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defined operator not constant folded #16266

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defined operator not constant folded#16266
#23349
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richardleach
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Feature Requesttype-core
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@p5pRT
p5pRT
opened on Nov 21, 2017

Migrated from rt.perl.org#132480 (status was 'new')

Searchable as RT132480$

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p5pRT

p5pRT commented on Nov 21, 2017

@p5pRT
p5pRT
on Nov 21, 2017 · edited by toddr
Author

From @bulk88

The defined operator on a constant should be folded, it isn't. The 9 is folded, but it stops at the defined operator.

use strict;
use B::Concise;
use constant (PARENT_STATION => 9);

my %stop_id_translate;
sub import_stop_times {
my $record = shift;
return defined(PARENT_STATION) && exists
$stop_id_translate{$record->[3]}
? $stop_id_translate{$record->[3]}
: $record->[3];
}
my $walker = B::Concise::compile('-exec','import_stop_times',
\&import_stop_times); # 1
$walker->();
main::import_stop_times:
1 <;> nextstate(main 175 t.pl:7) v:*,&,x*,x&,x$,$
2 <0> shift s*
3 <0> padsv[$record:175,176] sRM*/LVINTRO
4 <2> sassign vKS/2
5 <;> nextstate(main 176 t.pl:9) v:*,&,x*,x&,x$,$
6 <$> const[IV 9] s*/FOLD
7 <1> defined sK/1
8 <|> and(other->9) sK/1
9 <0> padhv[%stop_id_translate:FAKE:] sR
a <+> multideref($record->[3]) sK/STRICT
b <1> exists sK/1
c <|> cond_expr(other->d) K/1
d <0> padhv[%stop_id_translate:FAKE:] sR
e <+> multideref($record->[3]) sK/STRICT
f <2> helem sK/2
goto g
h <+> multideref($record->[3]) sK/STRICT
g <1> leavesub[1 ref] K/REFC,1

If I do a different expression

use strict;
use B::Concise;
use constant (PARENT_STATION => 9);

my %stop_id_translate;
sub import_stop_times {
my $record = shift;
return PARENT_STATION == 0 && exists $stop_id_translate{$record->[3]}
? $stop_id_translate{$record->[3]}
: $record->[3];
}
my $walker = B::Concise::compile('-exec','import_stop_times',
\&import_stop_times); # 1
$walker->();
main::import_stop_times:
1 <;> nextstate(main 175 t.pl:7) v:*,&,x*,x&,x$,$
2 <0> shift s*
3 <0> padsv[$record:175,176] sRM*/LVINTRO
4 <2> sassign vKS/2
5 <;> nextstate(main 176 t.pl:9) v:*,&,x*,x&,x$,$
6 <+> multideref($record->[3]) sK/STRICT
7 <1> leavesub[1 ref] K/REFC,1

The correct branch is correctly removed. Another example

use strict;
use B::Concise;
use constant (PARENT_STATION => 9);

my %stop_id_translate;
sub import_stop_times {
my $record = shift;
return PARENT_STATION == 9 && exists $stop_id_translate{$record->[3]}
? $stop_id_translate{$record->[3]}
: $record->[3];
}
my $walker = B::Concise::compile('-exec','import_stop_times',
\&import_stop_times); # 1
$walker->();
main::import_stop_times:
1 <;> nextstate(main 175 t.pl:7) v:*,&,x*,x&,x$,$
2 <0> shift s*
3 <0> padsv[$record:175,176] sRM*/LVINTRO
4 <2> sassign vKS/2
5 <;> nextstate(main 176 t.pl:9) v:*,&,x*,x&,x$,$
6 <0> padhv[%stop_id_translate:FAKE:] sR
7 <+> multideref($record->[3]) sK/STRICT
8 <1> exists sK/1,FOLD
9 <|> cond_expr(other->a) K/1
a <0> padhv[%stop_id_translate:FAKE:] sR
b <+> multideref($record->[3]) sK/STRICT
c <2> helem sK/2
goto d
e <+> multideref($record->[3]) sK/STRICT
d <1> leavesub[1 ref] K/REFC,1
Perl Info 

Flags:
    category=core
    severity=low

Site configuration information for perl 5.22.1:

Configured by strawberry-perl at Mon Dec 14 09:30:58 2015.

Summary of my perl5 (revision 5 version 22 subversion 1) configuration:
   
  Platform:
    osname=MSWin32, osvers=6.3, archname=MSWin32-x86-multi-thread-64int
    uname='Win32 strawberry-perl 5.22.1.1 #1 Mon Dec 14 09:28:33 2015 i386'
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    use64bitint=define, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags =' -s -O2 -DWIN32  -DPERL_TEXTMODE_SCRIPTS 
-DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -fwrapv -fno-strict-aliasing 
-mms-bitfields',
    optimize='-s -O2',
    cppflags='-DWIN32'
    ccversion='', gccversion='4.9.2', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678, 
doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12, 
longdblkind=3
    ivtype='long long', ivsize=8, nvtype='double', nvsize=8, Off_t='long 
long', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='g++', ldflags ='-s -L"C:\sperl\perl\lib\CORE" -L"C:\sperl\c\lib"'
    libpth=C:\sperl\c\lib C:\sperl\c\i686-w64-mingw32\lib 
C:\sperl\c\lib\gcc\i686-w64-mingw32\4.9.2
    libs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 
-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr 
-lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    perllibs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool 
-lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid 
-lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    libc=, so=dll, useshrplib=true, libperl=libperl522.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=xs.dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-mdll -s -L"C:\sperl\perl\lib\CORE" 
-L"C:\sperl\c\lib"'



@INC for perl 5.22.1:
    C:/sperl/perl/site/lib/MSWin32-x86-multi-thread-64int
    C:/sperl/perl/site/lib
    C:/sperl/perl/vendor/lib
    C:/sperl/perl/lib
    .


Environment for perl 5.22.1:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    
PATH=C:\sperl\c\bin;C:\sperl\perl\site\bin;C:\sperl\perl\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\system32\wbem;
    PERL_BADLANG (unset)
    PERL_JSON_BACKEND=Cpanel::JSON::XS
    PERL_YAML_BACKEND=YAML
    SHELL (unset)
p5pRT
added
Severity Low
affects-5.22
distro-mswin32
type-core
on Oct 19, 2019
toddr
added
Feature Request
and removed
distro-mswin32
on Feb 13, 2020
xenu
removed
affects-5.22
on Nov 19, 2021
xenu
removed
Severity Low
on Dec 29, 2021
richardleach
self-assigned this
on Jun 1, 2025
richardleach

richardleach commented on Jun 1, 2025

@richardleach
richardleach
on Jun 1, 2025
Contributor

The defined operator isn't marked as foldable in regen/opcodes. Not sure why - because it would break something, or trying to avoid spending compile time on something that probably isn't going to be foldable very often?

richardleach

richardleach commented on Jun 1, 2025

@richardleach
richardleach
on Jun 1, 2025
Contributor

After a quick test run, setting defined to be foldable does cause failures, but I haven't looked into them yet.

porting/checkcfgvar.t                                              (Wstat: 0 Tests: 14 Failed: 7)
  Failed tests:  2, 4, 6, 8, 10, 12, 14
porting/exec-bit.t                                                 (Wstat: 0 Tests: 141 Failed: 1)
  Failed test:  141
richardleach

richardleach commented on Jun 1, 2025

@richardleach
richardleach
on Jun 1, 2025
Contributor

setting defined to be foldable does cause failures

Ran on the wrong branch. There are actually no test failures and folding does work.

./perl -MO=Concise -Ilib -e 'use constant ONE => "bibble"; if (defined(ONE)) { print "boop" }'
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter v ->2
2     <;> nextstate(main 186 -e:1) v:{ ->3
-     <@> scope vK/FOLD ->6
-        <;> ex-nextstate(main 188 -e:1) v ->3
5        <@> print vK ->6
3           <0> pushmark s ->4
4           <$> const[PV "boop"] s ->5
-e syntax OK

And on the original example:

main::import_stop_times:
1  <;> nextstate(main 178 88test.pl:7) v:*,&,x*,x&,x$,$
2  <0> shift s*
3  <1> padsv_store[$record:178,179] vKS/LVINTRO
4  <;> nextstate(main 179 88test.pl:10) v:*,&,x*,x&,x$,$
5  <0> padhv[%stop_id_translate:FAKE:] sR
6  <+> multideref($record->[3]) sK/STRICT
7  <1> exists sK/1,FOLD
8  <|> cond_expr(other->9) K/1
9      <0> padhv[%stop_id_translate:FAKE:] sR
a      <+> multideref($record->[3]) sK/STRICT
b      <2> helem sK/2
           goto c
d  <+> multideref($record->[3]) sK/STRICT
c  <1> leavesub[1 ref] K/REFC,1
richardleach
mentioned this on Jun 1, 2025
richardleach
closed this as completedin #23349on Jul 14, 2025
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      defined operator not constant folded · Issue #16266 · Perl/perl5