On Wed, Sep 6, 2017 at 4:44 AM, Dave Airlie <airl...@gmail.com> wrote: > On 6 September 2017 at 03:11, Marek Olšák <mar...@gmail.com> wrote: >> On Tue, Sep 5, 2017 at 5:50 PM, Brian Paul <bri...@vmware.com> wrote: >>> On 09/04/2017 05:29 AM, Marek Olšák wrote: >>>> >>>> On Sun, Sep 3, 2017 at 1:18 PM, Dave Airlie <airl...@gmail.com> wrote: >>>>> >>>>> From: Dave Airlie <airl...@redhat.com> >>>>> >>>>> reduces size from 1144 to 1128. >>>>> >>>>> Signed-off-by: Dave Airlie <airl...@redhat.com> >>>>> --- >>>>> src/mesa/main/mtypes.h | 10 +++++----- >>>>> 1 file changed, 5 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h >>>>> index d44897b..3d68a6d 100644 >>>>> --- a/src/mesa/main/mtypes.h >>>>> +++ b/src/mesa/main/mtypes.h >>>>> @@ -1012,7 +1012,6 @@ struct gl_texture_object >>>>> struct gl_sampler_object Sampler; >>>>> >>>>> GLenum DepthMode; /**< GL_ARB_depth_texture */ >>>> >>>> >>>> The patch looks good, but here are some ideas for future improvements: >>>> >>>> GLenum can be uint16_t everywhere, because GL doesn't set higher bits: >>>> >>>> typedef uint16_t GLenum16. >>>> s/GLenum/GLenum16/ >>>> >>>>> - bool StencilSampling; /**< Should we sample stencil instead of >>>>> depth? */ >>>>> >>>>> GLfloat Priority; /**< in [0,1] */ >>>>> GLint BaseLevel; /**< min mipmap level, OpenGL 1.2 */ >>>>> @@ -1033,12 +1032,17 @@ struct gl_texture_object >>>>> GLboolean Immutable; /**< GL_ARB_texture_storage */ >>>>> GLboolean _IsFloat; /**< GL_OES_float_texture */ >>>>> GLboolean _IsHalfFloat; /**< GL_OES_half_float_texture */ >>>>> + bool StencilSampling; /**< Should we sample stencil instead of >>>>> depth? */ >>>>> + bool HandleAllocated; /**< GL_ARB_bindless_texture */ >>>> >>>> >>>> All bools can be 1 bit: >>>> >>>> bool x:1; >>>> GLboolean y:1; >>>> >>>> etc. >>>> >>>>> >>>>> GLuint MinLevel; /**< GL_ARB_texture_view */ >>>>> GLuint MinLayer; /**< GL_ARB_texture_view */ >>>>> GLuint NumLevels; /**< GL_ARB_texture_view */ >>>>> GLuint NumLayers; /**< GL_ARB_texture_view */ >>>> >>>> >>>> MinLevel, NumLevels can be ubyte (uint8_t). MinLayer, NumLayers can be >>>> ushort (uint16_t)... simply by considering the range of possible >>>> values. >>> >>> >>> There's lots of opportunities along these lines in gl_texture_image. And >>> since we often have many gl_texture_images per gl_texture_object, and we >>> often have many textures, it'll probably have considerable impact. I've >>> suggested this in the past but never got around to working on it. >>> >>> I recall Eric Anholt mentioning a memory profiling tool that was helpful for >>> finding wasted space in structures, etc. I don't recall the name right now. >>> Eric? >> >> Dave used pahole for this patch series too. It can't obviously suggest >> what I suggested above (like changing the types and bits). > > Yup this was pahole, doing what Marek describes is definitely something > that can be done, but needs a lot more care and attention. > > Replacing bool with unsigned :1 fields isn't always a win, as you then > have a mask/shift on the accesses so overall may end up slowing things > down, and increasing instruction count etc.
bool:1 is better than unsigned:1, because it's has the behavior of bool. (and the 1-byte alignment might also matter) Testing bool:1 doesn't need a shift, only a mask, i.e. the compiler should do: if (structure->somebyte & 0x04) for testing a bool on the 3rd bit. The OR operator has the same complexity: if (structure->bool_val & 0x24) for testing 2 bools on the 3rd and 6th bit. And the AND operator: if ((structure->bool_val & 0x24) == 0x24) Setting a bool:1 to 1 is done by OR'ing the bit. Setting a bool to 0 is done by AND'ing the bit. No shifts anywhere. Marek _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
