[Mesa-dev] [PATCH 2/4] compiler: avoid 'unused variable' and 'may be used uninitialized' warnings

[andrey simiklit]

Hello,

Thanks for review.
Please find my comments below:

On Fri, Nov 9, 2018 at 2:52 PM Eric Engestrom <eric.engestrom at intel.com>
wrote:

> On Tuesday, 2018-09-11 15:42:05 +0300, asimiklit.work at gmail.com wrote:
> > From: Andrii Simiklit <andrii.simiklit at globallogic.com>
> >
> > 1. nir/nir_lower_vars_to_ssa.c:691:21: warning:
> >        unused variable ‘var’
> >        nir_variable *var = path->path[0]->var;
> >
> > 2. nir_types.cpp:558:31: warning:
> >     ‘elem_align’ may be used uninitialized in this function
> >            unsigned elem_size, elem_align;
> >    nir_types.cpp:558:20: warning:
> >    ‘elem_size’ may be used uninitialized in this function
> >            unsigned elem_size, elem_align;
> >
> > Signed-off-by: Andrii Simiklit <andrii.simiklit at globallogic.com>
> > ---
> >  src/compiler/nir/nir_lower_vars_to_ssa.c | 2 +-
> >  src/compiler/nir_types.cpp               | 4 ++--
> >  2 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/src/compiler/nir/nir_lower_vars_to_ssa.c
> b/src/compiler/nir/nir_lower_vars_to_ssa.c
> > index cd679be..96de261 100644
> > --- a/src/compiler/nir/nir_lower_vars_to_ssa.c
> > +++ b/src/compiler/nir/nir_lower_vars_to_ssa.c
> > @@ -688,7 +688,7 @@ nir_lower_vars_to_ssa_impl(nir_function_impl *impl)
> >        nir_deref_path *path = &node->path;
> >
> >        assert(path->path[0]->deref_type == nir_deref_type_var);
> > -      nir_variable *var = path->path[0]->var;
> > +      MAYBE_UNUSED nir_variable *var = path->path[0]->var;
> >
> >        /* We don't build deref nodes for non-local variables */
> >        assert(var->data.mode == nir_var_local);
>
> Sure, or you could simply remove the single-use extra local variable and
> just fold it into the assert :)
>

I agree,will fix :)


>
> > diff --git a/src/compiler/nir_types.cpp b/src/compiler/nir_types.cpp
> > index d24f094..d39d87b 100644
> > --- a/src/compiler/nir_types.cpp
> > +++ b/src/compiler/nir_types.cpp
> > @@ -542,7 +542,7 @@ glsl_get_natural_size_align_bytes(const struct
> glsl_type *type,
> >     }
> >
> >     case GLSL_TYPE_ARRAY: {
> > -      unsigned elem_size, elem_align;
> > +      unsigned elem_size = 0, elem_align = 0;
>
> Not really keen on these ones; it looks like your compiler is ignoring the
> unreachable() in glsl_get_natural_size_align_bytes() and mis-computing the
> possible code-paths, resulting in it wrongly printing a warning.
>

You are right when I added the 'default:' case to the switch the warning is
disappeared:

case GLSL_TYPE_INTERFACE:
case GLSL_TYPE_FUNCTION:
+default:
   unreachable("type does not have a natural size");

What do you think about such solution? Is it acceptable for you?


> I'd prefer to keep these two hunks as is, so that real issue in
> glsl_get_natural_size_align_bytes() would get flagged appropriately.
>
> >        glsl_get_natural_size_align_bytes(type->fields.array,
> >                                          &elem_size, &elem_align);
> >        *align = elem_align;
> > @@ -554,7 +554,7 @@ glsl_get_natural_size_align_bytes(const struct
> glsl_type *type,
> >        *size = 0;
> >        *align = 0;
> >        for (unsigned i = 0; i < type->length; i++) {
> > -         unsigned elem_size, elem_align;
> > +         unsigned elem_size = 0, elem_align = 0;
> >
>  glsl_get_natural_size_align_bytes(type->fields.structure[i].type,
> >                                             &elem_size, &elem_align);
> >           *align = MAX2(*align, elem_align);
> > --
> > 2.7.4
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
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