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pan/bi: Use the interference mechanism to describe blend shader reg use 

Blend shader might clobber r0-r15, we must make sure the RA is aware
when compiling fragment shaders that have BLEND operations.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8417>
This commit is contained in:
Boris Brezillon 2021-01-08 19:21:33 +01:00 committed by Marge Bot
parent f61be082d3
commit 4439757db2
1 changed files with 36 additions and 10 deletions
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46
src/panfrost/bifrost/bi_ra.c
View File

@ -32,28 +32,45 @@
static void
bi_compute_interference(bi_context *ctx, struct lcra_state *l)
{
unsigned node_count = bi_max_temp(ctx);
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));
uint16_t *live = mem_dup(_blk->live_out, 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 */
for (unsigned d = 0; d < ARRAY_SIZE(ins->dest); ++d) {
if (bi_get_node(ins->dest[d]) >= l->node_count)
if (bi_get_node(ins->dest[d]) >= node_count)
continue;
for (unsigned i = 1; i < l->node_count; ++i) {
for (unsigned i = 1; i < node_count; ++i) {
if (live[i])
lcra_add_node_interference(l, bi_get_node(ins->dest[d]), bi_writemask(ins), i, live[i]);
}
}
if (!ctx->is_blend && ins->op == BI_OPCODE_BLEND) {
/* Add blend shader interference: blend shaders might
* clobber r0-r15. */
for (unsigned i = 1; i < node_count; ++i) {
if (!live[i])
continue;
for (unsigned j = 0; j < 4; j++) {
lcra_add_node_interference(l, node_count + j,
0xFFFF,
i, live[i]);
}
}
}
/* Update live_in */
bi_liveness_ins_update(live, ins, l->node_count);
bi_liveness_ins_update(live, ins, node_count);
}
free(live);
@ -69,8 +86,15 @@ bi_allocate_registers(bi_context *ctx, bool *success)
{
unsigned node_count = bi_max_temp(ctx);
/* We need 4 hidden nodes to encode interference caused by non-terminal
* BLEND (blend shaders are allowed to use r0-r16).
*/
struct lcra_state *l =
lcra_alloc_equations(node_count, 1);
lcra_alloc_equations(node_count + 4, 1);
/* Preset solutions for the blend shader pseudo nodes */
for (unsigned i = 0; i < 4; i++)
l->solutions[node_count + i] = i * 16;
if (ctx->is_blend) {
/* R0-R3 are reserved for the blend input */
@ -109,16 +133,17 @@ bi_allocate_registers(bi_context *ctx, bool *success)
}
static bi_index
bi_reg_from_index(struct lcra_state *l, bi_index index)
bi_reg_from_index(bi_context *ctx, struct lcra_state *l, bi_index index)
{
/* Offsets can only be applied when we register allocated an index, or
* alternatively for FAU's encoding */
ASSERTED bool is_offset = (index.offset > 0) &&
(index.type != BI_INDEX_FAU);
unsigned node_count = bi_max_temp(ctx);
/* Did we run RA for this index at all */
if (bi_get_node(index) >= l->node_count) {
if (bi_get_node(index) >= node_count) {
assert(!is_offset);
return index;
}
@ -146,10 +171,10 @@ static void
bi_install_registers(bi_context *ctx, struct lcra_state *l)
{
bi_foreach_instr_global(ctx, ins) {
ins->dest[0] = bi_reg_from_index(l, ins->dest[0]);
ins->dest[0] = bi_reg_from_index(ctx, l, ins->dest[0]);
bi_foreach_src(ins, s)
ins->src[s] = bi_reg_from_index(l, ins->src[s]);
ins->src[s] = bi_reg_from_index(ctx, l, ins->src[s]);
}
}
@ -195,7 +220,8 @@ bi_choose_spill_node(bi_context *ctx, struct lcra_state *l)
}
}
for (unsigned i = PAN_IS_REG; i < l->node_count; i += 2)
unsigned node_count = bi_max_temp(ctx);
for (unsigned i = PAN_IS_REG; i < node_count; i += 2)
lcra_set_node_spill_cost(l, i, -1);
return lcra_get_best_spill_node(l);