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/*
* Copyright (C) 2020 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.
*
* Authors (Collabora):
* Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
*/
#include "compiler.h"
#include "panfrost/util/lcra.h"
#include "util/u_memory.h"
static void
bi_compute_interference(bi_context *ctx, struct lcra_state *l)
{
bi_compute_liveness(ctx);
bi_foreach_block(ctx, _blk) {
bi_block *blk = (bi_block *) _blk;
uint16_t *live = mem_dup(_blk->live_out, l->node_count * sizeof(uint16_t));
bi_foreach_instr_in_block_rev(blk, ins) {
/* Mark all registers live after the instruction as
* interfering with the destination */
if (ins->dest && (ins->dest < l->node_count)) {
for (unsigned i = 1; i < l->node_count; ++i) {
if (live[i])
lcra_add_node_interference(l, ins->dest, ins->writemask, i, live[i]);
}
}
/* Update live_in */
bi_liveness_ins_update(live, ins, l->node_count);
}
free(live);
}
}
enum {
BI_REG_CLASS_WORK = 0,
} bi_reg_class;
static struct lcra_state *
bi_allocate_registers(bi_context *ctx, bool *success)
{
unsigned node_count = bi_max_temp(ctx);
struct lcra_state *l =
lcra_alloc_equations(node_count, 1, 8, 16, 1);
l->class_start[BI_REG_CLASS_WORK] = 0;
l->class_size[BI_REG_CLASS_WORK] = 64 * 4; /* R0 - R63, all 32-bit */
bi_foreach_instr_global(ctx, ins) {
unsigned dest = ins->dest;
if (!dest || (dest >= node_count))
continue;
l->class[dest] = BI_REG_CLASS_WORK;
lcra_set_alignment(l, dest, 2); /* 2^2 = 4 */
lcra_restrict_range(l, dest, 4);
}
bi_compute_interference(ctx, l);
*success = lcra_solve(l);
return l;
}
static unsigned
bi_reg_from_index(struct lcra_state *l, unsigned index, unsigned offset)
{
/* Did we run RA for this index at all */
if (index >= l->node_count)
return index;
/* LCRA didn't bother solving this index (how lazy!) */
signed solution = l->solutions[index];
if (solution < 0)
return index;
solution += offset;
assert((solution & 0x3) == 0);
unsigned reg = solution / 4;
return BIR_INDEX_REGISTER | reg;
}
static void
bi_adjust_src_ra(bi_instruction *ins, struct lcra_state *l, unsigned src)
{
if (ins->src[src] >= l->node_count)
return;
bool vector = (bi_class_props[ins->type] & BI_VECTOR) && src == 0;
unsigned offset = 0;
if (vector) {
/* TODO: Do we do anything here? */
} else {
/* Use the swizzle as component select */
nir_alu_type T = ins->src_types[src];
unsigned size = nir_alu_type_get_type_size(T);
unsigned bytes = (MAX2(size, 8) / 8);
unsigned comps_per_reg = 4 / bytes;
unsigned components = bi_get_component_count(ins, src);
for (unsigned i = 0; i < components; ++i) {
unsigned off = ins->swizzle[src][i] / comps_per_reg;
off *= 4; /* 32-bit registers */
/* We can't cross register boundaries in a swizzle */
if (i == 0)
offset = off;
else
assert(off == offset);
ins->swizzle[src][i] %= comps_per_reg;
}
}
ins->src[src] = bi_reg_from_index(l, ins->src[src], offset);
}
static void
bi_adjust_dest_ra(bi_instruction *ins, struct lcra_state *l)
{
if (ins->dest >= l->node_count)
return;
bool vector = (bi_class_props[ins->type] & BI_VECTOR);
unsigned offset = 0;
if (!vector) {
/* Look at the writemask to get an offset, specifically the
* trailing zeros */
unsigned tz = __builtin_ctz(ins->writemask);
/* Recall writemask is one bit per byte, so tz is in bytes */
unsigned regs = tz / 4;
offset = regs * 4;
/* Adjust writemask to compensate */
ins->writemask >>= offset;
}
ins->dest = bi_reg_from_index(l, ins->dest, offset);
}
static void
bi_install_registers(bi_context *ctx, struct lcra_state *l)
{
bi_foreach_instr_global(ctx, ins) {
bi_adjust_dest_ra(ins, l);
bi_foreach_src(ins, s)
bi_adjust_src_ra(ins, l, s);
}
}
void
bi_register_allocate(bi_context *ctx)
{
struct lcra_state *l = NULL;
bool success = false;
do {
if (l) {
lcra_free(l);
l = NULL;
}
bi_invalidate_liveness(ctx);
l = bi_allocate_registers(ctx, &success);
/* TODO: Spilling */
assert(success);
} while(!success);
bi_install_registers(ctx, l);
lcra_free(l);
}
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