bugzilla-daemon at mindrot.org
2015-Jun-06 21:31 UTC
[Bug 1753] Use -funroll-loops with umac.c
https://bugzilla.mindrot.org/show_bug.cgi?id=1753 Michael Felt <aixtools at gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |aixtools at gmail.com --- Comment #3 from Michael Felt <aixtools at gmail.com> --- As far as POWER goes (more specifically, AIX and xlc) there is a PDF describing the optimization 'process' when using vac/xlc as a compiler. The document # for VAC-v11 is SC27-2478-00 (or higher for the last two digits - the revision number). Here is a starting point for documentation: http://www-01.ibm.com/support/knowledgecenter/SSGH2K_11.1.0/com.ibm.xlc111.aix.doc/conventions/compiler_pubs.html On page (printed) page 47 (Chapter 7. Optimizing your applications) the path of moving from -O2 to higher degrees of optimization is discussed. On pages 48 and 49 it discusses -O3, -O4 and -O5 - and the bottom of page 49 discusses only adding the a variation of the options -qhot to act on loop transformations. In summary, -funroll-loops is not a vac/xlc flag I am aware of - but there is documentation to be had to help setup your own customization. imho, anything beyond -O2 needs careful. At least for xlc/vac, unless you specify -qstrict with -O3 and above you are permitting the compiler to reorder code (blocks). -- You are receiving this mail because: You are watching someone on the CC list of the bug. You are watching the assignee of the bug.