[Mesa-dev] [PATCH v3 11/18] mesa/macros: add power-of-two assertions for alignment macros

[Nanley Chery]

How about if I create a patch which puts the greater than 0 check into
is_power_of_two()?

(value > 0) && (value & (value - 1)) == 0);

Thanks,
Nanley

On Wed, Jun 24, 2015 at 3:22 PM, Anuj Phogat <anuj.phogat at gmail.com> wrote:
> On Mon, Jun 22, 2015 at 4:02 PM, Nanley Chery <nanleychery at gmail.com> wrote:
>> From: Nanley Chery <nanley.g.chery at intel.com>
>>
>> ALIGN and ROUND_DOWN_TO both require that the alignment value passed
>> into the macro be a power of two in the comments. Using software assertions
>> verifies this to be the case.
>>
>> v2: use static inline functions instead of gcc-specific statement expressions.
>>
>> Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
>> ---
>>  src/mesa/drivers/dri/i965/brw_fs_nir.cpp |  2 +-
>>  src/mesa/main/macros.h                   | 16 +++++++++++++---
>>  2 files changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> index 59081ea..1a57784 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> @@ -134,7 +134,7 @@ fs_visitor::nir_setup_outputs(nir_shader *shader)
>>                                 : var->type->vector_elements;
>>
>>        if (stage == MESA_SHADER_VERTEX) {
>> -         for (int i = 0; i < ALIGN(type_size(var->type), 4) / 4; i++) {
>> +         for (unsigned int i = 0; i < ALIGN(type_size(var->type), 4) / 4; i++) {
>>              int output = var->data.location + i;
>>              this->outputs[output] = offset(reg, 4 * i);
>>              this->output_components[output] = vector_elements;
>> diff --git a/src/mesa/main/macros.h b/src/mesa/main/macros.h
>> index 0608650..4a640ad 100644
>> --- a/src/mesa/main/macros.h
>> +++ b/src/mesa/main/macros.h
>> @@ -684,7 +684,7 @@ minify(unsigned value, unsigned levels)
>>   * Note that this considers 0 a power of two.
>>   */
>>  static inline bool
>> -is_power_of_two(unsigned value)
>> +is_power_of_two(uintptr_t value)
>>  {
>>     return (value & (value - 1)) == 0;
>>  }
>> @@ -700,7 +700,12 @@ is_power_of_two(unsigned value)
>>   *
>>   * \sa ROUND_DOWN_TO()
>>   */
>> -#define ALIGN(value, alignment)  (((value) + (alignment) - 1) & ~((alignment) - 1))
>> +static inline uintptr_t
>> +ALIGN(uintptr_t value, uintptr_t alignment)
>> +{
>> +      assert(is_power_of_two(alignment));
> Also handle the 0 alignment. is_power_of_two() returns true for 0.
> Use assert(alignment > 0 && is_power_of_two(alignment))?
>> +      return (((value) + (alignment) - 1) & ~((alignment) - 1));
>> +}
>>
>>  /**
>>   * Align a value down to an alignment value
>> @@ -713,7 +718,12 @@ is_power_of_two(unsigned value)
>>   *
>>   * \sa ALIGN()
>>   */
>> -#define ROUND_DOWN_TO(value, alignment) ((value) & ~(alignment - 1))
>> +static inline uintptr_t
>> +ROUND_DOWN_TO(uintptr_t value, uintptr_t alignment)
>> +{
>> +      assert(is_power_of_two(alignment));
> Here as well.
>> +      return ((value) & ~(alignment - 1));
>> +}
>>
>>
>>  /** Cross product of two 3-element vectors */
>> --
>> 2.4.2
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
> With above changes and indentation fixes:
> Reviewed-by: Anuj Phogat <anuj.phogat at gmail.com>