Hello again, Valgrind community. I have filed the following bug report: https://bugs.kde.org/show_bug.cgi?id=294285
(By the way, "3.8.0SVN" is not presently an option for the "Version" drop-down when filing a bug.) Background: I am using Valgrind on optimized SSE4.2 output from the Intel C Compiler. I am seeing massive amounts of "Invalid read of size 8" false positives. I believe these false positives would disappear if "--partial-loads-ok=yes" worked as documented. The problem is that it does not work for 16-byte SSE loads; Valgrind's behavior appears to be to treat such loads as a pair of 8-byte loads. Note that GCC has started to emit similar code (https://bugs.kde.org/show_bug.cgi?id=294285), and I suspect it will only become more common as compilers get smarter. Questions: 1) Am I correct that this is a bug? 2) How hard would it be to fix? Specifically, is this something a skilled C programmer with no prior knowledge of Valgrind might be able to tackle in a reasonable timeframe? :-) Thanks. - Pat P.S. In my opinion, the documentation for "--partial-loads-ok" is overly discouraging (http://valgrind.org/docs/manual/mc-manual.html#opt.partial-loads-ok). Valgrind operates on machine code, not C/C++ code, so references to the C/C++ standards are not relevant. Aligned loads simply cannot generate a fault halfway through, and such loads are standard practice in optimized code. As long as the uninitialized portion of the word goes unused, there is no problem in theory nor practice. I would even argue that "--partial-loads-ok=yes" should be the default... P.P.S. Thank you for Valgrind; it is a tremendous tool. ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
