From cc4345a1c5fce8dec8a44b7fd80be8867ac6e649 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Mon, 25 Oct 2021 17:07:16 +0100 Subject: Clean up special function const checks Mark them as const and `#[rustc_do_not_const_check]` instead of hard-coding them in const-eval checks. --- .../rustc_const_eval/src/const_eval/machine.rs | 52 +++++++++------------- .../src/transform/check_consts/check.rs | 42 ++++++++--------- .../src/transform/check_consts/mod.rs | 18 -------- .../src/transform/promote_consts.rs | 6 +-- 4 files changed, 41 insertions(+), 77 deletions(-) (limited to 'compiler/rustc_const_eval/src') diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs index 8efe3eb868b..e01466f8fe2 100644 --- a/compiler/rustc_const_eval/src/const_eval/machine.rs +++ b/compiler/rustc_const_eval/src/const_eval/machine.rs @@ -30,34 +30,25 @@ impl<'mir, 'tcx> InterpCx<'mir, 'tcx, CompileTimeInterpreter<'mir, 'tcx>> { &mut self, instance: ty::Instance<'tcx>, args: &[OpTy<'tcx>], - is_const_fn: bool, ) -> InterpResult<'tcx, Option>> { - // The list of functions we handle here must be in sync with - // `is_lang_special_const_fn` in `transform/check_consts/mod.rs`. + // All `#[rustc_do_not_const_check]` functions should be hooked here. let def_id = instance.def_id(); - if is_const_fn { - if Some(def_id) == self.tcx.lang_items().const_eval_select() { - // redirect to const_eval_select_ct - if let Some(const_eval_select) = self.tcx.lang_items().const_eval_select_ct() { - return Ok(Some( - ty::Instance::resolve( - *self.tcx, - ty::ParamEnv::reveal_all(), - const_eval_select, - instance.substs, - ) - .unwrap() - .unwrap(), - )); - } + if Some(def_id) == self.tcx.lang_items().const_eval_select() { + // redirect to const_eval_select_ct + if let Some(const_eval_select) = self.tcx.lang_items().const_eval_select_ct() { + return Ok(Some( + ty::Instance::resolve( + *self.tcx, + ty::ParamEnv::reveal_all(), + const_eval_select, + instance.substs, + ) + .unwrap() + .unwrap(), + )); } - return Ok(None); - } - - if Some(def_id) == self.tcx.lang_items().panic_fn() - || Some(def_id) == self.tcx.lang_items().panic_str() - || Some(def_id) == self.tcx.lang_items().panic_display() + } else if Some(def_id) == self.tcx.lang_items().panic_display() || Some(def_id) == self.tcx.lang_items().begin_panic_fn() { // &str or &&str @@ -286,19 +277,16 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, } } - // Some functions we support even if they are non-const -- but avoid testing - // that for const fn! - // `const_eval_select` is a const fn because it must use const trait bounds. - if let Some(new_instance) = ecx.hook_special_const_fn(instance, args, is_const_fn)? { - // We call another const fn instead. - return Self::find_mir_or_eval_fn(ecx, new_instance, _abi, args, _ret, _unwind); - } - if !is_const_fn { // We certainly do *not* want to actually call the fn // though, so be sure we return here. throw_unsup_format!("calling non-const function `{}`", instance) } + + if let Some(new_instance) = ecx.hook_special_const_fn(instance, args)? { + // We call another const fn instead. + return Self::find_mir_or_eval_fn(ecx, new_instance, _abi, args, _ret, _unwind); + } } // This is a const fn. Call it. Ok(Some(ecx.load_mir(instance.def, None)?)) diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs index 85f37c813d8..a3f685fb747 100644 --- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs +++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs @@ -24,7 +24,7 @@ use std::ops::Deref; use super::ops::{self, NonConstOp, Status}; use super::qualifs::{self, CustomEq, HasMutInterior, NeedsDrop, NeedsNonConstDrop}; use super::resolver::FlowSensitiveAnalysis; -use super::{is_lang_panic_fn, is_lang_special_const_fn, ConstCx, Qualif}; +use super::{ConstCx, Qualif}; use crate::const_eval::is_unstable_const_fn; // We are using `MaybeMutBorrowedLocals` as a proxy for whether an item may have been mutated @@ -918,31 +918,27 @@ impl Visitor<'tcx> for Checker<'mir, 'tcx> { } // At this point, we are calling a function, `callee`, whose `DefId` is known... - if is_lang_special_const_fn(tcx, callee) { - // `begin_panic` and `panic_display` are generic functions that accept - // types other than str. Check to enforce that only str can be used in - // const-eval. - - // const-eval of the `begin_panic` fn assumes the argument is `&str` - if Some(callee) == tcx.lang_items().begin_panic_fn() { - match args[0].ty(&self.ccx.body.local_decls, tcx).kind() { - ty::Ref(_, ty, _) if ty.is_str() => (), - _ => self.check_op(ops::PanicNonStr), - } - } - // const-eval of the `panic_display` fn assumes the argument is `&&str` - if Some(callee) == tcx.lang_items().panic_display() { - match args[0].ty(&self.ccx.body.local_decls, tcx).kind() { - ty::Ref(_, ty, _) if matches!(ty.kind(), ty::Ref(_, ty, _) if ty.is_str()) => - {} - _ => self.check_op(ops::PanicNonStr), - } + // `begin_panic` and `panic_display` are generic functions that accept + // types other than str. Check to enforce that only str can be used in + // const-eval. + + // const-eval of the `begin_panic` fn assumes the argument is `&str` + if Some(callee) == tcx.lang_items().begin_panic_fn() { + match args[0].ty(&self.ccx.body.local_decls, tcx).kind() { + ty::Ref(_, ty, _) if ty.is_str() => return, + _ => self.check_op(ops::PanicNonStr), } + } - if is_lang_panic_fn(tcx, callee) { - // run stability check on non-panic special const fns. - return; + // const-eval of the `panic_display` fn assumes the argument is `&&str` + if Some(callee) == tcx.lang_items().panic_display() { + match args[0].ty(&self.ccx.body.local_decls, tcx).kind() { + ty::Ref(_, ty, _) if matches!(ty.kind(), ty::Ref(_, ty, _) if ty.is_str()) => + { + return; + } + _ => self.check_op(ops::PanicNonStr), } } diff --git a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs index 58d0f1a3ad8..dc44409d500 100644 --- a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs +++ b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs @@ -72,24 +72,6 @@ impl ConstCx<'mir, 'tcx> { } } -/// Returns `true` if this `DefId` points to one of the official `panic` lang items. -pub fn is_lang_panic_fn(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool { - Some(def_id) == tcx.lang_items().panic_fn() - || Some(def_id) == tcx.lang_items().panic_str() - || Some(def_id) == tcx.lang_items().panic_display() - || Some(def_id) == tcx.lang_items().begin_panic_fn() - || Some(def_id) == tcx.lang_items().panic_fmt() -} - -/// Returns `true` if this `DefId` points to one of the lang items that will be handled differently -/// in const_eval. -pub fn is_lang_special_const_fn(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool { - // We can allow calls to these functions because `hook_special_const_fn` in - // `const_eval/machine.rs` ensures the calls are handled specially. - // Keep in sync with what that function handles! - is_lang_panic_fn(tcx, def_id) || Some(def_id) == tcx.lang_items().const_eval_select() -} - pub fn rustc_allow_const_fn_unstable( tcx: TyCtxt<'tcx>, def_id: DefId, diff --git a/compiler/rustc_const_eval/src/transform/promote_consts.rs b/compiler/rustc_const_eval/src/transform/promote_consts.rs index ebcc8213c60..67664d2ede1 100644 --- a/compiler/rustc_const_eval/src/transform/promote_consts.rs +++ b/compiler/rustc_const_eval/src/transform/promote_consts.rs @@ -26,7 +26,7 @@ use rustc_index::vec::{Idx, IndexVec}; use std::cell::Cell; use std::{cmp, iter, mem}; -use crate::transform::check_consts::{is_lang_special_const_fn, qualifs, ConstCx}; +use crate::transform::check_consts::{qualifs, ConstCx}; use crate::transform::MirPass; /// A `MirPass` for promotion. @@ -656,9 +656,7 @@ impl<'tcx> Validator<'_, 'tcx> { } let is_const_fn = match *fn_ty.kind() { - ty::FnDef(def_id, _) => { - self.tcx.is_const_fn_raw(def_id) || is_lang_special_const_fn(self.tcx, def_id) - } + ty::FnDef(def_id, _) => self.tcx.is_const_fn_raw(def_id), _ => false, }; if !is_const_fn { -- cgit 1.4.1-3-g733a5