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Perl_debug_log and Perl_error_log macro handles must be cached to avoid multiple evaluation #12602

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p5pRT opened this issue Nov 22, 2012 · 4 comments
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Perl_debug_log and Perl_error_log macro handles must be cached to avoid multiple evaluation #12602

p5pRT opened this issue Nov 22, 2012 · 4 comments
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distro-mswin32 type-core

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@p5pRT
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p5pRT commented Nov 22, 2012

Migrated from rt.perl.org#115858 (status was 'rejected')

Searchable as RT115858$
@p5pRT
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p5pRT commented Nov 22, 2012

From @bulk88

Created by @bulk88

In gv_dump,
http​://perl5.git.perl.org/perl.git/blob/b3efb2487fa7bdef70865822dabaa2dc0000dde1​:/dump.c#l1165
, Perl_debug_log is a func call on my perl. Perl_debug_log is a macro
for Perl_PerlIO_stderr(my_perl), which is called 6 times in gv_dump
unnecessarily. Similar problems exist in ~1300 places (grepping the
interp, not any XS modules) in the interp as
"PerlIO_printf(Perl_debug_log". I suggest a PerlIO_printf_dbl (dbl=debug
log) that calls PerlIO_vprintf with the
Perl_debug_log/Perl_PerlIO_stderr(my_perl) call abstracted to
PerlIO_printf_dbl and not be in the caller wasting a couple bytes of L1
for an exceptional or rare branch. Debug channel stuff I don't think
deserved high performance. The other choice is to cache Perl_debug_log
at the start of the funcs that use it as an auto or at the start of a
block of a branch of stderr writes.

Perl_error_log macro is even worse than Perl_debug_log macro. It is
defined at
http​://perl5.git.perl.org/perl.git/blob/b3efb2487fa7bdef70865822dabaa2dc0000dde1​:/perl.h#l3651
and evaluates to this large tree of branches
______________________________________________________________
((my_perl->Istderrgv)
  && (((svtype) (((my_perl->Istderrgv))->sv_flags &
0xff)) == SVt_PVGV)
  && ((0 + ((my_perl->Istderrgv))->sv_u.svu_gp)->gp_io)
  && ((XPVIO *) (((0 +
((my_perl->Istderrgv))->sv_u.svu_gp)->gp_io))->sv_any)->
  xio_ofp ? ((XPVIO *) (((0 +
((my_perl->Istderrgv))->sv_u.svu_gp)->gp_io))->sv_any)->
  xio_ofp : Perl_PerlIO_stderr(my_perl))
______________________________________________________________

grepping says ~100 places for Perl_error_log. Sometimes its written 2 or
more times in the same func (
http​://perl5.git.perl.org/perl.git/blob/b3efb2487fa7bdef70865822dabaa2dc0000dde1​:/pp_ctl.c#l1664
), and of course the machine instructions are placed and executed twice
in a row (I checked that), compiler doesn't know that Perl_PerlIO_write
won't change PL_stderrgv.

Here is a list of all funcs on my perl build (no DEBUGGING/other special
debug macro defs are on), that call Perl_PerlIO_stderr more than once.
The number of times written, is the number of times that
Perl_PerlIO_stderr is referenced in that function.
___________________________________________________
Perl_call_list
Perl_call_list
Perl_debop
Perl_debop
Perl_debop
Perl_debop
Perl_debop
Perl_debop
Perl_debop
Perl_die_unwind
Perl_die_unwind
Perl_die_unwind
Perl_die_unwind
Perl_do_openn
Perl_do_openn
Perl_do_openn
Perl_dump_form
Perl_dump_form
Perl_dump_sub_perl
Perl_dump_sub_perl
Perl_dump_sub_perl
Perl_gv_dump
Perl_gv_dump
Perl_gv_dump
Perl_gv_dump
Perl_gv_dump
Perl_gv_dump
Perl_init_i18nl10n
Perl_init_i18nl10n
Perl_init_i18nl10n
Perl_init_i18nl10n
Perl_init_i18nl10n
Perl_init_i18nl10n
Perl_init_i18nl10n
Perl_init_i18nl10n
perl_parse
perl_parse
perl_parse
perl_parse
Perl_re_op_compile
Perl_re_op_compile
perl_run
perl_run
Perl_runops_debug
Perl_runops_debug
Perl_sighandler
Perl_sighandler
S_my_exit_jump
S_my_exit_jump
S_regatom
S_regatom
S_regatom
S_regatom
S_regmatch
S_regmatch
win32_start_child
win32_start_child
________________________________________________

Some relevant git blame links

http​://perl5.git.perl.org/perl.git/blobdiff/65cec58980c279c041788ef30ee8617e63ab5229..bf49b05​:/perl.h

http​://perl5.git.perl.org/perl.git/blobdiff/dedcbb81b3c2f4f742df48d1d5918ae3c9eed4de..42de951​:/perl.h
http​://perl5.git.perl.org/perl.git/blobdiff/b38af7adab46822ec7c92d231d7fbb058dc22c4c..01bb7c6​:/perl.h
http​://perl5.git.perl.org/perl.git/blobdiff/aed17120f1d71c676ff756013d9027da2cec8e83..6b78add​:/perl.h

Perl Info 

Flags:
    category=core
    severity=low

Site configuration information for perl 5.17.6:

Configured by Owner at Mon Nov 19 20:00:41 2012.

Summary of my perl5 (revision 5 version 17 subversion 6 patch blead 
2012-11-20.00:13:41 4c88d5e0740d796bf5064336d280bba72897f385 
v5.17.5-576-g4c88d5e) configuration:
  Snapshot of: 4c88d5e0740d796bf5064336d280bba72897f385
  Platform:
    osname=MSWin32, osvers=5.1, archname=MSWin32-x86-multi-thread
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cl', ccflags ='-nologo -GF -W3 -MD -Zi -DNDEBUG -O1 -GL -G7 
-DWIN32 -D_CONSOLE -DNO_STRICT  -DPERL_TEXTMODE_SCRIPTS 
-DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO 
-D_USE_32BIT_TIME_T',
    optimize='-MD -Zi -DNDEBUG -O1 -GL -G7',
    cppflags='-DWIN32'
    ccversion='13.10.6030', gccversion='', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=8
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='__int64', 
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='link', ldflags ='-nologo -nodefaultlib -debug -opt:ref,icf 
-ltcg  -libpath:"c:\perl517\lib\CORE"  -machine:x86'
    libpth="C:\Program Files\Microsoft Visual Studio .NET 2003\VC7\lib"
    libs=oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib  
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  
netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib  version.lib 
odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
    perllibs=oldnames.lib kernel32.lib user32.lib gdi32.lib 
winspool.lib  comdlg32.lib advapi32.lib shell32.lib ole32.lib 
oleaut32.lib  netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib  
version.lib odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
    libc=msvcrt.lib, so=dll, useshrplib=true, libperl=perl517.lib
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -debug 
-opt:ref,icf -ltcg  -libpath:"c:\perl517\lib\CORE"  -machine:x86'

Locally applied patches:
    


@INC for perl 5.17.6:
    C:/perl517/site/lib
    C:/perl517/lib
    .


Environment for perl 5.17.6:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=C:\perl517\bin;C:\Program Files\Microsoft Visual Studio .NET 
2003\Common7\IDE;C:\Program Files\Microsoft Visual Studio .NET 
2003\VC7\BIN;C:\Program Files\Microsoft Visual Studio .NET 
2003\Common7\Tools;C:\Program Files\Microsoft Visual Studio .NET 
2003\Common7\Tools\bin\prerelease;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\system32\wbem;
    PERL_BADLANG (unset)
    SHELL (unset)

@p5pRT
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p5pRT commented Nov 13, 2017

From zefram@fysh.org

, Perl_debug_log is a func call on my perl. Perl_debug_log is a macro
for Perl_PerlIO_stderr(my_perl), which is called 6 times in gv_dump
unnecessarily.

I'm not worried about the performance of exception and debugging code.
This ticket should be closed.

-zefram

@p5pRT
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p5pRT commented Nov 13, 2017

The RT System itself - Status changed from 'new' to 'open'

@p5pRT p5pRT closed this as completed Nov 13, 2017
@p5pRT
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p5pRT commented Nov 13, 2017

@cpansprout - Status changed from 'open' to 'rejected'

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