Very undeterministic handling of file: different output .s file every time

[Quuxplusone]

Bugzilla Link	PR34697
Status	NEW
Importance	P enhancement
Reported by	Jonas Paulsson (paulsson@linux.vnet.ibm.com)
Reported on	2017-09-22 01:53:30 -0700
Last modified on	2017-10-05 09:55:57 -0700
Version	trunk
Hardware	PC Linux
CC	dblaikie@gmail.com, dexonsmith@apple.com, gberry@codeaurora.org, llvm-bugs@lists.llvm.org, paulsson@linux.vnet.ibm.com, vsapsai@apple.com
Fixed by commit(s)
Attachments	Utilities_newsort.bc (130584 bytes, application/octet-stream) bugpoint-reduced-simplified.bc (5016 bytes, application/octet-stream)
Blocks
Blocked by
See also

Created attachment 19184
original test case

I noticed that one particular file in SPEC-2006 keeps changing in the .s output
every time as I recompile it (it was the only file to do so).

I tried to track this down with bugpoint and a bisect, but with no luck. The
reduced test case changes output every now and then, but the original input
changes every time. It looks like it could be related to regalloc as
spill/reload instructions show up in the diffs.

bin/clang -cc1 -triple s390x-ibm-linux -S -target-cpu z13 -O3 -vectorize-loops -
vectorize-slp -o out0 -x ir ./Utilities_newsort.bc
bin/clang -cc1 -triple s390x-ibm-linux -S -target-cpu z13 -O3 -vectorize-loops -
vectorize-slp -o out1 -x ir ./Utilities_newsort.bc
diff out0 out1 | less

[Quuxplusone]

Attached Utilities_newsort.bc (130584 bytes, application/octet-stream): original test case

[Quuxplusone]

Attached bugpoint-reduced-simplified.bc (5016 bytes, application/octet-stream): reduced testcase