[Bug string/28646] New: [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[Bug string/28646] New: [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

            Bug ID: 28646
           Summary: [2.35 Regression] mock -r fedora-36-x86_64
                    /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm&
                    fails to build
           Product: glibc
           Version: 2.35
            Status: NEW
          Severity: normal
          Priority: P2
         Component: string
          Assignee: unassigned at sourceware dot org
          Reporter: hjl.tools at gmail dot com
                CC: goldstein.w.n at gmail dot com
  Target Milestone: ---
            Target: x86-64

commit c46e9afb2df5fc9e39ff4d13777e4b4c26e04e55
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri Oct 29 12:40:20 2021 -0700

    x86-64: Improve EVEX strcmp with masked load

caused Fedora 36 openJDK mock build failure:

$ mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm
...
gmake[6]: *** No rule to make target 'SCCS/s.generation.cpp', needed by
'generation.cpp'.  Stop.
gmake[6]: *** Waiting for unfinished jobs....

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
It can be reproduced on machines with AVX512, like Ice Lake, Tiger Lake,
Skylake
server, ...

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://bugzilla.redhat.com
                   |                            |/show_bug.cgi?id=2026399
                 CC|                            |fweimer at redhat dot com

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #2 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
Do we know if the issue is strcmp, strncmp, wcscmp, or wcsncmp? Or just the
commit?

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
(gdb) f 0
#0  __strcmp_evex (
    s1=0x55f3e18d08f8
"/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/util/PathDocFileFactory.java", 
    s2=0x55f3e18ccff3
"/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/taglets/ThrowsTaglet.java")
    at ../sysdeps/x86_64/multiarch/strcmp-evex-check.c:14
14          asm ("hlt");
(gdb) list
9         int exp_result = __strcmp_avx2 (s1, s2);
10        int result = __strcmp_evex_real (s1, s2);
11        if ((exp_result == 0 && result != 0)
12            || (exp_result < 0 && result >= 0)
13            || (exp_result > 0 && result <= 0))
14          asm ("hlt");
15      
16        return result;
17      }
(gdb) p exp_result
$1 = 1
(gdb) p result
$2 = 0
(gdb)

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #4 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
(In reply to H.J. Lu from comment #3)
> (gdb) f 0
> #0  __strcmp_evex (
>     s1=0x55f3e18d08f8
> "/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/
> openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/
> util/PathDocFileFactory.java", 
>     s2=0x55f3e18ccff3
> "/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/
> openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/
> taglets/ThrowsTaglet.java")
>     at ../sysdeps/x86_64/multiarch/strcmp-evex-check.c:14
> 14	    asm ("hlt");
> (gdb) list
> 9	  int exp_result = __strcmp_avx2 (s1, s2);
> 10	  int result = __strcmp_evex_real (s1, s2);
> 11	  if ((exp_result == 0 && result != 0)
> 12	      || (exp_result < 0 && result >= 0)
> 13	      || (exp_result > 0 && result <= 0))
> 14	    asm ("hlt");
> 15	
> 16	  return result;
> 17	}
> (gdb) p exp_result
> $1 = 1
> (gdb) p result
> $2 = 0
> (gdb)

Dump of s1/s2?

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #5 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 13815
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13815&action=edit
A patch to add a testcase

On AVX512 machines, I got

[hjl@gnu-tgl-3 build-x86_64-linux]$ string/test-strcmp --direct
string/test-strcmp: Wrong result in function __strcmp_evex 0 1
                        simple_strcmp   stupid_strcmp   __strcmp_avx2  
__strcmp_evex   __strcmp_sse42  __strcmp_ssse3  __strcmp_sse2_unaligned
__strcmp_sse2
[hjl@gnu-tgl-3 build-x86_64-linux]$ 

Noah, any ideas?

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #6 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
(In reply to H.J. Lu from comment #5)
> Created attachment 13815 [details]
> A patch to add a testcase
> 
> On AVX512 machines, I got
> 
> [hjl@gnu-tgl-3 build-x86_64-linux]$ string/test-strcmp --direct
> string/test-strcmp: Wrong result in function __strcmp_evex 0 1
>                        	simple_strcmp	stupid_strcmp	__strcmp_avx2
> __strcmp_evex	__strcmp_sse42	__strcmp_ssse3	__strcmp_sse2_unaligned
> __strcmp_sse2
> [hjl@gnu-tgl-3 build-x86_64-linux]$ 
> 
> Noah, any ideas?

Looks to me that coming from:

L(cross_page_loop)
L(main_loop_header)

The number of iterations for the 4x VEC_SIZE loop is being miscomputed.

Still figuring out exactly whats going on though.

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #7 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
Created attachment 13816
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13816&action=edit
Patch with bugfix.

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[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #8 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Noah Goldstein from comment #7)
> Created attachment 13816 [details]
> Patch with bugfix.

This is incomplete since I still got

[hjl@gnu-tgl-3 build-x86_64-linux]$ wcsmbs/test-wcscmp --direct
Segmentation fault (core dumped)
[hjl@gnu-tgl-3 build-x86_64-linux]$

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[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #9 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
(In reply to Noah Goldstein from comment #6)
> (In reply to H.J. Lu from comment #5)
> > Created attachment 13815 [details]
> > A patch to add a testcase
> > 
> > On AVX512 machines, I got
> > 
> > [hjl@gnu-tgl-3 build-x86_64-linux]$ string/test-strcmp --direct
> > string/test-strcmp: Wrong result in function __strcmp_evex 0 1
> >                        	simple_strcmp	stupid_strcmp	__strcmp_avx2
> > __strcmp_evex	__strcmp_sse42	__strcmp_ssse3	__strcmp_sse2_unaligned
> > __strcmp_sse2
> > [hjl@gnu-tgl-3 build-x86_64-linux]$ 
> > 
> > Noah, any ideas?
> 
> Looks to me that coming from:
> 
> L(cross_page_loop)
> L(main_loop_header)
> 
> The number of iterations for the 4x VEC_SIZE loop is being miscomputed.

I'm incorrect about this. Was misunderstanding the control flow. Although
this input hits an extremely unfortunate slow case.

> 
> Still figuring out exactly whats going on though.

Issue is that since we are only using part of the comparison 
(the upper 64 - %cl) bits, we can't rely on the fact that 
first zero means exit condition so using `incl` can set the
 wrong value. Don't see any other places in the code but still
looking.

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #10 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
Created attachment 13817
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13817&action=edit
Possibly Fix

Missed the other side. Try the attached.

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[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #11 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
(In reply to Noah Goldstein from comment #10)
> Created attachment 13817 [details]
> Possibly Fix
> 
> Missed the other side. Try the attached.

Sorry thats no good either for wcscmp. Still looking into it.

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[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #12 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
(In reply to H.J. Lu from comment #8)
> (In reply to Noah Goldstein from comment #7)
> > Created attachment 13816 [details]
> > Patch with bugfix.
> 
> This is incomplete since I still got

Issue is strings need to be aligned % sizeof(wchar_t) for wcscmp.
The check3 test has s2 misaligned.

Don't think there is an issue there.
> 
> [hjl@gnu-tgl-3 build-x86_64-linux]$ wcsmbs/test-wcscmp --direct
> Segmentation fault (core dumped)
> [hjl@gnu-tgl-3 build-x86_64-linux]$

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[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #13815|0                           |1
        is obsolete|                            |

--- Comment #13 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 13818
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13818&action=edit
An updated test patch

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #14 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Noah Goldstein from comment #12)
> (In reply to H.J. Lu from comment #8)
> > (In reply to Noah Goldstein from comment #7)
> > > Created attachment 13816 [details]
> > > Patch with bugfix.
> > 
> > This is incomplete since I still got
> 
> Issue is strings need to be aligned % sizeof(wchar_t) for wcscmp.
> The check3 test has s2 misaligned.
> 
> Don't think there is an issue there.
> > 
> > [hjl@gnu-tgl-3 build-x86_64-linux]$ wcsmbs/test-wcscmp --direct
> > Segmentation fault (core dumped)
> > [hjl@gnu-tgl-3 build-x86_64-linux]$

You are right.  Please add some comments to describe why INC can't be used.

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[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #15 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
Created attachment 13819
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13819&action=edit
Patch with explanation

Added commit explaining the bug in commit message
and comments in the code around the fix.

Note the issue with wcscmp was alignment of s2, s2 was type CHAR
so adding 0xcff3 was multiplied by sizeof(CHAR) and was out of
range of the allocation.

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #13816|0                           |1
        is obsolete|                            |
  Attachment #13817|0                           |1
        is obsolete|                            |
  Attachment #13818|0                           |1
        is obsolete|                            |
  Attachment #13819|0                           |1
        is obsolete|                            |

--- Comment #16 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 13820
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13820&action=edit
A patch

I am testing this.

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[Bug string/28646] [2.35 Regression] mock -r fedora-36-x86_64 /tmp/java-1.8.0-openjdk-1.8.0.312.b07-2.fc36.src.rpm& fails to build

[goldstein.w.n at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #17 from Noah Goldstein <goldstein.w.n at gmail dot com> ---
(In reply to H.J. Lu from comment #16)
> Created attachment 13820 [details]
> A patch
> 
> I am testing this.

>From Tigerlake:

ran xcheck and looked normal.

checked and all wcsmbs / string functions passed.

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[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #18 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by H.J. Lu <hjl@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4df1fa6ddc8925a75f3da644d5da3bb16eb33f02

commit 4df1fa6ddc8925a75f3da644d5da3bb16eb33f02
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Fri Dec 3 15:29:25 2021 -0800

    x86-64: Use notl in EVEX strcmp [BZ #28646]

    Must use notl %edi here as lower bits are for CHAR comparisons
    potentially out of range thus can be 0 without indicating mismatch.
    This fixes BZ #28646.

    Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>

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[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING
   Target Milestone|---                         |2.35

--- Comment #19 from H.J. Lu <hjl.tools at gmail dot com> ---
Fixed.

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[hjl.tools at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|WAITING                     |RESOLVED

--- Comment #20 from H.J. Lu <hjl.tools at gmail dot com> ---
Fixed.

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[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #21 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The release/2.34/master branch has been updated by Sunil Pandey
<skpgkp2@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4bbd0f866ad0ff197f72346f776ebee9b7e1a706

commit 4bbd0f866ad0ff197f72346f776ebee9b7e1a706
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Fri Dec 3 15:29:25 2021 -0800

    x86-64: Use notl in EVEX strcmp [BZ #28646]

    Must use notl %edi here as lower bits are for CHAR comparisons
    potentially out of range thus can be 0 without indicating mismatch.
    This fixes BZ #28646.

    Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>
    (cherry picked from commit 4df1fa6ddc8925a75f3da644d5da3bb16eb33f02)

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[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28646

--- Comment #22 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The release/2.33/master branch has been updated by Sunil Pandey
<skpgkp2@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d77349767a308ac3efa5f113fb63fe39c82e5083

commit d77349767a308ac3efa5f113fb63fe39c82e5083
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Fri Dec 3 15:29:25 2021 -0800

    x86-64: Use notl in EVEX strcmp [BZ #28646]

    Must use notl %edi here as lower bits are for CHAR comparisons
    potentially out of range thus can be 0 without indicating mismatch.
    This fixes BZ #28646.

    Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>
    (cherry picked from commit 4df1fa6ddc8925a75f3da644d5da3bb16eb33f02)

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