[Mesa-dev] [PATCH 3/5] glsl: fall back to inexact function-match

[Erik Faye-Lund]

On Wed, 2018-10-31 at 15:46 +0200, Tapani Pälli wrote:
> 
> On 10/30/18 7:11 PM, Erik Faye-Lund wrote:
> > In GLES, we currently either need an exact match with a local
> > function,
> > or an exact match with a builtin.
> > 
> > However, if we add support for implicit conversions for GLES
> > shaders,
> > we also need to fall back to a non-exact match in the case where
> > there
> > were no builtin match either.
> > 
> > Luckily, we already have a variable ready with this, so let's just
> > return it if the builtin-search failed.
> > 
> > Signed-off-by: Erik Faye-Lund <erik.faye-lund at collabora.com>
> > ---
> >   src/compiler/glsl/ast_function.cpp | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/compiler/glsl/ast_function.cpp
> > b/src/compiler/glsl/ast_function.cpp
> > index 1fa3f7561ae..50fd8bc5f5d 100644
> > --- a/src/compiler/glsl/ast_function.cpp
> > +++ b/src/compiler/glsl/ast_function.cpp
> > @@ -667,7 +667,7 @@ match_function_by_name(const char *name,
> >      /* Local shader has no exact candidates; check the built-ins.
> > */
> >      _mesa_glsl_initialize_builtin_functions();
> >      sig = _mesa_glsl_find_builtin_function(state, name,
> > actual_parameters);
> > -   return sig;
> > +   return sig ? sig : local_sig;
> 
> I think this would deserve a comment about 'local_sig', it did not
> seem 
> obvious ... maybe something like:
> 
> /* Variable local_sig contains the result from 
> choose_best_inexact_overload(). */
> 

Yeah, good point. I've changed it to this, which feels like it explains
the point without spoon-feeding the reader too much... How does that
sound?

---8<---
diff --git a/src/compiler/glsl/ast_function.cpp
b/src/compiler/glsl/ast_function.cpp
index 1fa3f7561ae..6aa30400060 100644
--- a/src/compiler/glsl/ast_function.cpp
+++ b/src/compiler/glsl/ast_function.cpp
@@ -667,7 +667,11 @@ match_function_by_name(const char *name,
    /* Local shader has no exact candidates; check the built-ins. */
    _mesa_glsl_initialize_builtin_functions();
    sig = _mesa_glsl_find_builtin_function(state, name,
actual_parameters);
-   return sig;
+
+   /* if _mesa_glsl_find_builtin_function failed, fall back to the
result
+    * of choose_best_inexact_overload() instead
+    */
+   return sig ? sig : local_sig;
 }
 
 static ir_function_signature *
---8<---


> >   }
> >   
> >   static ir_function_signature *
> > 
> 
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