[Mesa-dev] [PATCH 08/15] glsl: Switch ast_type_qualifier to a 128-bit bitset.

[Francisco Jerez]

This should end the drought of bits in the ast_type_qualifier object.
The bitset_t type works pretty much as a drop-in replacement for the
current uint64_t bitset.

The only catch is that the bitset_t type as defined in the previous
commit doesn't have a trivial constructor (because it has a
user-defined constructor), so it cannot be used as union member
without providing a user-defined constructor for the union (which
causes it in turn to be non-trivially constructible).  This annoyance
could be easily addressed in C++11 by declaring the default
constructor of bitset_t to be the implicitly defined one -- IMO one
more reason to drop support for GCC 4.2-4.3.

The other minor change was required because glsl_parser_extras.cpp was
hard-coding the type of bitset temporaries as uint64_t, which (unlike
would have been the case if the uint64_t had been replaced with
e.g. an __int128) would otherwise have caused a build failure, because
the boolean conversion operator of bitset_t is marked explicit (if
C++11 is available), so the bitset won't be silently truncated down to
1 bit in order to use it to initialize the uint64_t temporaries
(yikes).
---
 src/compiler/glsl/ast.h                  | 8 ++++++--
 src/compiler/glsl/glsl_parser.yy         | 1 +
 src/compiler/glsl/glsl_parser_extras.cpp | 4 ++--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/compiler/glsl/ast.h b/src/compiler/glsl/ast.h
index eee22482812..b0db14e20b6 100644
--- a/src/compiler/glsl/ast.h
+++ b/src/compiler/glsl/ast.h
@@ -28,6 +28,7 @@
 #include "list.h"
 #include "glsl_parser_extras.h"
 #include "compiler/glsl_types.h"
+#include "util/bitset.h"
 
 struct _mesa_glsl_parse_state;
 
@@ -473,8 +474,11 @@ enum {
 
 struct ast_type_qualifier {
    DECLARE_RALLOC_CXX_OPERATORS(ast_type_qualifier);
+   DECLARE_BITSET_T(bitset_t, 128);
+
+   union flags {
+      flags() {}
 
-   union {
       struct {
 	 unsigned invariant:1;
          unsigned precise:1;
@@ -636,7 +640,7 @@ struct ast_type_qualifier {
       q;
 
       /** \brief Set of flags, accessed as a bitmask. */
-      uint64_t i;
+      bitset_t i;
    } flags;
 
    /** Precision of the type (highp/medium/lowp). */
diff --git a/src/compiler/glsl/glsl_parser.yy b/src/compiler/glsl/glsl_parser.yy
index 19147c7a3ec..4faf9602a08 100644
--- a/src/compiler/glsl/glsl_parser.yy
+++ b/src/compiler/glsl/glsl_parser.yy
@@ -96,6 +96,7 @@ static bool match_layout_qualifier(const char *s1, const char *s2,
 %parse-param {struct _mesa_glsl_parse_state *state}
 
 %union {
+   YYSTYPE() {}
    int n;
    int64_t n64;
    float real;
diff --git a/src/compiler/glsl/glsl_parser_extras.cpp b/src/compiler/glsl/glsl_parser_extras.cpp
index d99916d8ada..57589843776 100644
--- a/src/compiler/glsl/glsl_parser_extras.cpp
+++ b/src/compiler/glsl/glsl_parser_extras.cpp
@@ -1010,7 +1010,7 @@ _mesa_ast_process_interface_block(YYLTYPE *locp,
                            "an instance name are not allowed");
    }
 
-   uint64_t interface_type_mask;
+   ast_type_qualifier::bitset_t interface_type_mask;
    struct ast_type_qualifier temp_type_qualifier;
 
    /* Get a bitmask containing only the in/out/uniform/buffer
@@ -1029,7 +1029,7 @@ _mesa_ast_process_interface_block(YYLTYPE *locp,
     * production rule guarantees that only one bit will be set (and
     * it will be in/out/uniform).
     */
-   uint64_t block_interface_qualifier = q.flags.i;
+   ast_type_qualifier::bitset_t block_interface_qualifier = q.flags.i;
 
    block->default_layout.flags.i |= block_interface_qualifier;
 
-- 
2.16.1