Issue #8399 has been updated by jonforums (Jon Forums).


Interesting. What platform(s) did you test this MRI patch against?

I've not tried my Arch, Ubuntu Server, or Snow Leopard VMs yet, but on Win7 32bit with mingw-w64 gcc 4.7.2 I get this
build fail due to not using old C90 style coding in the second hunks `for` loop. I'll tweak your patch and try again.

C:\Users\Jon\Documents\RubyDev\ruby-git>git log -1
commit 00096bdf0dfd2f98f9265449a17f23374975eb3c
Author: nagachika <nagachika / b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date:   Sun May 12 13:51:54 2013 +0000

    * ChangeLog: fix a typo of r40667.

    git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40676 b2dd03c8-39d4-4d8f-98ff-823fe6

...

generating cparse-i386-mingw32.def
compiling ../../../../../../../Users/Jon/Documents/RubyDev/ruby-git/ext/racc/cparse/cparse.c
../../../../../../../Users/Jon/Documents/RubyDev/ruby-git/ext/racc/cparse/cparse.c: In function 'get_stack_tail':
../../../../../../../Users/Jon/Documents/RubyDev/ruby-git/ext/racc/cparse/cparse.c:108:5:
warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
../../../../../../../Users/Jon/Documents/RubyDev/ruby-git/ext/racc/cparse/cparse.c:110:5:
error: 'for' loop initial declarations are only allowed in C99 mode
../../../../../../../Users/Jon/Documents/RubyDev/ruby-git/ext/racc/cparse/cparse.c:110:5:
note: use option -std=c99 or -std=gnu99 to compile your code
make[2]: *** [cparse.o] Error 1
make[2]: Leaving directory `/c/projects/rubyinstaller-git/sandbox/ruby19_build/ext/racc/cparse'
make[1]: *** [ext/racc/cparse/all] Error 2
make[1]: Leaving directory `/c/projects/rubyinstaller-git/sandbox/ruby19_build'
make: *** [build-ext] Error 2
----------------------------------------
Bug #8399: Remove usage of RARRAY_PTR in C extensions when not needed
https://bugs.ruby-lang.org/issues/8399#change-39283

Author: dbussink (Dirkjan Bussink)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: trunk
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


Rubinius uses quite a few C extensions directly from MRI. Some of these use functionality such as RARRAY_PTR which is not necessary. For compatibility reasons, RARRAY_PTR works on Rubinius but suffers from a heavy performance penalty. Take for example the test of the parser gem (http://github.com/whitequark/parser). These run over 10x faster with the patch applied to Racc that is submitted here:

https://gist.github.com/dbussink/57c32c08fb21c7a41719

Consider issue #8339 where there is work being done on generational GC, I think it is also beneficial to remove usage of internal structures such as RARRAY_PTR where there is the problem of going around the write barrier. In Rubinius, an array is treated special if RARRAY_PTR is used on it in the C-API, so I can imagine MRI being able to optimize the GC better if extensions don't do this. There are functions available for both getting and setting elements in an array and they work fine.

I have only make a patch against Racc here as a showcase, I also want to update all the other extensions to remove RARRAY_PTR. Please consider this change to MRI since in my opinion it has benefits also for MRI and so Rubinius can keep using these extensions directly without having to maintain custom versions just for the considerations described here. I'm also already actively checking C extension gems and sending pull requests for updating this.



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