Mesa (master): aco: remove potential critical edge on loops.
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Wed Oct 30 19:48:52 UTC 2019
Module: Mesa
Branch: master
Commit: 655a7033493692961428cf0861477ae89f458e9b
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=655a7033493692961428cf0861477ae89f458e9b
Author: Daniel Schürmann <daniel at schuermann.dev>
Date: Tue Oct 29 11:57:11 2019 +0100
aco: remove potential critical edge on loops.
Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
---
src/amd/compiler/aco_insert_exec_mask.cpp | 8 ++-----
src/amd/compiler/aco_instruction_selection.cpp | 33 ++++++++++++++++----------
2 files changed, 23 insertions(+), 18 deletions(-)
diff --git a/src/amd/compiler/aco_insert_exec_mask.cpp b/src/amd/compiler/aco_insert_exec_mask.cpp
index 3f4b48e661f..530faab2167 100644
--- a/src/amd/compiler/aco_insert_exec_mask.cpp
+++ b/src/amd/compiler/aco_insert_exec_mask.cpp
@@ -895,15 +895,11 @@ void add_branch_code(exec_ctx& ctx, Block* block)
}
if (block->kind & block_kind_continue_or_break) {
+ assert(ctx.program->blocks[ctx.program->blocks[block->linear_succs[1]].linear_succs[0]].kind & block_kind_loop_header);
+ assert(ctx.program->blocks[ctx.program->blocks[block->linear_succs[0]].linear_succs[0]].kind & block_kind_loop_exit);
assert(block->instructions.back()->opcode == aco_opcode::p_branch);
block->instructions.pop_back();
- /* because of how linear_succs is created, this needs to be swapped */
- std::swap(block->linear_succs[0], block->linear_succs[1]);
-
- assert(ctx.program->blocks[block->linear_succs[1]].kind & block_kind_loop_header);
- assert(ctx.program->blocks[ctx.program->blocks[block->linear_succs[0]].linear_succs[0]].kind & block_kind_loop_exit);
-
if (ctx.info[idx].exec.back().second & mask_type_loop) {
bld.branch(aco_opcode::p_cbranch_nz, bld.exec(ctx.info[idx].exec.back().first), block->linear_succs[1], block->linear_succs[0]);
} else {
diff --git a/src/amd/compiler/aco_instruction_selection.cpp b/src/amd/compiler/aco_instruction_selection.cpp
index c279f04a031..e935dc11a9b 100644
--- a/src/amd/compiler/aco_instruction_selection.cpp
+++ b/src/amd/compiler/aco_instruction_selection.cpp
@@ -7057,26 +7057,35 @@ static void visit_loop(isel_context *ctx, nir_loop *loop)
* workaround, break the loop when the loop mask is empty instead of
* always continuing. */
ctx->block->kind |= (block_kind_continue_or_break | block_kind_uniform);
-
- /* create "loop_almost_exit" to avoid critical edges */
unsigned block_idx = ctx->block->index;
- Block *loop_almost_exit = ctx->program->create_and_insert_block();
- loop_almost_exit->loop_nest_depth = ctx->cf_info.loop_nest_depth;
- loop_almost_exit->kind = block_kind_uniform;
- bld.reset(loop_almost_exit);
+
+ /* create helper blocks to avoid critical edges */
+ Block *break_block = ctx->program->create_and_insert_block();
+ break_block->loop_nest_depth = ctx->cf_info.loop_nest_depth;
+ break_block->kind = block_kind_uniform;
+ bld.reset(break_block);
bld.branch(aco_opcode::p_branch);
+ add_linear_edge(block_idx, break_block);
+ add_linear_edge(break_block->index, &loop_exit);
- add_linear_edge(block_idx, loop_almost_exit);
- add_linear_edge(loop_almost_exit->index, &loop_exit);
+ Block *continue_block = ctx->program->create_and_insert_block();
+ continue_block->loop_nest_depth = ctx->cf_info.loop_nest_depth;
+ continue_block->kind = block_kind_uniform;
+ bld.reset(continue_block);
+ bld.branch(aco_opcode::p_branch);
+ add_linear_edge(block_idx, continue_block);
+ add_linear_edge(continue_block->index, &ctx->program->blocks[loop_header_idx]);
+ add_logical_edge(block_idx, &ctx->program->blocks[loop_header_idx]);
ctx->block = &ctx->program->blocks[block_idx];
} else {
ctx->block->kind |= (block_kind_continue | block_kind_uniform);
+ if (!ctx->cf_info.parent_loop.has_divergent_branch)
+ add_edge(ctx->block->index, &ctx->program->blocks[loop_header_idx]);
+ else
+ add_linear_edge(ctx->block->index, &ctx->program->blocks[loop_header_idx]);
}
- if (!ctx->cf_info.parent_loop.has_divergent_branch)
- add_edge(ctx->block->index, &ctx->program->blocks[loop_header_idx]);
- else
- add_linear_edge(ctx->block->index, &ctx->program->blocks[loop_header_idx]);
+
bld.reset(ctx->block);
bld.branch(aco_opcode::p_branch);
}
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