Version 1 regressed the expansion of atomics, which means the addition
of CC clobber to all conditional branches is flawed. Version 2 goes
the other way: remove CC clobber from all conditional branches.
This requires the out-of-range TBZ->TST+B.cond expansion be removed,
falling back to the far_branch expansion TBNZ+B.
I have fixed target/121388, the condition inversion problem, by
requiring the immediate ranges of CB be symmetric. This omits 64
as a valid input to GE and -1 as a valid input to LE.
I have dropped the removal of cbranch<SHORT>4 expanding to CBB/CBH.
I still think that's the correct way to go, but given the change to
mov<ALLI>cc, it is no longer required to fix an ICE.
TODO list:
- Drop cbranch<SHORT>4, and direct expansion of CMPBR from cbranch<GPI>4,
so that we always get CCmode comparisons out of expand. Rely on combine
to re-assemble CBB/CBH when there's no other use of the compare.
Consider e.g. cmpbr-3.c, introduced by the final patch, where
CMP+CSEL is a better choice than CBHLT+MOV.
- Re-add branch patterns containing cc clobbers, and maybe accept the
full range of constants. These can expand to CMP+Bcond for ranges
between 1KiB and 1MiB, and when condition inversion produces an
invalid immediate for CB.
- Reorg the post-reload splitters that emit conditional branches.
There's a fair bit of by-hand generation of CMP+Bcond which
could be turned into CBcond, but even without CMPBR could benefit
from a well-designed helper function.
I don't know if I'll get around to doing any of these, since I'm
supposed to be working on 128-bit page tables for qemu. :-)
r~
Richard Henderson (13):
aarch64: Fix spelling of BRANCH_LEN_N_1KiB
aarch64: Remove an indentation level from aarch64_if_then_else_costs
aarch64: Reorg aarch64_if_the_else_costs, conditional branch
aarch64: Use aarch64_gen_compare_zero_and_branch in aarch64_restore_za
aarch64: Fix gcs save/restore_stack_nonlocal
aarch64: Rename and improve aarch64_split_imm24
aarch64: Fix aarch64_split_imm24 patterns
aarch64: Disable TARGET_CMPBR with aarch64_track_speculation
aarch64: Remove cc clobber from *aarch64_tbz<LTGE><ALLI>1
aarch64: Fix gcc.target/aarch64/cmpbr.c
aarch64: Consider TARGET_CMPBR in rtx costs
aarch64: CMPBR branches must be invertable
aarch64: Fix condition accepted by mov<ALLI>cc
gcc/config/aarch64/aarch64-protos.h | 4 +
gcc/config/aarch64/aarch64-sme.md | 3 +-
gcc/config/aarch64/aarch64.cc | 134 ++++++++----
gcc/config/aarch64/aarch64.h | 5 +-
gcc/config/aarch64/aarch64.md | 201 +++++++-----------
gcc/config/aarch64/constraints.md | 10 +-
gcc/config/aarch64/iterators.md | 34 +--
gcc/config/aarch64/predicates.md | 23 +-
gcc/testsuite/gcc.target/aarch64/cmpbr-1.c | 25 +++
gcc/testsuite/gcc.target/aarch64/cmpbr-2.c | 110 ++++++++++
gcc/testsuite/gcc.target/aarch64/cmpbr-3.c | 15 ++
gcc/testsuite/gcc.target/aarch64/cmpbr.c | 10 +-
.../gcc.target/aarch64/gcs-nonlocal-3.c | 2 +-
gcc/testsuite/gcc.target/aarch64/pr109078.c | 2 +-
14 files changed, 378 insertions(+), 200 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/aarch64/cmpbr-1.c
create mode 100644 gcc/testsuite/gcc.target/aarch64/cmpbr-2.c
create mode 100644 gcc/testsuite/gcc.target/aarch64/cmpbr-3.c
--
2.34.1
