[Mesa-dev] [PATCH 3/9] nir/opt_peephole_select: Don't peephole_select expensive math instructions
Timothy Arceri
tarceri at itsqueeze.com
Tue Oct 9 22:42:08 UTC 2018
Hi Ian,
You might be interested in doing something like this [1]. It needs some
tidy up (and likely further testing) but my initial results showed a
fairly large number of select can be converted to ifs just based on
having a ubo load.
[1] https://gitlab.freedesktop.org/tarceri/mesa/commits/bcsel-to-if
On 30/8/18 3:35 pm, Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
>
> On some GPUs, especially older Intel GPUs, some math instructions are
> very expensive. On those architectures, don't reduce flow control to a
> csel if one of the branches contains one of these expensive math
> instructions.
>
> This prevents a bunch of cycle count regressions on pre-Gen6 platforms
> with a later patch (intel/compiler: More peephole select for pre-Gen6).
>
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> ---
> src/amd/vulkan/radv_shader.c | 2 +-
> src/broadcom/compiler/nir_to_vir.c | 2 +-
> src/compiler/nir/nir.h | 2 +-
> src/compiler/nir/nir_opt_peephole_select.c | 46 +++++++++++++++++++++++-----
> src/gallium/drivers/freedreno/ir3/ir3_nir.c | 2 +-
> src/gallium/drivers/radeonsi/si_shader_nir.c | 2 +-
> src/gallium/drivers/vc4/vc4_program.c | 2 +-
> src/intel/compiler/brw_nir.c | 4 +--
> src/mesa/state_tracker/st_glsl_to_nir.cpp | 2 +-
> 9 files changed, 47 insertions(+), 17 deletions(-)
>
> diff --git a/src/amd/vulkan/radv_shader.c b/src/amd/vulkan/radv_shader.c
> index 632512db09b..c8d502a9e3a 100644
> --- a/src/amd/vulkan/radv_shader.c
> +++ b/src/amd/vulkan/radv_shader.c
> @@ -143,7 +143,7 @@ radv_optimize_nir(struct nir_shader *shader, bool optimize_conservatively)
> NIR_PASS(progress, shader, nir_opt_if);
> NIR_PASS(progress, shader, nir_opt_dead_cf);
> NIR_PASS(progress, shader, nir_opt_cse);
> - NIR_PASS(progress, shader, nir_opt_peephole_select, 8, true);
> + NIR_PASS(progress, shader, nir_opt_peephole_select, 8, true, true);
> NIR_PASS(progress, shader, nir_opt_algebraic);
> NIR_PASS(progress, shader, nir_opt_constant_folding);
> NIR_PASS(progress, shader, nir_opt_undef);
> diff --git a/src/broadcom/compiler/nir_to_vir.c b/src/broadcom/compiler/nir_to_vir.c
> index 0d23cea4d5b..ec0ff4b907a 100644
> --- a/src/broadcom/compiler/nir_to_vir.c
> +++ b/src/broadcom/compiler/nir_to_vir.c
> @@ -1210,7 +1210,7 @@ v3d_optimize_nir(struct nir_shader *s)
> NIR_PASS(progress, s, nir_opt_dce);
> NIR_PASS(progress, s, nir_opt_dead_cf);
> NIR_PASS(progress, s, nir_opt_cse);
> - NIR_PASS(progress, s, nir_opt_peephole_select, 8, true);
> + NIR_PASS(progress, s, nir_opt_peephole_select, 8, true, true);
> NIR_PASS(progress, s, nir_opt_algebraic);
> NIR_PASS(progress, s, nir_opt_constant_folding);
> NIR_PASS(progress, s, nir_opt_undef);
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index 67fa46d5557..feb69be6b59 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -3003,7 +3003,7 @@ bool nir_opt_move_comparisons(nir_shader *shader);
> bool nir_opt_move_load_ubo(nir_shader *shader);
>
> bool nir_opt_peephole_select(nir_shader *shader, unsigned limit,
> - bool indirect_load_ok);
> + bool indirect_load_ok, bool expensive_alu_ok);
>
> bool nir_opt_remove_phis_impl(nir_function_impl *impl);
> bool nir_opt_remove_phis(nir_shader *shader);
> diff --git a/src/compiler/nir/nir_opt_peephole_select.c b/src/compiler/nir/nir_opt_peephole_select.c
> index 6808d3eda6c..09b55f3739e 100644
> --- a/src/compiler/nir/nir_opt_peephole_select.c
> +++ b/src/compiler/nir/nir_opt_peephole_select.c
> @@ -59,7 +59,8 @@
>
> static bool
> block_check_for_allowed_instrs(nir_block *block, unsigned *count,
> - bool alu_ok, bool indirect_load_ok)
> + bool alu_ok, bool indirect_load_ok,
> + bool expensive_alu_ok)
> {
> nir_foreach_instr(instr, block) {
> switch (instr->type) {
> @@ -117,6 +118,25 @@ block_check_for_allowed_instrs(nir_block *block, unsigned *count,
> case nir_op_vec3:
> case nir_op_vec4:
> break;
> +
> + case nir_op_fcos:
> + case nir_op_fdiv:
> + case nir_op_fexp2:
> + case nir_op_flog2:
> + case nir_op_fmod:
> + case nir_op_fpow:
> + case nir_op_frcp:
> + case nir_op_frem:
> + case nir_op_frsq:
> + case nir_op_fsin:
> + case nir_op_idiv:
> + case nir_op_irem:
> + case nir_op_udiv:
> + if (!alu_ok || !expensive_alu_ok)
> + return false;
> +
> + break;
> +
> default:
> if (!alu_ok) {
> /* It must be a move-like operation. */
> @@ -160,7 +180,8 @@ block_check_for_allowed_instrs(nir_block *block, unsigned *count,
>
> static bool
> nir_opt_peephole_select_block(nir_block *block, nir_shader *shader,
> - unsigned limit, bool indirect_load_ok)
> + unsigned limit, bool indirect_load_ok,
> + bool expensive_alu_ok)
> {
> if (nir_cf_node_is_first(&block->cf_node))
> return false;
> @@ -180,10 +201,17 @@ nir_opt_peephole_select_block(nir_block *block, nir_shader *shader,
>
> /* ... and those blocks must only contain "allowed" instructions. */
> unsigned count = 0;
> +#if 1
> if (!block_check_for_allowed_instrs(then_block, &count, limit != 0,
> - indirect_load_ok) ||
> + indirect_load_ok, expensive_alu_ok) ||
> !block_check_for_allowed_instrs(else_block, &count, limit != 0,
> - indirect_load_ok))
> + indirect_load_ok, expensive_alu_ok))
> +#else
> + if (!block_check_for_allowed_instrs(then_block, &count, shader->info.stage,
> + limit != 0, indirect_load_ok, expensive_alu_ok) ||
> + !block_check_for_allowed_instrs(else_block, &count, shader->info.stage,
> + limit != 0, indirect_load_ok, expensive_alu_ok))
> +#endif
> return false;
>
> if (count > limit)
> @@ -250,14 +278,15 @@ nir_opt_peephole_select_block(nir_block *block, nir_shader *shader,
>
> static bool
> nir_opt_peephole_select_impl(nir_function_impl *impl, unsigned limit,
> - bool indirect_load_ok)
> + bool indirect_load_ok, bool expensive_alu_ok)
> {
> nir_shader *shader = impl->function->shader;
> bool progress = false;
>
> nir_foreach_block_safe(block, impl) {
> progress |= nir_opt_peephole_select_block(block, shader, limit,
> - indirect_load_ok);
> + indirect_load_ok,
> + expensive_alu_ok);
> }
>
> if (progress)
> @@ -268,14 +297,15 @@ nir_opt_peephole_select_impl(nir_function_impl *impl, unsigned limit,
>
> bool
> nir_opt_peephole_select(nir_shader *shader, unsigned limit,
> - bool indirect_load_ok)
> + bool indirect_load_ok, bool expensive_alu_ok)
> {
> bool progress = false;
>
> nir_foreach_function(function, shader) {
> if (function->impl)
> progress |= nir_opt_peephole_select_impl(function->impl, limit,
> - indirect_load_ok);
> + indirect_load_ok,
> + expensive_alu_ok);
> }
>
> return progress;
> diff --git a/src/gallium/drivers/freedreno/ir3/ir3_nir.c b/src/gallium/drivers/freedreno/ir3/ir3_nir.c
> index 5f66ef5d170..bb3bb73644a 100644
> --- a/src/gallium/drivers/freedreno/ir3/ir3_nir.c
> +++ b/src/gallium/drivers/freedreno/ir3/ir3_nir.c
> @@ -107,7 +107,7 @@ ir3_optimize_loop(nir_shader *s)
> progress |= OPT(s, nir_opt_gcm, true);
> else if (gcm == 2)
> progress |= OPT(s, nir_opt_gcm, false);
> - progress |= OPT(s, nir_opt_peephole_select, 16, true);
> + progress |= OPT(s, nir_opt_peephole_select, 16, true, true);
> progress |= OPT(s, nir_opt_intrinsics);
> progress |= OPT(s, nir_opt_algebraic);
> progress |= OPT(s, nir_opt_constant_folding);
> diff --git a/src/gallium/drivers/radeonsi/si_shader_nir.c b/src/gallium/drivers/radeonsi/si_shader_nir.c
> index 9a7a8264283..cb1e208be8f 100644
> --- a/src/gallium/drivers/radeonsi/si_shader_nir.c
> +++ b/src/gallium/drivers/radeonsi/si_shader_nir.c
> @@ -813,7 +813,7 @@ si_lower_nir(struct si_shader_selector* sel)
> NIR_PASS(progress, sel->nir, nir_opt_if);
> NIR_PASS(progress, sel->nir, nir_opt_dead_cf);
> NIR_PASS(progress, sel->nir, nir_opt_cse);
> - NIR_PASS(progress, sel->nir, nir_opt_peephole_select, 8, true);
> + NIR_PASS(progress, sel->nir, nir_opt_peephole_select, 8, true, true);
>
> /* Needed for algebraic lowering */
> NIR_PASS(progress, sel->nir, nir_opt_algebraic);
> diff --git a/src/gallium/drivers/vc4/vc4_program.c b/src/gallium/drivers/vc4/vc4_program.c
> index 39f7db9148c..fa2a32922f4 100644
> --- a/src/gallium/drivers/vc4/vc4_program.c
> +++ b/src/gallium/drivers/vc4/vc4_program.c
> @@ -1580,7 +1580,7 @@ vc4_optimize_nir(struct nir_shader *s)
> NIR_PASS(progress, s, nir_opt_dce);
> NIR_PASS(progress, s, nir_opt_dead_cf);
> NIR_PASS(progress, s, nir_opt_cse);
> - NIR_PASS(progress, s, nir_opt_peephole_select, 8, true);
> + NIR_PASS(progress, s, nir_opt_peephole_select, 8, true, true);
> NIR_PASS(progress, s, nir_opt_algebraic);
> NIR_PASS(progress, s, nir_opt_constant_folding);
> NIR_PASS(progress, s, nir_opt_undef);
> diff --git a/src/intel/compiler/brw_nir.c b/src/intel/compiler/brw_nir.c
> index 1d65107a93d..04d399fd0b4 100644
> --- a/src/intel/compiler/brw_nir.c
> +++ b/src/intel/compiler/brw_nir.c
> @@ -587,9 +587,9 @@ brw_nir_optimize(nir_shader *nir, const struct brw_compiler *compiler,
> const bool is_vec4_tessellation = !is_scalar &&
> (nir->info.stage == MESA_SHADER_TESS_CTRL ||
> nir->info.stage == MESA_SHADER_TESS_EVAL);
> - OPT(nir_opt_peephole_select, 0, is_vec4_tessellation);
> + OPT(nir_opt_peephole_select, 0, is_vec4_tessellation, false);
> if (compiler->devinfo->gen >= 6)
> - OPT(nir_opt_peephole_select, 1, is_vec4_tessellation);
> + OPT(nir_opt_peephole_select, 1, is_vec4_tessellation, true);
>
> OPT(nir_opt_intrinsics);
> OPT(nir_opt_algebraic);
> diff --git a/src/mesa/state_tracker/st_glsl_to_nir.cpp b/src/mesa/state_tracker/st_glsl_to_nir.cpp
> index bfcef3a293f..098a1e98833 100644
> --- a/src/mesa/state_tracker/st_glsl_to_nir.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_nir.cpp
> @@ -344,7 +344,7 @@ st_nir_opts(nir_shader *nir, bool scalar)
> NIR_PASS(progress, nir, nir_opt_if);
> NIR_PASS(progress, nir, nir_opt_dead_cf);
> NIR_PASS(progress, nir, nir_opt_cse);
> - NIR_PASS(progress, nir, nir_opt_peephole_select, 8, true);
> + NIR_PASS(progress, nir, nir_opt_peephole_select, 8, true, true);
>
> NIR_PASS(progress, nir, nir_opt_algebraic);
> NIR_PASS(progress, nir, nir_opt_constant_folding);
>
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