GCC 3.4.0 Released

AaronW writes "While checking the GCC website I saw that GCC version 3.4 was officially released on April 18th. Version 3.4 includes numerous changes and enhancements, including better optimization, and the ability to build a profiled version of gcc which is 7.5-11% faster on i386 hardware. Be kind and please use one of the mirror sites."

Comments

Not officially released yet

[RML]

This announcement is premature, it's still propagating to mirrors; the "announcment" is an error. The official release will be tomorrow.

Thanks

[Markus Registrada]

I don't know about the other bundled compilers, but the 3.4 C++ compiler and library are the best ever in Gcc, by far.

If you run across them, be sure to thank Paolo Carlini, Petur Runolfsson, and Jerry Quinn for making 3.4 iostreams as fast as (and often faster than) Glibc's stdio. Thank them, too for making filebuf support large files (>2G) natively without any code or build changes needed, on any target that allows them.

Worth noting, too, is that this is the first release in which the library is part of the ABI. Every previous release since 2.95 has had to increment the libstdc++.so version number, but future 3.4 (and maybe 3.5) releases should be backward compatible. Ask your distribution maintainers to ship 3.4-built versions of all C++ libraries they package, so that they will be compatible with programs built with this and future releases.

Broken C++ ABI ... again

[Lumpish Scholar]

They broke binary compatibility in gcc 3.0, and again in 3.2, and now in 3.4.

What do you think the outlook is for binary compatibility with 3.6?

Re:GCJ

[rmathew]

Swing/AWT using Gtk+ peers has been making tremendous progress in the last few months thanks to a bunch of Red Hat hackers and is quite usable as can be seen here for example.

Unfortunately, these changes are not a part of the 3.4.0 release of GCC/GCJ and will only be available from 3.5.0 (or 4.0.0, as the case might be).

New Features

[AT]

In addition to the usual bug fixes, there are some cool new features in gcc 3.4. Here is the full list; some of the more interesting stuff:

• unit (file) at a time compilation with -funit-at-a-time; now gcc can finally do some limited global (cross-function) optimization
  
• profile feedback (-fprofile-generate -fprofile-use options) that allows gcc to optimize based on feedback from runtime
  
• precompiled header files for huge compilation speed gains
  
• C++ now much closer to ISO standard
  

Re:Fixed C++ ABI ... finally

[cimetmc]

A post above contradicts this, so I may be wrong about this...but I DO think I was remembering the binary incompatibility occurring in the 3.3 series correctly in this case. (My impression is that 3.4 doesn't have too many 'new features' beyond 3.3, but had more of a focus on optimizing the compile speed of 3.3.)

Well, you are wrong in a number of ways:

1) Like you already noticed yourself, GCC doesn't have the even/odd numbered version logic of Linux. Each version number is a release version. Development versions have the next release version with a date attached to the version. The development process is formalized and is described here

2) GCC 3.4 is a regular new version with a number of new features. It is certainly not a minor version with just some compile speed tuning. I would consider the changes from 3.3 to 3.4 bigger than the previous changes from 3.2 to 3.3.

3) The real oddball in the GCC 3.x series is GCC 3.2.x. This is just a bugfix version of GCC 3.1. However as some of the bugs fixed were a major C++ ABI issue and fixing those bugs lead to incompatibility, the GCC developers decicded to exceptionally increment the version number not following the regular release scheme.

Marcel