glsl: Support the 'invariant(all)' pragma

Previously the 'STDGL invariant(all)' pragma added in GLSL 1.20 was
simply ignored by the compiler.  This adds support for setting all
variable invariant.

In GLSL 1.10 and GLSL ES 1.00 the pragma is ignored, per the specs,
but a warning is generated.

Fixes piglit test glsl-invariant-pragma and bugzilla #31925.

NOTE: This is a candidate for the 7.9 and 7.10 branches.

4 files changed, 42 insertions, 0 deletions

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index 80c4ef4314c..a8dcae6e810 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -1852,6 +1852,23 @@ apply_type_qualifier_to_variable(const struct ast_type_qualifier *qual,
    else if (qual->flags.q.uniform)
       var->mode = ir_var_uniform;
 
+   if (state->all_invariant && (state->current_function == NULL)) {
+      switch (state->target) {
+      case vertex_shader:
+	 if (var->mode == ir_var_out)
+	    var->invariant = true;
+	 break;
+      case geometry_shader:
+	 if ((var->mode == ir_var_in) || (var->mode == ir_var_out))
+	    var->invariant = true;
+	 break;
+      case fragment_shader:
+	 if (var->mode == ir_var_in)
+	    var->invariant = true;
+	 break;
+      }
+   }
+
    if (qual->flags.q.flat)
       var->interpolation = ir_var_flat;
    else if (qual->flags.q.noperspective)
diff --git a/src/glsl/glsl_lexer.lpp b/src/glsl/glsl_lexer.lpp
index 15742ac3636..d30759be2b8 100644
--- a/src/glsl/glsl_lexer.lpp
+++ b/src/glsl/glsl_lexer.lpp
@@ -145,6 +145,10 @@ HASH		^{SPC}#{SPC}
 				  BEGIN PP;
 				  return PRAGMA_OPTIMIZE_OFF;
 				}
+^{SPC}#{SPC}pragma{SPCP}STDGL{SPCP}invariant{SPC}\({SPC}all{SPC}\) {
+				  BEGIN PP;
+				  return PRAGMA_INVARIANT_ALL;
+				}
 ^{SPC}#{SPC}pragma{SPCP}	{ BEGIN PRAGMA; }
 
 <PRAGMA>\n			{ BEGIN 0; yylineno++; yycolumn = 0; }
diff --git a/src/glsl/glsl_parser.ypp b/src/glsl/glsl_parser.ypp
index 6d7d148eb04..41b51a74725 100644
--- a/src/glsl/glsl_parser.ypp
+++ b/src/glsl/glsl_parser.ypp
@@ -108,6 +108,7 @@
 %token VERSION EXTENSION LINE COLON EOL INTERFACE OUTPUT
 %token PRAGMA_DEBUG_ON PRAGMA_DEBUG_OFF
 %token PRAGMA_OPTIMIZE_ON PRAGMA_OPTIMIZE_OFF
+%token PRAGMA_INVARIANT_ALL
 %token LAYOUT_TOK
 
    /* Reserved words that are not actually used in the grammar.
@@ -241,6 +242,19 @@ pragma_statement:
 	| PRAGMA_DEBUG_OFF EOL
 	| PRAGMA_OPTIMIZE_ON EOL
 	| PRAGMA_OPTIMIZE_OFF EOL
+	| PRAGMA_INVARIANT_ALL EOL
+	{
+	   if (state->language_version < 120) {
+	      _mesa_glsl_warning(& @1, state,
+				 "pragma `invariant(all)' not supported in "
+				 "GLSL%s %d.%02d",
+				 state->es_shader ? " ES" : "",
+				 state->language_version / 100,
+				 state->language_version % 100);
+	   } else {
+	      state->all_invariant = true;
+	   }
+	}
 	;
 
 extension_statement_list:
diff --git a/src/glsl/glsl_parser_extras.h b/src/glsl/glsl_parser_extras.h
index 98c4e70173d..13d3a2979e4 100644
--- a/src/glsl/glsl_parser_extras.h
+++ b/src/glsl/glsl_parser_extras.h
@@ -108,6 +108,13 @@ struct _mesa_glsl_parse_state {
    /** Was there an error during compilation? */
    bool error;
 
+   /**
+    * Are all shader inputs / outputs invariant?
+    *
+    * This is set when the 'STDGL invariant(all)' pragma is used.
+    */
+   bool all_invariant;
+
    /** Loop or switch statement containing the current instructions. */
    class ir_instruction *loop_or_switch_nesting;
    class ast_iteration_statement *loop_or_switch_nesting_ast;