Make more arithmetic functions unstably const #68809

ecstatic-morse · 2020-02-03T22:12:16Z

This is a smaller version of #66884 (thanks @9999years) that constifies many of the arithmetic functions on integer primitives from #53718 that were blocked on #49146.

This makes the following things unstably const.

feature = const_int_unchecked_arith
- intrinsics::unchecked_add
- intrinsics::unchecked_sub
- intrinsics::unchecked_mul
- intrinsics::unchecked_div
- intrinsics::unchecked_rem
feature = const_checked_int_methods
- checked_add
- checked_sub
- checked_mul
- checked_div (Uses intrinsics::unchecked_div internally)
- checked_rem (Uses intrinsics::unchecked_rem internally)
- checked_neg
- checked_shl
- checked_shr
- checked_abs
feature = const_saturating_int_methods
- saturating_mul
- saturating_neg (Uses intrinsics::unchecked_sub internally)
- saturating_abs (Uses intrinsics::unchecked_sub internally)
feature = const_wrapping_int_methods
- wrapping_div
- wrapping_rem
feature = const_overflowing_int_methods
- overflowing_div
- overflowing_rem
feature = const_euclidean_int_methods
- checked_div_euclid
- checked_rem_euclid
- wrapping_div_euclid
- wrapping_rem_euclid
- overflowing_div_euclid
- overflowing_rem_euclid

Exponentiation and operations on the NonZero types are left to a later PR.

r? @oli-obk
cc @rust-lang/wg-const-eval @rust-lang/libs

RalfJung · 2020-02-03T22:37:22Z

#67466 changed the way the compiler marked intrinsics as const, so this requires a few #![cfg(bootstrap)]s. It may be prudent to wait until the beta version is bumped to land this, or we could just land the first five commits for now, which don't require any conditional compilation.

A release just happened, so it can't be long until the bootstrap compiler gets bumped. Work is in progress at #68708.

oli-obk · 2020-02-04T18:43:50Z

The bootstrap compiler has been bumped

Co-Authored-By: 9999years <rbt@sent.as>

ecstatic-morse · 2020-02-05T01:16:38Z

@oli-obk. This should be ready now, and with no conditional compilation. I updated the feature names to jibe with the preexisting saturating_int_methods gate and avoid conflict with the already stabilized const_int_overflow gate. I don't think there's a policy around this, but it seemed prudent.

This PR also implements five unchecked arithmetic intrinsics in MIRI and marks them as rustc_const_unstable. The error message suggest that this requires an RFC but was written in before rustc_const_unstable worked on intrinsics. Since these should be uncontroversial, perhaps an FCP on this PR would suffice.

Centril · 2020-02-05T02:31:42Z

Since these should be uncontroversial, perhaps an FCP on this PR would suffice.

Not sure what you want FCP for... landing the gates unstably? That doesn't need FCP, Oliver can just r+.

src/test/ui/consts/const-int-arithmetic.rs

rust-highfive · 2020-02-05T04:54:14Z

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2020-02-05T04:37:21.0663012Z ========================== Starting Command Output ===========================
2020-02-05T04:37:21.0665773Z [command]/bin/bash --noprofile --norc /home/vsts/work/_temp/7e462e2e-b1bc-42d0-91bb-672149a06716.sh
2020-02-05T04:37:21.0665810Z 
2020-02-05T04:37:21.0670863Z ##[section]Finishing: Disable git automatic line ending conversion
2020-02-05T04:37:21.0676641Z ##[section]Starting: Checkout rust-lang/rust@refs/pull/68809/merge to s
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2020-02-05T04:37:21.0678732Z Version      : 1.0.0
2020-02-05T04:37:21.0678771Z Author       : Microsoft
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2020-02-05T04:37:21.8963367Z ##[command]git remote add origin https://github.com/rust-lang/rust
2020-02-05T04:37:21.9071221Z ##[command]git config gc.auto 0
2020-02-05T04:37:21.9106863Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
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---
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oli-obk · 2020-02-05T08:42:27Z

@bors r+

bors · 2020-02-05T08:42:29Z

📌 Commit 78f8ad3 has been approved by oli-obk

@9999years

… r=oli-obk Make more arithmetic functions unstably const This is a smaller version of rust-lang#66884 (thanks @9999years) that constifies many of the arithmetic functions on integer primitives from rust-lang#53718 that were blocked on rust-lang#49146. This makes the following things unstably const. - `feature = const_int_unchecked_arith` - `intrinsics::unchecked_add` - `intrinsics::unchecked_sub` - `intrinsics::unchecked_mul` - `intrinsics::unchecked_div` - `intrinsics::unchecked_rem` - `feature = const_checked_int_methods` - `checked_add` - `checked_sub` - `checked_mul` - `checked_div` (Uses `intrinsics::unchecked_div` internally) - `checked_rem` (Uses `intrinsics::unchecked_rem` internally) - `checked_neg` - `checked_shl` - `checked_shr` - `checked_abs` - `feature = const_saturating_int_methods` - `saturating_mul` - `saturating_neg` (Uses `intrinsics::unchecked_sub` internally) - `saturating_abs` (Uses `intrinsics::unchecked_sub` internally) - `feature = const_wrapping_int_methods` - `wrapping_div` - `wrapping_rem` - `feature = const_overflowing_int_methods` - `overflowing_div` - `overflowing_rem` - `feature = const_euclidean_int_methods` - `checked_div_euclid` - `checked_rem_euclid` - `wrapping_div_euclid` - `wrapping_rem_euclid` - `overflowing_div_euclid` - `overflowing_rem_euclid` Exponentiation and operations on the `NonZero` types are left to a later PR. r? @oli-obk cc @rust-lang/wg-const-eval @rust-lang/libs

@ghost

Rollup of 8 pull requests Successful merges: - #68762 (Strip unnecessary subexpression) - #68790 (Improve `merge_from_succ`) - #68809 (Make more arithmetic functions unstably const) - #68832 (Clean up E0264, E0267 and E0268 explanations) - #68840 (On suggesting `#![recursion_limit = "X"]`, note current crate name) - #68846 (doc fix on doc attribute) - #68851 (Fix issue number of `capacity` method) - #68858 (Merge item id stable hashing functions) Failed merges: r? @ghost

@ghost

Rollup of 8 pull requests Successful merges: - #68762 (Strip unnecessary subexpression) - #68790 (Improve `merge_from_succ`) - #68809 (Make more arithmetic functions unstably const) - #68832 (Clean up E0264, E0267 and E0268 explanations) - #68840 (On suggesting `#![recursion_limit = "X"]`, note current crate name) - #68846 (doc fix on doc attribute) - #68851 (Fix issue number of `capacity` method) - #68858 (Merge item id stable hashing functions) Failed merges: r? @ghost

RalfJung · 2020-02-06T10:26:33Z

src/librustc_mir/interpret/intrinsics.rs

+                    if let sym::unchecked_shl | sym::unchecked_shr = intrinsic_name {
+                        throw_ub_format!("Overflowing shift by {} in `{}`", r_val, intrinsic_name);
+                    } else {
+                        throw_ub_format!("Overflow executing `{}`", intrinsic_name);


Are there any tests that check that these errors work? Miri has them, but so far I think nothing tests this on the CTFE side.

Added in #68937.

@RalfJung

…-test, r=RalfJung Test failure of unchecked arithmetic intrinsics in const eval Test that the unchecked arithmetic intrinsics that were made unstably const in rust-lang#68809 emit an error during const-eval if given invalid input. Addresses [this comment](rust-lang#68809 (comment)). r? @RalfJung

rust-highfive assigned oli-obk Feb 3, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Feb 3, 2020

ecstatic-morse changed the title ~~Make more arithmetic function unstably const~~ Make more arithmetic functions unstably const Feb 3, 2020

ecstatic-morse force-pushed the const-int-functions branch from 6742dd7 to a5f40bb Compare February 3, 2020 22:24

9999years mentioned this pull request Feb 3, 2020

More const int functions #66884

Closed

ecstatic-morse and others added 9 commits February 4, 2020 11:04

Make euclidean division const

d9e3d2a

Co-Authored-By: 9999years <rbt@sent.as>

Make checked arithmetic besides division const

37c1418

Co-Authored-By: 9999years <rbt@sent.as>

Make overflowing arithmetic const

de52a54

Co-Authored-By: 9999years <rbt@sent.as>

Make saturating_mul a const fn

b422a19

Co-Authored-By: 9999years <rbt@sent.as>

Make wrapping arithmetic const

b46d1d2

Co-Authored-By: 9999years <rbt@sent.as>

Const-stabilize some arithmetic intrinsics

d4529be

Make checked division const

526304d

Make saturating arithmetic using intrinsics const

dda015a

Add tests for newly const arithmetic fns

3e9fd80

Co-Authored-By: 9999years <rbt@sent.as>

ecstatic-morse force-pushed the const-int-functions branch from a5f40bb to ecad633 Compare February 4, 2020 19:48

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ecstatic-morse force-pushed the const-int-functions branch from a4eee60 to 8d856cb Compare February 4, 2020 22:43

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Centril reviewed Feb 5, 2020

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src/test/ui/consts/const-int-arithmetic.rs Outdated Show resolved Hide resolved

ecstatic-morse added 3 commits February 4, 2020 20:36

Use consistent feature naming

09160d1

Fix test

040d987

Implement remaining unchecked arithmetic intrinsics

78f8ad3

ecstatic-morse force-pushed the const-int-functions branch from 1df3d6b to 78f8ad3 Compare February 5, 2020 04:36

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Feb 5, 2020

Dylan-DPC-zz mentioned this pull request Feb 5, 2020

Rollup of 8 pull requests #68861

Merged

bors merged commit 78f8ad3 into rust-lang:master Feb 6, 2020

RalfJung reviewed Feb 6, 2020

View reviewed changes

ecstatic-morse mentioned this pull request Feb 7, 2020

Test failure of unchecked arithmetic intrinsics in const eval #68937

Merged

TimDiekmann mentioned this pull request Feb 8, 2020

Tracking Issue for more const int functions #53718

Closed

59 tasks

RalfJung mentioned this pull request Aug 7, 2020

constify some checked arithmetics #65107

Closed

ecstatic-morse deleted the const-int-functions branch October 6, 2020 01:42

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