On Tue, Jun 18, 2024 at 7:56 PM Takayuki 'January June' Suwa <jjsuwa_sys3...@yahoo.co.jp> wrote: > > The previous constant synthesis logic had some issues that were non-fatal > but worth considering: > > - It didn't work with DFmode literals, because those were cast to SImode > rather SFmode when splitting into two natural-width words by > split_double(). > > - It didn't work with large literals when TARGET_AUTO_LITPOOLS was enabled, > because those were relaxed MOVI immediates rather references to literal > pool entries, > > - It didn't take into account that when literals with the same RTL > representation are pooled multiple times within a function, those entries > are shared (especially important when optimizing for size). > > This patch addresses the above issues by making appropriate tweaks to the > constant synthesis logic. > > gcc/ChangeLog: > > * config/xtensa/xtensa-protos.h (xtensa_constantsynth): > Change the second argument from HOST_WIDE_INT to rtx. > * config/xtensa/xtensa.cc (#include): > Add "context.h" and "pass_manager.h". > (machine_function): Add a new hash_map field "litpool_usage". > (xtensa_constantsynth): Make "src" (the second operand) accept > RTX literal instead of its value, and treat both bare and pooled > SI/SFmode literals equally by bit-exact canonicalization into > CONST_INT RTX internally. And then, make avoid synthesis if > such multiple identical canonicalized literals are found in same > function when optimizing for size. Finally, for literals where > synthesis is not possible or has been avoided, re-emit "move" > RTXes with canonicalized ones to increase the chances of sharing > literal pool entries. > * config/xtensa/xtensa.md (split patterns for constant synthesis): > Change to simply invoke xtensa_constantsynth() as mentioned above, > and add new patterns for when TARGET_AUTO_LITPOOLS is enabled. > --- > gcc/config/xtensa/xtensa-protos.h | 2 +- > gcc/config/xtensa/xtensa.cc | 75 ++++++++++++++++++++++++++++--- > gcc/config/xtensa/xtensa.md | 56 ++++++++++++++--------- > 3 files changed, 103 insertions(+), 30 deletions(-)
Regtested for target=xtensa-linux-uclibc, no new regressions. Committed to master. -- Thanks. -- Max
