[Mesa-dev] [PATCH 1/2] glsl: Optimize (not A) or (not B) into not (A and B).

[Matt Turner]

On Thu, Oct 24, 2013 at 1:46 AM, Erik Faye-Lund <kusmabite at gmail.com> wrote:
> On Thu, Oct 24, 2013 at 2:19 AM, Matt Turner <mattst88 at gmail.com> wrote:
>> A few Serious Sam 3 shaders affected:
>>
>> instructions in affected programs:     4384 -> 4344 (-0.91%)
>> ---
>>  src/glsl/opt_algebraic.cpp | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
>> index 37b2f02..3bf0689 100644
>> --- a/src/glsl/opt_algebraic.cpp
>> +++ b/src/glsl/opt_algebraic.cpp
>> @@ -32,8 +32,11 @@
>>  #include "ir_visitor.h"
>>  #include "ir_rvalue_visitor.h"
>>  #include "ir_optimization.h"
>> +#include "ir_builder.h"
>>  #include "glsl_types.h"
>>
>> +using namespace ir_builder;
>> +
>>  namespace {
>>
>>  /**
>> @@ -436,6 +439,15 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
>>
>>          this->progress = true;
>>          return new(mem_ctx) ir_constant(ir->type, &data);
>> +      } else if (op_expr[0] && op_expr[0]->operation == ir_unop_logic_not &&
>> +                 op_expr[1] && op_expr[1]->operation == ir_unop_logic_not) {
>> +         /* De Morgan's Law:
>> +          *    (not A) or (not B) === not (A and B)
>> +          */
>> +         temp = logic_not(logic_and(op_expr[0]->operands[0],
>> +                                    op_expr[1]->operands[0]));
>> +         return swizzle_if_required(ir, temp);
>> +         this->progress = true;
>
> Returning before reporting progress?

Ouch! Thanks.