https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112454
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2023-11-18
Ever confirmed|0 |1
Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot
gnu.org
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Mine, looks like a cost issue not recording that 1 (and ~0) are free to create.
you can see the cost issue if we look at combine for the case of 1 csel:
Trying 37 -> 39:
37: r98:SI=0x1
39: r92:SI={(cc:CC!=0)?r100:SI:r98:SI}
REG_DEAD r100:SI
REG_DEAD cc:CC
REG_DEAD r98:SI
Successfully matched this instruction:
(set (reg:SI 92 [ <retval> ])
(if_then_else:SI (ne (reg:CC 66 cc)
(const_int 0 [0]))
(reg:SI 100)
(const_int 1 [0x1])))
allowing combination of insns 37 and 39
original costs 4 + 4 = 8
replacement cost 8
deferring deletion of insn with uid = 37.
modifying insn i3 39: r92:SI={(cc:CC!=0)?r100:SI:0x1}
REG_DEAD cc:CC
REG_DEAD r100:SI
deferring rescan insn with uid = 39.
The replacement cost should be still 4.
