[Mesa-dev] [PATCH 1/3 v2] glsl: prevent qualifiers modification of predeclared variables

andrey simiklit asimiklit.work at gmail.com
Tue Nov 13 10:21:46 UTC 2018


Hello,

Thanks a lot for review.

Regards,
Andrii.


On Sat, Nov 10, 2018 at 5:38 AM Timothy Arceri <tarceri at itsqueeze.com>
wrote:

> Nice! Series is:
>
> Reviewed-by: Timothy Arceri <tarceri at itsqueeze.com>
>
> On 10/10/18 9:07 am, Ian Romanick wrote:
> > From: Ian Romanick <ian.d.romanick at intel.com>
> >
> > Section 3.7 (Identifiers) of the GLSL spec says:
> >
> >      However, as noted in the specification, there are some cases where
> >      previously declared variables can be redeclared to change or add
> >      some property, and predeclared "gl_" names are allowed to be
> >      redeclared in a shader only for these specific purposes.  More
> >      generally, it is an error to redeclare a variable, including those
> >      starting "gl_".
> >
> > This patch should fix piglit tests:
> > clip-distance-redeclare-without-inout.frag
> > clip-distance-redeclare-without-inout.vert
> >
> > However, this causes a regression in
> > clip-distance-out-values.shader_test.  A fix for that test has been sent
> > to the piglit list for review:
> >
> >      https://patchwork.freedesktop.org/patch/255201/
> >
> > As far as I understood following mailing thread:
> > https://lists.freedesktop.org/archives/piglit/2013-October/007935.html
> > looks like we have accepted to remove an ability to change qualifiers
> > but have not done it yet. Unless I missed something)
> >
> > v2 (idr): Move 'earlier->data.mode != var->data.mode' test much earlier
> > in the function.  Add special handling for gl_LastFragData.
> >
> > Signed-off-by: Andrii Simiklit <andrii.simiklit at globallogic.com>
> > Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> > ---
> >   src/compiler/glsl/ast_to_hir.cpp | 51
> +++++++++++++++++++++-------------------
> >   1 file changed, 27 insertions(+), 24 deletions(-)
> >
> > diff --git a/src/compiler/glsl/ast_to_hir.cpp
> b/src/compiler/glsl/ast_to_hir.cpp
> > index 1082d6c91cf..2e4c9ef6776 100644
> > --- a/src/compiler/glsl/ast_to_hir.cpp
> > +++ b/src/compiler/glsl/ast_to_hir.cpp
> > @@ -4238,6 +4238,29 @@ get_variable_being_redeclared(ir_variable
> **var_ptr, YYLTYPE loc,
> >
> >      *is_redeclaration = true;
> >
> > +   if (earlier->data.how_declared == ir_var_declared_implicitly) {
> > +      /* Verify that the redeclaration of a built-in does not change the
> > +       * storage qualifier.  There are a couple special cases.
> > +       *
> > +       * 1. Some built-in variables that are defined as 'in' in the
> > +       *    specification are implemented as system values.  Allow
> > +       *    ir_var_system_value -> ir_var_shader_in.
> > +       *
> > +       * 2. gl_LastFragData is implemented as a ir_var_shader_out, but
> the
> > +       *    specification requires that redeclarations omit any
> qualifier.
> > +       *    Allow ir_var_shader_out -> ir_var_auto for this one
> variable.
> > +       */
> > +      if (earlier->data.mode != var->data.mode &&
> > +          !(earlier->data.mode == ir_var_system_value &&
> > +            var->data.mode == ir_var_shader_in) &&
> > +          !(strcmp(var->name, "gl_LastFragData") == 0 &&
> > +            var->data.mode == ir_var_auto)) {
> > +         _mesa_glsl_error(&loc, state,
> > +                          "redeclaration cannot change qualification of
> `%s'",
> > +                          var->name);
> > +      }
> > +   }
> > +
> >      /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec,
> >       *
> >       * "It is legal to declare an array without a size and then
> > @@ -4246,11 +4269,6 @@ get_variable_being_redeclared(ir_variable
> **var_ptr, YYLTYPE loc,
> >       */
> >      if (earlier->type->is_unsized_array() && var->type->is_array()
> >          && (var->type->fields.array == earlier->type->fields.array)) {
> > -      /* FINISHME: This doesn't match the qualifiers on the two
> > -       * FINISHME: declarations.  It's not 100% clear whether this is
> > -       * FINISHME: required or not.
> > -       */
> > -
> >         const int size = var->type->array_size();
> >         check_builtin_array_max_size(var->name, size, loc, state);
> >         if ((size > 0) && (size <= earlier->data.max_array_access)) {
> > @@ -4342,28 +4360,13 @@ get_variable_being_redeclared(ir_variable
> **var_ptr, YYLTYPE loc,
> >         earlier->data.precision = var->data.precision;
> >         earlier->data.memory_coherent = var->data.memory_coherent;
> >
> > -   } else if (earlier->data.how_declared == ir_var_declared_implicitly
> &&
> > -              state->allow_builtin_variable_redeclaration) {
> > +   } else if ((earlier->data.how_declared == ir_var_declared_implicitly
> &&
> > +               state->allow_builtin_variable_redeclaration) ||
> > +              allow_all_redeclarations) {
> >         /* Allow verbatim redeclarations of built-in variables. Not
> explicitly
> >          * valid, but some applications do it.
> >          */
> > -      if (earlier->data.mode != var->data.mode &&
> > -          !(earlier->data.mode == ir_var_system_value &&
> > -            var->data.mode == ir_var_shader_in)) {
> > -         _mesa_glsl_error(&loc, state,
> > -                          "redeclaration of `%s' with incorrect
> qualifiers",
> > -                          var->name);
> > -      } else if (earlier->type != var->type) {
> > -         _mesa_glsl_error(&loc, state,
> > -                          "redeclaration of `%s' has incorrect type",
> > -                          var->name);
> > -      }
> > -   } else if (allow_all_redeclarations) {
> > -      if (earlier->data.mode != var->data.mode) {
> > -         _mesa_glsl_error(&loc, state,
> > -                          "redeclaration of `%s' with incorrect
> qualifiers",
> > -                          var->name);
> > -      } else if (earlier->type != var->type) {
> > +      if (earlier->type != var->type) {
> >            _mesa_glsl_error(&loc, state,
> >                             "redeclaration of `%s' has incorrect type",
> >                             var->name);
> >
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