Re: Improve DOM's ability to derive equivalences when traversing edges

[Jeff Law <law at redhat dot com>]

On 08/29/2017 03:13 AM, Christophe Lyon wrote:
> Hi Jeff,
[ ... ]
>>
>> commit a370df2c52074abbb044d1921a0c7df235758050
>> Author: law <law@138bc75d-0d04-0410-961f-82ee72b054a4>
>> Date:   Tue Aug 29 05:03:36 2017 +0000
>>
>>             * tree-ssa-dom.c (edge_info::record_simple_equiv): Call
>>             derive_equivalences.
>>             (derive_equivalences_from_bit_ior, record_temporary_equivalences):
>>             Code moved into....
>>             (edge_info::derive_equivalences): New private member function
>>
>>             * gcc.dg/torture/pr57214.c: Fix type of loop counter.
>>             * gcc.dg/tree-ssa/ssa-sink-16.c: Disable DOM.
>>             * gcc.dg/tree-ssa/ssa-dom-thread-11.c: New test.
>>             * gcc.dg/tree-ssa/ssa-dom-thread-12.c: New test.
>>             * gcc.dg/tree-ssa/ssa-dom-thread-13.c: New test.
>>             * gcc.dg/tree-ssa/ssa-dom-thread-14.c: New test.
>>             * gcc.dg/tree-ssa/ssa-dom-thread-15.c: New test.
>>             * gcc.dg/tree-ssa/ssa-dom-thread-16.c: New test.
>>             * gcc.dg/tree-ssa/ssa-dom-thread-17.c: New test.
>>
>>     git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@251397 138bc75d-0d04-0410-961f-82ee72b054a4
>>
> 
> 3 of the new tests fail on arm-none-linux-gnueabihf
> --with-cpu=cortex-a15 --with-fpu=vfpv3-d16-fp16
> 
> FAIL:    gcc.dg/tree-ssa/ssa-dom-thread-11.c scan-tree-dump-times dom2
> "Threaded" 1
> FAIL:    gcc.dg/tree-ssa/ssa-dom-thread-14.c scan-tree-dump-times dom2
> "Threaded" 1
> FAIL:    gcc.dg/tree-ssa/ssa-dom-thread-16.c scan-tree-dump-times dom2
> "Threaded" 1
> 
> they do pass when configuring for cpu cortex-a9/a15 and fpu neon-fp16/neon-vfpv4
> 
> I do not have the dumps since it's automated testing; let me know if
> you need me to
> reproduce it manually and extract the dumps.
Strange.  I can't reproduce this.

/home/law/gcc-testing/gcc2/configure --target=arm-none-linux-gnueabihf
--with-cpu=cortex-a15 --with-fpu=vfpv3-d16-fp16

[ Wait for build... ]
make check-gcc RUNTESTFLAGS=tree-ssa.exp=ssa-dom-thread-11.c

Gets me 2 passes.  If I run it manually and look at the dumps it
produces exactly the code I would expect.

Is something perhaps passing down a -mtune or other option?

./cc1 -quiet -v -iprefix
/opt/notnfs/law/gcc-testing/arm/gcc/../lib/gcc/arm-none-linux-gnueabihf/8.0.0/
-isystem ./include -isystem ./include-fixed j.c -quiet -dumpbase j.c
-mcpu=cortex-a15 -mfpu=vfpv3-d16-fp16 -mtls-dialect=gnu -marm
-march=armv7ve -auxbase j -O2 -version -o /tmp/cc6vzJl6.s
-fdump-tree-all-blocks-details
GNU C11 (GCC) version 8.0.0 20170829 (experimental)
(arm-none-linux-gnueabihf)
        compiled by GNU C version 6.3.1 20161221 (Red Hat 6.3.1-1), GMP
version 6.1.1, MPFR version 3.1.5, MPC version 1.0.2, isl version none

I'm happy to dig further and make sure we get the selectors right, but I
have to be able to reproduce the problem first :-)

jeff