Instead of delaying the generation of command-lines to after all
dependencies are reported, compute them immediately. This is partly in
preparation for splitting the TU driver command into its constituent cc1
and other jobs, but it also just simplifies working with the compiler
invocation for modules if they are not "without paths".
Also change the computation of the default output path in
clang-scan-deps to scrape the implicit module cache from the
command-line rather than get it from the dependency, since that is now
unavailable at the time we make the callback.
Differential Revision: https://reviews.llvm.org/D131934
Since D129389 (and downstream PR https://github.com/apple/llvm-project/pull/4965), the dependency scanner is responsible for generating full command-lines, including the modules paths. This patch removes the flag that was making this an opt-in behavior in clang-scan-deps.
Reviewed By: benlangmuir
Differential Revision: https://reviews.llvm.org/D131420
Sharing the FileManager across implicit module builds currently leaks
paths looked up in an importer into the built module itself. This can
cause non-deterministic results across scans. It is especially bad for
modules since the path can be saved into the pcm file itself, leading to
stateful behaviour if the cache is shared.
This should not impact the number of real filesystem accesses in the
scanner, since it is already caching in the
DependencyScanningWorkerFilesystem.
Note: this change does not affect whether or not the FileManager is
shared across TUs in the scanner, which is a separate issue.
Differential Revision: https://reviews.llvm.org/D131412
It's an accident that we started return asbolute paths from
FileEntry::getName for all relative paths. Prepare for getName to get
(closer to) return the requested path. Note: conceptually it might make
sense for the dependency scanner to allow relative paths and have the
DependencyConsumer decide if it wants to make them absolute, but we
currently document that it's absolute and I didn't want to change
behaviour here.
Differential Revision: https://reviews.llvm.org/D130934
The "strict context hash" is insufficient to identify module
dependencies during scanning, leading to different module build commands
being produced for a single module, and non-deterministically choosing
between them. This commit switches to hashing the canonicalized
`CompilerInvocation` of the module. By hashing the invocation we are
converting these from correctness issues to performance issues, and we
can then incrementally improve our ability to canonicalize
command-lines.
This change can cause a regression in the number of modules needed. Of
the 4 projects I tested, 3 had no regression, but 1, which was
clang+llvm itself, had a 66% regression in number of modules (4%
regression in total invocations). This is almost entirely due to
differences between -W options across targets. Of this, 25% of the
additional modules are system modules, which we could avoid if we
canonicalized -W options when -Wsystem-headers is not present --
unfortunately this is non-trivial due to some warnings being enabled in
system headers by default. The rest of the additional modules are mostly
real differences in potential warnings, reflecting incorrect behaviour
in the current scanner.
There were also a couple of differences due to `-DFOO`
`-fmodule-ignore-macro=FOO`, which I fixed here.
Since the output paths for the module depend on its context hash, we
hash the invocation before filling in outputs, and rely on the build
system to always return the same output paths for a given module.
Note: since the scanner itself uses an implicit modules build, there can
still be non-determinism, but it will now present as different
module+hashes rather than different command-lines for the same
module+hash.
Differential Revision: https://reviews.llvm.org/D129884
Follow-up to 6626f6fec3, this fixes the handling of -MT
* If no targets are provided, we need to invent one since cc1 expects
the driver to have handled it. The default is to use -o, quoting as
necessary for a make target.
* Fix the splitting for empty string, which was incorrectly treated as
{""} instead of {}.
* Add a way to test this behaviour in clang-scan-deps.
Differential Revision: https://reviews.llvm.org/D129607
When building modules, override secondary outputs (dependency file,
dependency targets, serialized diagnostic file) in addition to the pcm
file path. This avoids inheriting per-TU command-line options that
cause non-determinism in the results (non-deterministic command-line for
the module build, non-determinism in which TU's .diag and .d files will
contain the module outputs). In clang-scan-deps we infer whether to
generate dependency or serialized diagnostic files based on an original
command-line. In a real build system this should be modeled explicitly.
Differential Revision: https://reviews.llvm.org/D129389
Dependency scanning does not care about the order of submodules for
correctness, so sort the submodules so that we get the same
command-lines to build the module across different TUs. The order of
inferred submodules can vary depending on the order of #includes in the
including TU.
Differential Revision: https://reviews.llvm.org/D128008
Disable or canonicalize compiler options that are not relevant in
explicit module builds, similar to what we already did for the modules
cache path. This reduces uninteresting differences between
command-lines, which is particularly useful if there is a tool that can
cache the compilations.
Differential Revision: https://reviews.llvm.org/D127883
This fixes the underlying module dependencies, which had a
non-deterministic order, which was also visible in the order of calls to
DependencyConsumer methods. This was not directly observable in
the clang-scan-deps utility, because it was previously seeing a sorted
order from std::map in DependencyScanningTool. However, the underlying
API previously created a likely issue for any other clients. Note: if
you only apply the change from DependencyScanningTool, you can see the
issue in clang-scan-deps, and existing tests will fail
non-deterministicaly.
Differential Revision: https://reviews.llvm.org/D127243
The command-line arguments for module builds are cc1 commands, so they
do not implicitly set -disable-free like a driver invocation, and
Tooling will disable it for the scanning instance itself. Set
-disable-free explicitly so that separate invocations for building
modules will not pay for freeing memory unnecessarily.
Differential Revision: https://reviews.llvm.org/D127229
This is a commit with the following changes:
* Remove `ExcludedPreprocessorDirectiveSkipMapping` and related functionality
Removes `ExcludedPreprocessorDirectiveSkipMapping`; its intended benefit for fast skipping of excluded directived blocks
will be superseded by a follow-up patch in the series that will use dependency scanning lexing for the same purpose.
* Refactor dependency scanning to produce pre-lexed preprocessor directive tokens, instead of minimized sources
Replaces the "source minimization" mechanism with a mechanism that produces lexed dependency directives tokens.
* Make the special lexing for dependency scanning a first-class feature of the `Preprocessor` and `Lexer`
This is bringing the following benefits:
* Full access to the preprocessor state during dependency scanning. E.g. a component can see what includes were taken and where they were located in the actual sources.
* Improved performance for dependency scanning. Measurements with a release+thin-LTO build shows ~ -11% reduction in wall time.
* Opportunity to use dependency scanning lexing to speed-up skipping of excluded conditional blocks during normal preprocessing (as follow-up, not part of this patch).
For normal preprocessing measurements show differences are below the noise level.
Since, after this change, we don't minimize sources and pass them in place of the real sources, `DependencyScanningFilesystem` is not technically necessary, but it has valuable performance benefits for caching file `stat`s along with the results of scanning the sources. So the setup of using the `DependencyScanningFilesystem` during a dependency scan remains.
Differential Revision: https://reviews.llvm.org/D125486
Differential Revision: https://reviews.llvm.org/D125487
Differential Revision: https://reviews.llvm.org/D125488
This is first of a series of patches for making the special lexing for dependency scanning a first-class feature of the `Preprocessor` and `Lexer`.
This patch only includes NFC renaming changes to make reviewing of the functionality changing parts easier.
Differential Revision: https://reviews.llvm.org/D125484
This is to improve maintenance a bit and remove need to maintain the additional option and related code-paths.
Differential Revision: https://reviews.llvm.org/D124558
This patch changes type of the `File` parameter in `PPCallbacks::InclusionDirective()` from `const FileEntry *` to `Optional<FileEntryRef>`.
With the API change in place, this patch then removes some uses of the deprecated `FileEntry::getName()` (e.g. in `DependencyGraph.cpp` and `ModuleDependencyCollector.cpp`).
Reviewed By: dexonsmith, bnbarham
Differential Revision: https://reviews.llvm.org/D123574
The code for traversing precompiled dependencies is somewhat complicated and contains a dangling iterator bug.
This patch simplifies the code and fixes the bug.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D121533
When pruning header search paths (to reduce the number of modules we need to build explicitly), we can't prune the search paths used in (transitive) dependencies of a module. Otherwise, we could end up with either of the following dependency graphs:
```
X:<hash1> -> Y:<hash2>
X:<hash1> -> Y:<hash3>
```
depending on the search paths of the translation unit we discovered `X` and `Y` from.
This patch fixes that.
Depends on D121295.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D121303
With explicit modules build, the '-fmodules-cache-path=' argument is unused.
This patch removes the argument to avoid warnings or errors (with '-Werror') stemming from that.
Depends on D118915.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D120474
The `clang-scan-deps` tool currently generates `-fmodule-file=` command-line arguments for the whole transitive closure of modular dependencies. This is not necessary, we only need to provide the direct dependencies on the command line. Information about transitive dependencies is stored within the `.pcm` files of direct dependencies. This makes the command lines shorter, but should be a NFC otherwise (unless there are bugs in the loading mechanism for explicit modules).
Depends on D120465.
Reviewed By: Bigcheese
Differential Revision: https://reviews.llvm.org/D118915
Since D113473, we don't report any module map files via `-fmodule-map-file=` in explicit builds. The ultimate goal here is to make sure Clang doesn't open/read/parse/evaluate unnecessary module maps.
However, implicit module maps still end up reading all reachable module maps. This patch disables implicit module maps in explicit builds.
Unfortunately, we still need to report some module map files that aren't encoded in PCM files of dependencies: module maps that are necessary to correctly evaluate includes in modules marked as `[no_undeclared_includes]`.
Depends on D120464.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D120465
The dependency scanner already generates canonical -cc1 command lines that can be used to compile discovered modular dependencies.
For translation unit command lines, the scanner only generates additional driver arguments the build system is expected to append to the original command line.
While this works most of the time, there are situations where that's not the case. For example with `-Wunused-command-line-argument`, Clang will complain about the `-fmodules-cache-path=` argument that's not being used in explicit modular builds. Combine that with `-Werror` and the build outright fails.
To prevent such failures, this patch changes the dependency scanner to return the full driver command line to compile the original translation unit. This gives us more opportunities to massage the arguments into something reasonable.
Reviewed By: Bigcheese
Differential Revision: https://reviews.llvm.org/D118986
In D113473, the dependency scanner stopped emitting "-fmodule-map-file=" arguments. Potential build systems are expected to not add any such arguments on their own. This commit removes mentions of such arguments to avoid confusion.
While scanning dependencies of a TU that depends on a PCH, the scanner basically performs mixed implicit/explicit modular compilation. (Explicit modules come from the PCH.) This seems to trip up the global module index.
This patch disables global module index in the dependency scanner.
Reviewed By: Bigcheese
Differential Revision: https://reviews.llvm.org/D118890
The minimizing and caching filesystem used by the dependency scanner can be configured to **not** minimize some files. That's necessary when scanning a TU with prebuilt inputs (i.e. PCH) that refer to the original (non-minimized) files. Minimizing such files in the dependency scanner would cause discrepancy between the current perceived state of the filesystem and the file sizes stored in the AST file. By not minimizing such files, we avoid creating the discrepancy.
The problem with the current approach is that files that should not be minimized are identified by their path. This breaks down when the prebuilt input (PCH) and the current TU refer to the same file via different paths (i.e. symlinks). This patch switches from paths to `llvm::sys::fs::UniqueID` when identifying ignored files. This is consistent with how the rest of Clang treats files.
Depends on D114966.
Reviewed By: dexonsmith, arphaman
Differential Revision: https://reviews.llvm.org/D114971
The minimizing filesystem used by the dependency scanner isn't great when it comes to the consistency of its caches. There are two problems that can be exposed by a filesystem that changes during dependency scan:
1. In-memory cache entries for original and minimized files are distinct, populated at different times using separate stat/open syscalls. This means that when a file is read with minimization disabled, its contents might be inconsistent when the same file is read with minimization enabled at later point (and vice versa).
2. In-memory cache entries are indexed by filename. This is problematic for symlinks, where the contents of the symlink might be inconsistent with contents of the original file (for the same reason as in problem 1).
This patch ensures consistency by always stating/reading a file exactly once. The original contents are always cached and minimized contents are derived from that on demand. The cache entries are now indexed by their `UniqueID` ensuring consistency for symlinks too. Moreover, the stat/read syscalls are now issued outside of critical section.
Depends on D115935.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D114966
The return types of some `CachedFileSystemEntry` member function are needlessly complex.
This patch attempts to simplify the code by unwrapping cached entries that represent errors early, and then asserting `!isError()`.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D115935
This reverts commits:
- 04192422c4.
- 015e08c6ba
D114206 was landed before it was approved - and was landed knowing that
the test crashed on windows, without an xfail. The promised follow-up
commit with fixes has not appeared since it was promised on December 14th.
The minimizing and caching filesystem used by the dependency scanner keeps minimized and original files in separate caches.
This setup is not well suited for dealing with files that are sometimes minimized and sometimes not. Such files are being stat-ed and read twice, which is wasteful and also means the two versions of the file can get "out of sync".
This patch squashes the two caches together. When a file is stat-ed or read, its original contents are populated. If a file needs to be minimized, we give the minimizer the already loaded contents instead of reading the file again.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D115346
The code and documentation around `CachedFileSystemEntry` use the following terms:
* "invalid stat" for `llvm::ErrorOr<llvm::vfs::Status>` that is *not* an error and contains an unknown status,
* "initialized entry" for an entry that contains "invalid stat",
* "valid entry" for an entry that contains "invalid stat", synonymous to "initialized" entry.
Having an entry be "valid" while it contains an "invalid" status object is counter-intuitive.
This patch cleans up the wording by referring to the status as "unknown" and to the entry as either "initialized" or "uninitialized".
Make clang-scan-deps use the virtual path for module maps instead of the on disk
path. This is needed so that modulemap relative lookups are done correctly in
the actual module builds. The file dependencies still use the on disk path as
that's what matters for build invalidation.
Differential Revision: https://reviews.llvm.org/D114206
This patch avoids unnecessarily copying contents of `mmap`-ed files into `CachedFileSystemEntry` by storing `MemoryBuffer` instead. The change leads to ~50% reduction of peak memory footprint when scanning LLVM+Clang via `clang-scan-deps`.
Depends on D115331.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D115043
This patch changes uses of `std::unique_lock` to `std::lock_guard`.
The `std::unique_lock` template provides some advanced capabilities (deferred locking, time-constrained locking attempts, etc.) we don't use in the caching filesystem. Plain `std::lock_guard` will do here.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D115332
Some command-line codegen arguments are likely to differ between identical modules discovered from different translation units. This patch removes them to make builds deterministic and/or reduce the number of built modules.
Reviewed By: Bigcheese
Differential Revision: https://reviews.llvm.org/D112923
The filesystem used during dependency scanning does two things: it caches file entries and minimizes source file contents. We use the term "ignored file" in a couple of places, but it's not clear what exactly that means. This commit clears up the semantics, explicitly spelling out this relates to minimization.
During explicit modules build, when all modules are provided via `-fmodule-file=<path>` and implicit modules and implicit module maps are disabled (`-fno-implicit-modules`, `-fno-implicit-module-maps`), we don't need to load the original module map files at all. This patch stops emitting the `-fmodule-map-file=` arguments we don't need, saving some compilation time due to avoiding parsing such module maps and making the command line shorter.
Reviewed By: bnbarham
Differential Revision: https://reviews.llvm.org/D113473
The dependency scanner works with multiple instances of `Compiler{Instance,Invocation}`. From names of the variables/members, their purpose is not obvious.
This patch gives descriptive name to the generated `CompilerInvocation` that can be used to derive the command-line to build a modular dependency.
Depends on D111725.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D111728
Ben Langmuir