[Bug bootstrap/83439] New: [7 Regression] Bootstrap failure with --enable-checking=yes,rtl,extra

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83439

            Bug ID: 83439
           Summary: [7 Regression] Bootstrap failure with
                    --enable-checking=yes,rtl,extra
           Product: gcc
           Version: 7.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

r255688 fails to bootstrap with
../configure --enable-languages=all,ada,obj-c++,lto,go,brig
--enable-checking=yes,rtl,extra
on both x86_64-linux and i686-linux, the error is:
../../gcc/ipa-icf.c: In static member function ‘static ipa_icf::sem_variable*
ipa_icf::sem_variable::parse(varpool_node*, bitmap_obstack*)’:
../../gcc/ipa-icf.c:3697:1: error: stmt (0x7fc209380ea0) marked modified after
optimization pass: 
 }
 ^
# .MEM_29 = VDEF <.MEM_27>
ipa_icf::sem_variable::init (_25);
../../gcc/ipa-icf.c:3697:1: internal compiler error: verify_ssa failed
0x15798c2 verify_ssa(bool, bool)
        ../../gcc/tree-ssa.c:1184
0x10f2420 execute_function_todo
        ../../gcc/passes.c:1973
0x10f1470 do_per_function
        ../../gcc/passes.c:1650
0x10f25ae execute_todo
        ../../gcc/passes.c:2016
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with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
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Makefile:1099: recipe for target 'ipa-icf.o' failed
make[3]: *** [ipa-icf.o] Error 1

This is during FRE, so I suspect some of the recent tree-ssa-pre.c backports.