Branch: refs/heads/yves/curlyx_curlym
Home: https://github.com/Perl/perl5
Commit: 5e3422bbf1af947a1319f5bd9ced09cfa48bf17b
https://github.com/Perl/perl5/commit/5e3422bbf1af947a1319f5bd9ced09cfa48bf17b
Author: Yves Orton <demer...@gmail.com>
Date: 2023-01-15 (Sun, 15 Jan 2023)
Changed paths:
M pod/perldebguts.pod
M pp_ctl.c
M regcomp.c
M regcomp.h
M regcomp.sym
M regcomp_debug.c
M regexec.c
M regexp.h
M regnodes.h
M t/re/pat.t
M t/re/pat_rt_report.t
M t/re/re_tests
Log Message:
-----------
regcomp.c - Resolve issues clearing buffers in CURLYX (MAJOR-CHANGE)
CURLYX doesn't reset capture buffers properly. It is possible
for multiple buffers to be defined at once with values from
different iterations of the loop, which doesn't make sense really.
An example is this:
"foobarfoo"=~/((foo)|(bar))+/
after this matches $1 should equal $2 and $3 should be undefined,
or $1 should equal $3 and $2 should be undefined. Prior to this
patch this would not be the case.
The solution that this patches uses is to introduce a form of
"layered transactional storage" for paren data. The existing
pair of start/end data for capture data is extended with a
start_new/end_new pair. When the vast majority of our code wants
to check if a given capture buffer is defined they first check
"start_new/end_new", if either is -1 then they fall back to
whatever is in start/end.
When a capture buffer is CLOSEd the data is written into the
start_new/end_new pair instead of the start/end pair. When a CURLYX
loop is executing and has matched something (at least one "A" in
/A*B/ -- thus actually in WHILEM) it "commits" the start_new/end_new
data by writing it into start/end. When we begin a new iteration of
the loop we clear the start_new/end_new pairs that are contained by
the loop, by setting them to -1. If the loop fails then we roll back
as we used to. If the loop succeeds we continue. When we hit an END
block we commit everything.
Consider the example above. We start off with everything set to -1.
$1 = (-1,-1):(-1,-1)
$2 = (-1,-1):(-1,-1)
$3 = (-1,-1):(-1,-1)
In the first iteration we have matched "foo" and end up with this:
$1 = (-1,-1):( 0, 3)
$2 = (-1,-1):( 0, 3)
$3 = (-1,-1):(-1,-1)
We commit the results of $2 and $3, and then clear the new data in
the beginning of the next loop:
$1 = (-1,-1):( 0, 3)
$2 = ( 0, 3):(-1,-1)
$3 = (-1,-1):(-1,-1)
We then match "bar":
$1 = (-1,-1):( 0, 3)
$2 = ( 0, 3):(-1,-1)
$3 = (-1,-1):( 3, 7)
and then commit the result and clear the new data:
$1 = (-1,-1):( 0, 3)
$2 = (-1,-1):(-1,-1)
$3 = ( 3, 7):(-1,-1)
and then we match "foo" again:
$1 = (-1,-1):( 0, 3)
$2 = (-1,-1):( 7,10)
$3 = ( 3, 7):(-1,-1)
And we then commit. We do a regcppush here as normal.
$1 = (-1,-1):( 0, 3)
$2 = ( 7,10):( 7,10)
$3 = (-1,-1):(-1,-1)
We then clear it again, but since we don't match when we regcppop
we store the buffers back to the above layout. When we finally
hit the END buffer we also do a commit as well on all buffers, including
the 0th (for the full match).
Fixes GH Issue #18865, and adds tests for it and other things.
Commit: 18d510bc522a1faef2f2d659a4435dcf0e9b0d62
https://github.com/Perl/perl5/commit/18d510bc522a1faef2f2d659a4435dcf0e9b0d62
Author: Yves Orton <demer...@gmail.com>
Date: 2023-01-15 (Sun, 15 Jan 2023)
Changed paths:
M pod/perldebguts.pod
M regcomp.c
M regcomp.h
M regcomp.sym
M regcomp_debug.c
M regcomp_trie.c
M regexec.c
M regexp.h
M regnodes.h
M t/re/re_tests
Log Message:
-----------
regexec.c - teach BRANCH and BRANCHJ nodes to reset capture buffers
In /((a)(b)|(a))+/ we should not end up with $2 and $4 being set at
the same time. When a branch fails it should reset any capture buffers
that might be touched by its branch.
We change BRANCH and BRANCHJ to store the number of parens before the
branch, and the number of parens after the branch was completed. When
a BRANCH operation fails, we clear the buffers it contains before we
continue on.
It is a bit more complex than it should be because we have BRANCHJ
and BRANCH. (One of these days we should merge them together.)
This is also made somewhat more complex because TRIE nodes are actually
branches, and may need to track capture buffers also, at two levels.
The overall TRIE op, and for jump tries especially where we emulate
the behavior of branches. So we have to do the same clearing logic if
a trie branch fails as well.
Commit: 9babd470eecba10fc402e34e231489d9b5e0a3f3
https://github.com/Perl/perl5/commit/9babd470eecba10fc402e34e231489d9b5e0a3f3
Author: Yves Orton <demer...@gmail.com>
Date: 2023-01-15 (Sun, 15 Jan 2023)
Changed paths:
M pod/perldelta.pod
M pod/perlre.pod
M regcomp.c
M regcomp.h
M regcomp_debug.c
M regcomp_internal.h
M regcomp_study.c
M regexec.c
M regnodes.h
M t/re/pat_re_eval.t
M t/re/pat_rt_report.t
M toke.c
Log Message:
-----------
regcomp.c - add optimistic eval
This adds (*{ ... }) and (**{ ... }) as equivalents to
(?{ ... }) and (??{ ... }). The only difference being that
the star variants are "optimisitic" and are defined to never
disable optimisations. This is especially relevant now that
use of (?{ ... }) prevents important optimisations anywhere
in the pattern, instead of the older and inconsistent rules
where it only affected the parts that contained the EVAL.
It is also very useful for injecting debugging style expressions
to the pattern to understand what the regex engine is actually
doing. The older style (?{ ... }) variants would change the
regex engines behavior, meaning this was not as effective a
tool as it could have been.
Commit: a566ac792f97ba6daa771e87591b56f97e0c1686
https://github.com/Perl/perl5/commit/a566ac792f97ba6daa771e87591b56f97e0c1686
Author: Yves Orton <demer...@gmail.com>
Date: 2023-01-15 (Sun, 15 Jan 2023)
Changed paths:
M pod/perldelta.pod
Log Message:
-----------
perldelta - add note about regex engine changes
capture buffer semantics should now be consistent.
Commit: d72e85e150004c2325a9fe942f8cedb2b780ca6b
https://github.com/Perl/perl5/commit/d72e85e150004c2325a9fe942f8cedb2b780ca6b
Author: Yves Orton <demer...@gmail.com>
Date: 2023-01-15 (Sun, 15 Jan 2023)
Changed paths:
M regexec.c
M regexp.h
M t/re/re_tests
Log Message:
-----------
regexec.c - incredibly inefficient solution to backref problem
Backrefs to unclosed parens inside of a quantified group were not being
properly handled, which revealed we are not unrolling the paren state properly
on failure and backtracking.
Much of the code assumes that when we execute a "conditional" operation (where
more than one thing could match) that we need not concern ourself with the
paren state unless the conditional operation itself represents a paren, and
that generally opcodes only needed to concern themselves with parens to their
right. When you exclude backrefs from the equation this is broadly reasonable
(i think), as on failure we typically dont care about the state of the paren
buffers. They either get reset as we find a new different accepting pathway,
or their state is irrelevant if the overal match is rejected (eg it fails).
However backreferences are different. Consider the following pattern
from the tests
"xa=xaaa" =~ /^(xa|=?\1a){2}\z/
in the first iteration through this the first branch matches, and in fact
because the \1 is in the second branch it can't match on the first iteration
at all. After this $1 = "xa". We then perform the second iteration. "xa" does
not match "=xaaa" so we fall to the second branch. The '=?' matches, but sets
up a backtracking action to not match if the rest of the pattern does not
match. \1 matches 'xa', and then the 'a' matches, leaving an unmatched 'a' in
the string, we exit the quantifier loop with $1 = "=xaa" and match \z against
the remaining "a" in the pattern, and fail.
Here is where things go wrong in the old code, we unwind to the outer loop,
but we do not unwind the paren state. We then unwind further into the 2nds
iteration of the loop, to the '=?' where we then try to match the tail with
the quantifier matching the empty string. We then match the old $1 (which was
not unwound) as "=xaa", and then the "a" matches, and we are the end of the
string and we have incorrectly accpeted this string as matching the pattern.
What should have happend was when the \1 was resolved the second time it
should have returned the same string as it did when the =? matched '=', which
then would have resulted in the tail matching again, and etc, eventually
unwinding the entire pattern when the second iteration failed entirely.
This patch is very crude. It simple pushes the state of the parens and creates
and unwind point for every case where we do a transition to a B or _next
operation, and we make the corresponding _next_fail do the appropriate
unwinding. The objective was to achieve correctness and then work towards
making it more efficient. We almost certainly overstore items on the stack.
In a future patch we can perhaps keep track of the unclosed parens before the
relevant operators and make sure that they are properly pushed and unwound at
the correct times.
Commit: 1c6c16b7c84133562c2d69873087b0c273f83d52
https://github.com/Perl/perl5/commit/1c6c16b7c84133562c2d69873087b0c273f83d52
Author: Yves Orton <demer...@gmail.com>
Date: 2023-01-15 (Sun, 15 Jan 2023)
Changed paths:
M regcomp.c
M regcomp.h
M regcomp.sym
M regcomp_internal.h
M regexec.c
M regexp.h
M regnodes.h
Log Message:
-----------
regexec.c - make REF into a backtracking state
This way we can do the required paren restoration only when it is in use. When
we match a REF type node which is potentially a reference to an unclosed paren
we push the match context information, currently for "everything", but in a
future patch we can teach it to be more efficient by adding a new parameter to
the REF regop to track which parens it should save.
This converts the backtracking changes from the previous commit, so that it is
run only when specifically enabled via the define RE_PESSIMISTIC_PARENS which
is by default 0. We don't make the new fields in the struct conditional as the
stack frames are large and our changes don't make any real difference and it
keeps things simpler to not have conditional members, especially since some of
the structures have to line up with each other.
If enabling RE_PESSIMISTIC_PARENS fixes a backtracking bug then it means
something is sensitive to us not necessarily restoring the parens properly on
failure. We make some assumptions that the paren state after a failing state
will be corrected by a future successful state, or that the state of the
parens is irrelevant as we will fail anyway. This can be made not true by
EVAL, backrefs, and potentially some other scenarios. Thus I have left this
inefficient logic in place but guarded by the flag.
Commit: 7fdd71fd619ed06f41db9b5000fce7f2380c33f1
https://github.com/Perl/perl5/commit/7fdd71fd619ed06f41db9b5000fce7f2380c33f1
Author: Yves Orton <demer...@gmail.com>
Date: 2023-01-15 (Sun, 15 Jan 2023)
Changed paths:
M pod/perldebguts.pod
M regcomp.c
M regcomp.h
M regcomp.sym
M regcomp_debug.c
M regcomp_study.c
M regcomp_trie.c
M regexec.c
M reginline.h
M regnodes.h
Log Message:
-----------
regex engine - simplify regnode structures and make them consistent
This eliminates the regnode_2L data structure, and merges it with the older
regnode_2 data structure. At the same time it makes each "arg" property of the
various regnode types that have one be consistently structured as an anonymous
union like this:
union {
U32 arg1u;
I32 arg2i;
struct {
U16 arg1a;
U16 arg1b;
};
};
We then expose four macros for accessing each slot: ARG1u() ARG1i() and
ARG1a() and ARG1b(). Code then explicitly designates which they want. The old
logic used ARG() to access an U32 arg1, and ARG1() to access an I32 arg1,
which was confusing to say the least. The regnode_2L structure had a U32 arg1,
and I32 arg2, and the regnode_2 data strucutre had two I32 args. With the new
set of macros we use the regnode_2 for both, and use the appropriate macros to
show whether we want to signed or unsigned values.
This also renames the regnode_4 to regnode_3. The 3 stands for "three 32-bit
args". However as each slot can also store two U16s, a regnode_3 can hold up
to 6 U16s, or as 3 I32's, or a combination. For instance the CURLY style nodes
use regnode_3 to store 4 values, ARG1i() for min count, ARG2i() for max count
and ARG3a() and ARG3b() for parens before and inside the quantifier.
Compare: https://github.com/Perl/perl5/compare/3667fb5504f1...7fdd71fd619e
