ifcvt/optabs: Allow using a CC comparison for emit_conditional_move.
Currently we only ever call emit_conditional_move with the comparison
(as well as its comparands) we got from the jump. Thus, backends are
going to emit a CC comparison for every conditional move that is being
generated instead of re-using the existing CC.
This, combined with emitting temporaries for each conditional move,
causes sky-high costs for conditional moves.
This patch allows to re-use a CC so the costing situation is improved a
bit.
gcc/ChangeLog:
* rtl.h (struct rtx_comparison): New struct that holds an rtx
comparison.
* config/rs6000/rs6000.cc (rs6000_emit_minmax): Use struct instead of
single parameters.
(rs6000_emit_swsqrt): Likewise.
* expmed.cc (expand_sdiv_pow2): Likewise.
(emit_store_flag): Likewise.
* expr.cc (expand_cond_expr_using_cmove): Likewise.
(expand_expr_real_2): Likewise.
* ifcvt.cc (noce_emit_cmove): Add compare and reversed compare
parameters.
* optabs.cc (emit_conditional_move_1): New function.
(expand_doubleword_shift_condmove): Use struct.
(emit_conditional_move): Use struct and allow to call directly
without going through preparation steps.
* optabs.h (emit_conditional_move): Use struct.