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Date: Mon, 30 Aug 2010 10:26:41 -0400
From: Edward Lam <edward AT sidefx DOT com>
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Subject: Uninitialized variable usage in cygthread?
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Hi,

In looking at slowdown problem on x64 systems by Sagi Ben-Akiva, I found 
some puzzling code that perhaps someone could enlighten me on. I must be 
reading it wrong.

Here's the code path that I'm tracing using cygwin-src-20100829.tar.bz2:

- In dcrt0.cc, if dynamically_loaded is true, then we call sigproc_init().

- In sigproc.cc, sigproc_init() creates a new thread:
   hwait_sig = new cygthread (wait_sig, 0, cygself, "sig");

- This calls the cygthread constructor for LPTHREAD_START_ROUTINE. 
(Actually, this doesn't really matter because the constructor for 
LPVOID_START_ROUTINE looks like it has the same problem.)

- The cygthread constructor calls create(). But prior to this, the 
following class members are initialized:
__name, func, arglen, arg, notify_detached

- The following class members are NOT initialized (assuming that the 
macro DEBUGGING is NOT set):
inuse, id, h, ev, thread_sync, stack_ptr, is_freerange

- Ok, now the cygthread constructor calls cygthread::create()

- In cygthread.cc, cygthread::create() immediately checks the value of 
the variable "h". But as mentioned previously, this is a variable that 
has not been initialized yet.


What am I missing?

Thanks,
-Edward

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