-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Dear users and developers of sdcc,
redundancy elimination currently is one of the weaker aspects of sdcc (it has just cse and gcse). I have implemented the AFAIK best currently known redundancy elimination technique, lifetime-optimal speculative partial redundancy elimination (lospre) in the lospre branch. For more theoretical background on lospre see "A life-time optimal algorithm for speculative PRE" by Jingling Xue and Qiong Cai. I have implemented lospre as an additional optimization pass, after gcse, since there are too many things interwined with the gcse code, even though in principle lospre can do anything gcse and cse (and some other redundancy elimination techniques) can do. If you want to try it, you can obtain it using svn co https://sdcc.svn.sourceforge.net/svnroot/sdcc/branches/lospre/sdcc sdcc-lospre In case you notice any bugs or regressions in code size compared to the realease candidates, please report them. The current state is as follows: Passes all regression tests for z80-related and hc08-related ports, giving a reduction in code size. For mcs51 (and ds390) there is a compiler crash in 1 (3) of the regression tests, but these are most likely bugs in the backends, not the lospre implementation. Otherwise there is one regression failure in mcs51 and two regression failures in ds390. There are two new command line options related to lospre: - --no-lospre : Disables lospre. - --lospre-unsafe-read : Allow unsafe read optimization. This can further reduce code size, but result in reads from random memory locations. You should not use this option if there is memory protection/management or memory-mapped I/O. My current plan is to merge the lospre branch sometime next week, after the 3.2.0 release. Due to the current problems on mcs51 and ds390, I will disable lospre except for the z80-related and hc08-related ports then. Philipp -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk/4QPAACgkQbtUV+xsoLprRsQCeJhuppTYNBzXO1iSdndjt7IIi 7ucAnRHuT/JTqkartGlY+WJhdRqVInJH =NPG7 -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Sdcc-user mailing list Sdcc-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sdcc-user
