[Bug debug/95576] New: [11 Regression] -fcompare-debug failure with -O3 -fno-tree-forwprop -fvect-cost-model=unlimited

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95576

            Bug ID: 95576
           Summary: [11 Regression] -fcompare-debug failure with -O3
                    -fno-tree-forwprop -fvect-cost-model=unlimited
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
                CC: aoliva at gcc dot gnu.org
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu

Created attachment 48703
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48703&action=edit
reduced testcase

Compiler output:
$ x86_64-pc-linux-gnu-g++ -O3 -fno-tree-forwprop -fvect-cost-model=unlimited
-fcompare-debug testcase.C
x86_64-pc-linux-gnu-g++: error: testcase.C: '-fcompare-debug' failure

$ diff -u *gkd
--- a-testcase.C.gkd    2020-06-08 13:05:48.719739159 +0200
+++ a-testcase.gk.C.gkd 2020-06-08 13:05:48.839739158 +0200
@@ -191,9 +191,9 @@
 3:   struct S * s;
 4:   int f;
 5:   void * d;
-1:   int (*) () * _vptr.S;
-2:   static int (*) () _ZTV1S[5] = <<< omitted >>>;
-0:   struct S D.xxxx;
+2:   int (*) () * _vptr.S;
+0:   static int (*) () _ZTV1S[5] = <<< omitted >>>;
+1:   struct S D.xxxx;

 ;; Function T::~T (_ZN1TD0Ev, funcdef_no=8, cgraph_uid=9, symbol_order=9)

$ x86_64-pc-linux-gnu-g++ -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest/bin/x86_64-pc-linux-gnu-g++
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r11-1029-20200608001623-g53d461e4e0f-checking-yes-rtl-df-extra-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/11.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=x86_64-pc-linux-gnu
--with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r11-1029-20200608001623-g53d461e4e0f-checking-yes-rtl-df-extra-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.0.0 20200608 (experimental) (GCC)