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Postings from February 2017
On 2017-02-06, at 19:18:20 +0100, Sawyer X wrote:
> Excellent work. Thanks, Dave!
>
> +1!
+1, thanks Dave!
Marcus
> On 02/06/2017 01:30 PM, Dave Mitchell wrote:
> > There are two main things I did in December (along with the usual
> > day-to-day stuff).
> >
> > First I sorted out infrastructure for ops which are called in boolean
> > context.
> >
> > Currently PADHV and RV2HV ops are flagged specially if they are not only
> > used in scalar context, but where the result they return will only
> > ever be used as a boolean value; for example 'if (%h) {...}'
> >
> > This was originally done since a hash in scalar context returned a bucket
> > usage ratio, which became expensive to calculate when we no longer
> > stored the bucket occupancy count with each hash.
> >
> > In 5.25.x we've changed it so that in scalar context it now only returns a
> > key count, which is always known and doesn't need to be calculated on the
> > fly. But it can still be quicker to return just a boolean value in
> > these cases rather than an integer.
> >
> > My work took this special-case boolean context detection code in the
> > peephole optimiser, and improved it so that:
> >
> > * it fixes a bunch of bugs - e.g. if (!%h) {...} wasn't recognised as
> > boolean;
> > * it expands the number of situations that are recognised as boolean
> > context, such as grep: e.g. grep %$_, @AoH;
> > * it adds a reasonably comprehensive set of tests for checking that ops
> > have been flagged as boolean under various boolean scenarios;
> > * it allows other ops to be easily added to the boolean detection in the
> > optimiser; and to the test suite.
> >
> > I've also tweaked RV2HV so that in the negative case it just returns
> > &PL_sv_no rather than sv_2mortal(newSViv(0)))
> >
> > I've also pushed a branch davem/boolref2 that allows the ref() function to
> > be optimised in boolean context; so 'if (ref $r) {...}' doesn't have to
> > generate a temporary string like "Foo=ARRAY(0xc8afd8)". I intend to merge
> > this after 5.26, and maybe booleanise a few more ops too (like length()).
> >
> > The other notable thing I did last month was to change the output format
> > produced by the op_dump() function (and perl -Dx). It now displays an
> > ASCII-art tree structure, and more low-level information is displayed,
> > such as each op's address and class.
> >
> >
> > SUMMARY:
> > 3:21 RT #129285 Perl_gv_fullname4 assertion
> > 0:36 RT #130617 Perl_rpeep: Assertion ....
> > 0:55 RT #130621 Segfault in Perl_vwarner (util.c:2051)
> > 0:49 RT #130648 S_pat_upgrade_to_utf8 Assertion ...
> > 1:17 RT #130651] regcomp.c:6881 Assertion `expr' failed
> > 1:19 RT #130661 perly.c:341: Perl_yyparse: Assertion failed
> > 1:03 RT #130667 Perl_sv_clear Assertion `SvTYPE(sv) != ...
> > 0:52 RT #130669 Perl_sv_2nv_flags: Assertion `SvTYPE(sv) != ...
> > 5:18 [perl #130198] chop(@x =~ tr///)
> > 3:00 [perl #130584] Slow pos function in taint mode with \G
> > 22:53 [perl #78288] ref and other ops are inefficient in boolean context
> > 12:08 change output format of op_dump()
> > 3:20 factor out common optree finalisation code
> > 4:30 general housekeeping
> > 10:41 process p5p mailbox
> > 2:51 review security tickets
> > ------
> > 74:53 TOTAL (HH::MM)
> >
> > 172.3 weeks
> > 2376.7 total hours
> > 13.8 average hours per week
> >
> > There are 423 hours left on the grant
> >
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