[Bug target/29900] [4.3 regression] stackreg to go wrongs after fwprop

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2006-11-19 21:01 -------
regstack is broken.
Before:
(insn:TI 70 69 71 3 (set (reg:SF 13 st(5) [orig:80 pretmp.77 ] [80])
        (plus:SF (reg:SF 13 st(5) [orig:80 pretmp.77 ] [80])
            (reg:SF 12 st(4) [orig:70 pretmp.92 ] [70]))) 417
{*fop_sf_comm_i387} (nil)
    (expr_list:REG_DEAD (reg:SF 12 st(4) [orig:70 pretmp.92 ] [70])
        (nil)))

(insn:TI 71 70 72 3 (set (reg:SF 13 st(5) [orig:80 pretmp.77 ] [80])
        (plus:SF (reg:SF 13 st(5) [orig:80 pretmp.77 ] [80])
            (reg:SF 10 st(2) [orig:76 pretmp.84 ] [76]))) 417
{*fop_sf_comm_i387} (nil)
    (expr_list:REG_DEAD (reg:SF 10 st(2) [orig:76 pretmp.84 ] [76])
        (nil)))

After:
(insn:TI 70 69 71 3 (set (reg:SF 9 st(1))
        (plus:SF (reg:SF 9 st(1))
            (reg:SF 8 st))) 417 {*fop_sf_comm_i387} (nil)
    (expr_list:REG_DEAD (reg:SF 8 st)
        (nil)))

(insn:TI 71 70 72 3 (set (reg:SF 11 st(3))
        (plus:SF (reg:SF 11 st(3))
            (reg:SF 8 st))) 417 {*fop_sf_comm_i387} (nil)
    (expr_list:REG_DEAD (reg:SF 8 st)
        (nil)))

See how we replace "reg:SF 13 st(5) " once with "(reg:SF 9 st(1))" but the
second time with "(reg:SF 11 st(3))"


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29900