[PATCH] simulate-thread tweaks and fixes

[Andrew MacLeod]

I've been toying with the simulate-thread framework a bit.  With the 
timeout threshold is back to where it originally was, the spectre of 
huge log files when an infinite loop happens is back.

This patch has the following modifications:

1) An instruction count threshold has been added.
       This will truly prevent infinite loops which were the original 
issue.  If the count reaches the threshold value, the test case fails.   
I've set the current limit to 10,000, which I would expect to be 
sufficient. The highest Ive seen so far is 877, but I'm sure someone 
will find something higher :-).  A testcase can override this value if 
it wishes.  If we encounter targets where this is not high enough, we 
can raise it further.  The main point is to avoid generating 10's of 
gigabytes of log files when a fast machine hits an infinite loop and the 
time based timeout doesnt kick in quickly enough.
   If a test does fail for this reason, the log file will issue a FAIL 
message indicating the instruction count threshold was exceeded.

2) I tweaked the atomic-load-int128.c testcase to avoid an inadvertent 
hostile thread situation that was not intended.

3) The  speculative-store.c testcase had a bug in it where the verify 
function was not returning a value when successful. ThIs resulted in an 
UNSUPPORTED result occasionally because the testcase didn't run far 
enough to indicate GDB had successfully run, yet no FAIL was issued.

4) I lowered the hostile thread threshold by an order of magnitude so 
that if a hostile thread is encountered frequently, it wont rapidly 
approach the new instruction count threshold.  This could happen on 
compare_and_swap loop targets.

I've tried this on x86_64-unknown-linux-gnu and everything seems good.   
If anyone wants to try it on their more stressed arch, all you need to 
do is apply the patch to the testsuite and run 'make check-gcc 
RUNTESTFLAGS=simulate-thread.exp' to see if the results are as expected.

OK for mainline?

Andrew




-------------- next part --------------
A non-text attachment was scrubbed...
Name: simulate.diff
Type: text/x-patch
Size: 7240 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/gcc-patches/attachments/20120224/b731c777/attachment.bin>