[Bug target/23488] [4.1 Regression] extra reads from static variable

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-19 23:31 -------
(In reply to comment #3)
> I am surprised that gcse.c load PRE can't already handle this situation.  Is 
> something broken, or is it really just not able to handle this?  What does the 
> RTL look like when we are in GCSE? 
(insn 11 9 12 0 (set (reg:CCZ 17 flags)
        (compare:CCZ (mem/i:SI (symbol_ref:SI ("result.1279") [flags 0x2] <var_decl 0xb7cb0108 result>) 
[2 result+0 S4 A32])
            (const_int 0 [0x0]))) 0 {*cmpsi_ccno_1} (nil)
    (nil))


Which is unlike what we got in 4.0.0:
(insn 11 9 12 0 (set (reg:SI 59 [ result ])
        (mem/i:SI (symbol_ref:SI ("result.1132") [flags 0x2] <var_decl 0xb7ce7a8c result>) [2 result+0 S4 
A32])) 35 {*movsi_1} (nil)
    (nil))

(insn 12 11 13 0 (set (reg:CCZ 17 flags)
        (compare:CCZ (reg:SI 59 [ result ])
            (const_int 0 [0x0]))) 0 {*cmpsi_ccno_1} (nil)
    (nil))


so either GCSE needs to be improved to recongized that or Honza's patch should be reverted.  We are in 
stage3, I would say the latter one untill this gets improved on the tree level.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23488