On Wed, Sep 5, 2018 at 10:44 AM Ilya Leoshkevich <i...@linux.ibm.com> wrote:
>
> Combine can change basic blocks in a way that they end up containing
> a single jump_insn. This creates an opportunity to improve code with
> jump threading.
Hmm, I think CFG cleanup performs this as well (if run in the correct mode)
so maybe combine should invoke that?
I don't think you should alter the pass pipeline this way in
archtecture specific
ways.
Richard.
> gcc/ChangeLog:
>
> 2018-08-28 Ilya Leoshkevich <i...@linux.ibm.com>
>
> PR target/80080
> * cfgcleanup.c: Make jump pass clonable.
> * config/s390/s390-passes.def (INSERT_PASS_AFTER): Perform jump
> threading after combine.
>
> gcc/testsuite/ChangeLog:
>
> 2018-08-28 Ilya Leoshkevich <i...@linux.ibm.com>
>
> PR target/80080
> * gcc.target/s390/pr80080-4.c: New test.
> ---
> gcc/cfgcleanup.c | 1 +
> gcc/config/s390/s390-passes.def | 1 +
> gcc/testsuite/gcc.target/s390/pr80080-4.c | 16 ++++++++++++++++
> 3 files changed, 18 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/s390/pr80080-4.c
>
> diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c
> index 4a5dc29d14f..35aa9f0ac4a 100644
> --- a/gcc/cfgcleanup.c
> +++ b/gcc/cfgcleanup.c
> @@ -3234,6 +3234,7 @@ public:
> {}
>
> /* opt_pass methods: */
> + virtual opt_pass *clone () { return new pass_jump (m_ctxt); }
> virtual unsigned int execute (function *);
>
> }; // class pass_jump
> diff --git a/gcc/config/s390/s390-passes.def b/gcc/config/s390/s390-passes.def
> index 035c6e8bc0a..2e9b208553e 100644
> --- a/gcc/config/s390/s390-passes.def
> +++ b/gcc/config/s390/s390-passes.def
> @@ -17,4 +17,5 @@ You should have received a copy of the GNU General Public
> License
> along with GCC; see the file COPYING3. If not see
> <http://www.gnu.org/licenses/>. */
>
> +INSERT_PASS_AFTER (pass_combine, 1, pass_jump);
> INSERT_PASS_BEFORE (pass_thread_prologue_and_epilogue, 1,
> pass_s390_early_mach);
> diff --git a/gcc/testsuite/gcc.target/s390/pr80080-4.c
> b/gcc/testsuite/gcc.target/s390/pr80080-4.c
> new file mode 100644
> index 00000000000..91d31ec7845
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/s390/pr80080-4.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=z196 -O2" } */
> +
> +extern void bar(int *mem);
> +
> +void foo4(int *mem)
> +{
> + int oldval = 0;
> + if (!__atomic_compare_exchange_n (mem, (void *) &oldval, 1,
> + 1, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED))
> + {
> + bar (mem);
> + }
> +}
> +
> +/* { dg-final { scan-assembler
> "\n\tlt\t.*\n\tjne\t(\\.L\\d+)\n(.*\n)*\tcs\t.*\n\tber\t%r14\n\\1:\n\tjg\tbar\n"
> } } */
> --
> 2.18.0
>
