Revert most of MaybeUninit, except for the new API itself
This reverts most of https://github.com/rust-lang/rust/pull/53508/ for perf reasons (first commit reverts that entire PR), except for the new API itself (added back in 2nd commit).
ignore {std,fast,vector,this}call on non-x86 windows
MSVC ignores these keywords for C/C++ and uses the standard system
calling convention. Rust should do so as well.
Fixes#54569.
rustc: keep a Span for each predicate in ty::GenericPredicates.
This should allow finer-grained diagnostics, including migration suggestions for #54090.
(Note that I haven't changed most of the users of `predicates_of` to use the new spans)
r? @nikomatsakis
Emit used rustc invocation in the save-analysis file
Blocked on https://github.com/nrc/rls-data/pull/19. (I'm guessing it won't pass CI due to an out-of-tree git dependency)
This should allow RLS to recreate a Rust compilation build plan from the save-analysis files alone, which should be useful when fetching those from external build systems, most notably Buck now.
Also this includes some more potentially useful compilation-specific options (e.g. sysroot or the actual path to extern crates) but that's not required for the build plan bits.
cc @jsgf @alexcrichton
r? @nrc
codegen_llvm: check inline assembly constraints with LLVM
---%<---
Hey all,
As issue #54130 highlights, constraints are not checked and passing bad constraints to LLVM can crash it since a `Verify()` call is placed inside an assertion (see: `src/llvm/lib/IR/InlineAsm.cpp:39`).
As this is my first PR to the Rust compiler (woot! 🎉), there might be better ways of achieving this result. In particular, I am not too happy about generating an error in codegen; it would be much nicer if we did it earlier. However, @rkruppe [noted on IRC](https://botbot.me/mozilla/rustc/2018-09-25/?msg=104791581&page=1) that this should be fine for an unstable feature and a much better solution than the _status quo_, which is an ICE.
Thanks!
--->%---
LLVM provides a way of checking whether the constraints and the actual
inline assembly make sense. This commit introduces a check before
emitting code for the inline assembly. If LLVM rejects the inline
assembly (or its constraints), then the compiler emits an error E0668
("malformed inline assembly").
Fixes: #54130
Signed-off-by: Levente Kurusa \<lkurusa@acm.org\>
Use full name to identify a macro in a `FileName`.
Before this two macros with same name would be indistinguishable inside a `FileName`. This caused a bug in incremental compilation (see #53097) since two different macros would map out to the same `StableFilemapId`.
Fixes#53097.
r? @nrc
RFC 2093 (tracking issue #44493) lets us leave off
commonsensically inferable `T: 'a` outlives requirements. (A separate
feature-gate was split off for the case of 'static lifetimes, for
which questions still remain.) Detecting these was requested as an
idioms-2018 lint.
It turns out that issuing a correct, autofixable suggestion here is
somewhat subtle in the presence of other bounds and generic
parameters. Basically, we want to handle these three cases:
• One outlives-bound. We want to drop the bound altogether, including
the colon—
MyStruct<'a, T: 'a>
^^^^ help: remove this bound
• An outlives bound first, followed by a trait bound. We want to
delete the outlives bound and the following plus sign (and
hopefully get the whitespace right, too)—
MyStruct<'a, T: 'a + MyTrait>
^^^^^ help: remove this bound
• An outlives bound after a trait bound. We want to delete the
outlives lifetime and the preceding plus sign—
MyStruct<'a, T: MyTrait + 'a>
^^^^^ help: remove this bound
This gets (slightly) even more complicated in the case of where
clauses, where we want to drop the where clause altogether if there's
just the one bound. Hopefully the comments are enough to explain
what's going on!
A script (in Python, sorry) was used to generate the
hopefully-sufficiently-exhaustive UI test input. Some of these are
split off into a different file because rust-lang-nursery/rustfix#141
(and, causally upstream of that, #53934) prevents them from being
`run-rustfix`-tested.
We also make sure to include a UI test of a case (copied from RFC
2093) where the outlives-bound can't be inferred. Special thanks to
Niko Matsakis for pointing out the `inferred_outlives_of` query,
rather than blindly stripping outlives requirements as if we weren't a
production compiler and didn't care.
This concerns #52042.
This function isn't strictly tied to LLVM (it's more of a utility) and
it's now near an analogous, almost identical `filename_for_input` (for
rlibs and so forth).
Also this means not depending on the backend when one wants to know the
accurate .rmeta output filename.
Migrate `src/test/ui/run-pass/*` back to `src/test/run-pass/`.
Moves all the tests from `src/test/ui/run-pass/**` back to `src/test/run-pass/`.
This should have no impact on our overall testing completeness due to PR #54223Fix#54047
[NLL] Get Polonius borrow check to work in simple cases
* Restores the generation of outlives facts from subtyping.
* Restore liveness facts.
* Generate invalidates facts at the start point of each location,
where we check for errors.
* Add a small test for simple cases (previously these cases have compiled, and more recently ICEd).
Closes#54212
cc #53142 (will need test)
### Known limitations
* Two phase borrows aren't implemented for Polonius yet
* Invalidation facts haven't been updated for some of the recent changes to make `Drop` terminators access fewer things.
* Fact generation is not as optimized as it could be.
* Around 30 tests fail in compare mode, often tests that are ignored in nll compare mode
r? @nikomatsakis
A few cleanups and minor improvements to typeck/check
- turn a `loop` into a `while let`
- turn a `push_back` loop into an `extend`
- turn a few `push` loops into collected iterators
- prefer `vec![x; n]` to `(0..n).map(|_| x).collect()`
- combine two loops doing the same thing on 2 data sets using `chain`
- use `unwrap_or` where applicable and readable
- add a `potentially_plural_count` helper function to simplify several `format!()` calls
- prefer `to_owned` to `to_string` for string literals
- change `match` to `if let` where only one branch matters
- a few other minor improvements
- whitespace fixes
NLL: regression test for "dropck: track order of destruction for r-value temporaries"
Once this lands, we can remove the E-needstest from #22323.
(We shouldn't close the bug itself, however, because we are leaving the NLL-fixed-by-NLL bugs open until NLL is turned on by default.)
Track whether module declarations are inline (fixes#12590)
To track whether module declarations are inline I added a field `inline: bool` to `ast::Mod`. The main use case is for pretty to know whether it should render the items associated with the module, but perhaps there are use cases for this information to not be forgotten in the AST.
* Restores the generation of outlives facts from subtyping.
* Restore liveness facts.
* Generate invalidates facts at the start point of each location,
where we check for errors.
* Add a small test for simple cases.
rework how we handle outlives relationships
When we encounter an outlives relationship involving a projection, we use to over-constrain in some cases with region constraints. We also used to evaluate whether the where-clauses in the environment might apply **before** running inference.
We now avoid doing both of those things:
- If there are where-clauses in the environment that might be useful, we add no constraints.
- After inference is done, we check if we wound up inferring values compatible with the where-clause, and make use of them if so.
I realize now that this PR includes some meandering commits and refactorings from when I expected to go in a different direction. If desired, I could try to remove some of those.
Fixes#53121Fixes#53789
r? @pnkfelix
[eRFC] add -Z emit-stack-sizes
# What
This PR exposes LLVM's ability to report the stack usage of each function through the unstable /
experimental `-Z emit-stack-sizes` flag.
# Motivation
The end goal is to enable whole program analysis of stack usage to prove absence of stack overflows
at compile time. Such property is important in systems that lack a MMU / MPU and where stack
overflows can corrupt memory. And in systems that have protection against stack overflows such proof
can be used to opt out of runtime checks (e.g. stack probes or the MPU).
Such analysis requires the call graph of the program, which can be obtained from MIR, and the stack
usage of each function in the program. Precise information about the later later can only be
obtained from LLVM as it depends on the optimization level and optimization options like LTO.
This PR does **not** attempt to add the ability to perform such whole program analysis to rustc;
it simply does the minimal amount of work to enable such analysis to be implemented out of tree.
# Implementation
This PR exposes a way to set LLVM's `EmitStackSizeSection` option from the command line. The option
is documented [here]; the documentation is copied below for convenience and posteriority:
[here]: https://llvm.org/docs/CodeGenerator.html#emitting-function-stack-size-information
> A section containing metadata on function stack sizes will be emitted when
> TargetLoweringObjectFile::StackSizesSection is not null, and TargetOptions::EmitStackSizeSection
> is set (-stack-size-section). The section will contain an array of pairs of function symbol values
> (pointer size) and stack sizes (unsigned LEB128). The stack size values only include the space
> allocated in the function prologue. Functions with dynamic stack allocations are not included.
Where the LLVM feature is not available (e.g. LLVM version < 6.0) or can't be applied (e.g. the
output format doesn't support sections e.g. .wasm files) the flag does nothing -- i.e. no error or
warning is emitted.
# Example usage
``` console
$ cargo new --bin hello && cd $_
$ cat >src/main.rs <<'EOF'
use std::{mem, ptr};
fn main() {
registers();
stack();
}
#[inline(never)]
fn registers() {
unsafe {
// values loaded into registers
ptr::read_volatile(&(0u64, 1u64));
}
}
#[inline(never)]
fn stack() {
unsafe {
// array allocated on the stack
let array: [i32; 4] = mem::uninitialized();
for elem in &array {
ptr::read_volatile(&elem);
}
}
}
EOF
$ # we need a custom linking step to preserve the .stack_sizes section
$ # (see unresolved questions for a solution that doesn't require custom linking)
$ cat > keep-stack-sizes.x <<'EOF'
SECTIONS
{
.stack_sizes :
{
KEEP(*(.stack_sizes));
}
}
EOF
$ cargo rustc --release -- \
-Z emit-stack-sizes \
-C link-arg=-Wl,-Tkeep-stack-sizes.x \
-C link-arg=-N
$ size -A target/release/hello | grep stack_sizes
.stack_sizes 117 185136
```
Then a tool like [`stack-sizes`] can be used to print the information in human readable format
[`stack-sizes`]: https://github.com/japaric/stack-sizes/#stack-sizes
``` console
$ stack-sizes target/release/hello
address size name
0x000000000004b0 0 core::array::<impl core::iter::traits::IntoIterator for &'a [T; _]>::into_iter::ha50e6661c0ec84aa
0x000000000004c0 8 std::rt::lang_start::ha02aea783e0e1b3e
0x000000000004f0 8 std::rt::lang_start::{{closure}}::h5115b527d5244952
0x00000000000500 8 core::ops::function::FnOnce::call_once::h6bfa1076da82b0fb
0x00000000000510 0 core::ptr::drop_in_place::hb4de82e57787bc70
0x00000000000520 8 hello::main::h08bb6cec0556bd66
0x00000000000530 0 hello::registers::h9d058a5d765ec1d2
0x00000000000540 24 hello::stack::h88c8cb66adfdc6f3
0x00000000000580 8 main
0x000000000005b0 0 __rust_alloc
0x000000000005c0 0 __rust_dealloc
0x000000000005d0 0 __rust_realloc
0x000000000005e0 0 __rust_alloc_zeroed
```
# Stability
Like `-Z sanitize` this is a re-export of an LLVM feature. To me knowledge, we don't have a policy
about stabilization of such features as they are incompatible with, or demand extra implementation
effort from, alternative backends (e.g. cranelift). As such this feature will remain experimental /
unstable for the foreseeable future.
# Unresolved questions
## Section name
Should we rename the `.stack_sizes` section to `.debug_stacksizes`?
With the former name linkers will strip the section unless told otherwise using a linker script,
which means getting this information requires both knowledge about linker scripts and a custom
linker invocation (see example above).
If we use the `.debug_stacksizes` name (I believe) linkers will always keep the section, which means
`-Z emit-stack-sizes` is the only thing required to get the stack usage information.
# ~TODOs~
~Investigate why this doesn't work with the `thumb` targets. I get the LLVM error shown below:~
``` console
$ cargo new --lib foo && cd $_
$ echo '#![no_std] pub fn foo() {}' > src/lib.rs
$ cargo rustc --target thumbv7m-none-eabi -- -Z emit-stack-sizes
LLVM ERROR: unsupported relocation on symbol
```
~which sounds like it might be related to the `relocation-model` option. Maybe `relocation-model =
static` is not supported for some reason?~
This fixed itself after the LLVM upgrade.
---
r? @nikomatsakis
cc @rust-lang/compiler @perlindgren @whitequark
