only set InputsRead bit if input is really used

src/mesa/shader/arbprogparse.c

@@ -1576,9 +1576,6 @@ parse_attrib_binding(GLcontext * ctx, const GLubyte ** inst,
    if (err) {
       program_error(ctx, Program->Position, "Bad attribute binding");
    }
-   else {
-      Program->Base.InputsRead |= (1 << *inputReg);
-   }
 
    return err;
 }
@@ -2557,6 +2554,11 @@ parse_src_reg (GLcontext * ctx, const GLubyte ** inst,
          return 1;
    }
 
+   /* Add attributes to InputsRead only if they are used the program.
+    * This avoids the handling of unused ATTRIB declarations in the drivers. */
+   if (*File == PROGRAM_INPUT)
+      Program->Base.InputsRead |= (1 << *Index);
+
    return 0;
 }