[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #12 from hp at gcc dot gnu dot org  2009-05-13 13:09 -------
The relax_delay_slots (first) call finds that there's a branch to a redundant
insn that it can eliminate.  It does this by redirecting the branch to a new or
existing label and deleting the insn, or rather move it and make it a USE-mark
at the "new" label.  When doing this, the old USE-mark quoted above (not
related to the new USE-mark by other means being before it in the execution
path) is now deemed unreachable and removed by jump.c:delete_related_insns. 
So, it seems a solution will include propagating existing USE-marks when
redirecting branch labels, perhaps in reorg_redirect_jump or update_block.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086