re PR debug/42630 ("-fcompare-debug failure (length)" with "-O1 -fvariable-expansion-in-unroller -funroll-loops")

gcc/ChangeLog:
PR debug/42630
* loop-unroll.c (referenced_in_one_insn_in_loop_p): Count debug
uses in new incoming argument.  Free body.
(reset_debug_uses_in_loop): New.
(analyze_insn_to_expand_var): Call the latter if the former found
anything.  Fix whitespace.  Reject invalid dest overlaps before
going through all insns in the loop.
gcc/testsuite/ChangeLog:
PR debug/42630
* gcc.dg/pr42630.c: New.

From-SVN: r155764