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supply our own implementation of the CTFE pointer comparison intrinsics

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This commit is contained in:
Ralf Jung 2020-06-27 11:57:43 +02:00
parent 76d99cfa68
commit b46f946c81
2 changed files with 33 additions and 11 deletions
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37
src/shims/intrinsics.rs
View File

@ -6,6 +6,7 @@ use rustc_middle::{mir, ty};
use rustc_middle::ty::layout::IntegerExt;
use rustc_apfloat::{Float, Round};
use rustc_target::abi::{Align, Integer, LayoutOf};
use rustc_span::symbol::sym;
use crate::*;
use helpers::check_arg_count;
@ -20,17 +21,19 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
unwind: Option<mir::BasicBlock>,
) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
if this.emulate_intrinsic(instance, args, ret)? {
let intrinsic_name = this.tcx.item_name(instance.def_id());
// We want to overwrite some of the intrinsic implementations that CTFE uses.
let prefer_miri_intrinsic = match intrinsic_name {
sym::ptr_guaranteed_eq | sym::ptr_guaranteed_ne => true,
_ => false,
};
if !prefer_miri_intrinsic && this.emulate_intrinsic(instance, args, ret)? {
return Ok(());
}
let substs = instance.substs;
// All these intrinsics take raw pointers, so if we access memory directly
// (as opposed to through a place), we have to remember to erase any tag
// that might still hang around!
let intrinsic_name = &*this.tcx.item_name(instance.def_id()).as_str();
// First handle intrinsics without return place.
let intrinsic_name = &*intrinsic_name.as_str();
let (dest, ret) = match ret {
None => match intrinsic_name {
"miri_start_panic" => return this.handle_miri_start_panic(args, unwind),
@ -42,13 +45,27 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
// Then handle terminating intrinsics.
match intrinsic_name {
// Miri overwriting CTFE intrinsics.
"ptr_guaranteed_eq" => {
let &[left, right] = check_arg_count(args)?;
let left = this.read_immediate(left)?;
let right = this.read_immediate(right)?;
this.binop_ignore_overflow(mir::BinOp::Eq, left, right, dest)?;
}
"ptr_guaranteed_ne" => {
let &[left, right] = check_arg_count(args)?;
let left = this.read_immediate(left)?;
let right = this.read_immediate(right)?;
this.binop_ignore_overflow(mir::BinOp::Ne, left, right, dest)?;
}
// Raw memory accesses
#[rustfmt::skip]
| "copy"
| "copy_nonoverlapping"
=> {
let &[src, dest, count] = check_arg_count(args)?;
let elem_ty = substs.type_at(0);
let elem_ty = instance.substs.type_at(0);
let elem_layout = this.layout_of(elem_ty)?;
let count = this.read_scalar(count)?.to_machine_usize(this)?;
let elem_align = elem_layout.align.abi;
@ -89,7 +106,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
"write_bytes" => {
let &[ptr, val_byte, count] = check_arg_count(args)?;
let ty = substs.type_at(0);
let ty = instance.substs.type_at(0);
let ty_layout = this.layout_of(ty)?;
let val_byte = this.read_scalar(val_byte)?.to_u8()?;
let ptr = this.read_scalar(ptr)?.not_undef()?;
@ -455,7 +472,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
"assert_zero_valid" |
"assert_uninit_valid" => {
let &[] = check_arg_count(args)?;
let ty = substs.type_at(0);
let ty = instance.substs.type_at(0);
let layout = this.layout_of(ty)?;
// Abort here because the caller might not be panic safe.
if layout.abi.is_uninhabited() {

7
tests/run-pass/intrinsics.rs
View File

@ -1,4 +1,4 @@
#![feature(core_intrinsics)]
#![feature(core_intrinsics, const_raw_ptr_comparison)]
use std::intrinsics;
use std::mem::{size_of, size_of_val};
@ -30,4 +30,9 @@ fn main() {
let _v = intrinsics::discriminant_value(&0);
let _v = intrinsics::discriminant_value(&true);
let _v = intrinsics::discriminant_value(&vec![1,2,3]);
let addr = &13 as *const i32;
let addr2 = (addr as usize).wrapping_add(usize::MAX).wrapping_add(1);
assert!(addr.guaranteed_eq(addr2 as *const _));
assert!(addr.guaranteed_ne(0x100 as *const _));
}