[Bug tree-optimization/54855] Unnecessary duplication when performing scalar operation on vector element

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54855



--- Comment #4 from Marc Glisse <glisse at gcc dot gnu.org> 2012-10-12 17:33:53 
UTC ---

Note that a V4SF version should be doable, since it is 3 insn there as well,

although the pattern is different.



(insn 34 61 36 4 (set (reg:SF 103 [ D.2551 ])

        (vec_select:SF (reg/v:V4SF 87 [ v ])

            (parallel [

                    (const_int 0 [0])

                ]))) d.c:13 1380 {*vec_extractv4sf_0}

     (nil))

(insn 36 34 37 4 (set (reg:SF 104 [ D.2551 ])

        (minus:SF (reg:SF 103 [ D.2551 ])

            (reg:SF 106))) d.c:13 759 {*fop_sf_1_sse}

     (expr_list:REG_DEAD (reg:SF 103 [ D.2551 ])

        (nil)))

(insn 37 36 38 4 (set (reg/v:V4SF 87 [ v ])

        (vec_merge:V4SF (vec_duplicate:V4SF (reg:SF 104 [ D.2551 ]))

            (reg/v:V4SF 87 [ v ])

            (const_int 1 [0x1]))) d.c:13 1377 {vec_setv4sf_0}

     (expr_list:REG_DEAD (reg:SF 104 [ D.2551 ])

        (nil)))