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Organize intrinsics promotion checks
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@vertexclique
vertexclique committed Jun 14, 2019
1 parent e699ea0 commit 0c2a54d
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Showing 4 changed files with 57 additions and 70 deletions.
1 change: 1 addition & 0 deletions src/libcore/intrinsics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -913,6 +913,7 @@ extern "rust-intrinsic" {
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_transmute")]
pub fn transmute<T, U>(e: T) -> U;

/// Returns `true` if the actual type given as `T` requires drop
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55 changes: 48 additions & 7 deletions src/librustc/ty/constness.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,12 @@ use crate::ty::query::Providers;
use crate::hir::def_id::DefId;
use crate::hir;
use crate::ty::TyCtxt;
<<<<<<< HEAD
use syntax_pos::symbol::{sym, Symbol};
=======
use syntax_pos::symbol::Symbol;
use rustc_target::spec::abi::Abi;
>>>>>>> Organize intrinsics promotion checks
use crate::hir::map::blocks::FnLikeNode;
use syntax::attr;

Expand Down Expand Up @@ -68,16 +73,52 @@ impl<'tcx> TyCtxt<'tcx, 'tcx> {


pub fn provide<'tcx>(providers: &mut Providers<'tcx>) {
/// only checks whether the function has a `const` modifier
fn is_const_fn_raw<'tcx>(tcx: TyCtxt<'tcx, 'tcx>, def_id: DefId) -> bool {
fn is_intrinsic_promotable(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> bool {
// Intrinsics promotion whitelist is here to check const context at the top level beforehand.
match tcx.fn_sig(def_id).abi() {
Abi::RustIntrinsic |
Abi::PlatformIntrinsic => {
match &tcx.item_name(def_id).as_str()[..] {
| "size_of"
| "min_align_of"
| "needs_drop"
| "type_id"
| "bswap"
| "bitreverse"
| "ctpop"
| "cttz"
| "cttz_nonzero"
| "ctlz"
| "ctlz_nonzero"
| "overflowing_add"
| "overflowing_sub"
| "overflowing_mul"
| "unchecked_shl"
| "unchecked_shr"
| "rotate_left"
| "rotate_right"
| "add_with_overflow"
| "sub_with_overflow"
| "mul_with_overflow"
| "saturating_add"
| "saturating_sub"
| "transmute"
=> true,

_ => false
}
}
_ => false
}
}

/// Checks whether the function has a `const` modifier and intrinsics can be promotable in it
fn is_const_fn_raw<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> bool {
let hir_id = tcx.hir().as_local_hir_id(def_id)
.expect("Non-local call to local provider is_const_fn");

let node = tcx.hir().get_by_hir_id(hir_id);
if let Some(fn_like) = FnLikeNode::from_node(node) {
fn_like.constness() == hir::Constness::Const
} else if let hir::Node::Ctor(_) = node {
true
if let Some(fn_like) = FnLikeNode::from_node(tcx.hir().get_by_hir_id(hir_id)) {
(fn_like.constness() == hir::Constness::Const) || is_intrinsic_promotable(tcx, def_id)
} else {
false
}
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68 changes: 8 additions & 60 deletions src/librustc_mir/transform/qualify_consts.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -489,49 +489,12 @@ impl Qualif for IsNotPromotable {
let fn_ty = callee.ty(cx.body, cx.tcx);
match fn_ty.sty {
ty::FnDef(def_id, _) => {
match cx.tcx.fn_sig(def_id).abi() {
Abi::RustIntrinsic |
Abi::PlatformIntrinsic => {
assert!(!cx.tcx.is_const_fn(def_id));
match &cx.tcx.item_name(def_id).as_str()[..] {
| "size_of"
| "min_align_of"
| "needs_drop"
| "type_id"
| "bswap"
| "bitreverse"
| "ctpop"
| "cttz"
| "cttz_nonzero"
| "ctlz"
| "ctlz_nonzero"
| "overflowing_add"
| "overflowing_sub"
| "overflowing_mul"
| "unchecked_shl"
| "unchecked_shr"
| "rotate_left"
| "rotate_right"
| "add_with_overflow"
| "sub_with_overflow"
| "mul_with_overflow"
| "saturating_add"
| "saturating_sub"
| "transmute"
=> return true,

_ => {}
}
}
_ => {
let is_const_fn =
cx.tcx.is_const_fn(def_id) ||
cx.tcx.is_unstable_const_fn(def_id).is_some() ||
cx.is_const_panic_fn(def_id);
if !is_const_fn {
return true;
}
}
let is_const_fn =
cx.tcx.is_const_fn(def_id) ||
cx.tcx.is_unstable_const_fn(def_id).is_some() ||
cx.is_const_panic_fn(def_id);
if !is_const_fn {
return true;
}
}
_ => return true,
Expand Down Expand Up @@ -1251,21 +1214,6 @@ impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
Abi::PlatformIntrinsic => {
assert!(!self.tcx.is_const_fn(def_id));
match &self.tcx.item_name(def_id).as_str()[..] {
// special intrinsic that can be called diretly without an intrinsic
// feature gate needs a language feature gate
"transmute" => {
if self.mode.requires_const_checking() {
// const eval transmute calls only with the feature gate
if !self.tcx.features().const_transmute {
emit_feature_err(
&self.tcx.sess.parse_sess, sym::const_transmute,
self.span, GateIssue::Language,
&format!("The use of std::mem::transmute() \
is gated in {}s", self.mode));
}
}
}

name if name.starts_with("simd_shuffle") => {
is_shuffle = true;
}
Expand All @@ -1276,8 +1224,8 @@ impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
}
}
_ => {
// In normal functions no calls are feature-gated.
if self.mode.requires_const_checking() {
// Apply normal functions' rules which are not feature-gated.
if self.mode != Mode::Fn {
let unleash_miri = self
.tcx
.sess
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3 changes: 0 additions & 3 deletions src/libsyntax/feature_gate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -489,9 +489,6 @@ declare_features! (
// This will likely be removed prior to stabilization of async/await.
(active, await_macro, "1.28.0", Some(50547), None),

// Allows reinterpretation of the bits of a value of one type as another type during const eval.
(active, const_transmute, "1.29.0", Some(53605), None),

// Allows using `try {...}` expressions.
(active, try_blocks, "1.29.0", Some(31436), None),

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