diff options
author | Jason Ekstrand <[email protected]> | 2019-09-02 12:54:31 -0500 |
---|---|---|
committer | Jason Ekstrand <[email protected]> | 2019-09-06 23:39:01 +0000 |
commit | a3268599f3c9bb1d92571e15df95750a06114811 (patch) | |
tree | 6bd228dbd76cb9721f7a173eeeb2cf73b03e8891 /src/compiler | |
parent | f81a2623d82ccad6177fe1fe5b80a6398df29b6e (diff) |
nir/repair_ssa: Repair dominance for unreachable blocks
NIR currently assumes that unreachable blocks are trivially dominated by
everything. However, when considering well-formed SSA, there is no path
from any block to an unreachable block. Therefore, we can break any
use-def chains where the use is in an unreachable block. This removes
any dependencies on code created by uses in unreachable blocks and lets
DCE do a better job of cleaning it up.
Cc: [email protected]
Reviewed-by: Caio Marcelo de Oliveira Filho <[email protected]>
Diffstat (limited to 'src/compiler')
-rw-r--r-- | src/compiler/nir/nir_repair_ssa.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/src/compiler/nir/nir_repair_ssa.c b/src/compiler/nir/nir_repair_ssa.c index f182818374d..b6ec1038843 100644 --- a/src/compiler/nir/nir_repair_ssa.c +++ b/src/compiler/nir/nir_repair_ssa.c @@ -71,7 +71,8 @@ repair_ssa_def(nir_ssa_def *def, void *void_state) bool is_valid = true; nir_foreach_use(src, def) { - if (!nir_block_dominates(def->parent_instr->block, get_src_block(src))) { + if (nir_block_is_unreachable(get_src_block(src)) || + !nir_block_dominates(def->parent_instr->block, get_src_block(src))) { is_valid = false; break; } @@ -80,7 +81,8 @@ repair_ssa_def(nir_ssa_def *def, void *void_state) nir_foreach_if_use(src, def) { nir_block *block_before_if = nir_cf_node_as_block(nir_cf_node_prev(&src->parent_if->cf_node)); - if (!nir_block_dominates(def->parent_instr->block, block_before_if)) { + if (nir_block_is_unreachable(block_before_if) || + !nir_block_dominates(def->parent_instr->block, block_before_if)) { is_valid = false; break; } @@ -101,7 +103,8 @@ repair_ssa_def(nir_ssa_def *def, void *void_state) nir_foreach_use_safe(src, def) { nir_block *src_block = get_src_block(src); - if (!nir_block_dominates(def->parent_instr->block, src_block)) { + if (nir_block_is_unreachable(src_block) || + !nir_block_dominates(def->parent_instr->block, src_block)) { nir_instr_rewrite_src(src->parent_instr, src, nir_src_for_ssa( nir_phi_builder_value_get_block_def(val, src_block))); } @@ -110,7 +113,8 @@ repair_ssa_def(nir_ssa_def *def, void *void_state) nir_foreach_if_use_safe(src, def) { nir_block *block_before_if = nir_cf_node_as_block(nir_cf_node_prev(&src->parent_if->cf_node)); - if (!nir_block_dominates(def->parent_instr->block, block_before_if)) { + if (nir_block_is_unreachable(block_before_if) || + !nir_block_dominates(def->parent_instr->block, block_before_if)) { nir_if_rewrite_condition(src->parent_if, nir_src_for_ssa( nir_phi_builder_value_get_block_def(val, block_before_if))); } |