[Mesa-dev] [PATCH 2/2] mesa: Add test for sorted extension table

[Matt Turner]

On Wed, Nov 18, 2015 at 4:08 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> On 18 November 2015 at 23:40, Nanley Chery <nanleychery at gmail.com> wrote:
>> On Wed, Nov 18, 2015 at 3:07 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>>
>>> Why have the count as an entry in the enum? Can't you just do
>>> ARRAY_SIZE(_mesa_extension_table) ?
>>>
>>
>> The compiler doesn't know the size of the array by just looking at the
>> header. To use ARRAY_SIZE, I'd have to modify the declaration of
>> _mesa_extension_table to specify a size of MESA_EXTENSION_COUNT.
>>
> Afaict there is no declaration, only a definition of the array. That
> aside I'm not sure what makes you think that - we have dozens of cases
> in mesa which use this approach.
>
>>> On Wed, Nov 18, 2015 at 6:01 PM, Nanley Chery <nanleychery at gmail.com>
>>> wrote:
>>> > From: Nanley Chery <nanley.g.chery at intel.com>
>>> >
>>> > Enable developers to know if the table's alphabetical sorting
>>> > is maintained or lost.
>>> >
>>> > Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
>>> > ---
>>> >  src/mesa/main/extensions.h              |  1 +
>>> >  src/mesa/main/tests/Makefile.am         |  1 +
>>> >  src/mesa/main/tests/mesa_extensions.cpp | 47
>>> > +++++++++++++++++++++++++++++++++
>>> >  3 files changed, 49 insertions(+)
>>> >  create mode 100644 src/mesa/main/tests/mesa_extensions.cpp
>>> >
>>> > diff --git a/src/mesa/main/extensions.h b/src/mesa/main/extensions.h
>>> > index 1615e1c..7114c96 100644
>>> > --- a/src/mesa/main/extensions.h
>>> > +++ b/src/mesa/main/extensions.h
>>> > @@ -85,6 +85,7 @@ enum {
>>> >  #define EXT(name_str, ...) MESA_EXTENSION_##name_str,
>>> >  #include "extensions_table.h"
>>> >  #undef EXT
>>> > +   MESA_EXTENSION_COUNT
>>> >  };
>>> >
>>> >
>>> > diff --git a/src/mesa/main/tests/Makefile.am
>>> > b/src/mesa/main/tests/Makefile.am
>>> > index bd7ab73..d6977e2 100644
>>> > --- a/src/mesa/main/tests/Makefile.am
>>> > +++ b/src/mesa/main/tests/Makefile.am
>>> > @@ -27,6 +27,7 @@ AM_CPPFLAGS += -DHAVE_SHARED_GLAPI
>>> >  main_test_SOURCES +=                   \
>>> >         dispatch_sanity.cpp             \
>>> >         mesa_formats.cpp                        \
>>> > +       mesa_extensions.cpp                     \
>>> >         program_state_string.cpp
>>> >
>>> >  main_test_LDADD += \
>>> > diff --git a/src/mesa/main/tests/mesa_extensions.cpp
>>> > b/src/mesa/main/tests/mesa_extensions.cpp
>>> > new file mode 100644
>>> > index 0000000..5154ae1
>>> > --- /dev/null
>>> > +++ b/src/mesa/main/tests/mesa_extensions.cpp
>>> > @@ -0,0 +1,47 @@
>>> > +/*
>>> > + * Copyright © 2015 Intel Corporation
>>> > + *
>>> > + * Permission is hereby granted, free of charge, to any person
>>> > obtaining a
>>> > + * copy of this software and associated documentation files (the
>>> > "Software"),
>>> > + * to deal in the Software without restriction, including without
>>> > limitation
>>> > + * the rights to use, copy, modify, merge, publish, distribute,
>>> > sublicense,
>>> > + * and/or sell copies of the Software, and to permit persons to whom
>>> > the
>>> > + * Software is furnished to do so, subject to the following conditions:
>>> > + *
>>> > + * The above copyright notice and this permission notice (including the
>>> > next
>>> > + * paragraph) shall be included in all copies or substantial portions
>>> > of the
>>> > + * Software.
>>> > + *
>>> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
>>> > EXPRESS OR
>>> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
>>> > MERCHANTABILITY,
>>> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT
>>> > SHALL
>>> > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
>>> > OTHER
>>> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
>>> > ARISING
>>> > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
>>> > + * DEALINGS IN THE SOFTWARE.
>>> > + */
>>> > +
>>> > +/**
>>> > + * \name mesa_extensions.cpp
>>> > + *
>>> > + * Verify that the extensions table is sorted.
>>> > + *
>>> > + */
>>> > +
>>> > +#include <gtest/gtest.h>
>>> > +#include "main/mtypes.h"
>>> > +#include "main/extensions.h"
>>> > +
>>> > +/**
>>> > + * Debug/test: verify the extension table is alphabetically sorted.
>>> > + */
>>> > +TEST(MesaExtensionsTest, AlphabeticallySorted)
>>> > +{
>>> > +   for (int i = 0; i < MESA_EXTENSION_COUNT - 1; ++i) {
>>> > +      const char * current_str = _mesa_extension_table[i].name;
>>> > +      const char * next_str = _mesa_extension_table[i+1].name;
>>> > +
>>> > +      /* We expect the extension table to be alphabetically sorted */
>>> > +      ASSERT_LT(strcmp(current_str, next_str), 0);
> Am I day dreaming or something's wrong here. On the last iteration
> you'll end up comparing the final extension name against ... null ?

It's safe (and as intended) as far as I can tell, because the loop
condition is i < MESA_EXTENSION_COUNT - 1.