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[Bug target/54902] [4.7 Regression], ICE (segfault) building on arm-linux-gnueabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54902

--- Comment #4 from zhenqiang.chen at linaro dot org 2012-10-23 05:35:17 UTC ---
Created attachment 28512
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28512
gdb backtrace

Root cause:

PRE bases on the result of value numbering (run_scc_vn). At the end, it
free_scc_vn. But before free_scc_vn, it might call cleanup_tree_cfg ();

  if (do_eh_cleanup || do_ab_cleanup)
    cleanup_tree_cfg ();

cleanup_tree_cfg might call make_ssa_name which might reuse some "name" from
the FREE_SSANAMES list. If the VN_INFO of the "name" is NULL, free_scc_vn will
"Segmentation fault".

Richard's patch makes "do_eh_cleanup" to false. So cleanup_tree_cfg is not
called in PRE. Then no new ssa name will be created.

bt.log shows the gdb backtrace to create a new ssa name.


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