Update e0017 to new format
Updated `span_err!` to use `struct_span_err!` and provide a `span_label` that describes the error in context.
Updated the test to look for the `span_label`s that are provided now.
refactor lvalue_ty to be method of lvalue
Currently `Mir` (and `MirContext`) implement a method `lvalue_ty` (and actually many more `foo_ty`). But this should be a method of `Lvalue`.
If you have an `lvalue` and you want to get its type, the natural thing to write is:
```
lvalue.ty()
```
Of course it needs context, but still:
```
lvalue.ty(mir, tcx)
```
Makes more sense than
```
mir.lvalue_ty(lvalue, tcx)
```
I actually think we should go a step farther and have traits so we could get the type of some value generically, but that's up for debate. The thing I'm running into a lot in the compiler is I have a value of type `Foo` and I know that there is some related type `Bar` which I can get through some combination of method calls, but it's often not as direct as I would imagine. Unless you already know the code, its not clear why you would look in `Mir` for a method to get the type of an `Lvalue`.
Address ICEs running w/ incremental compilation and building glium
Fixes for various ICEs I encountered trying to build glium with incremental compilation enabled. Building glium now works. Of the 4 ICEs, I have test cases for 3 of them -- I didn't isolate a test for the last commit and kind of want to go do other things -- most notably, figuring out why incremental isn't saving much *effort*.
But if it seems worthwhile and I can come back and try to narrow down the problem.
r? @michaelwoerister
Fixes#34991Fixes#32015
Per the discussion on #34765, we make one `DepNode::Mir` variant and use
it to represent both the MIR tracking map as well as passes that operate
on MIR. We also track loads of cached MIR (which naturally comes from
metadata).
Note that the "HAIR" pass adds a read of TypeckItemBody because it uses
a myriad of tables that are not individually tracked.
[MIR] Deaggregate structs to enable further optimizations
Currently, we generate MIR like:
```
tmp0 = ...;
tmp1 = ...;
tmp3 = Foo { a: ..., b: ... };
```
This PR implements "deaggregation," i.e.:
```
tmp3.0 = ...
tmp3.1 = ...
```
Currently, the code only deaggregates structs, not enums. My understanding is that we do not have MIR to set the discriminant of an enum.
Add MIR Optimization Tests
I've starting working on the infrastructure for testing MIR optimizations.
The plan now is to have a set of test cases (written in Rust), compile them with -Z dump-mir, and check the MIR before and after each pass.
Previously we would rebuild all drops on every early exit from a scope, which for code like:
```rust
match x {
a => return 1,
b => return 2,
...
z => return 27
}
```
would produce 27 exactly same chains of drops for each return, a O(n*m) explosion in drops.
Use it instead of a `panic` for inexhaustive matches and correct the
comment. I think we trust our match-generation algorithm enough to
generate these blocks, and not generating an `unreachable` means that
LLVM won't optimize `match void() {}` to an `unreachable`.
[MIR] Implement overflow checking
The initial set of changes is from @Aatch's #33255 PR, rebased on master, plus:
Added an `Assert` terminator to MIR, to simplify working with overflow and bounds checks.
With this terminator, error cases can be accounted for directly, instead of looking for lang item calls.
It also keeps the MIR slimmer, with no extra explicit blocks for the actual panic calls.
Warnings can be produced when the `Assert` is known to always panic at runtime, e.g.:
```rust
warning: index out of bounds: the len is 1 but the index is 3
--> <anon>:1:14
1 |> fn main() { &[std::io::stdout()][3]; }
|> ^^^^^^^^^^^^^^^^^^^^^^
```
Generalized the `OperandValue::FatPtr` optimization to any aggregate pair of immediates.
This allows us to generate the same IR for overflow checks as old trans, not something worse.
For example, addition on `i16` calls `llvm.sadd.with.overflow.i16`, which returns `{i16, i1}`.
However, the Rust type `(i16, bool)`, has to be `{i16, i8}`, only an immediate `bool` is `i1`.
But if we split the pair into an `i16` and an `i1`, we can pass them around as such for free.
The latest addition is a rebase of #34054, updated to work for pairs too. Closes#34054, fixes#33873.
Last but not least, the `#[rustc_inherit_overflow_checks]` attribute was introduced to control the
overflow checking behavior of generic or `#[inline]` functions, when translated in another crate.
It is **not** intended to be used by crates other than `libcore`, which is in the unusual position of
being distributed as only an optimized build with no checks, even when used from debug mode.
Before MIR-based translation, this worked out fine, as the decision for overflow was made at
translation time, in the crate being compiled, but MIR stored in `rlib` has to contain the checks.
To avoid always generating the checks and slowing everything down, a decision was made to
use an attribute in the few spots of `libcore` that need it (see #33255 for previous discussion):
* `core::ops::{Add, Sub, Mul, Neg, Shl, Shr}` implementations for integers, which have `#[inline]` methods and can be used in generic abstractions from other crates
* `core::ops::{Add, Sub, Mul, Neg, Shl, Shr}Assign` same as above, for augmented assignment
* `pow` and `abs` methods on integers, which intentionally piggy-back on built-in multiplication and negation, respectively, to get overflow checks
* `core::iter::{Iterator, Chain, Peek}::count` and `core::iter::Enumerate::{next, nth}`, also documented as panicking on overflow, from addition, counting elements of an iterator in an `usize`
generate fewer basic blocks for variant switches
CC #33567
Adds a new field to TestKind::Switch that tracks the variants that are actually matched against. The other candidates target a common "otherwise" block.
this introduces a DropAndReplace terminator as a fix to #30380. That terminator
is suppsoed to be translated by desugaring during drop elaboration, which is
not implemented in this commit, so this breaks `-Z orbit` temporarily.
Fixes to mir dataflow
Fixes to mir dataflow
This collects a bunch of changes to `rustc_borrowck::borrowck::dataflow` (which others have pointed out should probably migrate to some crate that isn't tied to the borrow-checker -- but I have not attempted that here, especially since there are competing approaches to dataflow that we should also evaluate).
These changes:
1. Provide a family of related analyses: MovingOutStatements (which is what the old AST-based dataflo computed), as well as MaybeInitialized, MaybeUninitalized, and DefinitelyInitialized.
* (The last two are actually inverses of each other; we should pick one and drop the other.)
2. Fix bugs in the pre-existing analysis implementation, which was untested and thus some obvious bugs went unnoticed, which brings us to the third point:
3. Add a unit test infrastructure for the MIR dataflow analysis.
* The tests work by adding a new intrinsic that is able to query the analysis state for a particular expression (technically, a particular L-value).
* See the examples in compile-fail/mir-dataflow/inits-1.rs and compile-fail/mir-dataflow/uninits-1.rs
* These tests are only checking the results for MaybeInitialized, MaybeUninitalized, and DefinitelyInitialized; I am not sure if it will be feasible to generalize this testing strategy to the MovingOutStatements dataflow operator.
(The crucial thing these changes are working toward (but are not yet
in this commit) is a way to pretty-print MIR without having the
`NodeId` for that MIR in hand.)
Some simple improvements to MIR pretty printing
In short, this PR changes the MIR printer so that it:
* places an empty line between the MIR for each item
* does *not* write an empty line before the first BB when there are no
var decls
* aligns the "// Scope" comments 50 chars in (makes the output more
readable)
* prints the scope comments as "// scope N at ..." instead of "//
Scope(N) at ..."
* prints a prettier scope tree:
* no more unbalanced delimiters!
* no more "Parent" entry (these convey no useful information)
* drop the "Scope()" and just print scope IDs
* no braces when the scope is empty
In action: https://gist.github.com/jonas-schievink/1c11226cbb112892a9470ce0f9870b65
Only break critical edges where actually needed
Currently, to prepare for MIR trans, we break _all_ critical edges,
although we only actually need to do this for edges originating from a
call that gets translated to an invoke instruction in LLVM.
This has the unfortunate effect of undoing a bunch of the things that
SimplifyCfg has done. A particularly bad case arises when you have a
C-like enum with N variants and a derived PartialEq implementation.
In that case, the match on the (&lhs, &rhs) tuple gets translated into
nested matches with N arms each and a basic block each, resulting in N²
basic blocks. SimplifyCfg reduces that to roughly 2*N basic blocks, but
breaking the critical edges means that we go back to N².
In nickel.rs, there is such an enum with roughly N=800. So we get about
640K basic blocks or 2.5M lines of LLVM IR. LLVM takes a while to
reduce that to the final "disr_a == disr_b".
So before this patch, we had 2.5M lines of IR with 640K basic blocks,
which took about about 3.6s in LLVM to get optimized and translated.
After this patch, we get about 650K lines with about 1.6K basic blocks
and spent a little less than 0.2s in LLVM.
cc #33111
r? @Aatch
mir: don't attempt to promote Unpromotable constant temps.
Fixes#33537. This was a non-problem in regular functions, but we also promote in `const fn`s.
There we always qualify temps so you can't depend on `Unpromotable` temps being `NOT_CONST`.
In short, this PR changes the MIR printer so that it:
* places an empty line between the MIR for each item
* does *not* write an empty line before the first BB when there are no
var decls
* aligns the "// Scope" comments 50 chars in (makes the output more
readable)
* prints the scope comments as "// scope N at ..." instead of "//
Scope(N) at ..."
* prints a prettier scope tree:
* no more unbalanced delimiters!
* no more "Parent" entry (these convey no useful information)
* drop the "Scope()" and just print scope IDs
* no braces when the scope is empty
Currently, to prepare for MIR trans, we break _all_ critical edges,
although we only actually need to do this for edges originating from a
call that gets translated to an invoke instruction in LLVM.
This has the unfortunate effect of undoing a bunch of the things that
SimplifyCfg has done. A particularly bad case arises when you have a
C-like enum with N variants and a derived PartialEq implementation.
In that case, the match on the (&lhs, &rhs) tuple gets translated into
nested matches with N arms each and a basic block each, resulting in N²
basic blocks. SimplifyCfg reduces that to roughly 2*N basic blocks, but
breaking the critical edges means that we go back to N².
In nickel.rs, there is such an enum with roughly N=800. So we get about
640K basic blocks or 2.5M lines of LLVM IR. LLVM takes a while to
reduce that to the final "disr_a == disr_b".
So before this patch, we had 2.5M lines of IR with 640K basic blocks,
which took about about 3.6s in LLVM to get optimized and translated.
After this patch, we get about 650K lines with about 1.6K basic blocks
and spent a little less than 0.2s in LLVM.
cc #33111
mir: drop temps outside-in by scheduling the drops inside-out.
It was backwards all along, but only noticeable with multiple drops in one rvalue scope. Fixes#32433.
