From 8462e8246720b868ef6f26cd6d8076ca7cfdb485 Mon Sep 17 00:00:00 2001 From: Alyssa Rosenzweig Date: Mon, 23 Sep 2019 15:57:58 -0400 Subject: [PATCH] pan/midgard: Implement load/store pairing We can bundle two load/store together. This eliminates the need for explicit load/store pairing in a prepass, as well. Signed-off-by: Alyssa Rosenzweig --- src/panfrost/midgard/midgard_schedule.c | 67 +++++-------------------- 1 file changed, 12 insertions(+), 55 deletions(-) diff --git a/src/panfrost/midgard/midgard_schedule.c b/src/panfrost/midgard/midgard_schedule.c index 92756e15189..e2641ea0180 100644 --- a/src/panfrost/midgard/midgard_schedule.c +++ b/src/panfrost/midgard/midgard_schedule.c @@ -1141,17 +1141,26 @@ mir_schedule_ldst( .exclude = ~0 }; + /* Try to pick two load/store ops. Second not gauranteed to exist */ + midgard_instruction *ins = mir_choose_instruction(instructions, worklist, len, &predicate); - mir_update_worklist(worklist, len, instructions, ins); + midgard_instruction *pair = + mir_choose_instruction(instructions, worklist, len, &predicate); struct midgard_bundle out = { .tag = TAG_LOAD_STORE_4, - .instruction_count = 1, - .instructions = { ins } + .instruction_count = pair ? 2 : 1, + .instructions = { ins, pair } }; + /* We have to update the worklist atomically, since the two + * instructions run concurrently (TODO: verify it's not pipelined) */ + + mir_update_worklist(worklist, len, instructions, ins); + mir_update_worklist(worklist, len, instructions, pair); + return out; } @@ -1341,54 +1350,6 @@ schedule_block(compiler_context *ctx, midgard_block *block) ctx->quadword_count += block->quadword_count; } -/* The following passes reorder MIR instructions to enable better scheduling */ - -static void -midgard_pair_load_store(compiler_context *ctx, midgard_block *block) -{ - mir_foreach_instr_in_block_safe(block, ins) { - if (ins->type != TAG_LOAD_STORE_4) continue; - - /* We've found a load/store op. Check if next is also load/store. */ - midgard_instruction *next_op = mir_next_op(ins); - if (&next_op->link != &block->instructions) { - if (next_op->type == TAG_LOAD_STORE_4) { - /* If so, we're done since we're a pair */ - ins = mir_next_op(ins); - continue; - } - - /* Maximum search distance to pair, to avoid register pressure disasters */ - int search_distance = 8; - - /* Otherwise, we have an orphaned load/store -- search for another load */ - mir_foreach_instr_in_block_from(block, c, mir_next_op(ins)) { - /* Terminate search if necessary */ - if (!(search_distance--)) break; - - if (c->type != TAG_LOAD_STORE_4) continue; - - /* We can only reorder if there are no sources */ - - bool deps = false; - - for (unsigned s = 0; s < ARRAY_SIZE(ins->src); ++s) - deps |= (c->src[s] != ~0); - - if (deps) - continue; - - /* We found one! Move it up to pair and remove it from the old location */ - - mir_insert_instruction_before(ctx, ins, *c); - mir_remove_instruction(c); - - break; - } - } - } -} - /* When we're 'squeezing down' the values in the IR, we maintain a hash * as such */ @@ -1665,10 +1626,6 @@ schedule_program(compiler_context *ctx) midgard_promote_uniforms(ctx, 16); - mir_foreach_block(ctx, block) { - midgard_pair_load_store(ctx, block); - } - /* Must be lowered right before RA */ mir_squeeze_index(ctx); mir_lower_special_reads(ctx); -- 2.30.2