[PATCH] i386: Don't peephole test to and on CPUs that don't like it

[PATCH] i386: Don't peephole test to and on CPUs that don't like it

[Pip Cet]

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Some AMD CPUs fuse "test" followed by a conditional branch into a
single uop, but don't fuse "and" followed by a conditional branch.
This patch makes the test-to-and peephole rules depend on not tuning
for BDVER. This is a slight improvement in many cases, but it becomes
more significant when combined with the rest of the patch at PR87104.

I think this could be improved further by enabling the peephole rule
if the insn following the peephole is not a conditional branch, but I
don't know whether NONJUMP_INSN_P (peep2_next_insn (...)) works or is
the right approach.

Bootstrapped, but "make check" produces errors which appear unrelated
to this patch.

2018-09-18  Pip Cet  <pipcet@gmail.com>

    PR 87104
    * config/i386/i386.h (TARGET_FUSE_TEST_AND_BRANCH): Add.
    * config/i386/i386.md (test to and peephole2s): Don't use for
    TARGET_FUSE_TEST_AND_BRANCH.
    * config/i386/x86-tune.def (TARGET_FUSE_TEST_AND_BRANCH): New.
    Define for AMD family 15h.

---
 gcc/ChangeLog                | 9 +++++++++
 gcc/config/i386/i386.h       | 2 ++
 gcc/config/i386/i386.md      | 9 ++++++---
 gcc/config/i386/x86-tune.def | 5 +++++
 4 files changed, 22 insertions(+), 3 deletions(-)

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