term can be inferred from this and
|
|
// the fact that the operation has overflowed (if either is 0 no
|
|
// overflow can occur)
|
|
let first_term: u128 = self.force_bits(l.to_scalar()?, l.layout.size)?;
|
|
let first_term_positive = first_term & (1 << (num_bits-1)) == 0;
|
|
if first_term_positive {
|
|
// Negative overflow not possible since the positive first term
|
|
// can only increase an (in range) negative term for addition
|
|
// or corresponding negated positive term for subtraction
|
|
Scalar::from_uint((1u128 << (num_bits - 1)) - 1, // max positive
|
|
Size::from_bits(num_bits))
|
|
} else {
|
|
// Positive overflow not possible for similar reason
|
|
// max negative
|
|
Scalar::from_uint(1u128 << (num_bits - 1), Size::from_bits(num_bits))
|
|
}
|
|
} else { // unsigned
|
|
if is_add {
|
|
// max unsigned
|
|
Scalar::from_uint(u128::max_value() >> (128 - num_bits),
|
|
Size::from_bits(num_bits))
|
|
} else { // underflow to 0
|
|
Scalar::from_uint(0u128, Size::from_bits(num_bits))
|
|
}
|
|
}
|
|
} else {
|
|
val
|
|
};
|
|
self.write_scalar(val, dest)?;
|
|
}
|
|
"unchecked_shl" | "unchecked_shr" => {
|
|
let l = self.read_immediate(args[0])?;
|
|
let r = self.read_immediate(args[1])?;
|
|
let bin_op = match intrinsic_name {
|
|
"unchecked_shl" => BinOp::Shl,
|
|
"unchecked_shr" => BinOp::Shr,
|
|
_ => bug!("Already checked for int ops")
|
|
};
|
|
let (val, overflowed, _ty) = self.overflowing_binary_op(bin_op, l, r)?;
|
|
if overflowed {
|
|
let layout = self.layout_of(substs.type_at(0))?;
|
|
let r_val = self.force_bits(r.to_scalar()?, layout.size)?;
|
|
throw_ub_format!("Overflowing shift by {} in `{}`", r_val, intrinsic_name);
|
|
}
|
|
self.write_scalar(val, dest)?;
|
|
}
|
|
"rotate_left" | "rotate_right" => {
|
|
// rotate_left: (X << (S % BW)) | (X >> ((BW - S) % BW))
|
|
// rotate_right: (X << ((BW - S) % BW)) | (X >> (S % BW))
|
|
let layout = self.layout_of(substs.type_at(0))?;
|
|
let val = self.read_scalar(args[0])?.not_undef()?;
|
|
let val_bits = self.force_bits(val, layout.size)?;
|
|
let raw_shift = self.read_scalar(args[1])?.not_undef()?;
|
|
let raw_shift_bits = self.force_bits(raw_shift, layout.size)?;
|
|
let width_bits = layout.size.bits() as u128;
|
|
let shift_bits = raw_shift_bits % width_bits;
|
|
let inv_shift_bits = (width_bits - shift_bits) % width_bits;
|
|
let result_bits = if intrinsic_name == "rotate_left" {
|
|
(val_bits << shift_bits) | (val_bits >> inv_shift_bits)
|
|
} else {
|
|
(val_bits >> shift_bits) | (val_bits << inv_shift_bits)
|
|
};
|
|
let truncated_bits = self.truncate(result_bits, layout);
|
|
let result = Scalar::from_uint(truncated_bits, layout.size);
|
|
self.write_scalar(result, dest)?;
|
|
}
|
|
|
|
"ptr_offset_from" => {
|
|
let isize_layout = self.layout_of(self.tcx.types.isize)?;
|
|
let a = self.read_immediate(args[0])?.to_scalar()?;
|
|
let b = self.read_immediate(args[1])?.to_scalar()?;
|
|
|
|
// Special case: if both scalars are *equal integers*
|
|
// and not NULL, we pretend there is an allocation of size 0 right there,
|
|
// and their offset is 0. (There's never a valid object at NULL, making it an
|
|
// exception from the exception.)
|
|
// This is the dual to the special exception for offset-by-0
|
|
// in the inbounds pointer offset operation (see the Miri code, `src/operator.rs`).
|
|
//
|
|
// Control flow is weird because we cannot early-return (to reach the
|
|
// `go_to_block` at the end).
|
|
let done = if a.is_bits() && b.is_bits() {
|
|
let a = a.to_machine_usize(self)?;
|
|
let b = b.to_machine_usize(self)?;
|
|
if a == b && a != 0 {
|
|
self.write_scalar(Scalar::from_int(0, isize_layout.size), dest)?;
|
|
true
|
|
} else { false }
|
|
} else { false };
|
|
|
|
if !done {
|
|
// General case: we need two pointers.
|
|
let a = self.force_ptr(a)?;
|
|
let b = self.force_ptr(b)?;
|
|
if a.alloc_id != b.alloc_id {
|
|
throw_ub_format!(
|
|
"ptr_offset_from cannot compute offset of pointers into different \
|
|
allocations.",
|
|
);
|
|
}
|
|
let usize_layout = self.layout_of(self.tcx.types.usize)?;
|
|
let a_offset = ImmTy::from_uint(a.offset.bytes(), usize_layout);
|
|
let b_offset = ImmTy::from_uint(b.offset.bytes(), usize_layout);
|
|
let (val, _overflowed, _ty) = self.overflowing_binary_op(
|
|
BinOp::Sub, a_offset, b_offset,
|
|
)?;
|
|
let pointee_layout = self.layout_of(substs.type_at(0))?;
|
|
let val = ImmTy::from_scalar(val, isize_layout);
|
|
let size = ImmTy::from_int(pointee_layout.size.bytes(), isize_layout);
|
|
self.exact_div(val, size, dest)?;
|
|
}
|
|
}
|
|
|
|
"transmute" => {
|
|
self.copy_op_transmute(args[0], dest)?;
|
|
}
|
|
"simd_insert" => {
|
|
let index = u64::from(self.read_scalar(args[1])?.to_u32()?);
|
|
let elem = args[2];
|
|
let input = args[0];
|
|
let (len, e_ty) = input.layout.ty.simd_size_and_type(self.tcx.tcx);
|
|
assert!(
|
|
index < len,
|
|
"Index `{}` must be in bounds of vector type `{}`: `[0, {})`",
|
|
index, e_ty, len
|
|
);
|
|
assert_eq!(
|
|
input.layout, dest.layout,
|
|
"Return type `{}` must match vector type `{}`",
|
|
dest.layout.ty, input.layout.ty
|
|
);
|
|
assert_eq!(
|
|
elem.layout.ty, e_ty,
|
|
"Scalar element type `{}` must match vector element type `{}`",
|
|
elem.layout.ty, e_ty
|
|
);
|
|
|
|
for i in 0..len {
|
|
let place = self.place_field(dest, i)?;
|
|
let value = if i == index {
|
|
elem
|
|
} else {
|
|
self.operand_field(input, i)?
|
|
};
|
|
self.copy_op(value, place)?;
|
|
}
|
|
}
|
|
"simd_extract" => {
|
|
let index = u64::from(self.read_scalar(args[1])?.to_u32()?);
|
|
let (len, e_ty) = args[0].layout.ty.simd_size_and_type(self.tcx.tcx);
|
|
assert!(
|
|
index < len,
|
|
"index `{}` is out-of-bounds of vector type `{}` with length `{}`",
|
|
index, e_ty, len
|
|
);
|
|
assert_eq!(
|
|
e_ty, dest.layout.ty,
|
|
"Return type `{}` must match vector element type `{}`",
|
|
dest.layout.ty, e_ty
|
|
);
|
|
self.copy_op(self.operand_field(args[0], index)?, dest)?;
|
|
}
|
|
_ => return Ok(false),
|
|
}
|
|
|
|
self.dump_place(*dest);
|
|
self.go_to_block(ret);
|
|
Ok(true)
|
|
}
|
|
|
|
/// "Intercept" a function call to a panic-related function
|
|
/// because we have something special to do for it.
|
|
/// Returns `true` if an intercept happened.
|
|
pub fn hook_panic_fn(
|
|
&mut self,
|
|
instance: ty::Instance<'tcx>,
|
|
args: &[OpTy<'tcx, M::PointerTag>],
|
|
_ret: Option<(PlaceTy<'tcx, M::PointerTag>, mir::BasicBlock)>,
|
|
) -> InterpResult<'tcx, bool> {
|
|
let def_id = instance.def_id();
|
|
if Some(def_id) == self.tcx.lang_items().panic_fn() {
|
|
// &'static str, &core::panic::Location { &'static str, u32, u32 }
|
|
assert!(args.len() == 2);
|
|
|
|
let msg_place = self.deref_operand(args[0])?;
|
|
let msg = Symbol::intern(self.read_str(msg_place)?);
|
|
|
|
let location = self.deref_operand(args[1])?;
|
|
let (file, line, col) = (
|
|
self.mplace_field(location, 0)?,
|
|
self.mplace_field(location, 1)?,
|
|
self.mplace_field(location, 2)?,
|
|
);
|
|
|
|
let file_place = self.deref_operand(file.into())?;
|
|
let file = Symbol::intern(self.read_str(file_place)?);
|
|
let line = self.read_scalar(line.into())?.to_u32()?;
|
|
let col = self.read_scalar(col.into())?.to_u32()?;
|
|
throw_panic!(Panic { msg, file, line, col })
|
|
} else if Some(def_id) == self.tcx.lang_items().begin_panic_fn() {
|
|
assert!(args.len() == 2);
|
|
// &'static str, &(&'static str, u32, u32)
|
|
let msg = args[0];
|
|
let place = self.deref_operand(args[1])?;
|
|
let (file, line, col) = (
|
|
self.mplace_field(place, 0)?,
|
|
self.mplace_field(place, 1)?,
|
|
self.mplace_field(place, 2)?,
|
|
);
|
|
|
|
let msg_place = self.deref_operand(msg.into())?;
|
|
let msg = Symbol::intern(self.read_str(msg_place)?);
|
|
let file_place = self.deref_operand(file.into())?;
|
|
let file = Symbol::intern(self.read_str(file_place)?);
|
|
let line = self.read_scalar(line.into())?.to_u32()?;
|
|
let col = self.read_scalar(col.into())?.to_u32()?;
|
|
throw_panic!(Panic { msg, file, line, col })
|
|
} else {
|
|
return Ok(false);
|
|
}
|
|
}
|
|
|
|
pub fn exact_div(
|
|
&mut self,
|
|
a: ImmTy<'tcx, M::PointerTag>,
|
|
b: ImmTy<'tcx, M::PointerTag>,
|
|
dest: PlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx> {
|
|
// Performs an exact division, resulting in undefined behavior where
|
|
// `x % y != 0` or `y == 0` or `x == T::min_value() && y == -1`.
|
|
// First, check x % y != 0.
|
|
if self.binary_op(BinOp::Rem, a, b)?.to_bits()? != 0 {
|
|
// Then, check if `b` is -1, which is the "min_value / -1" case.
|
|
let minus1 = Scalar::from_int(-1, dest.layout.size);
|
|
let b = b.to_scalar().unwrap();
|
|
if b == minus1 {
|
|
throw_ub_format!("exact_div: result of dividing MIN by -1 cannot be represented")
|
|
} else {
|
|
throw_ub_format!(
|
|
"exact_div: {} cannot be divided by {} without remainder",
|
|
a.to_scalar().unwrap(),
|
|
b,
|
|
)
|
|
}
|
|
}
|
|
self.binop_ignore_overflow(BinOp::Div, a, b, dest)
|
|
}
|
|
}
|