[Mesa-dev] [PATCH] nir/builder: fix C90 build errors

[Connor Abbott]

On Sat, Dec 19, 2015 at 9:18 PM, Rob Clark <robdclark at gmail.com> wrote:
> Note that this is *only* about the header files.. not the src files.
> I'm not proposing to make NIR support C90.

Why would you need to only make the header filef C90 compliant? If you
just need to pass around a nir_shader * or something, you can just use
a forward declaration.

>
> I will at some point, before it is ready to merge, need to arrange the
> NIR related bits in mesa st so that we can build without it, for
> benefit of the MSVC folks.
>
> (It might be useful someday to use NIR more extensively in mesa st,
> and use nir->tgsi pass, so we can do all the opt passes in NIR..
> although that is *way* more ambitious than what I want to do right
> now.  With any luck, by the time we get to that point, we can rely on
> a less braindead version of MSVC?)

My understanding is that mesa/st doesn't need to be built with old
MSVC, just gallium.

>
> BR,
> -R
>
> On Sat, Dec 19, 2015 at 8:58 PM, Connor Abbott <cwabbott0 at gmail.com> wrote:
>> We haven't allowed NIR in core gallium before, since core gallium has
>> to be built with some old version of MSVC that doesn't support many
>> C99 features that we really wanted to use. The only reason that
>> -Werror exists is for compatibility with old MSVC, and if you want to
>> use NIR with something that needs to build with old MSVC, there are
>> going to be much bigger changes needed, and we'd rather avoid that. If
>> you just want to add some NIR-specific stuff that e.g. softpipe
>> doesn't need to compile against, then you should fix the build system
>> not to add the warning.
>>
>> On Sat, Dec 19, 2015 at 5:39 PM, Rob Clark <robdclark at gmail.com> wrote:
>>> From: Rob Clark <robclark at freedesktop.org>
>>>
>>> We are going to start using nir_builder.h from some gallium code, which
>>> is currently only C90.  Which results in:
>>>
>>>    In file included from nir/nir_emulate.c:26:0:
>>>    ../../../src/glsl/nir/nir_builder.h: In function ‘nir_build_alu’:
>>>    ../../../src/glsl/nir/nir_builder.h:132:4: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]
>>>        unsigned num_components = op_info->output_size;
>>>        ^
>>>    In file included from nir/nir_emulate.c:26:0:
>>>    ../../../src/glsl/nir/nir_builder.h: In function ‘nir_ssa_for_src’:
>>>    ../../../src/glsl/nir/nir_builder.h:271:4: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]
>>>        nir_alu_src alu = { NIR_SRC_INIT };
>>>        ^
>>>    cc1: some warnings being treated as errors
>>>
>>> Signed-off-by: Rob Clark <robclark at freedesktop.org>
>>> ---
>>> Not sure if I should just go ahead and push this sort of thing.  Or
>>> if we can start requiring C99 for gallium?
>>>
>>>  src/glsl/nir/nir_builder.h | 7 +++++--
>>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/src/glsl/nir/nir_builder.h b/src/glsl/nir/nir_builder.h
>>> index 332bb02..6f30306 100644
>>> --- a/src/glsl/nir/nir_builder.h
>>> +++ b/src/glsl/nir/nir_builder.h
>>> @@ -115,6 +115,8 @@ nir_build_alu(nir_builder *build, nir_op op, nir_ssa_def *src0,
>>>  {
>>>     const nir_op_info *op_info = &nir_op_infos[op];
>>>     nir_alu_instr *instr = nir_alu_instr_create(build->shader, op);
>>> +   unsigned num_components;
>>> +
>>>     if (!instr)
>>>        return NULL;
>>>
>>> @@ -129,7 +131,7 @@ nir_build_alu(nir_builder *build, nir_op op, nir_ssa_def *src0,
>>>     /* Guess the number of components the destination temporary should have
>>>      * based on our input sizes, if it's not fixed for the op.
>>>      */
>>> -   unsigned num_components = op_info->output_size;
>>> +   num_components = op_info->output_size;
>>>     if (num_components == 0) {
>>>        for (unsigned i = 0; i < op_info->num_inputs; i++) {
>>>           if (op_info->input_sizes[i] == 0)
>>> @@ -265,10 +267,11 @@ nir_channel(nir_builder *b, nir_ssa_def *def, unsigned c)
>>>  static inline nir_ssa_def *
>>>  nir_ssa_for_src(nir_builder *build, nir_src src, int num_components)
>>>  {
>>> +   nir_alu_src alu = { NIR_SRC_INIT };
>>> +
>>>     if (src.is_ssa && src.ssa->num_components == num_components)
>>>        return src.ssa;
>>>
>>> -   nir_alu_src alu = { NIR_SRC_INIT };
>>>     alu.src = src;
>>>     for (int j = 0; j < 4; j++)
>>>        alu.swizzle[j] = j;
>>> --
>>> 2.5.0
>>>
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