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.
From-SVN: r264535
