[Bug rtl-optimization/70596] New: [6 Regression] -fcompare-debug failure with one extra NOTE_INSN_DELETED

["zsojka at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70596

            Bug ID: 70596
           Summary: [6 Regression] -fcompare-debug failure with one extra
                    NOTE_INSN_DELETED
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
            Target: x86_64-pc-linux-gnu

Created attachment 38222
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38222&action=edit
reduced testcase

Compiler output:
$ gcc testcase.c -O2 -fno-dce -fschedule-insns -fno-tree-coalesce-vars
-fno-tree-dce -fno-tree-fre -fno-tree-pre -fcompare-debug -mavx512f         
x86_64-pc-linux-gnu-gcc: error: testcase.c: -fcompare-debug failure (length)

$ diff -u testcase*gkd
@@ -648,7 +648,6 @@
 (note # 0 0 NOTE_INSN_DELETED)
 (note # 0 0 NOTE_INSN_DELETED)
 (note # 0 0 NOTE_INSN_DELETED)
-(note # 0 0 NOTE_INSN_DELETED)
 (insn/f:TI # 0 0 2 (set (reg:DI 39 r10)
         (plus:DI (reg/f:DI 7 sp)
             (const_int 8 [0x8]))) testcase.c:5# {*leadi}


The .reload dump is the first one where is one more NOTE_INSN_DELETED.

$ grep -c NOTE_INSN_DELETED *.c.*
...
testcase.c.255r.ira:155
testcase.c.256r.reload:646
testcase.c.257r.postreload:646
...
testcase.c.gk.255r.ira:155
testcase.c.gk.256r.reload:647
testcase.c.gk.257r.postreload:647
...