On 10/08/2015 03:31 AM, Iago Toral wrote:
> On Wed, 2015-10-07 at 14:34 -0700, Ian Romanick wrote:
>> From: Ian Romanick <ian.d.roman...@intel.com>
>>
>> Fixes:
>> ES3-CTS.shaders.negative.constant_sequence
>>
>> spec/glsl-es-3.00/compiler/global-initializer/from-sequence.vert
>> spec/glsl-es-3.00/compiler/global-initializer/from-sequence.frag
>>
>> Signed-off-by: Ian Romanick <ian.d.roman...@intel.com>
>> ---
>> src/glsl/ast_to_hir.cpp | 43 ++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
>> index 6af0f80..c7444ed 100644
>> --- a/src/glsl/ast_to_hir.cpp
>> +++ b/src/glsl/ast_to_hir.cpp
>> @@ -3311,8 +3311,49 @@ process_initializer(ir_variable *var, ast_declaration
>> *decl,
>> if (new_rhs != NULL) {
>> rhs = new_rhs;
>>
>> + /* Section 4.3.3 (Constant Expressions) of the GLSL ES 3.00.4 spec
>> + * says:
>> + *
>> + * "A constant expression is one of
>> + *
>> + * ...
>> + *
>> + * - an expression formed by an operator on operands that
>> are
>> + * all constant expressions, including getting an element
>> of
>> + * a constant array, or a field of a constant structure,
>> or
>> + * components of a constant vector. However, the sequence
>> + * operator ( , ) and the assignment operators ( =, +=,
>> ...)
>> + * are not included in the operators that can create a
>> + * constant expression."
>> + *
>> + * Section 12.43 (Sequence operator and constant expressions) says:
>> + *
>> + * "Should the following construct be allowed?
>> + *
>> + * float a[2,3];
>> + *
>> + * The expression within the brackets uses the sequence
>> operator
>> + * (',') and returns the integer 3 so the construct is decl
>> aring
>> + * a single-dimensional array of size 3. In some languages,
>> the
>> + * construct declares a two-dimensional array. It would be
>> + * preferable to make this construct illegal to avoid
>> confusion.
>> + *
>> + * One possibility is to change the definition of the sequence
>> + * operator so that it does not return a constant- expression
>> and
>> + * hence cannot be used to declare an array size.
>> + *
>> + * RESOLUTION: The result of a sequence operator is not a
>> + * constant-expression."
>> + *
>> + * Section 4.3.3 (Constant Expressions) of the GLSL 4.30.9 spec
>> + * contains language almost identical to the section 4.3.3 fomr the
>> + * GLSL ES 3.00.4 spec. This is a new limitation for these GLSL
>> + * versions.
>> + */
>> ir_constant *constant_value = rhs->constant_expression_value();
>> - if (!constant_value) {
>> + if (!constant_value ||
>> + (state->is_version(430, 300) &&
>> + decl->initializer->has_sequence_subexpression())) {
>> const char *const variable_mode =
>> (type->qualifier.flags.q.constant)
>> ? "const"
>
> This only seems to handle the case of sequence operators used in
> declaration initializers. Maybe this is all we really care about in
> practice, but the spec says that in code such as:
>
> float b = ... ;
> ...
> b = (a++, a > 0.0 ? 2.0 : 0.0);
>
> the RHS in the assignment is not a constant expression, and this patch
> would not address that, right? I wonder if this distinction has any
> actual implications in practice though.
That's fine, but there is another case that is not caught. There are
only a few places where a constant expression is required. Some
initializers (global variables in GLSL ES, uniforms, const-decorated
global variabes, and const-decorated local variables before GLSL 4.20),
array sizes, and maybe one other thing... that I can't think of right now.
I sent a test,
spec/glsl-es-3.00/compiler/array-sized-by-sequence-in-parenthesis.vert,
for the array size case. This patch does not cover that, but I have one
on the way.
> Iago
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
