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/*
* Copyright (C) 2019 Collabora, Ltd.
*
* 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.
*/
/* Midgard has some accelerated support for perspective projection on the
* load/store pipes. So the first perspective projection pass looks for
* lowered/open-coded perspective projection of the form "fmul (A.xyz,
* frcp(A.w))" or "fmul (A.xy, frcp(A.z))" and rewrite with a native
* perspective division opcode (on the load/store pipe). Caveats apply: the
* frcp should be used only once to make this optimization worthwhile. And the
* source of the frcp ought to be a varying to make it worthwhile...
*
* The second pass in this file is a step #2 of sorts: fusing that load/store
* projection into a varying load instruction (they can be done together
* implicitly). This depends on the combination pass. Again caveat: the vary
* should only be used once to make this worthwhile.
*/
#include "compiler.h"
static bool
is_swizzle_0(unsigned *swizzle)
{
for (unsigned c = 0; c < MIR_VEC_COMPONENTS; ++c)
if (swizzle[c])
return false;
return true;
}
bool
midgard_opt_combine_projection(compiler_context *ctx, midgard_block *block)
{
bool progress = false;
mir_foreach_instr_in_block_safe(block, ins) {
/* First search for fmul */
if (ins->type != TAG_ALU_4) continue;
if (ins->alu.op != midgard_alu_op_fmul) continue;
/* TODO: Flip */
/* Check the swizzles */
if (!mir_is_simple_swizzle(ins->swizzle[0], ins->mask)) continue;
if (!is_swizzle_0(ins->swizzle[1])) continue;
/* Awesome, we're the right form. Now check where src2 is from */
unsigned frcp = ins->src[1];
unsigned to = ins->dest;
if (frcp & IS_REG) continue;
if (to & IS_REG) continue;
bool frcp_found = false;
unsigned frcp_component = 0;
unsigned frcp_from = 0;
mir_foreach_instr_in_block_safe(block, sub) {
if (sub->dest != frcp) continue;
frcp_component = sub->swizzle[0][0];
frcp_from = sub->src[0];
frcp_found =
(sub->type == TAG_ALU_4) &&
(sub->alu.op == midgard_alu_op_frcp);
break;
}
if (!frcp_found) continue;
if (frcp_component != COMPONENT_W && frcp_component != COMPONENT_Z) continue;
if (!mir_single_use(ctx, frcp)) continue;
/* Heuristic: check if the frcp is from a single-use varying */
bool ok = false;
/* One for frcp and one for fmul */
if (mir_use_count(ctx, frcp_from) > 2) continue;
mir_foreach_instr_in_block_safe(block, v) {
if (v->dest != frcp_from) continue;
if (v->type != TAG_LOAD_STORE_4) break;
if (!OP_IS_LOAD_VARY_F(v->load_store.op)) break;
ok = true;
break;
}
if (!ok)
continue;
/* Nice, we got the form spot on. Let's convert! */
midgard_instruction accel = {
.type = TAG_LOAD_STORE_4,
.mask = ins->mask,
.dest = to,
.src = { frcp_from, ~0, ~0 },
.swizzle = SWIZZLE_IDENTITY_4,
.load_store = {
.op = frcp_component == COMPONENT_W ?
midgard_op_ldst_perspective_division_w :
midgard_op_ldst_perspective_division_z,
.arg_1 = 0x20
}
};
mir_insert_instruction_before(ctx, ins, accel);
mir_remove_instruction(ins);
progress |= true;
}
return progress;
}
bool
midgard_opt_varying_projection(compiler_context *ctx, midgard_block *block)
{
bool progress = false;
mir_foreach_instr_in_block_safe(block, ins) {
/* Search for a projection */
if (ins->type != TAG_LOAD_STORE_4) continue;
if (!OP_IS_PROJECTION(ins->load_store.op)) continue;
unsigned vary = ins->src[0];
unsigned to = ins->dest;
if (vary & IS_REG) continue;
if (to & IS_REG) continue;
if (!mir_single_use(ctx, vary)) continue;
/* Check for a varying source. If we find it, we rewrite */
bool rewritten = false;
mir_foreach_instr_in_block_safe(block, v) {
if (v->dest != vary) continue;
if (v->type != TAG_LOAD_STORE_4) break;
if (!OP_IS_LOAD_VARY_F(v->load_store.op)) break;
/* We found it, so rewrite it to project. Grab the
* modifier */
unsigned param = v->load_store.varying_parameters;
midgard_varying_parameter p;
memcpy(&p, ¶m, sizeof(p));
if (p.modifier != midgard_varying_mod_none)
break;
bool projects_w =
ins->load_store.op == midgard_op_ldst_perspective_division_w;
p.modifier = projects_w ?
midgard_varying_mod_perspective_w :
midgard_varying_mod_perspective_z;
/* Aliasing rules are annoying */
memcpy(¶m, &p, sizeof(p));
v->load_store.varying_parameters = param;
/* Use the new destination */
v->dest = to;
rewritten = true;
break;
}
if (rewritten)
mir_remove_instruction(ins);
progress |= rewritten;
}
return progress;
}
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