[Bug target/36713] [4.4 regression] r137252 breaks -O2 optimization on x86_64-unknown-linux-gnu

["dfranke at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #7 from dfranke at gcc dot gnu dot org  2008-07-03 11:42 -------
Differences in *.optimized dumps seem to be variable renaming only, e.g.
  -  temp.1140 = tdata->p;
  +  temp.1137 = tdata->p;

Differences in *.alias seems to be mostly of the kind:
  -PARM_NOALIAS.895 = &ANYTHING
  +PARM_NOALIAS.895 = &ESCAPED

However, I also found:
  -PARM_NOALIAS.895 = { ANYTHING ESCAPED NONLOCAL }
  -D.3410_6 = same as thread_data
  -thread_data = { ANYTHING }
  -D.3411_7 = same as thread_data
  +PARM_NOALIAS.895 = { ESCAPED NONLOCAL }
  +D.3410_6 = same as derefaddrtmp.893
  +thread_data = same as derefaddrtmp.893         <---- ?!?
  +D.3411_7 = same as derefaddrtmp.893

which might hint at the problem: the variable thread_data is an allocated
POINTER to a vector of structures (which hold more pointers), public within a
module. USE-ing it, makes it (sort of) local to the function. Most (>80% of
all) changes in *.optimized where in the one source file that uses this module
...

Richard, would this fit the bill?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36713