tgsi: Implement invariant atrib for TGSI to GLSL

The 'invariant' output data attrib was not properly implemented in
mesa's TGSI serialization, and was ignored in virglrender's conversion
from TGSI text to GLSL text.   This patch adds 'invariant' support
and sets a new virgl cap to enable it since older versions of
virglrenderer will fail if invariant appears in the TGSI stream.

Tested: chromeos on qemu + virglrenderer

Tested-by: Jakob Bornecrantz <jakob@collabora.com>
Reviewed-by: Jakob Bornecrantz <jakob@collabora.com>
Signed-off-by: Joe M. Kniss <djmk@google.com>
Signed-off-by: Jakob Bornecrantz <jakob@collabora.com>

src/gallium/auxiliary/tgsi/tgsi_strings.c

@@ -166,6 +166,8 @@ const char *tgsi_interpolate_locations[TGSI_INTERPOLATE_LOC_COUNT] =
    "SAMPLE",
 };
 
+const char *tgsi_invariant_name = "INVARIANT";
+
 const char *tgsi_primitive_names[PIPE_PRIM_MAX] =
 {
    "POINTS",

src/gallium/auxiliary/tgsi/tgsi_strings.h

@@ -52,6 +52,8 @@ extern const char *tgsi_interpolate_names[TGSI_INTERPOLATE_COUNT];
 
 extern const char *tgsi_interpolate_locations[TGSI_INTERPOLATE_LOC_COUNT];
 
+extern const char *tgsi_invariant_name;
+
 extern const char *tgsi_primitive_names[PIPE_PRIM_MAX];
 
 extern const char *tgsi_fs_coord_origin_names[2];

src/gallium/auxiliary/tgsi/tgsi_text.c

@@ -1393,10 +1393,6 @@ static boolean parse_declaration( struct translate_ctx *ctx )
             break;
          }
       }
-      if (i == TGSI_INTERPOLATE_COUNT) {
-         report_error( ctx, "Expected semantic or interpolate attribute" );
-         return FALSE;
-      }
    }
 
    cur = ctx->cur;
@@ -1416,6 +1412,20 @@ static boolean parse_declaration( struct translate_ctx *ctx )
       }
    }
 
+   cur = ctx->cur;
+   eat_opt_white( &cur );
+   if (*cur == ',' && !is_vs_input) {
+      cur++;
+      eat_opt_white( &cur );
+      if (str_match_nocase_whole( &cur, tgsi_invariant_name )) {
+         decl.Declaration.Invariant = 1;
+         ctx->cur = cur;
+      } else {
+         report_error( ctx, "Expected semantic, interpolate attribute, or invariant \"%.10s...\" ", cur );
+         return FALSE;
+      }
+   }
+
    advance = tgsi_build_full_declaration(
       &decl,
       ctx->tokens_cur,

src/virgl_hw.h

@@ -290,6 +290,7 @@ struct virgl_caps_v2 {
         int32_t max_texture_gather_offset;
         uint32_t texture_buffer_offset_alignment;
         uint32_t uniform_buffer_offset_alignment;
+        uint32_t tgsi_invariant;
 };
 
 union virgl_caps {

src/vrend_renderer.c

@@ -6871,6 +6871,8 @@ void vrend_renderer_fill_caps(uint32_t set, uint32_t version,
 
    if (gl_ver >= 43)
       glGetIntegerv(GL_TEXTURE_BUFFER_OFFSET_ALIGNMENT, &caps->v2.texture_buffer_offset_alignment);
+
+   caps->v2.tgsi_invariant = 1;
 }
 
 GLint64 vrend_renderer_get_timestamp(void)

src/vrend_shader.c

@@ -37,6 +37,7 @@ extern int vrend_dump_shaders;
 /* start convert of tgsi to glsl */
 
 #define INTERP_PREFIX "               "
+#define INVARI_PREFIX "invariant"
 
 struct vrend_shader_io {
    unsigned                name;
@@ -46,6 +47,7 @@ struct vrend_shader_io {
    unsigned                interpolate;
    unsigned first;
    bool                 centroid;
+   bool                    invariant;
    bool glsl_predefined_no_emit;
    bool glsl_no_index;
    bool glsl_gl_in;
@@ -468,6 +470,7 @@ iter_declaration(struct tgsi_iterate_context *iter,
       ctx->outputs[i].name = decl->Semantic.Name;
       ctx->outputs[i].sid = decl->Semantic.Index;
       ctx->outputs[i].interpolate = decl->Interp.Interpolate;
+      ctx->outputs[i].invariant = decl->Declaration.Invariant;
       ctx->outputs[i].first = decl->Range.First;
       ctx->outputs[i].glsl_predefined_no_emit = false;
       ctx->outputs[i].glsl_no_index = false;
@@ -2501,7 +2504,10 @@ static char *emit_ios(struct dump_ctx *ctx, char *glsl_hdr)
             } else
                prefix = "";
             /* ugly leave spaces to patch interp in later */
-            snprintf(buf, 255, "%sout vec4 %s;\n", prefix, ctx->outputs[i].glsl_name);
+            snprintf(buf, 255, "%s%sout vec4 %s;\n", prefix, ctx->outputs[i].invariant ? "invariant " : "", ctx->outputs[i].glsl_name);
+            STRCAT_WITH_RET(glsl_hdr, buf);
+         } else if (ctx->outputs[i].invariant) {
+            snprintf(buf, 255, "invariant %s;\n", ctx->outputs[i].glsl_name);
             STRCAT_WITH_RET(glsl_hdr, buf);
          }
       }