[Bug gas/19576] bogus code generation with on SunOS with 2.26

[richard at netbsd dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=19576

--- Comment #9 from Richard PALO <richard at netbsd dot org> ---
I believe the issue comes down to dtrace updating its symbol from
'__dtrace_Xserver___resource__free' to '__dtrace_Xserver___resource-free'

given that the input object file's strtab doesn't have a separate 'free' entry,
it seems to be riding on (optimised) to the tail end of
__dtrace_Xserver___resource__free'.

when dtrace updates the symbol, 'free' is effectively left shifted by 1
character.

before:
address@hidden:/home/richard/src/tdtrace$ dump -c resource.o.orig 

resource.o.orig:

     **** STRING TABLE INFORMATION ****

.shstrtab:
   <offset>     Name
   <0>          
   <1>          .symtab
   <9>          .strtab
   <17>         .shstrtab
   <27>         .rel.text
   <37>         .data
   <43>         .bss
   <48>         .text.unlikely
   <63>         .rodata.str1.1
   <78>         .rel.rodata
   <90>         .rodata.str1.4
   <105>        .rel.data.rel.ro
   <122>        .comment

.strtab:
   <offset>     Name
   <0>          
   <1>          resource.c
   <12>         GetDefaultBytes
   <28>         DefaultFindSubRes
   <46>         FindWindowSubRes
   <63>         FindGCSubRes
   <76>         GetPixmapBytes
   <91>         doFreeResource
   <106>        resourceTypes
   <120>        lastResourceClass
   <138>        GetGcBytes
   <149>        GetWindowBytes
   <164>        clientTable
   <176>        predefTypes
   <188>        __func__.15628
   <203>        AvailableID.part.1
   <222>        .L100
   <228>        .LC16
   <234>        .LC17
   <240>        .LC21
   <246>        .LC23
   <252>        .LC24
   <258>        .L89
   <263>        .L91
   <268>        .L92
   <273>        .L93
   <278>        .L94
   <283>        _GLOBAL_OFFSET_TABLE_
   <305>        ResourceStateCallback
   <327>        _CallCallbacks
   <342>        TypeMask
   <351>        CreateNewResourceType
   <373>        lastResourceType
   <390>        xreallocarray
   <404>        RegisterResourceName
   <425>        GetResourceTypeSizeFunc
   <449>        SetResourceTypeSizeFunc
   <473>        SetResourceTypeFindSubResFunc
   <503>        SetResourceTypeErrorValue
   <529>        CreateNewResourceClass
   <552>        ResourceClientBits
   <571>        LimitClients
   <584>        InitClientResources
   <604>        serverClient
   <617>        malloc
   <624>        HashResourceID
   <639>        __assert_c99
   <652>        GetXIDRange
   <664>        FakeClientID
   <677>        clients
   <685>        MarkClientException
   <705>        FatalError
   <716>        AddResource
   <728>        LookupResourceName
   <747>        __dtrace_Xserver___resource__alloc
   <782>        ErrorF
   <789>        __dtrace_Xserver___resource__free
   <823>        FreeResourceByType
   <842>        ChangeResourceValue
   <862>        FindClientResourcesByType
   <888>        FindSubResources
   <905>        FindAllClientResources
   <928>        LookupClientResourceComplex
   <956>        FreeClientNeverRetainResources
   <987>        FreeClientResources
   <1007>       HandleSaveSet
   <1021>       FreeAllResources
   <1038>       currentMaxClients
   <1056>       dixLookupResourceByType
   <1080>       XaceHook
   <1089>       dixLookupResourceByClass
   <1114>       GetXIDList
   <1125>       LegalNewID
   <1136>       noPanoramiXExtension
   <1157>       NoopDDA
   <1165>       DeleteWindow
   <1178>       dixDestroyPixmap
   <1195>       FreeGC
   <1202>       CloseFont
   <1212>       FreeCursor
   <1223>       FreeColormap
   <1236>       FreeClientPixels
   <1253>       OtherClientGone
   <1269>       DeletePassiveGrab

after:

address@hidden:/home/richard/src/tdtrace$ dump -c resource.o

resource.o:

     **** STRING TABLE INFORMATION ****

.shstrtab:
   <offset>     Name
   <0>          
   <1>          .symtab
   <9>          .strtab
   <17>         .shstrtab
   <27>         .rel.text
   <37>         .data
   <43>         .bss
   <48>         .text.unlikely
   <63>         .rodata.str1.1
   <78>         .rel.rodata
   <90>         .rodata.str1.4
   <105>        .rel.data.rel.ro
   <122>        .comment

.strtab:
   <offset>     Name
   <0>          
   <1>          resource.c
   <12>         GetDefaultBytes
   <28>         DefaultFindSubRes
   <46>         FindWindowSubRes
   <63>         FindGCSubRes
   <76>         GetPixmapBytes
   <91>         doFreeResource
   <106>        resourceTypes
   <120>        lastResourceClass
   <138>        GetGcBytes
   <149>        GetWindowBytes
   <164>        clientTable
   <176>        predefTypes
   <188>        __func__.15628
   <203>        AvailableID.part.1
   <222>        .L100
   <228>        .LC16
   <234>        .LC17
   <240>        .LC21
   <246>        .LC23
   <252>        .LC24
   <258>        .L89
   <263>        .L91
   <268>        .L92
   <273>        .L93
   <278>        .L94
   <283>        _GLOBAL_OFFSET_TABLE_
   <305>        ResourceStateCallback
   <327>        _CallCallbacks
   <342>        TypeMask
   <351>        CreateNewResourceType
   <373>        lastResourceType
   <390>        xreallocarray
   <404>        RegisterResourceName
   <425>        GetResourceTypeSizeFunc
   <449>        SetResourceTypeSizeFunc
   <473>        SetResourceTypeFindSubResFunc
   <503>        SetResourceTypeErrorValue
   <529>        CreateNewResourceClass
   <552>        ResourceClientBits
   <571>        LimitClients
   <584>        InitClientResources
   <604>        serverClient
   <617>        malloc
   <624>        HashResourceID
   <639>        __assert_c99
   <652>        GetXIDRange
   <664>        FakeClientID
   <677>        clients
   <685>        MarkClientException
   <705>        FatalError
   <716>        AddResource
   <728>        LookupResourceName
   <747>        __dtrace_Xserver___resource-alloc
   <781>        
   <782>        ErrorF
   <789>        __dtrace_Xserver___resource-free
   <822>        
   <823>        FreeResourceByType
   <842>        ChangeResourceValue
   <862>        FindClientResourcesByType
   <888>        FindSubResources
   <905>        FindAllClientResources
   <928>        LookupClientResourceComplex
   <956>        FreeClientNeverRetainResources
   <987>        FreeClientResources
   <1007>       HandleSaveSet
   <1021>       FreeAllResources
   <1038>       currentMaxClients
   <1056>       dixLookupResourceByType
   <1080>       XaceHook
   <1089>       dixLookupResourceByClass
   <1114>       GetXIDList
   <1125>       LegalNewID
   <1136>       noPanoramiXExtension
   <1157>       NoopDDA
   <1165>       DeleteWindow
   <1178>       dixDestroyPixmap
   <1195>       FreeGC
   <1202>       CloseFont
   <1212>       FreeCursor
   <1223>       FreeColormap
   <1236>       FreeClientPixels
   <1253>       OtherClientGone
   <1269>       DeletePassiveGrab

It seems dangerous to merge partial strings (for reasons such as this),
is it explicitly allowed in the ELF i386 ABI?  That is, is it possible
that the anomaly is in binutil as opposed to dtrace (in this case).

BTW the illumos issue is https://www.illumos.org/issues/6653
where the files are presented in a manner to easily reproduce the problem.

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