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[0/2] ifcvt: Allow if conversion of arithmetic in basic blocks with multiple sets

Message ID 20230701092413.2488806-1-manolis.tsamis@vrull.eu
Headers
Series ifcvt: Allow if conversion of arithmetic in basic blocks with multiple sets |

Message

Manolis Tsamis July 1, 2023, 9:24 a.m. UTC 
  noce_convert_multiple_sets has been introduced and extended over time to handle
if conversion for blocks with multiple sets. Currently this is focused on
register moves and rejects any sort of arithmetic operations.

This series is an extension to allow more sequences to take part in if
conversion. The first patch is a required change to emit correct code and the
second patch whitelists a larger number of operations through
bb_ok_for_noce_convert_multiple_sets.

For targets that have a rich selection of conditional instructions,
like aarch64, I have seen an ~5x increase of profitable if conversions for
multiple set blocks in SPEC benchmarks. Also tested with a wide variety of
benchmarks and I have not seen performance regressions on either x64 / aarch64.

Some samples that previously resulted in a branch but now better use these
instructions can be seen in the provided test case.

Tested on aarch64 and x64; On x64 some tests that use __builtin_rint are
failing with an ICE but I believe that it's not an issue of this change.
force_operand crashes when (and:DF (not:DF (reg:DF 88)) (reg/v:DF 83 [ x ]))
is provided through emit_conditional_move.



Manolis Tsamis (2):
  ifcvt: handle sequences that clobber flags in
    noce_convert_multiple_sets
  ifcvt: Allow more operations in multiple set if conversion

 gcc/ifcvt.cc                                  | 109 ++++++++++--------
 .../aarch64/ifcvt_multiple_sets_arithm.c      |  67 +++++++++++
 2 files changed, 127 insertions(+), 49 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/aarch64/ifcvt_multiple_sets_arithm.c