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Date: Mon, 27 Jul 2015 23:23:30 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Ambiguous pointer increments

The beignet OpenCL driver complained about oldoffice kernel, "multiple 
unsequenced modifications to 'p'" for things like the below:

-               for (i = 0; i < 32; i += 2)
-                       W[i >> 1] = (uint)*p++ | (*p++ << 16U);

I already changed it but I'm curious - no other driver complained.

+               for (i = 0; i < 32; i += 2) {
+                       W[i >> 1] = (uint)*p++;
+                       W[i >> 1] |= (*p++ << 16U);
+               }

Originally I thought they (the use/increments of p) were guaranteed to 
be left-to-right but after this I'm not sure at all. Anyone know for 
sure? Alexander Cherepanov perhaps? In case it matters, OpenCL is C99.

magnum

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