/*
* 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@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.
*/
/** Returns the resolve status for the given source
*
* If the source has a parent instruction then the resolve status is the
* status of the parent instruction. If the source does not have a parent
* instruction then we don't know so we return NON_BOOLEAN.
*/
static uint8_t
get_resolve_status_for_src(nir_src *src)
{
nir_instr *src_instr = nir_src_get_parent_instr(src);
if (src_instr) {
uint8_t resolve_status = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK;
/* If the source instruction needs resolve, then from the perspective
* of the user, it's a true boolean.
*/
if (resolve_status == BRW_NIR_BOOLEAN_NEEDS_RESOLVE)
resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE;
return resolve_status;
} else {
return BRW_NIR_NON_BOOLEAN;
}
}
/** Marks the given source as needing a resolve
*
* If the given source corresponds to an unresolved boolean it marks it as
* needing a resolve. Otherwise, we leave it alone.
*/
static bool
src_mark_needs_resolve(nir_src *src, void *void_state)
{
nir_instr *src_instr = nir_src_get_parent_instr(src);
if (src_instr) {
uint8_t resolve_status = src_instr->pass_flags & BRW_NIR_BOOLEAN_MASK;
/* If the source instruction is unresolved, then mark it as needing
* to be resolved.
*/
if (resolve_status == 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
analyze_boolean_resolves_block(nir_block *block, void *void_state)
{
nir_foreach_instr(block, instr) {
switch (instr->type) {
case nir_instr_type_alu: {
/* For ALU instructions, the resolve status is handled in a
* three-step process.
*
* 1) Look at the instruction type and sources and determine if it
* can be left unresolved.
*
* 2) Look at the destination and see if we have to resolve
* anyway. (This is the case if this instruction is not the
* only instruction writing to a given register.)
*
* 3) If the instruction has a resolve status other than
* BOOL_UNRESOLVED or BOOL_NEEDS_RESOLVE then we walk through
* the sources and ensure that they are also resolved. This
* ensures that we don't end up with any stray unresolved
* booleans going into ADDs or something like that.
*/
uint8_t resolve_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:
/* This instruction will turn into a CMP when we actually emit
* so the result will have to be resolved before it can be used.
*/
resolve_status = BRW_NIR_BOOLEAN_UNRESOLVED;
/* Even though the destination is allowed to be left unresolved,
* the sources are treated as regular integers or floats so
* they need to be resolved.
*/
nir_foreach_src(instr, src_mark_needs_resolve, NULL);
break;
case nir_op_imov:
case nir_op_inot:
/* This is a single-source instruction. Just copy the resolve
* status from the source.
*/
resolve_status = get_resolve_status_for_src(&alu->src[0].src);
break;
case nir_op_iand:
case nir_op_ior:
case nir_op_ixor: {
uint8_t src0_status = get_resolve_status_for_src(&alu->src[0].src);
uint8_t src1_status = get_resolve_status_for_src(&alu->src[1].src);
if (src0_status == src1_status) {
resolve_status = src0_status;
} else if (src0_status == BRW_NIR_NON_BOOLEAN ||
src1_status == BRW_NIR_NON_BOOLEAN) {
/* If one of the sources is a non-boolean then the whole
* thing is a non-boolean.
*/
resolve_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.
*/
resolve_status = BRW_NIR_BOOLEAN_NO_RESOLVE;
}
break;
}
default:
resolve_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 &&
resolve_status == BRW_NIR_BOOLEAN_UNRESOLVED) {
resolve_status = BRW_NIR_BOOLEAN_NEEDS_RESOLVE;
}
instr->pass_flags = (instr->pass_flags & ~BRW_NIR_BOOLEAN_MASK) |
resolve_status;
/* Finally, resolve sources if it's needed */
switch (resolve_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");
}
break;
}
case nir_instr_type_load_const: {
nir_load_const_instr *load = nir_instr_as_load_const(instr);
/* For load_const instructions, it's a boolean exactly when it holds
* one of the values NIR_TRUE or NIR_FALSE.
*
* Since load_const instructions don't have any sources, we don't
* have to worry about resolving them.
*/
instr->pass_flags &= ~BRW_NIR_BOOLEAN_MASK;
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 = (instr->pass_flags & ~BRW_NIR_BOOLEAN_MASK) |
BRW_NIR_NON_BOOLEAN;
nir_foreach_src(instr, src_mark_needs_resolve, NULL);
continue;
}
}
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
analyze_boolean_resolves_impl(nir_function_impl *impl)
{
nir_foreach_block(impl, analyze_boolean_resolves_block, NULL);
}
void
brw_nir_analyze_boolean_resolves(nir_shader *shader)
{
nir_foreach_overload(shader, overload)
if (overload->impl)
analyze_boolean_resolves_impl(overload->impl);
}