aco: only create parallelcopy to restore exec at loop exit if needed
The operand isn't fixed to exec, which can mess up the spiller. This also
adds a new situation where a phi is needed.
Fixes dEQP-VK.ssbo.layout.random.descriptor_indexing.2 and an assertion
when compiling a Detroit: Become Human shader.
Fixes: 93c8ebfa ('aco: Initial commit of independent AMD compiler')
Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3257>
diff --git a/src/amd/compiler/aco_insert_exec_mask.cpp b/src/amd/compiler/aco_insert_exec_mask.cpp
index bf7ccf8..539d0a2 100644
--- a/src/amd/compiler/aco_insert_exec_mask.cpp
+++ b/src/amd/compiler/aco_insert_exec_mask.cpp
@@ -487,6 +487,7 @@
assert(!(block->kind & block_kind_top_level) || info.num_exec_masks <= 2);
/* create the loop exit phis if not trivial */
+ bool need_parallelcopy = false;
for (unsigned k = 0; k < info.num_exec_masks; k++) {
Temp same = ctx.info[preds[0]].exec[k].first;
uint8_t type = ctx.info[header_preds[0]].exec[k].second;
@@ -497,12 +498,31 @@
trivial = false;
}
+ if (k == info.num_exec_masks - 1u) {
+ bool all_liveout_exec = true;
+ bool all_not_liveout_exec = true;
+ for (unsigned pred : preds) {
+ all_liveout_exec = all_liveout_exec && same == ctx.program->blocks[pred].live_out_exec;
+ all_not_liveout_exec = all_not_liveout_exec && same != ctx.program->blocks[pred].live_out_exec;
+ }
+ if (!all_liveout_exec && !all_not_liveout_exec)
+ trivial = false;
+ else if (all_not_liveout_exec)
+ need_parallelcopy = true;
+
+ need_parallelcopy |= !trivial;
+ }
+
if (trivial) {
ctx.info[idx].exec.emplace_back(same, type);
} else {
/* create phi for loop footer */
aco_ptr<Pseudo_instruction> phi{create_instruction<Pseudo_instruction>(aco_opcode::p_linear_phi, Format::PSEUDO, preds.size(), 1)};
phi->definitions[0] = bld.def(bld.lm);
+ if (k == info.num_exec_masks - 1) {
+ phi->definitions[0].setFixed(exec);
+ need_parallelcopy = false;
+ }
for (unsigned i = 0; i < phi->operands.size(); i++)
phi->operands[i] = Operand(ctx.info[preds[i]].exec[k].first);
ctx.info[idx].exec.emplace_back(bld.insert(std::move(phi)), type);
@@ -533,8 +553,15 @@
}
assert(ctx.info[idx].exec.back().first.size() == bld.lm.size());
- ctx.info[idx].exec.back().first = bld.pseudo(aco_opcode::p_parallelcopy, bld.def(bld.lm, exec),
- ctx.info[idx].exec.back().first);
+ if (need_parallelcopy) {
+ /* only create this parallelcopy is needed, since the operand isn't
+ * fixed to exec which causes the spiller to miscalculate register demand */
+ /* TODO: Fix register_demand calculation for spilling on loop exits.
+ * The problem is only mitigated because the register demand could be
+ * higher if the exec phi doesn't get assigned to exec. */
+ ctx.info[idx].exec.back().first = bld.pseudo(aco_opcode::p_parallelcopy, bld.def(bld.lm, exec),
+ ctx.info[idx].exec.back().first);
+ }
ctx.loop.pop_back();
return i;