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

[Kyriazis, George]

It also fixes the errors that I was getting with gcc 5.4.0 with configure build on ubuntu 16.04.

Tested-By: George Kyriazis <george.kyriazis at intel.com<mailto:george.kyriazis at intel.com>>

On Feb 25, 2018, at 6:52 PM, Roland Scheidegger <sroland at vmware.com<mailto:sroland at vmware.com>> wrote:

Am 25.02.2018 um 21:12 schrieb Francisco Jerez:
Roland Scheidegger <sroland at vmware.com<mailto:sroland at vmware.com>> writes:

Am 25.02.2018 um 03:35 schrieb Francisco Jerez:
Roland Scheidegger <sroland at vmware.com<mailto:sroland at vmware.com>> writes:

This seems to have broken compilation with some gcc versions (with scons
build):

In file included from src/compiler/glsl/ast_array_index.cpp:24:0:
src/compiler/glsl/ast.h:648:16: error: member
‘ast_type_qualifier::bitset_t ast_type_qualifier::flags::i’ with
constructor not allowed in union
      bitset_t i;
               ^

Oops...  And the only reason bitset_t has a default constructor was...
to avoid using another C++11 feature (defaulted member functions).
Does the attached patch fix the build failure for you?  The cleaner
alternative would be to define the default constructor of the bitset
object like 'T() = default', but that would imply dropping support for
GCC 4.2-4.3 which don't implement the feature...

FWIW the compile error was happening with gcc 4.8 - I didn't see it with
gcc 5.4.
(I don't think at vmware we'd care about anything older than gcc 4.4 at
least but last time someone wanted to bump gcc requirements there were
still people requiring gcc 4.2.)

The patch compiles albeit there's about two dozen warnings like the
following:
glsl/ast_type.cpp: In member function 'bool
ast_fully_specified_type::has_qualifiers(_mesa_glsl_parse_state*) const':
glsl/ast_type.cpp:50:67: warning: ISO C++ says that these are ambiguous,
even though the worst conversion for the first is better than the worst
conversion for the second: [enabled by default]
   return (this->qualifier.flags.i & ~subroutine_only.flags.i) != 0;
                                                                  ^
In file included from glsl/ast.h:31:0,
                from glsl/ast_type.cpp:24:
../../src/util/bitset.h:181:7: note: candidate 1: bool operator!=(const
ast_type_qualifier::bitset_t&, unsigned int)
      operator!=(const T &b, BITSET_WORD x)                     \
      ^
glsl/ast.h:477:4: note: in expansion of macro 'DECLARE_BITSET_T'
   DECLARE_BITSET_T(bitset_t, 128);
   ^
glsl/ast_type.cpp:50:67: note: candidate 2: operator!=(int, int) <built-in>
   return (this->qualifier.flags.i & ~subroutine_only.flags.i) != 0;
                                                                  ^
Roland


Ah, yeah, that's because I didn't provide overloads for signed integer
types, but it should be harmless since the two candidates have the same
semantics, and should go away with a C++11-capable compiler.  I think
the attached patch should shut the warnings on older compilers.

Yes, that compiles without warnings (with gcc 4.8)
Tested-by: Roland Scheidegger <sroland at vmware.com<mailto:sroland at vmware.com>>






src/compiler/glsl/ast.h:648:16: note: unrestricted unions only available
with -std=c++11 or -std=gnu++11
scons: *** [build/linux-x86_64-checked/compiler/glsl/ast_array_index.os]
Error 1
src/gallium/tests/unit/u_format_test.c: In function ‘main’:
src/gallium/tests/unit/u_format_test.c:649:44: warning: array subscript
is above array bounds [-Warray-bounds]
         unpacked[i][j] = test->unpacked[i][j][1];
                                           ^
In file included from src/compiler/glsl/ast_expr.cpp:24:0:
src/compiler/glsl/ast.h:648:16: error: member
‘ast_type_qualifier::bitset_t ast_type_qualifier::flags::i’ with
constructor not allowed in union
      bitset_t i;
               ^
src/compiler/glsl/ast.h:648:16: note: unrestricted unions only available
with -std=c++11 or -std=gnu++11

Roland

[...]



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