[Bug debug/107169] New: [13 Regression] -fcompare-debug failure at -O and above

[Bug debug/107169] New: [13 Regression] -fcompare-debug failure at -O and above

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107169

            Bug ID: 107169
           Summary: [13 Regression] -fcompare-debug failure at -O and
                    above
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: compare-debug-failure
          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 53671
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53671&action=edit
reduced testcase

Compiler output:
$ x86_64-pc-linux-gnu-gcc -O -fcompare-debug testcase.C
x86_64-pc-linux-gnu-gcc: error: testcase.C: '-fcompare-debug' failure

$ diff -u a-testcase*.C.gkd
--- a-testcase.C.gkd    2022-10-06 13:22:34.389297164 +0200
+++ a-testcase.gk.C.gkd 2022-10-06 13:22:34.419297164 +0200
@@ -66,7 +66,7 @@
  -> 6)
 (note # 0 0 [bb 3] NOTE_INSN_BASIC_BLOCK)
 (insn # 0 0 3 (set (mem/f/c:DI (symbol_ref:DI ("_class") [flags 0x2] 
<var_decl # _class>) [ _class+0 S8 A64])
-        (const_int 0 [0])) "testcase.C":170:31 discrim 2# {*movdi_internal}
+        (const_int 0 [0])) "testcase.C":170:31 discrim 3# {*movdi_internal}
      (nil))
 (code_label # 0 0 4 6 (nil) [1 uses])
 (note # 0 0 [bb 4] NOTE_INSN_BASIC_BLOCK)


$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r13-3128-20221006123905-gdb2f5d66123-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/13.0.0/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
--disable-bootstrap --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-r13-3128-20221006123905-gdb2f5d66123-checking-yes-rtl-df-extra-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 13.0.0 20221006 (experimental) (GCC)

[Bug debug/107169] [13 Regression] -fcompare-debug failure at -O and above since r13-2921-gf1adf45b17f7f1ed

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107169

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-10-06
     Ever confirmed|0                           |1
            Summary|[13 Regression]             |[13 Regression]
                   |-fcompare-debug failure at  |-fcompare-debug failure at
                   |-O and above                |-O and above since
                   |                            |r13-2921-gf1adf45b17f7f1ed
             Status|UNCONFIRMED                 |NEW
                 CC|                            |erozen at microsoft dot com,
                   |                            |marxin at gcc dot gnu.org

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Started with r13-2921-gf1adf45b17f7f1ed.

[Bug debug/107169] [13 Regression] -fcompare-debug failure at -O and above since r13-2921-gf1adf45b17f7f1ed

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107169

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |13.0

[Bug debug/107169] [13 Regression] -fcompare-debug failure at -O and above since r13-2921-gf1adf45b17f7f1ed

[erozen at microsoft dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107169

--- Comment #2 from Eugene Rozenfeld <erozen at microsoft dot com> ---
When -gstatement-frontiers is on, the IR coming from the front end may be
different with and without debug information turned on. That may cause e.g.,
different discriminator values and -fcompare-debug failures.

See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100733.

In  https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=f1adf45b17f7f1ed I added
-gno-statement-frontiers to gcc/testsuite/c-c++-common/ubsan/pr85213.c
b/gcc/testsuite/c-c++-common/ubsan/pr85213.c to work around this problem for
that test.

[Bug debug/107169] [13/14 Regression] -fcompare-debug failure at -O and above since r13-2921-gf1adf45b17f7f1ed

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107169

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|13.0                        |13.2

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 13.1 is being released, retargeting bugs to GCC 13.2.

[Bug debug/107169] [13/14 Regression] -fcompare-debug failure at -O and above since r13-2921-gf1adf45b17f7f1ed

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107169

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|13.2                        |13.3

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 13.2 is being released, retargeting bugs to GCC 13.3.

[Bug debug/107169] [13/14 Regression] -fcompare-debug failure at -O and above since r13-2921-gf1adf45b17f7f1ed

[aoliva at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107169

--- Comment #5 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
It looks like r14-5257-g61d2b4746300a604469df15789194d0a7c73791b fixes this.

[Bug debug/107169] [13 Regression] -fcompare-debug failure at -O and above since r13-2921-gf1adf45b17f7f1ed

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107169

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2