[PING] [PATCH v4 2/3] [RFC] ifcvt: Allow more operations in multiple set if conversion

[Jeff Law]

On 6/3/24 5:34 AM, Manolis Tsamis wrote:
> Currently the operations allowed for if conversion of a basic block with
> multiple sets are few, namely REG, SUBREG and CONST_INT (as controlled by
> bb_ok_for_noce_convert_multiple_sets).
> 
> This commit allows more operations (arithmetic, compare, etc) to participate
> in if conversion. The target's profitability hook and ifcvt's costing is
> expected to reject sequences that are unprofitable.
> 
> This is especially useful for targets which provide a rich selection of
> conditional instructions (like aarch64 which has cinc, csneg, csinv, ccmp, ...)
> which are currently not used in basic blocks with more than a single set.
> 
> gcc/ChangeLog:
> 
> 	* ifcvt.cc (try_emit_cmove_seq): Modify comments.
> 	(noce_convert_multiple_sets_1): Modify comments.
> 	(bb_ok_for_noce_convert_multiple_sets): Allow more operations.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.target/aarch64/ifcvt_multiple_sets_arithm.c: New test.
> 
> Signed-off-by: Manolis Tsamis <manolis.tsamis@vrull.eu>
> ---
> 
> Changes in v4:
>          - Remove unnecessary hardcoded list of allowed ops in
>          bb_ok_for_noce_convert_multiple_sets.
>          - Set need_cmov based on BB live_out instead of REG_DEAD notes.
>          - Fix preexisting issues and improve the code that sets read_comparison.
Do you need to avoid things like asms?  Or are those rejected elsewhere? 
  From a diff standpoint it seems quite sensible, but boy just removing 
all the guardrails makes me nervous.

So assuming asms are rejected somewhere else and this has been through a 
bootstrap and regression test, this is OK for the trunk.

jeff