I'd like to (re)start a discussion on a few gotchas in FileCheck that
I've
noticed working on various tests in llvm's suites. This begain in a review
[1], but I'll try to summarize here so it gets the right audience before
decisions are made on it (so to speak).
1: https://reviews.llvm.org/D77227
The main sticking point is the abundance of checks in FileCheck tests that
appear to be checking something, but are in fact silently hiding failures.
The biggest class of this bug appears to be CHECK lines that omit the
trailing colon, though there are a few others.
CHECK: legitimate test
CHECK gotcha A
CHECK : gotcha B
CHECKNEXT: gotcha C
CHECKDAG: gotcha D
CHECK_NOT: gotcha E
CHECK-LABEL-NOT: ??? F
CHECK-SAME-DAG: ??? G
Gotcha A
--------
CHECK gotcha A
A lot of cases of (A) are benign, but buried in there are cases where we
have tests that don't check what they intend to, which are broken when the
missing colons are added [2]. Some grep analysis from paulr in [3] found
some 178 tests across 72 test files that seem like likely mistakes,
suggesting that having some automated tooling to catch this is probably not
a bad idea.
In the review thread, a couple of issues surfaced with simply matching on
`${CHECKNAME}\b`, making that less attractive as a remedy:
A1) There are quite a lot of RUN: lines that have CHECK names on them from
their --check-prefix/--check-prefixes arguments, and we don't want tooling
to match on those. This could be addressed with a script that quotes them
all, but that would mean touching pretty much every test file, which is
less than ideal.
A2) There are a few RUN lines with missing colons, though those seem
infrequent enough to not worry about [5].
A3) There are quite a lot of mentions of CHECK names in comments that are
clearly not meant to be tests [6]. Any solution to this, as far as I can
tell, will likely need to reword many of those.
A4) We need some way to comment out CHECK lines that conveys intent better
than removing the colon. This appears to be intentional in some testcases,
but unintentional in the vast majority of them.
To address (A1), a number of rules were proposed in [1], the best of which
seems to be that we look for lines matching `[#/;*!]\s*CHECK[ \t]`, and
emit a diagnostic of some form to help correct it. This gave a pretty good
false positive rate of 25% on the 186 tests it "broke" [7].
An open question here from jdenny is whether it makes sense to require all
checks to follow that pattern (with the colon, of course) to make things
less user-hostile [8]:
> Consider this example that has a well formed directive that doesn't
follow the rule:>
> // FIXME(201806L) CHECK: assert: 0
> Approach A (from a previous comment): FileCheck executes the directive.
If the user later accidentally removes the :, FileCheck won't execute the
directive and won't diagnose the error unless the user is wiling to endure
false positives by opting into the more verbose mode Paul
suggested.>
> Approach B (from that some comment): FileCheck ignores the directive.
That just makes things worse because the above otherwise well formed
directive is then an undiagnosed malformed directive (unless the user opts
into a more verbose mode).>
> Approach C (new proposal): FileCheck reports the directive as an error
(in any mode). The more verbose mode is still needed to catch the case that
the : is missing here, but at least users are guaranteed to get a slap when
they write them with :
2: llvm/test/Transforms/InstCombine/phi-preserve-ir-flags.ll
3: https://reviews.llvm.org/D77227#1955596
4:
https://github.com/llvm/llvm-project/blob/56decd982dc03a74d1796d9d4dbd7d9e0cea98dc/llvm/lib/Support/FileCheck.cpp#L1141
5: llvm/test/CodeGen/AArch64/speculation-hardening.ll
6: llvm/test/MC/ARM/dwarf-asm-multiple-sections.s:88
7: https://reviews.llvm.org/differential/diff/254562
8: https://reviews.llvm.org/D77227#1958228
Gotcha B
--------
CHECK : gotcha B
This pattern is a variant of (A) that also disables perfectly good tests,
but in a way that isn't obvious that it doesn't work. jhenderson brings
up
some good points [9] in favor of extending FileCheck to make FileCheck do
what the user intended here. Luckily, that doesn't seem to conflict with
the rules proposed in (A).
9: https://reviews.llvm.org/D77227#1959041
Gotchas C, D, E
---------------
I believe these can be handled pretty simply in FileCheck itself, but I
have not spent much time trying to estimate how many tests are affected by
this class of bug.
??? F, G
--------
There are a number of check suffix combinations that are not explicitly
supported (in the docs), but appear (maybe) useful. For these, there is
some precedent on mitigating them within FileCheck itself [4], though the
combinatorial explosion warrants being careful about how we go about
detecting them (if at all).
--
Jon Roelofs
jroelofs at jroelofs.com
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First of all, thanks for working on this. In my opinion, filecheck needs help,
and anybody trying to make it better is a hero.
That said, from skimming the review thread, it seems to me that perhaps
automatically detecting bad CHECKs might not be feasible. Perhaps better
debugging tools might be a solution. If I could ask filecheck to list all
directives in a file, I could easily find this stuff manually. If I used this
hypothetical filecheck --list-directives, and I don’t see the one I just added,
then I know it’s bad. This would be much easier to catch in code review in the
future.
Such a debugging framework could be expanded in the future to do more fancy
things. I’d love it if there were some sort of REPL like functionality where I
can throw inputs at a directive and see what it finds.
From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of Jon
Roelofs via llvm-dev
Sent: Friday, April 3, 2020 9:58 AM
To: llvm-dev at lists.llvm.org
Subject: [EXT] [llvm-dev] [RFC] Improving FileCheck
I'd like to (re)start a discussion on a few gotchas in FileCheck that
I've noticed working on various tests in llvm's suites. This begain in a
review [1], but I'll try to summarize here so it gets the right audience
before decisions are made on it (so to speak).
1: https://reviews.llvm.org/D77227
The main sticking point is the abundance of checks in FileCheck tests that
appear to be checking something, but are in fact silently hiding failures. The
biggest class of this bug appears to be CHECK lines that omit the trailing
colon, though there are a few others.
CHECK: legitimate test
CHECK gotcha A
CHECK : gotcha B
CHECKNEXT: gotcha C
CHECKDAG: gotcha D
CHECK_NOT: gotcha E
CHECK-LABEL-NOT: ??? F
CHECK-SAME-DAG: ??? G
Gotcha A
--------
CHECK gotcha A
A lot of cases of (A) are benign, but buried in there are cases where we have
tests that don't check what they intend to, which are broken when the
missing colons are added [2]. Some grep analysis from paulr in [3] found some
178 tests across 72 test files that seem like likely mistakes, suggesting that
having some automated tooling to catch this is probably not a bad idea.
In the review thread, a couple of issues surfaced with simply matching on
`${CHECKNAME}\b`, making that less attractive as a remedy:
A1) There are quite a lot of RUN: lines that have CHECK names on them from their
--check-prefix/--check-prefixes arguments, and we don't want tooling to
match on those. This could be addressed with a script that quotes them all, but
that would mean touching pretty much every test file, which is less than ideal.
A2) There are a few RUN lines with missing colons, though those seem infrequent
enough to not worry about [5].
A3) There are quite a lot of mentions of CHECK names in comments that are
clearly not meant to be tests [6]. Any solution to this, as far as I can tell,
will likely need to reword many of those.
A4) We need some way to comment out CHECK lines that conveys intent better than
removing the colon. This appears to be intentional in some testcases, but
unintentional in the vast majority of them.
To address (A1), a number of rules were proposed in [1], the best of which seems
to be that we look for lines matching `[#/;*!]\s*CHECK[ \t]`, and emit a
diagnostic of some form to help correct it. This gave a pretty good false
positive rate of 25% on the 186 tests it "broke" [7].
An open question here from jdenny is whether it makes sense to require all
checks to follow that pattern (with the colon, of course) to make things less
user-hostile [8]:
> Consider this example that has a well formed directive that doesn't
follow the rule:
>
> // FIXME(201806L) CHECK: assert: 0
> Approach A (from a previous comment): FileCheck executes the directive. If
the user later accidentally removes the :, FileCheck won't execute the
directive and won't diagnose the error unless the user is wiling to endure
false positives by opting into the more verbose mode Paul suggested.
>
> Approach B (from that some comment): FileCheck ignores the directive. That
just makes things worse because the above otherwise well formed directive is
then an undiagnosed malformed directive (unless the user opts into a more
verbose mode).
>
> Approach C (new proposal): FileCheck reports the directive as an error (in
any mode). The more verbose mode is still needed to catch the case that the : is
missing here, but at least users are guaranteed to get a slap when they write
them with :
2: llvm/test/Transforms/InstCombine/phi-preserve-ir-flags.ll
3: https://reviews.llvm.org/D77227#1955596
4:
https://github.com/llvm/llvm-project/blob/56decd982dc03a74d1796d9d4dbd7d9e0cea98dc/llvm/lib/Support/FileCheck.cpp#L1141
5: llvm/test/CodeGen/AArch64/speculation-hardening.ll
6: llvm/test/MC/ARM/dwarf-asm-multiple-sections.s:88
7: https://reviews.llvm.org/differential/diff/254562
8: https://reviews.llvm.org/D77227#1958228
Gotcha B
--------
CHECK : gotcha B
This pattern is a variant of (A) that also disables perfectly good tests, but in
a way that isn't obvious that it doesn't work. jhenderson brings up some
good points [9] in favor of extending FileCheck to make FileCheck do what the
user intended here. Luckily, that doesn't seem to conflict with the rules
proposed in (A).
9: https://reviews.llvm.org/D77227#1959041
Gotchas C, D, E
---------------
I believe these can be handled pretty simply in FileCheck itself, but I have not
spent much time trying to estimate how many tests are affected by this class of
bug.
??? F, G
--------
There are a number of check suffix combinations that are not explicitly
supported (in the docs), but appear (maybe) useful. For these, there is some
precedent on mitigating them within FileCheck itself [4], though the
combinatorial explosion warrants being careful about how we go about detecting
them (if at all).
--
Jon Roelofs
jroelofs at jroelofs.com<mailto:jroelofs at jroelofs.com>
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(Repost, remembering to cc llvm-dev this time)
Thanks Jon!
I’ve done some grepping for a few of these gotchas in llvm/test and clang/test.
Of course this isn’t looking for the check prefixes that are actually used, but
CHECK would be by far the most common, so I think we can take it as a
non-definitive proxy for other cases.
Gotcha A (missing colon): This has a fair number of examples in the wild.
Usually the colon is just missing, although I’ve seen a few examples that had a
semicolon instead of colon, which is an easy typo to make. The real problem
here is coming up with a heuristic that will distinguish “things that are likely
a mistake” from “things that are likely just a comment” so that the diagnostic
has a reasonably low false-positive rate.
For example, in the wild I’ve seen `// TEMPORARY CHECK: X` which FileCheck will
treat as a real directive. On the other hand we *don’t* want it to look at `//
These CHECK lines are here on purpose` and diagnose that as a missing colon.
I’ve been poking at this over the past day or so and I now think the most
reasonable heuristic is: If the directive is preceded by an alphanumeric (+
whitespace) or an `=` or ‘,’ then it’s likely a comment or a RUN: line that we
don’t want to diagnose. This means we would not diagnose a missing colon in `//
TEMPORARY CHECK; X` but that sort of case is extremely rare. We *would*
diagnose `// (TEMPORARY) CHECK; X` however.
Another question was whether we should *require* FileCheck directives to be
preceded by a punctuation mark of some kind. I think that ought to be its own
separate discussion.
Gotcha B (space between the directive and the colon): Some tests have this bug,
so it would be worth catching.
James Henderson observed that legalizing it could help prettify some cases where
we’re matching whitespace or the entire line. I don’t think it’s that valuable
personally.
If we implement a reasonable diagnostic heuristic for the missing-colon case
(Gotcha A), then we’ll catch this mistake in the same net.
Gotchas C,D (missing hyphen): I found exactly one case in the wild. I’d say
the value is debatable.
(It’s a CHECKNEXT in llvm/test/CodeGen/PowerPC/testCompareslleqsi.ll if someone
wants to fix it.)
Gotcha E (underscore instead of hyphen): I found 40 examples across clang/test
and llvm/test. I am certain I have caught a few cases in review and pretty sure
I’ve had to fix some of these that I typo’d myself. I’d say this is worth
doing.
Multiple suffixes: I believe there are NO multiple-suffix combinations that
FileCheck currently supports. The tool should detect any multiple suffix
combinations and report them as errors. Currently it looks for a limited set
(basically, -NOT in combination with almost anything else), but it’s easy for
someone to infer that if FileCheck doesn’t complain, then it will Do The Right
Thing™ with other combinations. We should not be that user-unfriendly; we
should complain about all multiple-suffix combinations.
--paulr
From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of Jon
Roelofs via llvm-dev
Sent: Friday, April 3, 2020 12:58 PM
To: llvm-dev at lists.llvm.org
Subject: [llvm-dev] [RFC] Improving FileCheck
I'd like to (re)start a discussion on a few gotchas in FileCheck that
I've noticed working on various tests in llvm's suites. This begain in a
review [1], but I'll try to summarize here so it gets the right audience
before decisions are made on it (so to speak).
1: https://reviews.llvm.org/D77227
The main sticking point is the abundance of checks in FileCheck tests that
appear to be checking something, but are in fact silently hiding failures. The
biggest class of this bug appears to be CHECK lines that omit the trailing
colon, though there are a few others.
CHECK: legitimate test
CHECK gotcha A
CHECK : gotcha B
CHECKNEXT: gotcha C
CHECKDAG: gotcha D
CHECK_NOT: gotcha E
CHECK-LABEL-NOT: ??? F
CHECK-SAME-DAG: ??? G
Gotcha A
--------
CHECK gotcha A
A lot of cases of (A) are benign, but buried in there are cases where we have
tests that don't check what they intend to, which are broken when the
missing colons are added [2]. Some grep analysis from paulr in [3] found some
178 tests across 72 test files that seem like likely mistakes, suggesting that
having some automated tooling to catch this is probably not a bad idea.
In the review thread, a couple of issues surfaced with simply matching on
`${CHECKNAME}\b`, making that less attractive as a remedy:
A1) There are quite a lot of RUN: lines that have CHECK names on them from their
--check-prefix/--check-prefixes arguments, and we don't want tooling to
match on those. This could be addressed with a script that quotes them all, but
that would mean touching pretty much every test file, which is less than ideal.
A2) There are a few RUN lines with missing colons, though those seem infrequent
enough to not worry about [5].
A3) There are quite a lot of mentions of CHECK names in comments that are
clearly not meant to be tests [6]. Any solution to this, as far as I can tell,
will likely need to reword many of those.
A4) We need some way to comment out CHECK lines that conveys intent better than
removing the colon. This appears to be intentional in some testcases, but
unintentional in the vast majority of them.
To address (A1), a number of rules were proposed in [1], the best of which seems
to be that we look for lines matching `[#/;*!]\s*CHECK[ \t]`, and emit a
diagnostic of some form to help correct it. This gave a pretty good false
positive rate of 25% on the 186 tests it "broke" [7].
An open question here from jdenny is whether it makes sense to require all
checks to follow that pattern (with the colon, of course) to make things less
user-hostile [8]:
> Consider this example that has a well formed directive that doesn't
follow the rule:
>
> // FIXME(201806L) CHECK: assert: 0
> Approach A (from a previous comment): FileCheck executes the directive. If
the user later accidentally removes the :, FileCheck won't execute the
directive and won't diagnose the error unless the user is wiling to endure
false positives by opting into the more verbose mode Paul suggested.
>
> Approach B (from that some comment): FileCheck ignores the directive. That
just makes things worse because the above otherwise well formed directive is
then an undiagnosed malformed directive (unless the user opts into a more
verbose mode).
>
> Approach C (new proposal): FileCheck reports the directive as an error (in
any mode). The more verbose mode is still needed to catch the case that the : is
missing here, but at least users are guaranteed to get a slap when they write
them with :
2: llvm/test/Transforms/InstCombine/phi-preserve-ir-flags.ll
3: https://reviews.llvm.org/D77227#1955596
4:
https://github.com/llvm/llvm-project/blob/56decd982dc03a74d1796d9d4dbd7d9e0cea98dc/llvm/lib/Support/FileCheck.cpp#L1141
5: llvm/test/CodeGen/AArch64/speculation-hardening.ll
6: llvm/test/MC/ARM/dwarf-asm-multiple-sections.s:88
7: https://reviews.llvm.org/differential/diff/254562
8: https://reviews.llvm.org/D77227#1958228
Gotcha B
--------
CHECK : gotcha B
This pattern is a variant of (A) that also disables perfectly good tests, but in
a way that isn't obvious that it doesn't work. jhenderson brings up some
good points [9] in favor of extending FileCheck to make FileCheck do what the
user intended here. Luckily, that doesn't seem to conflict with the rules
proposed in (A).
9: https://reviews.llvm.org/D77227#1959041
Gotchas C, D, E
---------------
I believe these can be handled pretty simply in FileCheck itself, but I have not
spent much time trying to estimate how many tests are affected by this class of
bug.
??? F, G
--------
There are a number of check suffix combinations that are not explicitly
supported (in the docs), but appear (maybe) useful. For these, there is some
precedent on mitigating them within FileCheck itself [4], though the
combinatorial explosion warrants being careful about how we go about detecting
them (if at all).
--
Jon Roelofs
jroelofs at jroelofs.com<mailto:jroelofs at jroelofs.com>
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On Fri, Apr 3, 2020 at 2:58 PM Robinson, Paul via llvm-dev < llvm-dev at lists.llvm.org> wrote:> (Repost, remembering to cc llvm-dev this time) > > > > Thanks Jon! >+1> > > I’ve done some grepping for a few of these gotchas in llvm/test and > clang/test. Of course this isn’t looking for the check prefixes that are > actually used, but CHECK would be by far the most common, so I think we can > take it as a non-definitive proxy for other cases. > > > > Gotcha A (missing colon): This has a fair number of examples in the > wild. Usually the colon is just missing, although I’ve seen a few examples > that had a semicolon instead of colon, which is an easy typo to make. The > real problem here is coming up with a heuristic that will distinguish > “things that are likely a mistake” from “things that are likely just a > comment” so that the diagnostic has a reasonably low false-positive rate. > > For example, in the wild I’ve seen `// TEMPORARY CHECK: X` which FileCheck > will treat as a real directive. On the other hand we **don’t** want it > to look at `// These CHECK lines are here on purpose` and diagnose that as > a missing colon. > > I’ve been poking at this over the past day or so and I now think the most > reasonable heuristic is: If the directive is preceded by an alphanumeric (+ > whitespace) or an `=` or ‘,’ then it’s likely a comment or a RUN: line that > we don’t want to diagnose. This means we would not diagnose a missing > colon in `// TEMPORARY CHECK; X` but that sort of case is extremely rare. > We **would** diagnose `// (TEMPORARY) CHECK; X` however. >The previous heuristic we discussed was that the diagnostic is reported only if, other than whitespace, the directive is at the beginning of a line or at the beginning of a comment (for some definition of comment). It appears that your new heuristic strictly expands the cases that would be diagnosed. Is that right? Is there a specific case you saw in the test suites that is covered by your new heuristic but not by the previous heuristic? Your new heuristic does have additional false positives in the test suites, like the following: // NOTE: CHECK lines have been autogenerated by gen_ast_dump_json_test.py // FIXME: CHECK-NOT is broken somehow, it doesn't work here. Check adjacency instead. This makes me wonder if such heuristics are going to create a frustrating FileCheck user experience when trying to write comments. Consider what happens if we implement your heuristic in a parameterized way using new environment variables with the following defaults: FILECHECK_COMMENT_REGEX='([a-zA-Z0-9]\s*|[=,])$' FILECHECK_COMMENT_APPLY=diagnostics So far, this is exactly your proposed heuristic except: 1. It's slightly more to implement: just a couple of environment variables to read. Not that hard. 2. We can easily tweak the regex per test suite as we discover how this heuristic fares with the rest of check-all and with the rest of the prefixes (beyond CHECK). 3. Specific test suites that want total freedom in writing comments and are ready to protect them with something like 'COM:' could specify something like: FILECHECK_COMMENT_REGEX='\bRUN:|\bCOM:' FILECHECK_COMMENT_APPLY=diagnostics,directives At some point in the future, when all test suites are compatible with 3, it could become the default (and we might then drop FILECHECK_COMMENT_APPLY). At that point: A. Diagnostics would no longer be limited by heuristics' shaky assumptions about intentions within comments. They know precisely what are just comments. B. Users would know precisely where they can and cannot write the names of directives (both with and without the colon). C. Users would have a way to comment out directives while making their intention very obvious (no more mangling). This seems like both a short-term and long-term win for very little extra upfront effort. Another question was whether we should **require** FileCheck directives to> be preceded by a punctuation mark of some kind. I think that ought to be > its own separate discussion. >Well, if we eventually require directive-like text to be FileCheck-commented, as described above, this question goes away.> Gotcha B (space between the directive and the colon): Some tests have > this bug, so it would be worth catching. > > James Henderson observed that legalizing it could help prettify some cases > where we’re matching whitespace or the entire line. I don’t think it’s > that valuable personally. > > If we implement a reasonable diagnostic heuristic for the missing-colon > case (Gotcha A), then we’ll catch this mistake in the same net. >Agreed. Gotchas C,D (missing hyphen): I found exactly one case in the wild. I’d> say the value is debatable. > > (It’s a CHECKNEXT in llvm/test/CodeGen/PowerPC/testCompareslleqsi.ll if > someone wants to fix it.) > > > > Gotcha E (underscore instead of hyphen): I found 40 examples across > clang/test and llvm/test. I am certain I have caught a few cases in review > and pretty sure I’ve had to fix some of these that I typo’d myself. I’d > say this is worth doing. >No arguments here.> Multiple suffixes: I believe there are NO multiple-suffix combinations > that FileCheck currently supports. The tool should detect any multiple > suffix combinations and report them as errors. Currently it looks for a > limited set (basically, -NOT in combination with almost anything else), but > it’s easy for someone to infer that if FileCheck doesn’t complain, then it > will Do The Right Thing™ with other combinations. We should not be that > user-unfriendly; we should complain about all multiple-suffix combinations. >Agreed. Thanks. Joel> > > --paulr > > > > > > *From:* llvm-dev <llvm-dev-bounces at lists.llvm.org> *On Behalf Of *Jon > Roelofs via llvm-dev > *Sent:* Friday, April 3, 2020 12:58 PM > *To:* llvm-dev at lists.llvm.org > *Subject:* [llvm-dev] [RFC] Improving FileCheck > > > > I'd like to (re)start a discussion on a few gotchas in FileCheck that I've > noticed working on various tests in llvm's suites. This begain in a review > [1], but I'll try to summarize here so it gets the right audience before > decisions are made on it (so to speak). > > 1: https://reviews.llvm.org/D77227 > > The main sticking point is the abundance of checks in FileCheck tests that > appear to be checking something, but are in fact silently hiding failures. > The biggest class of this bug appears to be CHECK lines that omit the > trailing colon, though there are a few others. > > CHECK: legitimate test > CHECK gotcha A > CHECK : gotcha B > CHECKNEXT: gotcha C > CHECKDAG: gotcha D > CHECK_NOT: gotcha E > CHECK-LABEL-NOT: ??? F > CHECK-SAME-DAG: ??? G > > > Gotcha A > -------- > > CHECK gotcha A > > A lot of cases of (A) are benign, but buried in there are cases where we > have tests that don't check what they intend to, which are broken when the > missing colons are added [2]. Some grep analysis from paulr in [3] found > some 178 tests across 72 test files that seem like likely mistakes, > suggesting that having some automated tooling to catch this is probably not > a bad idea. > > In the review thread, a couple of issues surfaced with simply matching on > `${CHECKNAME}\b`, making that less attractive as a remedy: > > A1) There are quite a lot of RUN: lines that have CHECK names on them from > their --check-prefix/--check-prefixes arguments, and we don't want tooling > to match on those. This could be addressed with a script that quotes them > all, but that would mean touching pretty much every test file, which is > less than ideal. > > A2) There are a few RUN lines with missing colons, though those seem > infrequent enough to not worry about [5]. > > A3) There are quite a lot of mentions of CHECK names in comments that are > clearly not meant to be tests [6]. Any solution to this, as far as I can > tell, will likely need to reword many of those. > > A4) We need some way to comment out CHECK lines that conveys intent better > than removing the colon. This appears to be intentional in some testcases, > but unintentional in the vast majority of them. > > To address (A1), a number of rules were proposed in [1], the best of which > seems to be that we look for lines matching `[#/;*!]\s*CHECK[ \t]`, and > emit a diagnostic of some form to help correct it. This gave a pretty good > false positive rate of 25% on the 186 tests it "broke" [7]. > > An open question here from jdenny is whether it makes sense to require all > checks to follow that pattern (with the colon, of course) to make things > less user-hostile [8]: > > > Consider this example that has a well formed directive that doesn't > follow the rule: > > > > // FIXME(201806L) CHECK: assert: 0 > > Approach A (from a previous comment): FileCheck executes the directive. > If the user later accidentally removes the :, FileCheck won't execute the > directive and won't diagnose the error unless the user is wiling to endure > false positives by opting into the more verbose mode Paul suggested. > > > > Approach B (from that some comment): FileCheck ignores the directive. > That just makes things worse because the above otherwise well formed > directive is then an undiagnosed malformed directive (unless the user opts > into a more verbose mode). > > > > Approach C (new proposal): FileCheck reports the directive as an error > (in any mode). The more verbose mode is still needed to catch the case that > the : is missing here, but at least users are guaranteed to get a slap when > they write them with : > 2: llvm/test/Transforms/InstCombine/phi-preserve-ir-flags.ll > 3: https://reviews.llvm.org/D77227#1955596 > 4: > https://github.com/llvm/llvm-project/blob/56decd982dc03a74d1796d9d4dbd7d9e0cea98dc/llvm/lib/Support/FileCheck.cpp#L1141 > 5: llvm/test/CodeGen/AArch64/speculation-hardening.ll > 6: llvm/test/MC/ARM/dwarf-asm-multiple-sections.s:88 > 7: https://reviews.llvm.org/differential/diff/254562 > 8: https://reviews.llvm.org/D77227#1958228 > > > Gotcha B > -------- > > CHECK : gotcha B > > This pattern is a variant of (A) that also disables perfectly good tests, > but in a way that isn't obvious that it doesn't work. jhenderson brings up > some good points [9] in favor of extending FileCheck to make FileCheck do > what the user intended here. Luckily, that doesn't seem to conflict with > the rules proposed in (A). > > 9: https://reviews.llvm.org/D77227#1959041 > > > Gotchas C, D, E > --------------- > > I believe these can be handled pretty simply in FileCheck itself, but I > have not spent much time trying to estimate how many tests are affected by > this class of bug. > > > ??? F, G > -------- > > There are a number of check suffix combinations that are not explicitly > supported (in the docs), but appear (maybe) useful. For these, there is > some precedent on mitigating them within FileCheck itself [4], though the > combinatorial explosion warrants being careful about how we go about > detecting them (if at all). > > > -- > Jon Roelofs > jroelofs at jroelofs.com > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... 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On Fri, 3 Apr 2020 at 19:59, Robinson, Paul via llvm-dev < llvm-dev at lists.llvm.org> wrote:> Gotcha B (space between the directive and the colon): Some tests have > this bug, so it would be worth catching. > > James Henderson observed that legalizing it could help prettify some cases > where we’re matching whitespace or the entire line. I don’t think it’s > that valuable personally. > > If we implement a reasonable diagnostic heuristic for the missing-colon > case (Gotcha A), then we’ll catch this mistake in the same net. > >Fine by me, as long as "# CHECK:" continues to be acceptable instead to allow the colons to line up with other check directives on other lines.> > Gotchas C,D (missing hyphen): I found exactly one case in the wild. I’d > say the value is debatable. > > (It’s a CHECKNEXT in llvm/test/CodeGen/PowerPC/testCompareslleqsi.ll if > someone wants to fix it.) >I'm not keen on this becoming something that is forbidden, since I could imagine myself running into this on occasion, particularly when using custom check prefixes shared between cases - it's not unusual for me to name such prefixes as something like "FOO", "BAR" and "FOOBAR", where FOO is for case 1, BAR is for case2 and FOOBAR is used by both. If BAR happened to be a different name that clashes with a known suffix (e.g. LABEL), then I'd get an unwanted false positive.> > Gotcha E (underscore instead of hyphen): I found 40 examples across > clang/test and llvm/test. I am certain I have caught a few cases in review > and pretty sure I’ve had to fix some of these that I typo’d myself. I’d > say this is worth doing. > > > > Multiple suffixes: I believe there are NO multiple-suffix combinations > that FileCheck currently supports. The tool should detect any multiple > suffix combinations and report them as errors. Currently it looks for a > limited set (basically, -NOT in combination with almost anything else), but > it’s easy for someone to infer that if FileCheck doesn’t complain, then it > will Do The Right Thing™ with other combinations. We should not be that > user-unfriendly; we should complain about all multiple-suffix combinations. >I agree that checking for them all seems reasonable, though perhaps it might be nice for this to be user-configurable somehow (I'm thinking FileCheck tests themselves might run into things confusingly). It seems to me that it would be easy to auto-generate the combinatorial list in code and then do a simple check for the prefix being in the list.> > --paulr > > > > > > *From:* llvm-dev <llvm-dev-bounces at lists.llvm.org> *On Behalf Of *Jon > Roelofs via llvm-dev > *Sent:* Friday, April 3, 2020 12:58 PM > *To:* llvm-dev at lists.llvm.org > *Subject:* [llvm-dev] [RFC] Improving FileCheck > > > > I'd like to (re)start a discussion on a few gotchas in FileCheck that I've > noticed working on various tests in llvm's suites. This begain in a review > [1], but I'll try to summarize here so it gets the right audience before > decisions are made on it (so to speak). > > 1: https://reviews.llvm.org/D77227 > > The main sticking point is the abundance of checks in FileCheck tests that > appear to be checking something, but are in fact silently hiding failures. > The biggest class of this bug appears to be CHECK lines that omit the > trailing colon, though there are a few others. > > CHECK: legitimate test > CHECK gotcha A > CHECK : gotcha B > CHECKNEXT: gotcha C > CHECKDAG: gotcha D > CHECK_NOT: gotcha E > CHECK-LABEL-NOT: ??? F > CHECK-SAME-DAG: ??? G > > > Gotcha A > -------- > > CHECK gotcha A > > A lot of cases of (A) are benign, but buried in there are cases where we > have tests that don't check what they intend to, which are broken when the > missing colons are added [2]. Some grep analysis from paulr in [3] found > some 178 tests across 72 test files that seem like likely mistakes, > suggesting that having some automated tooling to catch this is probably not > a bad idea. > > In the review thread, a couple of issues surfaced with simply matching on > `${CHECKNAME}\b`, making that less attractive as a remedy: > > A1) There are quite a lot of RUN: lines that have CHECK names on them from > their --check-prefix/--check-prefixes arguments, and we don't want tooling > to match on those. This could be addressed with a script that quotes them > all, but that would mean touching pretty much every test file, which is > less than ideal. > > A2) There are a few RUN lines with missing colons, though those seem > infrequent enough to not worry about [5]. > > A3) There are quite a lot of mentions of CHECK names in comments that are > clearly not meant to be tests [6]. Any solution to this, as far as I can > tell, will likely need to reword many of those. > > A4) We need some way to comment out CHECK lines that conveys intent better > than removing the colon. This appears to be intentional in some testcases, > but unintentional in the vast majority of them. > > To address (A1), a number of rules were proposed in [1], the best of which > seems to be that we look for lines matching `[#/;*!]\s*CHECK[ \t]`, and > emit a diagnostic of some form to help correct it. This gave a pretty good > false positive rate of 25% on the 186 tests it "broke" [7]. > > An open question here from jdenny is whether it makes sense to require all > checks to follow that pattern (with the colon, of course) to make things > less user-hostile [8]: > > > Consider this example that has a well formed directive that doesn't > follow the rule: > > > > // FIXME(201806L) CHECK: assert: 0 > > Approach A (from a previous comment): FileCheck executes the directive. > If the user later accidentally removes the :, FileCheck won't execute the > directive and won't diagnose the error unless the user is wiling to endure > false positives by opting into the more verbose mode Paul suggested. > > > > Approach B (from that some comment): FileCheck ignores the directive. > That just makes things worse because the above otherwise well formed > directive is then an undiagnosed malformed directive (unless the user opts > into a more verbose mode). > > > > Approach C (new proposal): FileCheck reports the directive as an error > (in any mode). The more verbose mode is still needed to catch the case that > the : is missing here, but at least users are guaranteed to get a slap when > they write them with : > 2: llvm/test/Transforms/InstCombine/phi-preserve-ir-flags.ll > 3: https://reviews.llvm.org/D77227#1955596 > 4: > https://github.com/llvm/llvm-project/blob/56decd982dc03a74d1796d9d4dbd7d9e0cea98dc/llvm/lib/Support/FileCheck.cpp#L1141 > 5: llvm/test/CodeGen/AArch64/speculation-hardening.ll > 6: llvm/test/MC/ARM/dwarf-asm-multiple-sections.s:88 > 7: https://reviews.llvm.org/differential/diff/254562 > 8: https://reviews.llvm.org/D77227#1958228 > > > Gotcha B > -------- > > CHECK : gotcha B > > This pattern is a variant of (A) that also disables perfectly good tests, > but in a way that isn't obvious that it doesn't work. jhenderson brings up > some good points [9] in favor of extending FileCheck to make FileCheck do > what the user intended here. Luckily, that doesn't seem to conflict with > the rules proposed in (A). > > 9: https://reviews.llvm.org/D77227#1959041 > > > Gotchas C, D, E > --------------- > > I believe these can be handled pretty simply in FileCheck itself, but I > have not spent much time trying to estimate how many tests are affected by > this class of bug. > > > ??? F, G > -------- > > There are a number of check suffix combinations that are not explicitly > supported (in the docs), but appear (maybe) useful. For these, there is > some precedent on mitigating them within FileCheck itself [4], though the > combinatorial explosion warrants being careful about how we go about > detecting them (if at all). > > > -- > Jon Roelofs > jroelofs at jroelofs.com > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... 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As an update, after lots of fixes from a number of different people (thanks everyone!), the current list of false-positives on `ninja check-llvm` for the more stringent Gotcha A diagnostic is: LLVM :: Analysis/CostModel/X86/vselect-cost.ll LLVM :: CodeGen/AMDGPU/GlobalISel/smrd.ll LLVM :: CodeGen/AMDGPU/fp_to_uint.ll LLVM :: CodeGen/AMDGPU/global-constant.ll LLVM :: CodeGen/AMDGPU/merge-tbuffer.mir LLVM :: CodeGen/AMDGPU/smrd.ll LLVM :: CodeGen/AMDGPU/unhandled-loop-condition-assertion.ll LLVM :: CodeGen/ARM/build-attributes.ll LLVM :: CodeGen/ARM/float-helpers.s LLVM :: CodeGen/ARM/select-imm.ll LLVM :: CodeGen/ARM/struct_byval_arm_t1_t2.ll LLVM :: CodeGen/Mips/cconv/arguments-float.ll LLVM :: CodeGen/Mips/cconv/arguments-hard-float-varargs.ll LLVM :: CodeGen/Mips/cconv/arguments-hard-float.ll LLVM :: CodeGen/Mips/cconv/arguments-varargs.ll LLVM :: CodeGen/Mips/cconv/arguments.ll LLVM :: CodeGen/Mips/cconv/return-hard-fp128.ll LLVM :: CodeGen/Mips/cconv/return-hard-struct-f128.ll LLVM :: CodeGen/Mips/ci2.ll LLVM :: CodeGen/Mips/countleading.ll LLVM :: CodeGen/Mips/divrem.ll LLVM :: CodeGen/Mips/dynamic-stack-realignment.ll LLVM :: CodeGen/Mips/inlineasm-operand-code.ll LLVM :: CodeGen/Mips/mips64muldiv.ll LLVM :: CodeGen/PowerPC/ppc64-crsave.mir LLVM :: CodeGen/X86/avx-cast.ll LLVM :: CodeGen/X86/fp-intrinsics.ll LLVM :: CodeGen/X86/splat-for-size.ll LLVM :: CodeGen/X86/sse-scalar-fp-arith.ll LLVM :: CodeGen/X86/vec_shift6.ll LLVM :: CodeGen/X86/vector-compare-combines.ll LLVM :: CodeGen/X86/vector-narrow-binop.ll LLVM :: DebugInfo/COFF/vframe-fpo.ll LLVM :: DebugInfo/X86/debug-info-static-member.ll LLVM :: FileCheck/check-empty-tag.txt LLVM :: FileCheck/dump-input-annotations.txt LLVM :: FileCheck/no-multi-suffixes.txt LLVM :: FileCheck/var-scope.txt LLVM :: MC/AsmParser/expr-shr.s LLVM :: MC/Mips/relocation-n64.s LLVM :: MC/Mips/relocation.s LLVM :: MC/RISCV/compressed-relocations.s LLVM :: MC/RISCV/relocations.s LLVM :: MC/RISCV/rv32b-aliases-valid.s LLVM :: MC/RISCV/rv64b-aliases-valid.s LLVM :: MC/RISCV/rva-aliases-valid.s LLVM :: MC/RISCV/rvi-aliases-valid.s LLVM :: Transforms/InstCombine/double-float-shrink-2.ll LLVM :: Transforms/LoopFusion/cannot_fuse.ll LLVM :: tools/llvm-objdump/ELF/dynamic-section-machine-specific.test LLVM :: tools/llvm-readobj/ELF/RISCV/section-types.test LLVM :: tools/llvm-readobj/ELF/section-types.test LLVM :: tools/llvm-readobj/ELF/symbol-binding.test All of these are variants in some form or another of comments that contain the check prefix, but which are intentionally not actual CHECK lines. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200413/0a17fc27/attachment.html>
On Mon, Apr 13, 2020 at 1:16 PM Jon Roelofs via llvm-dev < llvm-dev at lists.llvm.org> wrote:> As an update, after lots of fixes from a number of different people > (thanks everyone!), the current list of false-positives on `ninja > check-llvm` for the more stringent Gotcha A diagnostic is: > > LLVM :: Analysis/CostModel/X86/vselect-cost.ll > LLVM :: CodeGen/AMDGPU/GlobalISel/smrd.ll > LLVM :: CodeGen/AMDGPU/fp_to_uint.ll > LLVM :: CodeGen/AMDGPU/global-constant.ll > LLVM :: CodeGen/AMDGPU/merge-tbuffer.mir > LLVM :: CodeGen/AMDGPU/smrd.ll > LLVM :: CodeGen/AMDGPU/unhandled-loop-condition-assertion.ll > LLVM :: CodeGen/ARM/build-attributes.ll > LLVM :: CodeGen/ARM/float-helpers.s > LLVM :: CodeGen/ARM/select-imm.ll > LLVM :: CodeGen/ARM/struct_byval_arm_t1_t2.ll > LLVM :: CodeGen/Mips/cconv/arguments-float.ll > LLVM :: CodeGen/Mips/cconv/arguments-hard-float-varargs.ll > LLVM :: CodeGen/Mips/cconv/arguments-hard-float.ll > LLVM :: CodeGen/Mips/cconv/arguments-varargs.ll > LLVM :: CodeGen/Mips/cconv/arguments.ll > LLVM :: CodeGen/Mips/cconv/return-hard-fp128.ll > LLVM :: CodeGen/Mips/cconv/return-hard-struct-f128.ll > LLVM :: CodeGen/Mips/ci2.ll > LLVM :: CodeGen/Mips/countleading.ll > LLVM :: CodeGen/Mips/divrem.ll > LLVM :: CodeGen/Mips/dynamic-stack-realignment.ll > LLVM :: CodeGen/Mips/inlineasm-operand-code.ll > LLVM :: CodeGen/Mips/mips64muldiv.ll > LLVM :: CodeGen/PowerPC/ppc64-crsave.mir > LLVM :: CodeGen/X86/avx-cast.ll > LLVM :: CodeGen/X86/fp-intrinsics.ll > LLVM :: CodeGen/X86/splat-for-size.ll > LLVM :: CodeGen/X86/sse-scalar-fp-arith.ll > LLVM :: CodeGen/X86/vec_shift6.ll > LLVM :: CodeGen/X86/vector-compare-combines.ll > LLVM :: CodeGen/X86/vector-narrow-binop.ll > LLVM :: DebugInfo/COFF/vframe-fpo.ll > LLVM :: DebugInfo/X86/debug-info-static-member.ll > LLVM :: FileCheck/check-empty-tag.txt > LLVM :: FileCheck/dump-input-annotations.txt > LLVM :: FileCheck/no-multi-suffixes.txt > LLVM :: FileCheck/var-scope.txt > LLVM :: MC/AsmParser/expr-shr.s > LLVM :: MC/Mips/relocation-n64.s > LLVM :: MC/Mips/relocation.s > LLVM :: MC/RISCV/compressed-relocations.s > LLVM :: MC/RISCV/relocations.s > LLVM :: MC/RISCV/rv32b-aliases-valid.s > LLVM :: MC/RISCV/rv64b-aliases-valid.s > LLVM :: MC/RISCV/rva-aliases-valid.s > LLVM :: MC/RISCV/rvi-aliases-valid.s > LLVM :: Transforms/InstCombine/double-float-shrink-2.ll > LLVM :: Transforms/LoopFusion/cannot_fuse.ll > LLVM :: tools/llvm-objdump/ELF/dynamic-section-machine-specific.test > LLVM :: tools/llvm-readobj/ELF/RISCV/section-types.test > LLVM :: tools/llvm-readobj/ELF/section-types.test > LLVM :: tools/llvm-readobj/ELF/symbol-binding.test > > All of these are variants in some form or another of comments that contain > the check prefix, but which are intentionally not actual CHECK lines. >Thanks for working on this. That report makes me think the diagnostic is going to be frustrating. What do you think? Joel> _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200417/873b48b6/attachment.html>
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