On Wed, Dec 21, 2016 at 6:33 PM, Jason Ekstrand <ja...@jlekstrand.net> wrote:
> On Dec 21, 2016 8:11 PM, "Timothy Arceri" <timothy.arc...@collabora.com> > wrote: > > On Mon, 2016-12-19 at 20:11 -0800, Jason Ekstrand wrote: > > --- > > src/compiler/Makefile.sources | 1 + > > src/compiler/nir/nir.h | 2 + > > src/compiler/nir/nir_opt_trivial_continues.c | 141 > > +++++++++++++++++++++++++++ > > 3 files changed, 144 insertions(+) > > create mode 100644 src/compiler/nir/nir_opt_trivial_continues.c > > > > diff --git a/src/compiler/Makefile.sources > > b/src/compiler/Makefile.sources > > index ae3e5f0..a0abede 100644 > > --- a/src/compiler/Makefile.sources > > +++ b/src/compiler/Makefile.sources > > @@ -242,6 +242,7 @@ NIR_FILES = \ > > nir/nir_opt_loop_unroll.c \ > > nir/nir_opt_peephole_select.c \ > > nir/nir_opt_remove_phis.c \ > > + nir/nir_opt_trivial_continues.c \ > > nir/nir_opt_undef.c \ > > nir/nir_phi_builder.c \ > > nir/nir_phi_builder.h \ > > diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h > > index 89b0c70..a6c8956 100644 > > --- a/src/compiler/nir/nir.h > > +++ b/src/compiler/nir/nir.h > > @@ -2563,6 +2563,8 @@ bool nir_opt_peephole_select(nir_shader > > *shader, unsigned limit); > > > > bool nir_opt_remove_phis(nir_shader *shader); > > > > +bool nir_opt_trivial_continues(nir_shader *shader); > > + > > bool nir_opt_undef(nir_shader *shader); > > > > bool nir_opt_conditional_discard(nir_shader *shader); > > diff --git a/src/compiler/nir/nir_opt_trivial_continues.c > > b/src/compiler/nir/nir_opt_trivial_continues.c > > new file mode 100644 > > index 0000000..ff3205d > > --- /dev/null > > +++ b/src/compiler/nir/nir_opt_trivial_continues.c > > @@ -0,0 +1,141 @@ > > +/* > > + * Copyright © 2016 Intel Corporation > > + * > > + * Permission is hereby granted, free of charge, to any person > > obtaining a > > + * copy of this software and associated documentation files (the > > "Software"), > > + * to deal in the Software without restriction, including without > > limitation > > + * the rights to use, copy, modify, merge, publish, distribute, > > sublicense, > > + * and/or sell copies of the Software, and to permit persons to whom > > the > > + * Software is furnished to do so, subject to the following > > conditions: > > + * > > + * The above copyright notice and this permission notice (including > > the next > > + * paragraph) shall be included in all copies or substantial > > portions of the > > + * Software. > > + * > > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, > > EXPRESS OR > > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF > > MERCHANTABILITY, > > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO > > EVENT SHALL > > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES > > OR OTHER > > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, > > ARISING > > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR > > OTHER DEALINGS > > + * IN THE SOFTWARE. > > + */ > > + > > +#include "nir.h" > > + > > +static bool > > +instr_is_continue(nir_instr *instr) > > +{ > > + if (instr->type != nir_instr_type_jump) > > + return false; > > + > > + return nir_instr_as_jump(instr)->type == nir_jump_continue; > > +} > > + > > +static bool > > +lower_trivial_continues_block(nir_block *block, nir_loop *loop) > > +{ > > + bool progress = false; > > + nir_instr *first_instr = nir_block_first_instr(block); > > + if (!first_instr || instr_is_continue(first_instr)) { > > + /* The block contains only a continue if anything */ > > + nir_cf_node *prev_node = nir_cf_node_prev(&block->cf_node); > > + if (prev_node && prev_node->type == nir_cf_node_if) { > > + nir_if *prev_if = nir_cf_node_as_if(prev_node); > > + progress |= lower_trivial_continues_block( > > + nir_if_last_then_block(prev_if), loop); > > + progress |= lower_trivial_continues_block( > > + nir_if_last_else_block(prev_if), loop); > > + } > > + > > + /* The lower_phis_to_regs helper is smart enough to push phi > > sources as > > + * far up if-ladders as it possibly can. In other words, the > > recursive > > + * calls above shouldn't be adding instructions to this block > > since it > > + * follows an if statement. > > + */ > > + first_instr = nir_block_first_instr(block); > > + assert(!first_instr || instr_is_continue(first_instr)); > > + } > > + > > + nir_instr *last_instr = nir_block_last_instr(block); > > + if (!last_instr || !instr_is_continue(last_instr)) > > + return progress; > > + > > + /* We're at the end of a block that goes straight through to the > > end of the > > + * loop and continues to the top. We can exit normally instead > > of jump. > > + */ > > + nir_lower_phis_to_regs_block(nir_loop_first_block(loop)); > > + nir_instr_remove(last_instr); > > + return true; > > +} > > + > > +static bool > > +lower_trivial_continues_list(struct exec_list *cf_list, > > + bool list_ends_at_loop_tail, > > + nir_loop *loop) > > +{ > > + bool progress = false; > > + foreach_list_typed(nir_cf_node, cf_node, node, cf_list) { > > + bool at_loop_tail = list_ends_at_loop_tail && > > + &cf_node->node == > > exec_list_get_tail(cf_list); > > + switch (cf_node->type) { > > + case nir_cf_node_block: > > + break; > > + > > + case nir_cf_node_if: { > > + nir_if *nif = nir_cf_node_as_if(cf_node); > > + if (lower_trivial_continues_list(&nif->then_list, > > at_loop_tail, loop)) > > + progress = true; > > + if (lower_trivial_continues_list(&nif->else_list, > > at_loop_tail, loop)) > > + progress = true; > > + break; > > + } > > + > > + case nir_cf_node_loop: { > > + nir_loop *loop = nir_cf_node_as_loop(cf_node); > > + if (lower_trivial_continues_list(&loop->body, true, loop)) > > + progress = true; > > + if > > (lower_trivial_continues_block(nir_loop_last_block(loop), loop)) > > + progress = true; > > + break; > > + } > > + > > + case nir_cf_node_function: > > + unreachable("Invalid cf type"); > > + } > > + } > > + > > + return progress; > > +} > > + > > +/** > > + * This simple pass gets rid of any "trivial" continues, i.e. those > > that are > > + * at the tail of a loop where we can just delete the continue > > instruction and > > + * control-flow will naturally and harmlessly take us back to the > > top of the > > + * loop. > > + */ > > +bool > > +nir_opt_trivial_continues(nir_shader *shader) > > +{ > > + bool progress = false; > > + > > + nir_foreach_function(function, shader) { > > + if (function->impl == NULL) > > + continue; > > + > > + /* First we run the simple pass to get rid of pesky continues > > */ > > + if (lower_trivial_continues_list(&function->impl->body, false, > > NULL)) { > > + nir_metadata_preserve(function->impl, nir_metadata_none); > > + > > + /* If that made progress, we're no longer really in SSA > > form. Go > > + * back into SSA form and clean up. > > + */ > > + nir_convert_to_ssa_impl(function->impl); > > + nir_copy_prop_impl(function->impl); > > + nir_opt_dce_impl(function->impl); > > Just curious why you explicitly call these rather than just let them > get cleaned up normally? Does it cut compile times to get rid of them > straight away? > > > The nir_opt_if pass I wrote relies on this pass. Of this pass is run, it > also needs copy_prop and dce. This potentially allows is to drop an > iteration of the optimization loop. Another option would be to do this in > brw_nir.c: > > if (OPT(nir_opt_trivial_continues)) { > OPT(nir_opt_copy_prop); > OPT(nir_opt_dce); > } > > I don't have a strong preference either way. > I've updated the brw_nir code to do this for us: https://cgit.freedesktop.org/~jekstrand/mesa/commit/?h=wip/ nir-opt-continues-v1.1&id=dd7f6934063b27101a4face52fd8bc3c8cadea78 I've also deleted 3/6 because it's no longer needed. > > Anyway this looks good to me and very easy to follow: > > Reviewed-by: Timothy Arceri <timothy.arc...@collabora.com> > > > + progress = true; > > + } > > + } > > + > > + return progress; > > +} > >
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