[Bug target/80080] S390: Isses with emitted cs-instructions for __atomic builtins.

[iii at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80080

--- Comment #15 from iii at gcc dot gnu.org ---
Author: iii
Date: Mon Sep 24 14:21:03 2018
New Revision: 264535

URL: https://gcc.gnu.org/viewcvs?rev=264535&root=gcc&view=rev
Log:
S/390: Fix conditional returns on z196+

S/390 epilogue ends with (parallel [(return) (use %r14)]) instead of
the more usual (return) or (simple_return).  This sequence is not
recognized by the conditional return logic in try_optimize_cfg ().

This was introduced for processors older than z196, where it is
sometimes profitable to use call-clobbered register for returning
instead of %r14.  On newer processors we always return via %r14,
for which the fact that it's used is already reflected by
EPILOGUE_USES.  In this case a simple (return) suffices.

This patch changes return_use () to emit simple (return)s when
returning via %r14.  The resulting sequences are recognized by the
conditional return logic in try_optimize_cfg ().

gcc/ChangeLog:

2018-09-24  Ilya Leoshkevich  <iii@linux.ibm.com>

        PR target/80080
        * config/s390/s390.c (s390_emit_epilogue): Do not use PARALLEL
        RETURN+USE when returning via %r14.

gcc/testsuite/ChangeLog:

2018-09-24  Ilya Leoshkevich  <iii@linux.ibm.com>

        PR target/80080
        * gcc.target/s390/risbg-ll-3.c: Expect conditional returns.
        * gcc.target/s390/zvector/vec-cmp-2.c: Likewise.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/s390/s390.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.target/s390/risbg-ll-3.c
    trunk/gcc/testsuite/gcc.target/s390/zvector/vec-cmp-2.c