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| author | Richard Sandiford <richard.sandiford@arm.com> | 2024-11-18 19:32:50 +0000 |
|---|---|---|
| committer | Richard Sandiford <richard.sandiford@arm.com> | 2024-11-18 19:32:50 +0000 |
| commit | 428f3cacdd6aa631040379cb3c39eb8832957ef1 (patch) | |
| tree | f2cdf3225b1a148932ef7c599673c82c30ab0fce | |
| parent | 102e42a0dffafdd389604f877dbf6430c7394f73 (diff) | |
| download | gcc-428f3cacdd6aa631040379cb3c39eb8832957ef1.zip gcc-428f3cacdd6aa631040379cb3c39eb8832957ef1.tar.gz gcc-428f3cacdd6aa631040379cb3c39eb8832957ef1.tar.bz2 | |
aarch64: Relax early_ra treatment of modes_tieable_p
At least on aarch64, modes_tieable_p is a stricter condition than
can_change_mode_class. can_change_mode_class tells us whether the
subreg rules produce a sensible result for a particular mode change.
modes_tieable_p in addition tells us whether a mode change is
reasonable for optimisation purposes.
A false return from either hook should (and does) prevent early_ra
from attempting an allocation. But only a false return from
can_change_mode_class should invalidate the liveness tracking;
we can still analyse subregs for which can_change_mode_class is
true and modes_tieable_p is false.
This doesn't make a difference on its own, but it helps later
patches.
gcc/
* config/aarch64/aarch64-early-ra.cc
(early_ra::get_allocno_subgroup): Split can_change_mode_class test
out from modes_tieable_p test and only invalidate the live range
information for the former.
| -rw-r--r-- | gcc/config/aarch64/aarch64-early-ra.cc | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/gcc/config/aarch64/aarch64-early-ra.cc b/gcc/config/aarch64/aarch64-early-ra.cc index 68e96bd..79ac7b0 100644 --- a/gcc/config/aarch64/aarch64-early-ra.cc +++ b/gcc/config/aarch64/aarch64-early-ra.cc @@ -1434,8 +1434,8 @@ early_ra::get_allocno_subgroup (rtx reg) if (!inner) return {}; - if (!targetm.modes_tieable_p (GET_MODE (SUBREG_REG (reg)), - GET_MODE (reg))) + if (!targetm.can_change_mode_class (GET_MODE (SUBREG_REG (reg)), + GET_MODE (reg), FP_REGS)) { record_live_range_failure ([&](){ fprintf (dump_file, "cannot refer to r%d:%s in mode %s", @@ -1446,6 +1446,15 @@ early_ra::get_allocno_subgroup (rtx reg) return {}; } + if (!targetm.modes_tieable_p (GET_MODE (SUBREG_REG (reg)), + GET_MODE (reg))) + record_allocation_failure ([&](){ + fprintf (dump_file, "r%d's mode %s is not tieable to mode %s", + REGNO (SUBREG_REG (reg)), + GET_MODE_NAME (GET_MODE (SUBREG_REG (reg))), + GET_MODE_NAME (GET_MODE (reg))); + }); + subreg_info info; subreg_get_info (V0_REGNUM, GET_MODE (SUBREG_REG (reg)), SUBREG_BYTE (reg), GET_MODE (reg), &info); |