[Bug debug/100304] New: [11/12 Regression] -fcompare-debug failure (length) with custom flags

[Bug debug/100304] New: [11/12 Regression] -fcompare-debug failure (length) with custom flags

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100304

            Bug ID: 100304
           Summary: [11/12 Regression] -fcompare-debug failure (length)
                    with custom flags
           Product: gcc
           Version: 12.0
            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 50694
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50694&action=edit
auto-reduced testcase (from OpenTTD sources)

The same set of compiler flags after reduction was observed twice on two
different testcases, so it might be important.

Compiler output:
$ x86_64-pc-linux-gnu-gcc -O2 -fno-cse-follow-jumps
-fno-guess-branch-probability -fno-tree-coalesce-vars -fno-tree-forwprop
-funroll-loops -fno-web -fcompare-debug testcase.C -w
x86_64-pc-linux-gnu-gcc: error: testcase.C: '-fcompare-debug' failure (length)


$ 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-r12-174-20210427141825-g37d2b98100c-checking-yes-rtl-df-extra-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/12.0.0/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-r12-174-20210427141825-g37d2b98100c-checking-yes-rtl-df-extra-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.0 20210427 (experimental) (GCC)

[Bug debug/100304] [11/12 Regression] -fcompare-debug failure (length) with custom flags

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100304

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.2

[Bug debug/100304] [11/12 Regression] -fcompare-debug failure (length) with custom flags

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100304

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Can't reproduce this one.

[Bug debug/100304] [11/12 Regression] -fcompare-debug failure (length) with custom flags

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100304

--- Comment #2 from Zdenek Sojka <zsojka at seznam dot cz> ---
(In reply to Jakub Jelinek from comment #1)
> Can't reproduce this one.

Thank you for checking this. I've updated the sources, and rebuilt with release
checking, no bootstrap:
$ 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-r12-212-20210428120349-gf7ee6a1e8ac-checking-release-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/12.0.0/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=release
--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-r12-212-20210428120349-gf7ee6a1e8ac-checking-release-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.0 20210428 (experimental) (GCC) 

Valgrind doesn't report any issues during compilation.

The diff is:
$ diff -u a-testcase.C.gkd a-testcase.gk.C.gkd
--- a-testcase.C.gkd    2021-04-28 13:08:24.000000000 +0200
+++ a-testcase.gk.C.gkd 2021-04-28 13:08:40.000000000 +0200
@@ -526,10 +526,13 @@
                 (nil))))
     (expr_list:DI (use (reg:DI 5 di))
         (nil)))
-(insn # 0 0 18 (set (reg/f:DI 5 di [orig:89 __first$_M_current ] [89])
-        (plus:DI (reg/f:DI 3 bx [orig:86 _9 ] [86])
-            (const_int 24 [0x18])))# {*leadi}
-     (nil))
+(insn # 0 0 18 (parallel [
+            (set (reg/f:DI 5 di [orig:89 __first$_M_current ] [89])
+                (const_int 0 [0]))
+            (clobber (reg:CC 17 flags))
+        ]) "testcase.C":82:3# {*movdi_xor}
+     (expr_list:REG_UNUSED (reg:CC 17 flags)
+        (nil)))
 (call_insn:TI # 0 0 18 (call (mem:QI (symbol_ref:DI
("_ZN12_Vector_baseI9allocatorIiEED2Ev") [flags 0x41]  <function_decl #
__dt_base >) [ __dt_base  S1 A8])
         (const_int 0 [0])) "testcase.C":82:3# {*call}
      (expr_list:REG_DEAD (reg:DI 5 di)

[Bug debug/100304] [11/12 Regression] -fcompare-debug failure (length) with custom flags

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100304

--- Comment #3 from Zdenek Sojka <zsojka at seznam dot cz> ---
(In reply to Jakub Jelinek from comment #1)
> Can't reproduce this one.

Were you testing with a clean build, or did you have PR100303 fix applied?
On master, it stopped failing for me between r12-285 (BAD) and r12-293 (OK).

[Bug debug/100304] [11/12 Regression] -fcompare-debug failure (length) with custom flags

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100304

--- Comment #4 from Zdenek Sojka <zsojka at seznam dot cz> ---
I can't reproduce this anymore on r12-581 ; but it still reproduces for me on
the 11-branch.

[Bug debug/100304] [11/12 Regression] -fcompare-debug failure (length) with custom flags

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100304

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.2                        |11.3

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 11.2 is being released, retargeting bugs to GCC 11.3

[Bug debug/100304] [11/12 Regression] -fcompare-debug failure (length) with custom flags

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100304

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |DUPLICATE
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=100303

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Since it was fixed by the patch for PR 100303, I am just goign to declare this
as a dup of bug 100303.

*** This bug has been marked as a duplicate of bug 100303 ***