[Bug tree-optimization/42494] [4.4 Regression] Missed dead-code-elimination

[steven at gcc dot gnu dot org]

------- Comment #9 from steven at gcc dot gnu dot org  2010-01-07 21:36 -------
At -Os, in the .188r.postreload RTL dump:

(insn 46 12 17 2 t.c:8 (parallel [
            (set (reg/v:SI 2 r2 [orig:133 flags ] [133])
                (if_then_else:SI (ne (reg:SI 2 r2 [orig:138 bool_var ] [138])
                        (const_int 0 [0x0]))
                    (const_int 2 [0x2])
                    (const_int 0 [0x0])))
            (clobber (reg:CC 24 cc))
        ]) 291 {movcond} (nil))



And one pass later, in the .190r.split2 RTL dump:

(insn 49 12 50 2 t.c:8 (set (reg:CC 24 cc)
        (compare:CC (reg:SI 2 r2 [orig:138 bool_var ] [138])
            (const_int 0 [0x0]))) 220 {*arm_cmpsi_insn} (nil))

(insn 50 49 51 2 t.c:8 (cond_exec (ne (reg:CC 24 cc)
            (const_int 0 [0x0]))
        (set (reg/v:SI 2 r2 [orig:133 flags ] [133])
            (const_int 2 [0x2]))) 2367 {neon_vornv2di+77} (nil))

(insn 51 50 17 2 t.c:8 (cond_exec (eq (reg:CC 24 cc)
            (const_int 0 [0x0]))
        (set (reg/v:SI 2 r2 [orig:133 flags ] [133])
            (const_int 0 [0x0]))) 2367 {neon_vornv2di+77} (nil))


There's your redundant mov, from an insn splitter.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42494