From 8d8c864beba399ae4ee2267f680d1f600ad32767 Mon Sep 17 00:00:00 2001 From: Rhys Perry Date: Fri, 31 Jan 2020 16:39:20 +0000 Subject: [PATCH] aco: improve check for unreachable loop continue blocks MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The old code would have previously caught: loop { ... break } when it was meant to just catch: loop { if (...) break else break } Signed-off-by: Rhys Perry CC: Reviewed-by: Daniel Schürmann Part-of: --- src/amd/compiler/aco_instruction_selection.cpp | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/src/amd/compiler/aco_instruction_selection.cpp b/src/amd/compiler/aco_instruction_selection.cpp index 59668fb4bc1..a8b318c63c5 100644 --- a/src/amd/compiler/aco_instruction_selection.cpp +++ b/src/amd/compiler/aco_instruction_selection.cpp @@ -90,7 +90,7 @@ struct if_context { Block BB_endif; }; -static void visit_cf_list(struct isel_context *ctx, +static bool visit_cf_list(struct isel_context *ctx, struct exec_list *list); static void add_logical_edge(unsigned pred_idx, Block *succ) @@ -8566,7 +8566,7 @@ static void visit_loop(isel_context *ctx, nir_loop *loop) unsigned loop_header_idx = loop_header->index; loop_info_RAII loop_raii(ctx, loop_header_idx, &loop_exit); append_logical_start(ctx->block); - visit_cf_list(ctx, &loop->body); + bool unreachable = visit_cf_list(ctx, &loop->body); //TODO: what if a loop ends with a unconditional or uniformly branched continue and this branch is never taken? if (!ctx->cf_info.has_branch) { @@ -8611,8 +8611,11 @@ static void visit_loop(isel_context *ctx, nir_loop *loop) bld.branch(aco_opcode::p_branch); } - /* fixup phis in loop header from unreachable blocks */ - if (ctx->cf_info.has_branch || ctx->cf_info.parent_loop.has_divergent_branch) { + /* Fixup phis in loop header from unreachable blocks. + * has_branch/has_divergent_branch also indicates if the loop ends with a + * break/continue instruction, but we don't emit those if unreachable=true */ + if (unreachable) { + assert(ctx->cf_info.has_branch || ctx->cf_info.parent_loop.has_divergent_branch); bool linear = ctx->cf_info.has_branch; bool logical = ctx->cf_info.has_branch || ctx->cf_info.parent_loop.has_divergent_branch; for (aco_ptr& instr : ctx->program->blocks[loop_header_idx].instructions) { @@ -8956,7 +8959,7 @@ static bool visit_if(isel_context *ctx, nir_if *if_stmt) } } -static void visit_cf_list(isel_context *ctx, +static bool visit_cf_list(isel_context *ctx, struct exec_list *list) { foreach_list_typed(nir_cf_node, node, node, list) { @@ -8966,7 +8969,7 @@ static void visit_cf_list(isel_context *ctx, break; case nir_cf_node_if: if (!visit_if(ctx, nir_cf_node_as_if(node))) - return; + return true; break; case nir_cf_node_loop: visit_loop(ctx, nir_cf_node_as_loop(node)); @@ -8975,6 +8978,7 @@ static void visit_cf_list(isel_context *ctx, unreachable("unimplemented cf list type"); } } + return false; } static void export_vs_varying(isel_context *ctx, int slot, bool is_pos, int *next_pos) -- 2.30.2