Re: [RFC 6/7] Lazily and dynamically create i386-linux target descriptions

[Yao Qi <qiyaoltc at gmail dot com>]

Pedro Alves <palves@redhat.com> writes:

>> +
>> +  struct xml_and_mask array[] = {
>> +    { "i386/i386-linux.xml", X86_XSTATE_SSE_MASK },
>> +    { "i386/i386-mmx-linux.xml", X86_XSTATE_X87_MASK },
>> +    { "i386/i386-avx-linux.xml", X86_XSTATE_AVX_MASK },
>> +    { "i386/i386-mpx-linux.xml", X86_XSTATE_MPX_MASK },
>> +    { "i386/i386-avx-mpx-linux.xml", X86_XSTATE_AVX_MPX_MASK },
>> +    { "i386/i386-avx-avx512-linux.xml", X86_XSTATE_AVX_AVX512_MASK },
>> +    { "i386/i386-avx-mpx-avx512-pku-linux.xml",
>> +      X86_XSTATE_AVX_MPX_AVX512_PKU_MASK },
>
> About these xml files.  Is your idea that:
>
>  #1 - we remove these xml description files at some point, keeping only
>       the description fragments which are currently xi:included by the xml
>       files above?
>  #2 - or, we'll still continue adding new xml files and grow this
>       list here?
>  #3 - or, we'll keep the existing xml files as representative / legacy,
>       and use them in the unit tests going forward, just to make sure
>       the machinery builds correct descriptions?
>
> (I don't expect to answer to be #2, I just put it there for completeness.)

In short, #2 and #3.

IIUC, you are not against "continue adding new xml files" in #2, you are
against that we have to maintain the list here as we add new xml files.
Even we finished the transition for all ports to dynamic tdesc creation,
we still need to add new xml files to features/ directory for new
hardware features, because GDBserver needs them (regformats/*.dat need
them).  We may add i386/i386-avx-mpx-avx512-linux.xml, GDB
doesn't need it, but GDBserver still needs it.  Given we need to add
such .xml file, it is better to grow the list so that we can do the
test.  So the answer is #2.  Suppose one day, we don't need these XML
files to generate regformats/*.dat for GDBserver, we can remove all
i386-*linux.xml files except i386-avx-mpx-avx512-pku-linux.xml, but I
still want to move them to somewhere in testsuite directory to keep them
as tests.  Then, it becomes #3.

The purpose of this test is to make sure these lazily/dynamically
created tdesc (using create_feature_org_gnu_gdb_XXX functions) equal to
the tdesc created from XML files.  The dynamic tdesc creation is still
new, needs more tests.

During the process that we change other targets (amd64, arm, mips, etc)
to the dynamic tdesc creation, the lists like this are expected to be
added for each target.

When we finish the transition to dynamic tdesc creation for all ports,
and dynamic tdesc creation is quite stable, we can remove all these
tests and lists, but I prefer to keeping the tests.

Before we remove these tests and lists, we still need to update the
lists when,

 1) add a new port with target description, a new list should be added
 in its -tdep.c file.
 2) add a new xml target description for the existing port,

Let me think about how to generate this list instead of manually
maintain this list.

-- 
Yao (齐尧)