Adds a new mir_dump output file in HTML/CSS to visualize code regions
and the MIR features that they came from (including overlapping spans).
See example below:
Includes a basic, MIR-block-based implementation of coverage injection,
available via `-Zexperimental-coverage`. This implementation has known
flaws and omissions, but is simple enough to validate the new tools and
tests.
The existing `-Zinstrument-coverage` option currently enables
function-level coverage only, which at least appears to generate
accurate coverage reports at that level.
Experimental coverage is not accurate at this time. When branch coverage
works as intended, the `-Zexperimental-coverage` option should be
removed.
This PR replaces the bulk of PR #75828, with the remaining parts of
that PR distributed among other separate and indentpent PRs.
This PR depends on three of those other PRs: #76000, #76002, and
Rust compiler MCP rust-lang/compiler-team#278
Relevant issue: #34701 - Implement support for LLVMs code coverage
instrumentation
Similar to `-Z dump-mir-graphviz`, this adds the option to write
HTML+CSS files that allow users to analyze the spans associated with MIR
elements (by individual statement, just terminator, or overall basic
block).
This PR was split out from PR #76004, and exposes an API for spanview
HTML+CSS files that is also used to analyze code regions chosen for
coverage instrumentation (in a follow-on PR).
Rust compiler MCP rust-lang/compiler-team#278
Relevant issue: #34701 - Implement support for LLVMs code coverage
instrumentation
Fix `-Z instrument-coverage` on MSVC
Found that `-C link-dead-code` (which was enabled automatically
under `-Z instrument-coverage`) was causing the linking error that
resulted in segmentation faults in coverage instrumented binaries. Link
dead code is now disabled under MSVC, allowing `-Z instrument-coverage`
to be enabled under MSVC for the first time.
More details are included in Issue #76038 .
Note this PR makes it possible to support `Z instrument-coverage` but
does not enable instrument coverage for MSVC in existing tests. It will be
enabled in another PR to follow this one (both PRs coming from original
PR #75828).
r? @tmandry
FYI: @wesleywiser
Found that -C link-dead-code (which was enabled automatically
under -Z instrument-coverage) was causing the linking error that
resulted in segmentation faults in coverage instrumented binaries. Link
dead code is now disabled under MSVC, allowing `-Z instrument-coverage`
to be enabled under MSVC for the first time.
More details are included in Issue #76038.
(This PR was broken out from PR #75828)
This commit removes the obsolete printer and replaces all uses of it
with `FmtPrinter`. Of the replaced uses, all but one use was in `debug!`
logging, two cases were notable:
- `MonoItem::to_string` is used in `-Z print-mono-items` and therefore
affects the output of all codegen-units tests.
- `DefPathBasedNames` was used in `librustc_codegen_llvm/type_of.rs`
with `LLVMStructCreateNamed` and that'll now get different values, but
this should result in no functional change.
Signed-off-by: David Wood <david@davidtw.co>
