[Mesa-dev] [PATCH] radeonsi: don't preload constants at the beginning of shaders
Edward O'Callaghan
funfunctor at folklore1984.net
Sat Sep 10 00:55:19 UTC 2016
On 09/10/2016 10:02 AM, Bas Nieuwenhuizen wrote:
> Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Reviewed-by: Edward O'Callaghan <funfunctor at folklore1984.net>
>
> On Sat, Sep 10, 2016 at 12:40 AM, Marek Olšák <maraeo at gmail.com> wrote:
>> From: Marek Olšák <marek.olsak at amd.com>
>>
>> LLVM can CSE the loads, thus we can always re-load constants before each
>> use. The decrease in SGPR spilling is huge.
>>
>> The best improvements are the dumbest ones.
>>
>> 26011 shaders in 14651 tests
>> Totals:
>> SGPRS: 1453346 -> 1251920 (-13.86 %)
>> VGPRS: 742576 -> 728421 (-1.91 %)
>> Spilled SGPRs: 52298 -> 16644 (-68.17 %)
>> Spilled VGPRs: 397 -> 369 (-7.05 %)
>> Scratch VGPRs: 1372 -> 1344 (-2.04 %) dwords per thread
>> Code Size: 36136488 -> 36001064 (-0.37 %) bytes
>> LDS: 767 -> 767 (0.00 %) blocks
>> Max Waves: 219315 -> 222221 (1.33 %)
>> ---
>> src/gallium/drivers/radeonsi/si_shader.c | 30 +++++++++++-------------------
>> 1 file changed, 11 insertions(+), 19 deletions(-)
>>
>> diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
>> index 0b7de18..08e3cee 100644
>> --- a/src/gallium/drivers/radeonsi/si_shader.c
>> +++ b/src/gallium/drivers/radeonsi/si_shader.c
>> @@ -1874,26 +1874,33 @@ static LLVMValueRef fetch_constant(
>> for (chan = 0; chan < TGSI_NUM_CHANNELS; ++chan)
>> values[chan] = fetch_constant(bld_base, reg, type, chan);
>>
>> return lp_build_gather_values(bld_base->base.gallivm, values, 4);
>> }
>>
>> buf = reg->Register.Dimension ? reg->Dimension.Index : 0;
>> idx = reg->Register.Index * 4 + swizzle;
>>
>> if (!reg->Register.Indirect && !reg->Dimension.Indirect) {
>> + LLVMValueRef c0, c1;
>> +
>> + c0 = buffer_load_const(ctx, ctx->const_buffers[buf],
>> + LLVMConstInt(ctx->i32, idx * 4, 0));
>> +
>> if (!tgsi_type_is_64bit(type))
>> - return bitcast(bld_base, type, ctx->constants[buf][idx]);
>> + return bitcast(bld_base, type, c0);
>> else {
>> + c1 = buffer_load_const(ctx, ctx->const_buffers[buf],
>> + LLVMConstInt(ctx->i32,
>> + (idx + 1) * 4, 0));
>> return radeon_llvm_emit_fetch_64bit(bld_base, type,
>> - ctx->constants[buf][idx],
>> - ctx->constants[buf][idx + 1]);
>> + c0, c1);
>> }
>> }
>>
>> if (reg->Register.Dimension && reg->Dimension.Indirect) {
>> LLVMValueRef ptr = LLVMGetParam(ctx->radeon_bld.main_fn, SI_PARAM_CONST_BUFFERS);
>> LLVMValueRef index;
>> index = get_bounded_indirect_index(ctx, ®->DimIndirect,
>> reg->Dimension.Index,
>> SI_NUM_CONST_BUFFERS);
>> bufp = build_indexed_load_const(ctx, ptr, index);
>> @@ -5789,39 +5796,26 @@ static void create_function(struct si_shader_context *ctx)
>>
>> static void preload_constants(struct si_shader_context *ctx)
>> {
>> struct lp_build_tgsi_context *bld_base = &ctx->radeon_bld.soa.bld_base;
>> struct gallivm_state *gallivm = bld_base->base.gallivm;
>> const struct tgsi_shader_info *info = bld_base->info;
>> unsigned buf;
>> LLVMValueRef ptr = LLVMGetParam(ctx->radeon_bld.main_fn, SI_PARAM_CONST_BUFFERS);
>>
>> for (buf = 0; buf < SI_NUM_CONST_BUFFERS; buf++) {
>> - unsigned i, num_const = info->const_file_max[buf] + 1;
>> -
>> - if (num_const == 0)
>> + if (info->const_file_max[buf] == -1)
>> continue;
>>
>> - /* Allocate space for the constant values */
>> - ctx->constants[buf] = CALLOC(num_const * 4, sizeof(LLVMValueRef));
>> -
>> /* Load the resource descriptor */
>> ctx->const_buffers[buf] =
>> build_indexed_load_const(ctx, ptr, lp_build_const_int32(gallivm, buf));
>> -
>> - /* Load the constants, we rely on the code sinking to do the rest */
>> - for (i = 0; i < num_const * 4; ++i) {
>> - ctx->constants[buf][i] =
>> - buffer_load_const(ctx,
>> - ctx->const_buffers[buf],
>> - lp_build_const_int32(gallivm, i * 4));
>> - }
>> }
>> }
>>
>> static void preload_shader_buffers(struct si_shader_context *ctx)
>> {
>> struct gallivm_state *gallivm = &ctx->radeon_bld.gallivm;
>> LLVMValueRef ptr = LLVMGetParam(ctx->radeon_bld.main_fn, SI_PARAM_SHADER_BUFFERS);
>> int buf, maxbuf;
>>
>> maxbuf = MIN2(ctx->shader->selector->info.file_max[TGSI_FILE_BUFFER],
>> @@ -6898,22 +6892,20 @@ int si_compile_tgsi_shader(struct si_screen *sscreen,
>> ctx.shader = shader->gs_copy_shader;
>> if ((r = si_generate_gs_copy_shader(sscreen, &ctx,
>> shader, debug))) {
>> free(shader->gs_copy_shader);
>> shader->gs_copy_shader = NULL;
>> goto out;
>> }
>> }
>>
>> out:
>> - for (int i = 0; i < SI_NUM_CONST_BUFFERS; i++)
>> - FREE(ctx.constants[i]);
>> return r;
>> }
>>
>> /**
>> * Create, compile and return a shader part (prolog or epilog).
>> *
>> * \param sscreen screen
>> * \param list list of shader parts of the same category
>> * \param key shader part key
>> * \param tm LLVM target machine
>> --
>> 2.7.4
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
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