rustc_target: Move some target options from `Target` to `TargetOptions`
The only reason for `Target` to `TargetOptions` to be separate structures is that options in `TargetOptions` have reasonable defaults and options in `Target` don't.
(Otherwise all the options logically belong to a single `Target` struct.)
This PR moves a number of options with reasonable defaults from `Target` to `TargetOptions`, so they no longer needs to be specified explicitly for majority of the targets.
The move also allows to inherit the options from `rustc_target/src/spec/*_base.rs` files in a nicer way.
I didn't change any specific option values here.
The moved options are `target_c_int_width` (defaults to `"32"`), `target_endian` (defaults to `"little"`), `target_os` (defaults to `"none"`), `target_env` (defaults to `""`), `target_vendor` (defaults to `"unknown"`) and `linker_flavor` (defaults to `LinkerFlavor::Gcc`).
Next steps (in later PRs):
- Find a way to merge `TargetOptions` into `Target`
- If not, always access `TargetOptions` fields through `Deref` making it a part of `Target` at least logically (`session.target.target.options.foo` -> `session.target.target.foo`)
- ~Eliminate `session::config::Config` and use `Target` instead (`session.target.target.foo` -> `session.target.foo`)~ Done in https://github.com/rust-lang/rust/pull/77943.
- Avoid tautologies in option names (`target.target_os` -> `target.os`)
- Resolve _ https://github.com/rust-lang/rust/issues/77730 (rustc_target: The differences between `target_os = "none"` and `target_os = "unknown"`, and `target_vendor = "unknown"` and `target_vendor = ""` are unclear) noticed during implementation of this PR.
Revert "Revert "resolve: Avoid "self-confirming" import resolutions in one more case""
Specifically, this reverts commit b20bce8ce54ea9d47c2e3eb0b17cbb6baf916ae2 from #77421 to fix#77586.
The lang team has decided that for the time being we want to avoid the breakage here (perhaps for a future edition; though almost certainly not the upcoming one), though a future PR may want to add a lint around this case (and perhaps others) which are unlikely to be readable code.
r? `@petrochenkov` to confirm this is the right way to fix#77586.
This reverts commit b20bce8ce54ea9d47c2e3eb0b17cbb6baf916ae2.
It retains the test added in that commit as a check-pass test, intended to
prevent future (unintentional) regressions.
The renumber pass is long gone
Originally, there has been a dedicated pass for renumbering
AST NodeIds to have actual values. This pass had been added by
commit a5ad4c379466519a0bf977864a5cdc50a7ade385.
Then, later, this step was moved to where it resides now,
macro expansion. See commit c86c8d41a26b2037e80c9fd028a59313a78b3a66
or PR #36438.
The comment snippet, added by the original commit, has
survived the times without any change, becoming outdated
at removal of the dedicated pass.
Nowadays, grepping for the next_node_id function will show up
multiple places in the compiler that call it, but the main
rewriting that the comment talks about is still done in the
expansion step, inside an innocious looking visit_id function
that's called during macro invocation collection.
inliner: Copy unevaluated constants only after successful inlining
Inliner copies the unevaluated constants from the callee body to the
caller at the point where decision to inline is yet to be made. The
constants will be unnecessary if inlining were to fail.
Organize the code moving items from callee to the caller together in one
place to avoid the issue.
Fix unreachable sub-branch detection in or-patterns
The previous implementation was too eager to avoid unnecessary "unreachable pattern" warnings. I feel more confident about this implementation than I felt about the previous one.
Fixes https://github.com/rust-lang/rust/issues/76836.
``@rustbot`` modify labels: +A-exhaustiveness-checking
Working expression optimization, and some improvements to branch-level source coverage
This replaces PR #78040 after reorganizing the original commits (by request) into a more logical sequence of major changes.
Most of the work is in the MIR `transform/coverage/` directory (originally, `transform/instrument_coverage.rs`).
Note this PR includes some significant additional debugging capabilities, to help myself and any future developer working on coverage improvements or issues.
In particular, there's a new Graphviz (.dot file) output for the coverage graph (the `BasicCoverageBlock` control flow graph) that provides ways to get some very good insight into the relationships between the MIR, the coverage graph BCBs, coverage spans, and counters. (There are also some cool debugging options, available via environment variable, to alter how some data in the graph appears.)
And the code for this Graphviz view is actually generic... it can be used by any implementation of the Rust `Graph` traits.
Finally (for now), I also now output information from `llvm-cov` that shows the actual counters and spans it found in the coverage map, and their counts (from the `--debug` flag). I found this to be enormously helpful in debugging some coverage issues, so I kept it in the test results as well for additional context.
`@tmandry` `@wesleywiser`
r? `@tmandry`
Here's an example of the new coverage graph:
* Within each `BasicCoverageBlock` (BCB), you can see each `CoverageSpan` and its contributing statements (MIR `Statement`s and/or `Terminator`s)
* Each `CoverageSpan` has a `Counter` or and `Expression`, and `Expression`s show their Add/Subtract operation with nested operations. (This can be changed to show the Counter and Expression IDs instead, or in addition to, the BCB.)
* The terminators of all MIR `BasicBlock`s in the BCB, including one final `Terminator`
* If an "edge counter" is required (because we need to count an edge between blocks, in some cases) the edge's Counter or Expression is shown next to its label. (Not shown in the example below.) (FYI, Edge Counters are converted into a new MIR `BasicBlock` with `Goto`)
<img width="1116" alt="Screen Shot 2020-10-17 at 12 23 29 AM" src="https://user-images.githubusercontent.com/3827298/96331095-616cb480-100f-11eb-8212-60f2d433e2d8.png">
r? `@tmandry`
FYI: `@wesleywiser`
Implementing the Graph traits for the BasicCoverageBlock
graph.
optimized replacement of counters with expressions plus new BCB graphviz
* Avoid adding coverage to unreachable blocks.
* Special case for Goto at the end of the body. Make it non-reportable.
Improved debugging and formatting options (from env)
Don't automatically add counters to BCBs without CoverageSpans. They may
still get counters but only if there are dependencies from
other BCBs that have spans, I think.
Make CodeRegions optional for Counters too. It is
possible to inject counters (`llvm.instrprof.increment` intrinsic calls
without corresponding code regions in the coverage map. An expression
can still uses these counter values.
Refactored instrument_coverage.rs -> instrument_coverage/mod.rs, and
then broke up the mod into multiple files.
Compiling with coverage, with the expression optimization, works on
the json5format crate and its dependencies.
Refactored debug features from mod.rs to debug.rs
Originally, there has been a dedicated pass for renumbering
AST NodeIds to have actual values. This pass had been added by
commit a5ad4c379466519a0bf977864a5cdc50a7ade385.
Then, later, this step was moved to where it resides now,
macro expansion. See commit c86c8d41a26b2037e80c9fd028a59313a78b3a66
or PR #36438.
The comment snippet, added by the original commit, has
survived the times without any change, becoming outdated
at removal of the dedicated pass.
Nowadays, grepping for the next_node_id function will show up
multiple places in the compiler that call it, but the main
rewriting that the comment talks about is still done in the
expansion step, inside an innocious looking visit_id function
that's called during macro invocation collection.
reverse binding order in matches to allow the subbinding of copyable fields in bindings after @
Fixes#69971
### TODO
- [x] Regression tests
r? `@oli-obk`
Inliner copies the unevaluated constants from the callee body to the
caller at the point where decision to inline is yet to be made. The
constants will be unnecessary if inlining were to fail.
Organize the code moving items from callee to the caller together in one
place to avoid the issue.
