Investigate data padding within classes and structs

[Mauller]

the most significant number of warnings when /Wall is used revolves around padding bytes being added to various classes and structs.

In some instances dozens of bytes can be added to a single object as padding due to the ordering of data within it.

Optimising this should help with memory usage and cache friendliness of data structures.

The warning is C4820 for reference and requires /Wall to be used.

Some examples of some of the most used classes:

'Object': '5' bytes padding added after data member 'Object::m_lastWeaponCondition'
'Object': '4' bytes padding added after data member 'Object::m_isReceivingDifficultyBonus'
'Object': '4' bytes padding added after data member 'Object::m_prev'
'Object': '2' bytes padding added after data member 'Object::m_visionSpiedMask'

'PointGroupClass': '3' bytes padding added after data member 'PointGroupClass::FrameRowColumnCountLog2'
'PointGroupClass': '2' bytes padding added after data member 'PointGroupClass::DefaultPointFrame'
'PointGroupClass': '3' bytes padding added after data member 'PointGroupClass::Billboard'

'Render2DSentenceClass': '3' bytes padding added after data member 'Render2DSentenceClass::MonoSpaced'
'Render2DSentenceClass': '3' bytes padding added after data member 'Render2DSentenceClass::Centered'
'Render2DSentenceClass': '1' bytes padding added after data member 'Render2DSentenceClass::useHardWordWrap'
'FontCharsClass': '3' bytes padding added after data member 'FontCharsClass::IsBold'

'StealthUpdate': '3' bytes padding added after data member 'StealthUpdate::m_xferRestoreDisguise'
'StealthUpdateModuleData': '3' bytes padding added after data member 'StealthUpdateModuleData::m_grantedBySpecialPower'
'StealthUpdate': '3' bytes padding added after data member 'StealthUpdate::m_enabled'
'StealthUpdate': '1' bytes padding added after data member 'StealthUpdate::m_disguised'

'WeaponTemplate': '3' bytes padding added after data member 'WeaponTemplate::m_isScaleWeaponSpeed'
'WeaponTemplate': '3' bytes padding added after data member 'WeaponTemplate::m_damageDealtAtSelfPosition'
'WeaponTemplate': '3' bytes padding added after data member 'WeaponTemplate::m_playFXWhenStealthed'
'WeaponTemplate': '3' bytes padding added after data member 'WeaponTemplate::m_dieOnDetonate'
'Weapon': '2' bytes padding added after data member 'Weapon::m_leechWeaponRangeActive'

[aliendroid1]

the most significant number of warnings when /Wall is used revolves around padding bytes being added to various classes and structs.

In some instances dozens of bytes are being added to a single object as padding due to the ordering of data within it.

Optimising this should help with memory usage and cache friendliness of data structures.

The warning is C4820 for reference and requires /Wall to be used.

Since you mentioned dozens, this is probably not the case, but could it be to make them 16 bit aligned for direct x matrices?

[Mauller]

Since you mentioned dozens, this is probably not the case, but could it be to make them 16 bit aligned for direct x matrices?

No this really is a case of poor layout of variables within the class creating misaligned data, therefore the compiler padding out the objects.

I deal with this stuff all the time as i work in embedded, you should always properly align data and manually pad out your classes and structs.

[Mauller]

Added some examples.