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Re: [PATCH] doloop_optimize miscompiles openssl

Franz Sirl writes:

 > Hmm, already lying in bed, it occurred to me that I'm not sure about the 
 > exact definition for loop->exit_count. I seem to remember (I can't test 
 > right now) that it was set to 3 for the testcase, this would mean the main 
 > loop exit isn't counted here and I have to compare for >0, not >1.

Unfortunately, some of this is rather ad-hoc and is one of the reasons
I'm rewriting the loop optimizer to use the CFG.  Reading between the
lines, I assume that loop->exit_count is 3 but
loop_info->has_multiple-exit_targets is 0 for your testcase?

 > In the meantime, while browsing the code, I found another suspicious code 
 > fragment:

<code snipped>

 > Do we need to prefer loop->top here too? The comment doesn't specify if the 
 > initialization is needed on every loop run...

 > Maybe the originator of the code should comment on the patches?

It's only needed once before the loop starts.  

 > BTW, I will try to turn both testcases in this thread into executable 
 > testcases.

This would be useful.  I haven't had a chance to look at this thread
yet; could you post me a simple testcase?


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