Currently both True/False counts were folded. It lost the information,
"It is True or False before folding." It prevented recalling branch
counts in merging template instantiations.
In `llvm-cov`, a folded branch is shown as:
- `[True: n, Folded]`
- `[Folded, False n]`
In the case If `n` is zero, a branch is reported as "uncovered". This is
distinguished from "folded" branch. When folded branches are merged,
`Folded` may be dissolved.
In the coverage map, either `Counter` is `Zero`. Currently both were
`Zero`.
Since "partial fold" has been introduced, either case in `switch` is
omitted as `Folded`.
Each `case:` in `switch` is reported as `[True: n, Folded]`, since
`False` count doesn't show meaningful value.
When `switch` doesn't have `default:`, `switch (Cond)` is reported as
`[Folded, False: n]`, since `True` count was just the sum of `case`(s).
`switch` with `default` can be considered as "the statement that doesn't
have any `False`(s)".
By storing possible test vectors instead of combinations of conditions,
the restriction is dramatically relaxed.
This introduces two options to `cc1`:
* `-fmcdc-max-conditions=32767`
* `-fmcdc-max-test-vectors=2147483646`
This change makes coverage mapping, profraw, and profdata incompatible
with Clang-18.
- Bitmap semantics changed. It is incompatible with previous format.
- `BitmapIdx` in `Decision` points to the end of the bitmap.
- Bitmap is packed per function.
- `llvm-cov` can understand `profdata` generated by `llvm-profdata-18`.
RFC:
https://discourse.llvm.org/t/rfc-coverage-new-algorithm-and-file-format-for-mc-dc/76798
--
Change(s) since llvmorg-19-init-14288-g7ead2d8c7e91
- Update compiler-rt/test/profile/ContinuousSyncMode/image-with-mcdc.c
This broke the lit tests on Mac:
https://green.lab.llvm.org/job/llvm.org/job/clang-stage1-RA/1096/
> By storing possible test vectors instead of combinations of conditions,
> the restriction is dramatically relaxed.
>
> This introduces two options to `cc1`:
>
> * `-fmcdc-max-conditions=32767`
> * `-fmcdc-max-test-vectors=2147483646`
>
> This change makes coverage mapping, profraw, and profdata incompatible
> with Clang-18.
>
> - Bitmap semantics changed. It is incompatible with previous format.
> - `BitmapIdx` in `Decision` points to the end of the bitmap.
> - Bitmap is packed per function.
> - `llvm-cov` can understand `profdata` generated by `llvm-profdata-18`.
>
> RFC:
> https://discourse.llvm.org/t/rfc-coverage-new-algorithm-and-file-format-for-mc-dc/76798
This reverts commit 7ead2d8c7e9114b3f23666209a1654939987cb30.
By storing possible test vectors instead of combinations of conditions,
the restriction is dramatically relaxed.
This introduces two options to `cc1`:
* `-fmcdc-max-conditions=32767`
* `-fmcdc-max-test-vectors=2147483646`
This change makes coverage mapping, profraw, and profdata incompatible
with Clang-18.
- Bitmap semantics changed. It is incompatible with previous format.
- `BitmapIdx` in `Decision` points to the end of the bitmap.
- Bitmap is packed per function.
- `llvm-cov` can understand `profdata` generated by `llvm-profdata-18`.
RFC:
https://discourse.llvm.org/t/rfc-coverage-new-algorithm-and-file-format-for-mc-dc/76798
This replaces `SmallVector<CondState>` and emulates it.
- -------- True False DontCare
- Values: True False False
- Visited: True True False
`findIndependencePairs()` can be optimized with logical ops.
FIXME: Specialize `findIndependencePairs()` for the single word.
To reduce conditional judges in the loop in `findIndependencePairs()`, I
have tried a couple of tweaks.
* Isolate the final result in `TestVectors`
`using TestVectors = llvm::SmallVector<std::pair<TestVector,
CondState>>;`
The final result was just piggybacked on `TestVector`, so it has been
isolated.
* Filter out and sort `ExecVectors` by the final result
It will cost more in constructing `ExecVectors`, but it can reduce at
least one conditional judgement in the loop.
This patch inserts 1-byte counters instead of an 8-byte counters into
llvm profiles for source-based code coverage. The origial idea was
proposed as block-cov for PGO, and this patch repurposes that idea for
coverage: https://groups.google.com/g/llvm-dev/c/r03Z6JoN7d4
The current 8-byte counters mechanism add counters to minimal regions,
and infer the counters in the remaining regions via adding or
subtracting counters. For example, it infers the counter in the if.else
region by subtracting the counters between if.entry and if.then regions
in an if statement. Whenever there is a control-flow merge, it adds the
counters from all the incoming regions. However, we are not going to be
able to infer counters by subtracting two execution counts when using
single-byte counters. Therefore, this patch conservatively inserts
additional counters for the cases where we need to add or subtract
counters.
RFC:
https://discourse.llvm.org/t/rfc-single-byte-counters-for-source-based-code-coverage/75685
This is a preparation of incoming Clang changes (#82448) and just checks
`TVIdx` is calculated correctly. NFC.
`TVIdxBuilder` calculates deterministic Indices for each Condition Node.
It is used for `clang` to emit `TestVector` indices (aka ID) and for
`llvm-cov` to reconstruct `TestVectors`.
This includes the unittest `CoverageMappingTest.TVIdxBuilder`.
See also
https://discourse.llvm.org/t/rfc-coverage-new-algorithm-and-file-format-for-mc-dc/76798
- Prune `RegionMCDCBitmapMap` and `RegionCondIDMap`. They are handled
by `MCDCState`.
- Rename `s/BitmapMap/DecisionByStmt/`. It can handle Decision stuff.
- Rename `s/CondIDMap/BranchByStmt/`. It can be handle Branch stuff.
- `MCDCRecordProcessor`: Use `DecisionParams.BitmapIdx` directly.
Also, Let `NumConditions` `uint16_t`.
It is smarter to handle the ID as signed.
Narrowing to `int16_t` will reduce costs of handling byvalue. (See also
#81221 and #81227)
External behavior doesn't change. They below handle values as internal
values plus 1.
* `-dump-coverage-mapping`
* `CoverageMappingReader.cpp`
* `CoverageMappingWriter.cpp`
Introduce `mcdc::DecisionParameters` and `mcdc::BranchParameters` and make
sure them not initialized as zero.
FIXME: Could we make `CoverageMappingRegion` as a smart tagged union?
They can be also used in `clang`.
Introduce the lightweight header instead of `CoverageMapping.h`.
This includes for now:
* `mcdc::ConditionID`
* `mcdc::Parameters`
Deprecate `TestVectors`, since no one uses it.
This affects the output order of ExecVectors.
The current impl emits sorted by binary value of ExecVector. This impl
emits along the traversal of `buildTestVector()`.
* `getFunctionBitmap()` stores not `std::vector<uint8_t>` but
`BitVector`.
* `CounterMappingContext` holds `Bitmap` (instead of the ref of bytes)
* `Bitmap` and `BitmapIdx` are used instead of `evaluateBitmap()`.
FIXME: `InstrProfRecord` itself should handle `Bitmap` as `BitVector`.
The current implementation (D138849) assumes `Branch`(es) would follow
after the corresponding `Decision`. It is not true if `Branch`(es) are
forwarded to expanded file ID. As a result, consecutive `Decision`(s)
would be confused with insufficient number of `Branch`(es).
`Expansion` will point `Branch`(es) in other file IDs if `Expansion` is
included in the range of `Decision`.
Fixes#77871
---------
Co-authored-by: Alan Phipps <a-phipps@ti.com>
Update code from https://reviews.llvm.org/D138847
`buildTestVector` is a standard DFS (walking a reduced ordered binary
decision diagram). Avoid shouldCopyOffTestVectorFor{True,False}Path
complexity and redundant `Map[ID]` lookups.
`findIndependencePairs` unnecessarily uses four nested loops (n<=6) to
find independence pairs. Instead, enumerate the two execution vectors
and find the number of mismatches. This algorithm can be optimized using
the marking function technique described in _Efficient Test Coverage
Measurement for MC/DC, 2013_, but this may be overkill.
In `CoverageMapping.cpp:getMaxBitmapSize()`,
this assumed that the last `Decision` has the maxmum `BitmapIdx`.
Let it scan `max(BitmapIdx)`.
Note that `<=` is used insted of `<`, because `BitmapIdx == 0` is valid
and `MaxBitmapID` is `unsigned`. `BitmapIdx` is unique in the record.
Fixes#78922
The life of `MCDCRecordProcessor`'s instance is short. It may accept
`const` objects to process.
On the other hand, the life of `MCDCBranches` is shorter than `Record`.
It may be rewritten with reference, rather than copying.
`if constexpr` and `if consteval` conditional statements code coverage
should behave more like a preprocesor `#if`-s than normal
ConditionalStmt. This PR should fix that.
---------
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
Fixes a build failure introduced by
commit 8ecbb0404d74 ("Reland [Coverage][llvm-cov]
Enable MC/DC Support in LLVM Source-based Code Coverage (2/3)")
Use of pow() is not necessary.
This causes stack overflows for real-world coverage reports.
Tested with build/bin/llvm-lit -a llvm/test/tools/llvm-cov
Co-authored-by: Qing Shen <qingshen@google.com>
This reverts commit 32db121b29f78e4c41116b2a8f1c730f9522b202 and subsequent commits.
This causes time regression on llvm-cov even with debug info correlation off.
This patch fixes:
llvm/lib/ProfileData/Coverage/CoverageMapping.cpp:219:5: error:
default label in switch which covers all enumeration values
[-Werror,-Wcovered-switch-default]
This causes stack overflows for real-world coverage reports.
Ran $ build/bin/llvm-lit -a llvm/test/tools/llvm-cov locally and passed.
Co-authored-by: Qing Shen <qingshen@google.com>
Debug info correlation is an option in InstrProfiling pass, which is used by
both IR instrumentation and front-end instrumentation. So, Clang coverage can
also benefits the binary size saving from it.
Reviewed By: ellis
Differential Revision: https://reviews.llvm.org/D157913
The current llvm-cov error message for kind `coveragemap_error::malforme`, just gives the issue kind without any reason for what caused the issue. This patch is aimed at improving the llvm-cov error message to help identify what caused the issue.
Reviewed By: MaskRay
Close: https://github.com/llvm/llvm-project/pull/65264
When a user uses a mismatched clang + llvm-profdata, they didn't get a very
informative error message. It would just say "unsupported version".
As a result, users are often confused as to what they are supposed to do and
tend to assume that it's a bug in the profiling runtime.
This patch improves the error message by:
- Adding a new class of error (`raw_profile_version_mismatch`) to make it clear
that, specifically, the *raw profile* version is unsupported because of a
tool mismatch.
- Adding an error message that tells the user which raw profile version was
encountered, which version was expected, and instructs them to align their
tool versions.
To support this, this patch also updates `InstrProfError::take` to also
propagate the optional error message.
Differential Revision: https://reviews.llvm.org/D149361
This adds the --check-binary-id flag that makes sure that an object file
is available for every binary ID mentioned in the given profile. This
should help make the tool more robust in CI environments where it's
expected that coverage mappings should be available for every object
contributing to the profile.
Reviewed By: gulfem
Differential Revision: https://reviews.llvm.org/D144308
Make the access to profile data going through virtual file system so the
inputs can be remapped. In the context of the caching, it can make sure
we capture the inputs and provided an immutable input as profile data.
Reviewed By: akyrtzi, benlangmuir
Differential Revision: https://reviews.llvm.org/D139052
