Branch: refs/heads/blead
Home: https://github.com/Perl/perl5
Commit: c107bb0b9c05a0ad0390ca4d42f0eaf567047bcd
https://github.com/Perl/perl5/commit/c107bb0b9c05a0ad0390ca4d42f0eaf567047bcd
Author: Richard Leach <[email protected]>
Date: 2025-01-13 (Mon, 13 Jan 2025)
Changed paths:
M peep.c
M pp.h
Log Message:
-----------
Add MAXARG3 for neater checking of small argument counts
Variants are named to match the style of macros in op.h
Commit: cdbed2a40eb1292d5be2fd59c091cf78f6a4be69
https://github.com/Perl/perl5/commit/cdbed2a40eb1292d5be2fd59c091cf78f6a4be69
Author: Richard Leach <[email protected]>
Date: 2025-01-13 (Mon, 13 Jan 2025)
Changed paths:
M MANIFEST
M ext/Opcode/Opcode.pm
M lib/B/Deparse.pm
M lib/B/Deparse.t
M lib/B/Op_private.pm
M opcode.h
M opnames.h
M peep.c
M pp.c
M pp_proto.h
M regen/op_private
M regen/opcodes
A t/op/substr_left.t
M t/perf/benchmarks
M t/perf/opcount.t
Log Message:
-----------
OP_SUBSTR_LEFT - a specialised OP_SUBSTR variant
This commit adds OP_SUBSTR_LEFT and associated machinery for fast
handling of the constructions:
substr EXPR,0,LENGTH,''
and
substr EXPR,0,LENGTH
Where EXPR is a scalar lexical, the OFFSET is zero, and either there
is no REPLACEMENT or it is the empty string. LENGTH can be anything
that OP_SUBSTR supports. These constraints allow for a very stripped
back and optimised version of pp_substr.
The primary motivation was for situations where a scalar, containing
some network packets or other binary data structure, is being parsed
piecemeal. Nibbling away at the scalar can be useful when you don't
know how exactly it will be parsed and unpacked until you get started.
It also means that you don't need to worry about correctly updating
a separate offset variable.
This operator also turns out to be an efficient way to (destructively)
break an expression up into fixed size chunks. For example, given:
my $x = ''; my $str = "A"x100_000_000;
This code:
$x = substr($str, 0, 5, "") while ($str);
is twice as fast as doing:
for ($pos = 0; $pos < length($str); $pos += 5) {
$x = substr($str, $pos, 5);
}
Compared with blead, `$y = substr($x, 0, 5)` runs 40% faster and
`$y = substr($x, 0, 5, '')` runs 45% faster.
Commit: a3a7684e4cf709f359f6dc550a9712044d24cfec
https://github.com/Perl/perl5/commit/a3a7684e4cf709f359f6dc550a9712044d24cfec
Author: Richard Leach <[email protected]>
Date: 2025-01-13 (Mon, 13 Jan 2025)
Changed paths:
M peep.c
M pp.c
Log Message:
-----------
Use new MAXARG3 macros for readability
Commit: 61978476912ee303cc78e7bf09602a4b38f3d75e
https://github.com/Perl/perl5/commit/61978476912ee303cc78e7bf09602a4b38f3d75e
Author: Richard Leach <[email protected]>
Date: 2025-01-13 (Mon, 13 Jan 2025)
Changed paths:
M pp.c
Log Message:
-----------
pp_substr: tweak len_is_uv assignment for readability
As suggested in https://github.com/Perl/perl5/pull/22785
Compare: https://github.com/Perl/perl5/compare/8282950bdf10...61978476912e
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