[Bug debug/107231] New: [13 Regression] c-c++-common/goacc/kernels-loop-g.c: '-fcompare-debug' failure (length)

[Bug debug/107231] New: [13 Regression] c-c++-common/goacc/kernels-loop-g.c: '-fcompare-debug' failure (length)

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107231

            Bug ID: 107231
           Summary: [13 Regression] c-c++-common/goacc/kernels-loop-g.c:
                    '-fcompare-debug' failure (length)
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: compare-debug-failure, openacc
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tschwinge at gcc dot gnu.org
                CC: erozen at microsoft dot com
            Blocks: 104277
  Target Milestone: ---

In a native x86_64-pc-linux-gnu build, when also running testing with '-m32'
('RUNTESTFLAGS="--target_board=unix\{,-m32\}"') I'm seeing a regression for
'-m32' (but not for default '-m64'):

    [-PASS:-]{+FAIL:+} c-c++-common/goacc/kernels-loop-g.c (test for excess
errors)
    PASS: c-c++-common/goacc/kernels-loop-g.c scan-tree-dump-not parloops1
"FAILED:"
    PASS: c-c++-common/goacc/kernels-loop-g.c scan-tree-dump-times optimized
"(?n);; Function .*main._omp_fn.0" 1
    PASS: c-c++-common/goacc/kernels-loop-g.c scan-tree-dump-times parloops1
"(?n)__attribute__\\(\\(oacc kernels parallelized, oacc function \\(, , \\),
oacc kernels, omp target entrypoint, noclone\\)\\)" 1
    PASS: c-c++-common/goacc/kernels-loop-g.c scan-tree-dump-times parloops1
"SUCCESS: may be parallelized" 1

    xgcc: error:
[...]/source-gcc/gcc/testsuite/c-c++-common/goacc/kernels-loop-g.c:
'-fcompare-debug' failure (length)

That's for both C and C++ testing.

Note that this test case is a bit "degenerate" in that it needs
'-fcompare-debug' to compile (safe-guard; refer to PR100400).

Reproduce:

    $ build-gcc/gcc/xgcc -Bbuild-gcc/gcc/
source-gcc/gcc/testsuite/c-c++-common/goacc/kernels-loop-g.c -fopenacc
--param=openacc-kernels=decompose -O2 -g -S -fcompare-debug -m32 -save-temps
    xgcc: error: source-gcc/gcc/testsuite/c-c++-common/goacc/kernels-loop-g.c:
‘-fcompare-debug’ failure (length)
    $ diff -u kernels-loop-g.c.gkd kernels-loop-g.gk.c.gkd
    --- kernels-loop-g.c.gkd        2022-10-12 11:10:24.902809164 +0200
    +++ kernels-loop-g.gk.c.gkd     2022-10-12 11:10:24.950809149 +0200
    @@ -601,7 +601,7 @@
                 (set (reg/v:SI 0 ax [orig:96 i ] [96])
                     (const_int 0 [0]))
                 (clobber (reg:CC 17 flags))
    -        ])
"source-gcc/gcc/testsuite/c-c++-common/goacc/kernels-loop.c":36:21 discrim 3#
{*movsi_xor}
    +        ])
"source-gcc/gcc/testsuite/c-c++-common/goacc/kernels-loop.c":36:21#
{*movsi_xor}
          (expr_list:REG_UNUSED (reg:CC 17 flags)
             (nil)))
     (code_label # 0 0 7 13 (nil) [1 uses])

The issue goes away if I revert commit
r13-3213-g80f414e6d73f9f1683f93d83ce63a6a482e54bee "Fix PR107193", commit
r13-3172-gf30e9fd33e56a5a721346ea6140722e1b193db42 "Set discriminators for call
stmts on the same line within the same basic block".

Alternatively, the issue goes away if I pass '-gno-statement-frontiers' (as I
found in the 'c-c++-common/ubsan/pr85213.c' hunk of commit
r13-2921-gf1adf45b17f7f1ede463524d80032bb2ec866ead "Add instruction level
discriminator support", referring to PR100733 "-fcompare-debug failure for
pr85213.c at -O1 -fdisable-tree-phiopt2").  If you confirm that this is indeed
what should currently be done, I'll push that flag onto
'c-c++-common/goacc/kernels-loop-g.c', for the time being?


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104277
[Bug 104277] [meta-bug] gstatement-frontiers causes fcompare-debug issues

[Bug debug/107231] [13 Regression] c-c++-common/goacc/kernels-loop-g.c: '-fcompare-debug' failure (length)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107231

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

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

[Bug debug/107231] [13 Regression] c-c++-common/goacc/kernels-loop-g.c: '-fcompare-debug' failure (length)

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107231

Rainer Orth <ro at gcc dot gnu.org> changed:

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

--- Comment #1 from Rainer Orth <ro at gcc dot gnu.org> ---
The same error is also seen in libgomp testing:

+FAIL: libgomp.oacc-c++/../libgomp.oacc-c-c++-common/kernels-loop-g.c
-DACC_DEVICE_TYPE_host=1 -DACC_MEM_SHARED=1 -foffload=disable  -O2  (test for
excess errors)
+UNRESOLVED: libgomp.oacc-c++/../libgomp.oacc-c-c++-common/kernels-loop-g.c
-DACC_DEVICE_TYPE_host=1 -DACC_MEM_SHARED=1 -foffload=disable  -O2  compilation
failed to produce executable
+FAIL: libgomp.oacc-c/../libgomp.oacc-c-c++-common/kernels-loop-g.c
-DACC_DEVICE_TYPE_host=1 -DACC_MEM_SHARED=1 -foffload=disable  -O2  (test for
excess errors)
+UNRESOLVED: libgomp.oacc-c/../libgomp.oacc-c-c++-common/kernels-loop-g.c
-DACC_DEVICE_TYPE_host=1 -DACC_MEM_SHARED=1 -foffload=disable  -O2  compilation
failed to produce executable

Excess errors:
xgcc: error:
/vol/gcc/src/hg/master/local/libgomp/testsuite/libgomp.oacc-c++/../libgomp.oacc-c-c++-common/kernels-loop-g.c:
'-fcompare-debug' failure (length)

on i386-pc-solaris2.11.

[Bug debug/107231] [13 Regression] c-c++-common/goacc/kernels-loop-g.c: '-fcompare-debug' failure (length)

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107231

John David Anglin <danglin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-12-14
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |danglin at gcc dot gnu.org

[Bug debug/107231] [13/14 Regression] c-c++-common/goacc/kernels-loop-g.c: '-fcompare-debug' failure (length)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107231

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

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

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 13.1 is being released, retargeting bugs to GCC 13.2.

[Bug debug/107231] [13/14 Regression] c-c++-common/goacc/kernels-loop-g.c: '-fcompare-debug' failure (length)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107231

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

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

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 13.2 is being released, retargeting bugs to GCC 13.3.

[Bug debug/107231] [13/14 Regression] c-c++-common/goacc/kernels-loop-g.c: '-fcompare-debug' failure (length)

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107231

Thomas Schwinge <tschwinge at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |aoliva at gcc dot gnu.org

--- Comment #4 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
Resolved by Alexandre's recent commit
r14-5257-g61d2b4746300a604469df15789194d0a7c73791b "skip debug stmts when
assigning locus discriminators", thanks!

Is this desirable to also cherry-pick into GCC 13?