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References: <bug-28868-6528@http.gcc.gnu.org/bugzilla/>
Subject: [Bug tree-optimization/28868] [4.0/4.1/4.2 Regression] Not elimintating the PHIs which have the same agruments
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From: "dberlin at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
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------- Comment #6 from dberlin at gcc dot gnu dot org  2006-08-29 14:59 -------
SCCVN comes up with

Value numbers:
d_2 = c_1
c_7 = b_6
d_8 = b_6
c_10 = a_9
d_11 = a_9


where
  # PRED: 3 (fallthru,exec) 4 (fallthru,exec)
  # dD.1526_2 = PHI <dD.1526_11(3), dD.1526_8(4)>;
  # cD.1525_1 = PHI <cD.1525_10(3), cD.1525_7(4)>;
...


As a result, once integrated into PRE/FRE, it will eliminate uses of the d_2
phi with the c_1 phi, which is what you want.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28868