[Mesa-dev] [PATCH 7/9] i965: Add a NIR analysis pass for determining when a boolean resolve is needed
Jason Ekstrand
jason at jlekstrand.net
Wed Mar 18 18:54:29 PDT 2015
On Wed, Mar 18, 2015 at 6:40 PM, Connor Abbott <cwabbott0 at gmail.com> wrote:
> On Wed, Mar 18, 2015 at 9:10 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
>> On Wed, Mar 18, 2015 at 6:07 PM, Connor Abbott <cwabbott0 at gmail.com> wrote:
>>> Overall, I think it might be better to do this as a SSA pass right
>>> before lowering to source modifiers. I don't think we would be running
>>> any optimizations after it that depend on the output being all 0's or
>>> all 1's, but if you're concerned about that then we could add separate
>>> gen5-compare compare opcodes and lower the normal ones to those plus
>>> any necessary resolves.
>>
>> Sure, we could do that. However, the logic required is the same either way.
>
> Well, you wouldn't have to worry about registers with no parent_instr,
> so it would be simpler. And you wouldn't need backend-specific pass
> flags that rely on other passes not stomping on them, so it would be a
> little cleaner too.
Yes and no. Doing so would turn it into a three-pass analysis: 1) Do
what the current pass does. 2) Force resolves on things used by phi
nodes (because of back-edges). 3) Add resolve instructions.
Given that this saves us all of 3 lines dealing with registers and 4
lines in the backend, I'm not sure it's worth it.
--Jason
>>
>>> On Tue, Mar 17, 2015 at 10:17 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
>>>> ---
>>>> src/mesa/drivers/dri/i965/Makefile.sources | 2 +
>>>> src/mesa/drivers/dri/i965/brw_nir.h | 45 ++++
>>>> .../dri/i965/brw_nir_analize_boolean_resolves.c | 228 +++++++++++++++++++++
>>>> 3 files changed, 275 insertions(+)
>>>> create mode 100644 src/mesa/drivers/dri/i965/brw_nir.h
>>>> create mode 100644 src/mesa/drivers/dri/i965/brw_nir_analize_boolean_resolves.c
>>>>
>>>> diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
>>>> index c69441b..05ebbe9 100644
>>>> --- a/src/mesa/drivers/dri/i965/Makefile.sources
>>>> +++ b/src/mesa/drivers/dri/i965/Makefile.sources
>>>> @@ -73,6 +73,8 @@ i965_FILES = \
>>>> brw_meta_util.h \
>>>> brw_misc_state.c \
>>>> brw_multisample_state.h \
>>>> + brw_nir.h \
>>>> + brw_nir_analize_boolean_resolves.c \
>>>
>>> I must say, this is a rather unfortunate typo/spelling mistake... I
>>> always read it as anal-ize and then my inner 5 year old comes out and
>>> I giggle. To be honest, I couldn't even get through the entire thing
>>> because of this. You're not the first person to do it though.
>>
>> Sorry... I'll fix that. /me and spelling...
>>
>>>> brw_object_purgeable.c \
>>>> brw_packed_float.c \
>>>> brw_performance_monitor.c \
>>>> diff --git a/src/mesa/drivers/dri/i965/brw_nir.h b/src/mesa/drivers/dri/i965/brw_nir.h
>>>> new file mode 100644
>>>> index 0000000..f79c5f1
>>>> --- /dev/null
>>>> +++ b/src/mesa/drivers/dri/i965/brw_nir.h
>>>> @@ -0,0 +1,45 @@
>>>> +/*
>>>> + * Copyright © 2015 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.
>>>> + */
>>>> +
>>>> +#pragma once
>>>> +
>>>> +#include "glsl/nir/nir.h"
>>>> +
>>>> +#ifdef __cplusplus
>>>> +extern "C" {
>>>> +#endif
>>>> +
>>>> +/* Flags set in the instr->pass_flags field by i965 analysis passes */
>>>> +enum {
>>>> + BRW_NIR_NON_BOOLEAN = 0x0,
>>>> + BRW_NIR_BOOLEAN_NEEDS_RESOLVE = 0x1,
>>>> + BRW_NIR_BOOLEAN_UNRESOLVED = 0x2,
>>>> + BRW_NIR_BOOLEAN_NO_RESOLVE = 0x3,
>>>> + BRW_NIR_BOOLEAN_MASK = 0x3,
>>>> +};
>>>> +
>>>> +void brw_nir_analize_boolean_resolves(nir_shader *nir);
>>>> +
>>>> +#ifdef __cplusplus
>>>> +}
>>>> +#endif
>>>> diff --git a/src/mesa/drivers/dri/i965/brw_nir_analize_boolean_resolves.c b/src/mesa/drivers/dri/i965/brw_nir_analize_boolean_resolves.c
>>>> new file mode 100644
>>>> index 0000000..7d93471
>>>> --- /dev/null
>>>> +++ b/src/mesa/drivers/dri/i965/brw_nir_analize_boolean_resolves.c
>>>> @@ -0,0 +1,228 @@
>>>> +/*
>>>> + * Copyright © 2015 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.
>>>> + *
>>>> + * Authors:
>>>> + * Jason Ekstrand <jason at jlekstrand.net>
>>>> + */
>>>> +
>>>> +#include "brw_nir.h"
>>>> +
>>>> +/*
>>>> + * This file implements an analysis pass that determines when we have to do
>>>> + * a boolean resolve on GEN <= 5. Instructions that need a boolean resolve
>>>> + * will have the booleans portion of the instr->pass_flags field set to
>>>> + * BRW_NIR_BOOLEAN_NEEDS_RESOLVE.
>>>> + */
>>>> +
>>>> +static uint8_t
>>>> +get_resolve_state_for_src(nir_alu_instr *alu, unsigned src_idx)
>>>> +{
>>>> + nir_instr *src_instr;
>>>> + if (alu->src[src_idx].src.is_ssa) {
>>>> + src_instr = alu->src[src_idx].src.ssa->parent_instr;
>>>> + } else {
>>>> + src_instr = alu->src[src_idx].src.reg.reg->parent_instr;
>>>> + }
>>>> +
>>>> + if (src_instr) {
>>>> + uint8_t state = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK;
>>>> +
>>>> + /* If the source instruction nees resolve then, from the perspective
>>>> + * of the user, it's a true boolean.
>>>> + */
>>>> + if (state == BRW_NIR_BOOLEAN_NEEDS_RESOLVE)
>>>> + state = BRW_NIR_BOOLEAN_NO_RESOLVE;
>>>> + return state;
>>>> + } else {
>>>> + return BRW_NIR_NON_BOOLEAN;
>>>> + }
>>>> +}
>>>> +
>>>> +static bool
>>>> +src_mark_needs_resolve(nir_src *src, void *void_state)
>>>> +{
>>>> + if (src->is_ssa)
>>>> + return true;
>>>> +
>>>> + if (src->reg.reg->parent_instr == NULL)
>>>> + return true;
>>>> +
>>>> + nir_instr *src_instr = src->reg.reg->parent_instr;
>>>> +
>>>> + uint8_t bool_flags = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK;
>>>> + if (bool_flags == BRW_NIR_BOOLEAN_UNRESOLVED) {
>>>> + src_instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK;
>>>> + src_instr->pass_flags |= BRW_NIR_BOOLEAN_NEEDS_RESOLVE;
>>>> + }
>>>> +
>>>> + return true;
>>>> +}
>>>> +
>>>> +static bool
>>>> +analize_boolean_resolves_block(nir_block *block, void *void_state)
>>>> +{
>>>> + nir_foreach_instr(block, instr) {
>>>> + /* Clear the boolean state */
>>>> + instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK;
>>>> +
>>>> + switch (instr->type) {
>>>> + case nir_instr_type_alu:
>>>> + /* For ALU instructions, we handle [un]resolved booleans below. */
>>>
>>> Might it be better to put the code for handling ALU instructions here
>>> instead? In effect we're only running it for ALU instructions since
>>> the rest of the cases end in a continue, so why not make that more
>>> obvious by just moving it up here under the ALU case?
>>
>> Sure. That's fine with me.
>>
>>>> + break;
>>>> +
>>>> + case nir_instr_type_load_const: {
>>>> + /* For load_const instructions, it's a boolean exactly when it holds
>>>> + * one of the values NIR_TRUE or NIR_FALSE.
>>>> + */
>>>> + nir_load_const_instr *load = nir_instr_as_load_const(instr);
>>>> + if (load->value.u[0] == NIR_TRUE || load->value.u[0] == NIR_FALSE) {
>>>> + instr->pass_flags |= BRW_NIR_BOOLEAN_NO_RESOLVE;
>>>> + } else {
>>>> + instr->pass_flags |= BRW_NIR_NON_BOOLEAN;
>>>> + }
>>>> + continue;
>>>> + }
>>>> +
>>>> + default:
>>>> + /* Everything else is an unknown non-boolean value and needs to
>>>> + * have all sources resolved.
>>>> + */
>>>> + instr->pass_flags |= BRW_NIR_NON_BOOLEAN;
>>>> + nir_foreach_src(instr, src_mark_needs_resolve, NULL);
>>>> + continue;
>>>> + }
>>>> +
>>>> + uint8_t bool_status;
>>>> + nir_alu_instr *alu = nir_instr_as_alu(instr);
>>>> + switch (alu->op) {
>>>> + case nir_op_flt:
>>>> + case nir_op_ilt:
>>>> + case nir_op_ult:
>>>> + case nir_op_fge:
>>>> + case nir_op_ige:
>>>> + case nir_op_uge:
>>>> + case nir_op_feq:
>>>> + case nir_op_ieq:
>>>> + case nir_op_fne:
>>>> + case nir_op_ine:
>>>> + case nir_op_f2b:
>>>> + case nir_op_i2b:
>>>> + bool_status = BRW_NIR_BOOLEAN_UNRESOLVED;
>>>> +
>>>> + /* Even though the destination is allowed to be left unresolved,
>>>> + * we need to resolve all the sources of a compare.
>>>> + */
>>>> + nir_foreach_src(instr, src_mark_needs_resolve, NULL);
>>>> + break;
>>>> +
>>>> + case nir_op_imov:
>>>> + case nir_op_inot:
>>>> + if (alu->dest.write_mask == 1) {
>>>> + /* This is a single-source instruction. Just copy the resolution
>>>> + * state from the source.
>>>> + */
>>>> + bool_status = get_resolve_state_for_src(alu, 0);
>>>> + } else {
>>>> + bool_status = BRW_NIR_NON_BOOLEAN;
>>>> + }
>>>> + break;
>>>> +
>>>> + case nir_op_iand:
>>>> + case nir_op_ior:
>>>> + case nir_op_ixor: {
>>>> + assert(alu->dest.write_mask == 1);
>>>> +
>>>> + uint8_t src0_flags = get_resolve_state_for_src(alu, 0);
>>>> + uint8_t src1_flags = get_resolve_state_for_src(alu, 1);
>>>> +
>>>> + if (src0_flags == src1_flags) {
>>>> + bool_status = src0_flags;
>>>> + } else if (src0_flags == BRW_NIR_NON_BOOLEAN ||
>>>> + src1_flags == BRW_NIR_NON_BOOLEAN) {
>>>> + bool_status = BRW_NIR_NON_BOOLEAN;
>>>> + } else {
>>>> + /* At this point one of them is a true boolean and one is a
>>>> + * boolean that needs a resolve. We could either resolve the
>>>> + * unresolved source or we could resolve here. If we resolve
>>>> + * the unresolved source then we get two resolves for the price
>>>> + * of one. Just set this one to BOOLEAN_NO_RESOLVE and we'll
>>>> + * let the code below force a resolve on the unresolved source.
>>>> + */
>>>> + bool_status = BRW_NIR_BOOLEAN_NO_RESOLVE;
>>>> + }
>>>> + break;
>>>> + }
>>>> +
>>>> + default:
>>>> + bool_status = BRW_NIR_NON_BOOLEAN;
>>>> + }
>>>> +
>>>> + /* If the destination is SSA-like, go ahead allow unresolved booleans.
>>>> + * If the destination register doesn't have a well-defined parent_instr
>>>> + * we need to resolve immediately.
>>>> + */
>>>> + if (alu->dest.dest.reg.reg->parent_instr == NULL &&
>>>> + bool_status == BRW_NIR_BOOLEAN_UNRESOLVED) {
>>>> + bool_status = BRW_NIR_BOOLEAN_NEEDS_RESOLVE;
>>>> + }
>>>> +
>>>> + instr->pass_flags |= bool_status;
>>>> +
>>>> + /* Finally, resolve sources if it's needed */
>>>> + switch (bool_status) {
>>>> + case BRW_NIR_BOOLEAN_NEEDS_RESOLVE:
>>>> + case BRW_NIR_BOOLEAN_UNRESOLVED:
>>>> + /* This instruction is either unresolved or we're doing the
>>>> + * resolve here; leave the sources alone.
>>>> + */
>>>> + break;
>>>> +
>>>> + case BRW_NIR_BOOLEAN_NO_RESOLVE:
>>>> + case BRW_NIR_NON_BOOLEAN:
>>>> + nir_foreach_src(instr, src_mark_needs_resolve, NULL);
>>>> + break;
>>>> +
>>>> + default:
>>>> + unreachable("Invalid boolean flag");
>>>> + }
>>>> + }
>>>> +
>>>> + nir_if *following_if = nir_block_get_following_if(block);
>>>> + if (following_if)
>>>> + src_mark_needs_resolve(&following_if->condition, NULL);
>>>> +
>>>> + return true;
>>>> +}
>>>> +
>>>> +static void
>>>> +analize_boolean_resolves_impl(nir_function_impl *impl)
>>>> +{
>>>> + nir_foreach_block(impl, analize_boolean_resolves_block, NULL);
>>>> +}
>>>> +
>>>> +void
>>>> +brw_nir_analize_boolean_resolves(nir_shader *shader)
>>>> +{
>>>> + nir_foreach_overload(shader, overload)
>>>> + if (overload->impl)
>>>> + analize_boolean_resolves_impl(overload->impl);
>>>> +}
>>>> --
>>>> 2.3.2
>>>>
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