On Fri, Aug 28, 2015 at 2:20 AM, Matt Turner <matts...@gmail.com> wrote:
> On Thu, Aug 20, 2015 at 6:00 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote:
>> It is fairly tricky to detect the proper conditions for using bitfield
>> insert, but easy to just use it up front. This removes a lot of
>> instructions on nvc0 when invoking the packing builtins.
>>
>> Signed-off-by: Ilia Mirkin <imir...@alum.mit.edu>
>> ---
>>
>> Not sure if all backends will benefit from this, but nvc0 definitely
>> does, since it has a "insert bitfield" instruction which handles
>> everything all-in-one (the combined offset/bits argument takes the
>> position of the third source, which requires no extra logic when
>> they're both immediate).
>>
>> It would be just as easy to use the 3-arg bfi op (no masking necessary
>> since we know that we start with a clean value), but gallium doesn't
>> support it. (Not for the least of reasons is that nvc0 doesn't support
>> it and I'm the one that added BFI to TGSI.)
>>
>> Unpacking could use BFE, really the snorm logic would greatly benefit
>> from using an IBFE (thus avoiding the shifts back and forth),
>> but... later.
>>
>> src/glsl/ir_optimization.h | 4 +++-
>> src/glsl/lower_packing_builtins.cpp | 24 +++++++++++++++++++++++-
>> src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 3 +++
>> 3 files changed, 29 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
>> index eef107e..b955874 100644
>> --- a/src/glsl/ir_optimization.h
>> +++ b/src/glsl/ir_optimization.h
>> @@ -66,7 +66,9 @@ enum lower_packing_builtins_op {
>> LOWER_UNPACK_SNORM_4x8 = 0x0200,
>>
>> LOWER_PACK_UNORM_4x8 = 0x0400,
>> - LOWER_UNPACK_UNORM_4x8 = 0x0800
>> + LOWER_UNPACK_UNORM_4x8 = 0x0800,
>> +
>> + LOWER_PACK_USE_BFI = 0x1000,
>> };
>>
>> bool do_common_optimization(exec_list *ir, bool linked,
>> diff --git a/src/glsl/lower_packing_builtins.cpp
>> b/src/glsl/lower_packing_builtins.cpp
>> index a6fb8a8..be17e1d 100644
>> --- a/src/glsl/lower_packing_builtins.cpp
>> +++ b/src/glsl/lower_packing_builtins.cpp
>> @@ -225,6 +225,14 @@ private:
>> "tmp_pack_uvec2_to_uint");
>> factory.emit(assign(u, uvec2_rval));
>>
>> + if (op_mask & LOWER_PACK_USE_BFI) {
>> + return bitfield_insert(
>> + bit_and(swizzle_x(u), constant(0xffffu)),
>> + swizzle_y(u),
>> + constant(16),
>> + constant(16));
>
> Indent bitfield_insert's arguments to align with its "(" (and probably
> put bit_and on the same line)
Hm, well there was an earlier time when I had more arguments and it
wouldn't fit in 80 chars. However I believe that this indentation is
perfectly valid. This is how I've always done it if I put the first
arg on the next line. emacs agrees.
Anyways, I'll try to fit the first bit_and on the same line, in which
case indenting to the ( will make sense.
>
>> + }
>> +
>> /* return (u.y << 16) | (u.x & 0xffff); */
>> return bit_or(lshift(swizzle_y(u), constant(16u)),
>> bit_and(swizzle_x(u), constant(0xffffu)));
>> @@ -242,9 +250,23 @@ private:
>> {
>> assert(uvec4_rval->type == glsl_type::uvec4_type);
>>
>> - /* uvec4 u = UVEC4_RVAL; */
>> ir_variable *u = factory.make_temp(glsl_type::uvec4_type,
>> "tmp_pack_uvec4_to_uint");
>> +
>> + if (op_mask & LOWER_PACK_USE_BFI) {
>> + /* uvec4 u = UVEC4_RVAL; */
>> + factory.emit(assign(u, uvec4_rval));
>> +
>> + return bitfield_insert(
>> + bitfield_insert(
>> + bitfield_insert(
>> + bit_and(swizzle_x(u), constant(0xffu)),
>> + swizzle_y(u), constant(8), constant(8)),
>> + swizzle_z(u), constant(16), constant(8)),
>> + swizzle_w(u), constant(24), constant(8));
>
> I don't know if there's a nice way to indent such a long expression,
> but I'd indent the lines after the return three spaces more than the
> first bitfield_insert.
Again, this is how emacs does it, and also the way I've always done it
(Have I always done it that way because that's how emacs does it? Hard
to tell by now, but I think I did it like this before I used emacs). I
could put the first bitfield_insert on the next line after the return,
perhaps that'll result in a more pleasing indentation? i.e.
return
bitfield_insert(
bitfield_insert(
...
If you'd like to make rules for emacs for the glsl dir that do things
just the way you like them, I probably won't object too much, but I
tend to let the author determine such smaller details as long as its
within the regular rules of indentation, even if it's not exactly the
way I'd do it.
>
>> + }
>> +
>> + /* uvec4 u = UVEC4_RVAL & 0xff */
>> factory.emit(assign(u, bit_and(uvec4_rval, constant(0xffu))));
>>
>> /* return (u.w << 24) | (u.z << 16) | (u.y << 8) | u.x; */
>> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>> b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>> index eb47685..d3c7238 100644
>> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>> @@ -5995,6 +5995,9 @@ st_link_shader(struct gl_context *ctx, struct
>> gl_shader_program *prog)
>> LOWER_PACK_HALF_2x16 |
>> LOWER_UNPACK_HALF_2x16;
>>
>> + if (ctx->Extensions.ARB_gpu_shader5)
>> + lower_inst |= LOWER_PACK_USE_BFI;
>> +
>> lower_packing_builtins(ir, lower_inst);
>> }
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