Never inline naked functions
The `#[naked]` attribute disabled prologue / epilogue emission for the
function and it is responsibility of a developer to provide them. The
compiler is no position to inline such functions correctly.
Disable inlining of naked functions at LLVM and MIR level.
Closes#60919.
The `#[naked]` attribute disabled prologue / epilogue emission for the
function and it is responsibility of a developer to provide them. The
compiler is no position to inline such functions correctly.
Disable inlining of naked functions at LLVM and MIR level.
add optimization fuel checks to some mir passes
Fixes#77402
Inserts a bunch of calls to `consider_optimizing`. Note that `consider_optimizing` is the method that actually decrements the fuel count, so the point at which it's called is when the optimization takes place, from a fuel perspective. This means that where we call it has some thought behind it:
1. We probably don't want to decrement the fuel count before other simple checks, otherwise we count an optimization as being performed even if nothing was mutated (ie. it returned early).
2. In cases like `InstCombine`, where we gather optimizations in a pass and then mutate values, we probably would rather skip the gathering pass for performance reasons rather than skip the mutations afterwards.
Allow making `RUSTC_BOOTSTRAP` conditional on the crate name
Motivation: This came up in the [Zulip stream](https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/Require.20users.20to.20confirm.20they.20know.20RUSTC_.E2.80.A6.20compiler-team.23350/near/208403962) for https://github.com/rust-lang/compiler-team/issues/350.
See also https://github.com/rust-lang/cargo/pull/6608#issuecomment-458546258; this implements https://github.com/rust-lang/cargo/issues/6627.
The goal is for this to eventually allow prohibiting setting `RUSTC_BOOTSTRAP` in build.rs (https://github.com/rust-lang/cargo/issues/7088).
## User-facing changes
- `RUSTC_BOOTSTRAP=1` still works; there is no current plan to remove this.
- Things like `RUSTC_BOOTSTRAP=0` no longer activate nightly features. In practice this shouldn't be a big deal, since `RUSTC_BOOTSTRAP` is the opposite of stable and everyone uses `RUSTC_BOOTSTRAP=1` anyway.
- `RUSTC_BOOTSTRAP=x` will enable nightly features only for crate `x`.
- `RUSTC_BOOTSTRAP=x,y` will enable nightly features only for crates `x` and `y`.
## Implementation changes
The main change is that `UnstableOptions::from_environment` now requires
an (optional) crate name. If the crate name is unknown (`None`), then the new feature is not available and you still have to use `RUSTC_BOOTSTRAP=1`. In practice this means the feature is only available for `--crate-name`, not for `#![crate_name]`; I'm interested in supporting the second but I'm not sure how.
Other major changes:
- Added `Session::is_nightly_build()`, which uses the `crate_name` of
the session
- Added `nightly_options::match_is_nightly_build`, a convenience method
for looking up `--crate-name` from CLI arguments.
`Session::is_nightly_build()`should be preferred where possible, since
it will take into account `#![crate_name]` (I think).
- Added `unstable_features` to `rustdoc::RenderOptions`
I'm not sure whether this counts as T-compiler or T-lang; _technically_ RUSTC_BOOTSTRAP is an implementation detail, but it's been used so much it seems like this counts as a language change too.
r? `@joshtriplett`
cc `@Mark-Simulacrum` `@hsivonen`
Normalize function type during validation
During inlining, the callee body is normalized and has types revealed,
but some of locals corresponding to the arguments might come from the
caller body which is not. As a result the caller body does not pass
validation without additional normalization.
Closes#78442.
Lower intrinsics calls: forget, size_of, unreachable, wrapping_*
This allows constant propagation to evaluate `size_of` and `wrapping_*`,
and unreachable propagation to propagate a call to `unreachable`.
The lowering is performed as a MIR optimization, rather than during MIR
building to preserve the special status of intrinsics with respect to
unsafety checks and promotion.
Currently enabled by default to determine the performance impact (no
significant impact expected). In practice only useful when combined with
inlining since intrinsics are rarely used directly (with exception of
`unreachable` and `discriminant_value` used by built-in derive macros).
Closes#32716.
This allows constant propagation to evaluate `size_of` and `wrapping_*`,
and unreachable propagation to propagate a call to `unreachable`.
The lowering is performed as a MIR optimization, rather than during MIR
building to preserve the special status of intrinsics with respect to
unsafety checks and promotion.
During inlining, the callee body is normalized and has types revealed,
but some of locals corresponding to the arguments might come from the
caller body which is not. As a result the caller body does not pass
validation without additional normalization.
The inliner looks if a sanitizer is enabled before considering
`no_sanitize` attribute as possible source of incompatibility.
The MIR inlining could happen in a crate with sanitizer disabled, but
code generation in a crate with sanitizer enabled, thus the attribute
would be incorrectly ignored.
To avoid the issue never inline functions with different `no_sanitize`
attributes.
Support inlining diverging function calls
The existing heuristic does penalize diverging calls to some degree, but since
it never inlined them previously it might need some further modifications.
Additionally introduce storage markers for all temporaries created by
the inliner. The temporary introduced for destination rebrorrow, didn't
use them previously.
Add flags customizing behaviour of MIR inlining
* `-Zinline-mir-threshold` to change the default threshold.
* `-Zinline-mir-hint-threshold` to change the threshold used by
functions with inline hint.
Having those as configurable flags makes it possible to experiment with with
different inlining thresholds and substantially increase test coverage of MIR
inlining when used with increased thresholds (for example, necessary to test
#78844).
Assert that a return place is not used for indexing during integration
The inliner integrates call destination place with callee return place
by remapping the local and adding extra projections as necessary.
If a call destination place contains any projections (which is already
possible) and a return place is used in an indexing projection (most
likely doesn't happen yet) the end result would be incorrect.
Add an assertion to ensure that potential issue won't go unnoticed in
the presence of more sophisticated copy propagation scheme.
* `-Zinline-mir-threshold` to change the default threshold.
* `-Zinline-mir-hint-threshold` to change the threshold used by
functions with inline hint.
Additionally introduce storage markers for all temporaries created by
the inliner. The temporary introduced for destination rebrorrow, didn't
use them previously.
When examining candidates for inlining, reject those that are determined
to be recursive either because of self-recursive calls or calls to any
instances already inlined.
inliner: Use substs_for_mir_body
Changes from 68965 extended the kind of instances that are being
inlined. For some of those, the `instance_mir` returns a MIR body that
is already expressed in terms of the types found in substitution array,
and doesn't need further substitution.
Use `substs_for_mir_body` to take that into account.
Resolves#78529.
Resolves#78560.
Rollup of 19 pull requests
Successful merges:
- #76097 (Stabilize hint::spin_loop)
- #76227 (Stabilize `Poll::is_ready` and `is_pending` as const)
- #78065 (make concurrency helper more pleasant to read)
- #78570 (Remove FIXME comment in print_type_sizes ui test suite)
- #78572 (Use SOCK_CLOEXEC and accept4() on more platforms.)
- #78658 (Add a tool to run `x.py` from any subdirectory)
- #78706 (Fix run-make tests running when LLVM is disabled)
- #78728 (Constantify `UnsafeCell::into_inner` and related)
- #78775 (Bump Rustfmt and RLS)
- #78788 (Correct unsigned equivalent of isize to be usize)
- #78811 (Make some std::io functions `const`)
- #78828 (use single char patterns for split() (clippy::single_char_pattern))
- #78841 (Small cleanup in `TypeFoldable` derive macro)
- #78842 (Honor the rustfmt setting in config.toml)
- #78843 (Less verbose debug logging from inlining integrator)
- #78852 (Convert a bunch of intra-doc links)
- #78860 (rustc_resolve: Use `#![feature(format_args_capture)]`)
- #78861 (typo and formatting)
- #78865 (Don't fire `CONST_ITEM_MUTATION` lint when borrowing a deref)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Don't fire `CONST_ITEM_MUTATION` lint when borrowing a deref
Fixes#78819
This extends the check for dereferences added in PR #77324
to cover mutable borrows, as well as direct writes. If we're operating
on a dereference of a `const` item, we shouldn't be firing the lint.
Less verbose debug logging from inlining integrator
The inlining integrator produces relatively verbose and uninteresting
logs. Move them from a debug log level to a trace level, so that they
can be easily isolated from others.
