Matt Turner <matts...@gmail.com> writes: > The first pass marked dead instructions as opcode = NOP, and a second > pass deleted those instructions so that the live ranges used in the > first pass wouldn't change. > > But since we're walking the instructions in reverse order, we can just > do everything in one pass. The only thing we have to do is walk the > blocks in reverse as well.
Seems reasonable to me, for the series:
Reviewed-by: Francisco Jerez <curroje...@riseup.net>
> ---
> src/mesa/drivers/dri/i965/brw_cfg.h | 3 +++
> .../drivers/dri/i965/brw_fs_dead_code_eliminate.cpp | 21
> ++++++---------------
> .../dri/i965/brw_vec4_dead_code_eliminate.cpp | 21
> +++++++--------------
> 3 files changed, 16 insertions(+), 29 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_cfg.h
> b/src/mesa/drivers/dri/i965/brw_cfg.h
> index 69e39e8..405020b 100644
> --- a/src/mesa/drivers/dri/i965/brw_cfg.h
> +++ b/src/mesa/drivers/dri/i965/brw_cfg.h
> @@ -314,6 +314,9 @@ struct cfg_t {
> #define foreach_block_safe(__block, __cfg) \
> foreach_list_typed_safe (bblock_t, __block, link, &(__cfg)->block_list)
>
> +#define foreach_block_reverse_safe(__block, __cfg) \
> + foreach_list_typed_reverse_safe (bblock_t, __block, link,
> &(__cfg)->block_list)
> +
> #define foreach_inst_in_block(__type, __inst, __block) \
> foreach_in_list(__type, __inst, &(__block)->instructions)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
> b/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
> index 6b4b602..bd57e09 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_dead_code_eliminate.cpp
> @@ -45,13 +45,13 @@ fs_visitor::dead_code_eliminate()
> BITSET_WORD *live = ralloc_array(NULL, BITSET_WORD,
> BITSET_WORDS(num_vars));
> BITSET_WORD *flag_live = ralloc_array(NULL, BITSET_WORD, 1);
>
> - foreach_block (block, cfg) {
> + foreach_block_reverse_safe(block, cfg) {
> memcpy(live, live_intervals->block_data[block->num].liveout,
> sizeof(BITSET_WORD) * BITSET_WORDS(num_vars));
> memcpy(flag_live, live_intervals->block_data[block->num].flag_liveout,
> sizeof(BITSET_WORD));
>
> - foreach_inst_in_block_reverse(fs_inst, inst, block) {
> + foreach_inst_in_block_reverse_safe(fs_inst, inst, block) {
> if (inst->dst.file == VGRF && !inst->has_side_effects()) {
> bool result_live = false;
>
> @@ -72,7 +72,6 @@ fs_visitor::dead_code_eliminate()
> inst->dst = fs_reg(retype(brw_null_reg(), inst->dst.type));
> } else {
> inst->opcode = BRW_OPCODE_NOP;
> - continue;
> }
> }
> }
> @@ -81,7 +80,6 @@ fs_visitor::dead_code_eliminate()
> if (!BITSET_TEST(flag_live, inst->flag_subreg)) {
> inst->opcode = BRW_OPCODE_NOP;
> progress = true;
> - continue;
> }
> }
>
> @@ -93,7 +91,6 @@ fs_visitor::dead_code_eliminate()
> !inst->writes_accumulator) {
> inst->opcode = BRW_OPCODE_NOP;
> progress = true;
> - continue;
> }
>
> if (inst->dst.file == VGRF) {
> @@ -109,9 +106,10 @@ fs_visitor::dead_code_eliminate()
> BITSET_CLEAR(flag_live, inst->flag_subreg);
> }
>
> - /* Don't mark dead instructions' sources as live */
> - if (inst->opcode == BRW_OPCODE_NOP)
> + if (inst->opcode == BRW_OPCODE_NOP) {
> + inst->remove(block);
> continue;
> + }
>
> for (int i = 0; i < inst->sources; i++) {
> if (inst->src[i].file == VGRF) {
> @@ -132,15 +130,8 @@ fs_visitor::dead_code_eliminate()
> ralloc_free(live);
> ralloc_free(flag_live);
>
> - if (progress) {
> - foreach_block_and_inst_safe (block, backend_instruction, inst, cfg) {
> - if (inst->opcode == BRW_OPCODE_NOP) {
> - inst->remove(block);
> - }
> - }
> -
> + if (progress)
> invalidate_live_intervals();
> - }
>
> return progress;
> }
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp
> index 369941b..2d0722a 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_dead_code_eliminate.cpp
> @@ -71,13 +71,13 @@ vec4_visitor::dead_code_eliminate()
> BITSET_WORD *live = ralloc_array(NULL, BITSET_WORD,
> BITSET_WORDS(num_vars));
> BITSET_WORD *flag_live = ralloc_array(NULL, BITSET_WORD, 1);
>
> - foreach_block(block, cfg) {
> + foreach_block_reverse_safe(block, cfg) {
> memcpy(live, live_intervals->block_data[block->num].liveout,
> sizeof(BITSET_WORD) * BITSET_WORDS(num_vars));
> memcpy(flag_live, live_intervals->block_data[block->num].flag_liveout,
> sizeof(BITSET_WORD));
>
> - foreach_inst_in_block_reverse(vec4_instruction, inst, block) {
> + foreach_inst_in_block_reverse_safe(vec4_instruction, inst, block) {
> if ((inst->dst.file == VGRF && !inst->has_side_effects()) ||
> (inst->dst.is_null() && inst->writes_flag())){
> bool result_live[4] = { false };
> @@ -115,7 +115,7 @@ vec4_visitor::dead_code_eliminate()
> inst->dst = dst_reg(retype(brw_null_reg(),
> inst->dst.type));
> } else {
> inst->opcode = BRW_OPCODE_NOP;
> - continue;
> + break;
> }
> }
> }
> @@ -130,7 +130,6 @@ vec4_visitor::dead_code_eliminate()
> if (!combined_live) {
> inst->opcode = BRW_OPCODE_NOP;
> progress = true;
> - continue;
> }
> }
>
> @@ -150,9 +149,10 @@ vec4_visitor::dead_code_eliminate()
> BITSET_CLEAR(flag_live, c);
> }
>
> - /* Don't mark dead instructions' sources as live */
> - if (inst->opcode == BRW_OPCODE_NOP)
> + if (inst->opcode == BRW_OPCODE_NOP) {
> + inst->remove(block);
> continue;
> + }
>
> for (int i = 0; i < 3; i++) {
> if (inst->src[i].file == VGRF) {
> @@ -176,15 +176,8 @@ vec4_visitor::dead_code_eliminate()
> ralloc_free(live);
> ralloc_free(flag_live);
>
> - if (progress) {
> - foreach_block_and_inst_safe(block, backend_instruction, inst, cfg) {
> - if (inst->opcode == BRW_OPCODE_NOP) {
> - inst->remove(block);
> - }
> - }
> -
> + if (progress)
> invalidate_live_intervals();
> - }
>
> return progress;
> }
> --
> 2.4.9
>
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> mesa-dev@lists.freedesktop.org
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