Mesa (master): glsl: Relax combinations of layout qualifiers with other qualifiers.

[Chris Forbes]

Module: Mesa
Branch: master
Commit: d4703f94460b4571c82167dbe29207c448aeed7c
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d4703f94460b4571c82167dbe29207c448aeed7c

Author: Chris Forbes <chrisf at ijw.co.nz>
Date:   Thu Jun 12 19:48:58 2014 +1200

glsl: Relax combinations of layout qualifiers with other qualifiers.

Previously we disallowed any combination of layout with interpolation,
invariant, or precise qualifiers. There is very little spec guidance on
exactly which combinations should be allowed, but with ARB_sso it's
useful to allow these qualifiers with rendezvous-by-location.

Since it's unclear exactly where the layout qualifier should appear when
combined with other qualifiers, we will allow it anywhere before the
auxiliary storage qualifier.

This allows enough flexibility for all examples I've seen, while keeping
the auxiliary-storage-qualifier / storage-qualifier pair together (as
they are a single qualifier in the spec prior to
ARB_shading_language_420pack)

Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

---

 src/glsl/glsl_parser.yy |   36 ++++++++----------------------------
 1 file changed, 8 insertions(+), 28 deletions(-)

diff --git a/src/glsl/glsl_parser.yy b/src/glsl/glsl_parser.yy
index 97b6c3f..2409959 100644
--- a/src/glsl/glsl_parser.yy
+++ b/src/glsl/glsl_parser.yy
@@ -1558,11 +1558,6 @@ type_qualifier:
       if ($2.flags.q.invariant)
          _mesa_glsl_error(&@1, state, "duplicate \"invariant\" qualifier");
 
-      if ($2.has_layout()) {
-         _mesa_glsl_error(&@1, state,
-                          "\"invariant\" cannot be used with layout(...)");
-      }
-
       if (!state->ARB_shading_language_420pack_enable && $2.flags.q.precise)
          _mesa_glsl_error(&@1, state,
                           "\"invariant\" must come after \"precise\"");
@@ -1585,11 +1580,6 @@ type_qualifier:
       if ($2.has_interpolation())
          _mesa_glsl_error(&@1, state, "duplicate interpolation qualifier");
 
-      if ($2.has_layout()) {
-         _mesa_glsl_error(&@1, state, "interpolation qualifiers cannot be used "
-                          "with layout(...)");
-      }
-
       if (!state->ARB_shading_language_420pack_enable &&
           ($2.flags.q.precise || $2.flags.q.invariant)) {
          _mesa_glsl_error(&@1, state, "interpolation qualifiers must come "
@@ -1601,28 +1591,18 @@ type_qualifier:
    }
    | layout_qualifier type_qualifier
    {
-      /* The GLSL 1.50 grammar indicates that a layout(...) declaration can be
-       * used standalone or immediately before a storage qualifier.  It cannot
-       * be used with interpolation qualifiers or invariant.  There does not
-       * appear to be any text indicating that it must come before the storage
-       * qualifier, but always seems to in examples.
+      /* In the absence of ARB_shading_language_420pack, layout qualifiers may
+       * appear no later than auxiliary storage qualifiers. There is no
+       * particularly clear spec language mandating this, but in all examples
+       * the layout qualifier precedes the storage qualifier.
+       *
+       * We allow combinations of layout with interpolation, invariant or
+       * precise qualifiers since these are useful in ARB_separate_shader_objects.
+       * There is no clear spec guidance on this either.
        */
       if (!state->ARB_shading_language_420pack_enable && $2.has_layout())
          _mesa_glsl_error(&@1, state, "duplicate layout(...) qualifiers");
 
-      if ($2.flags.q.invariant)
-         _mesa_glsl_error(&@1, state, "layout(...) cannot be used with "
-                          "the \"invariant\" qualifier");
-
-      if ($2.flags.q.precise)
-         _mesa_glsl_error(&@1, state, "layout(...) cannot be used with "
-                          "the \"precise\" qualifier");
-
-      if ($2.has_interpolation()) {
-         _mesa_glsl_error(&@1, state, "layout(...) cannot be used with "
-                          "interpolation qualifiers");
-      }
-
       $$ = $1;
       $$.merge_qualifier(&@1, state, $2);
    }