nir: allow divergence information to be updated when inserting instruction
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/6558>
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 20b31e9..0bf59e4 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -4801,6 +4801,7 @@
void nir_convert_loop_to_lcssa(nir_loop *loop);
bool nir_convert_to_lcssa(nir_shader *shader, bool skip_invariants, bool skip_bool_invariants);
void nir_divergence_analysis(nir_shader *shader);
+bool nir_update_instr_divergence(nir_shader *shader, nir_instr *instr);
/* If phi_webs_only is true, only convert SSA values involved in phi nodes to
* registers. If false, convert all values (even those not involved in a phi
diff --git a/src/compiler/nir/nir_builder.h b/src/compiler/nir/nir_builder.h
index 2b340ba..1b43892 100644
--- a/src/compiler/nir/nir_builder.h
+++ b/src/compiler/nir/nir_builder.h
@@ -36,6 +36,10 @@
/* Whether new ALU instructions will be marked "exact" */
bool exact;
+ /* Whether to run divergence analysis on inserted instructions (loop merge
+ * and header phis are not updated). */
+ bool update_divergence;
+
nir_shader *shader;
nir_function_impl *impl;
} nir_builder;
@@ -54,6 +58,7 @@
gl_shader_stage stage,
const nir_shader_compiler_options *options)
{
+ memset(build, 0, sizeof(*build));
build->shader = nir_shader_create(mem_ctx, stage, options, NULL);
nir_function *func = nir_function_create(build->shader, "main");
func->is_entrypoint = true;
@@ -110,6 +115,9 @@
{
nir_instr_insert(build->cursor, instr);
+ if (build->update_divergence)
+ nir_update_instr_divergence(build->shader, instr);
+
/* Move the cursor forward. */
build->cursor = nir_after_instr(instr);
}
@@ -237,6 +245,8 @@
return NULL;
nir_instr_insert(nir_before_cf_list(&build->impl->body), &undef->instr);
+ if (build->update_divergence)
+ nir_update_instr_divergence(build->shader, &undef->instr);
return &undef->def;
}
diff --git a/src/compiler/nir/nir_divergence_analysis.c b/src/compiler/nir/nir_divergence_analysis.c
index ccfc7de..cd33996 100644
--- a/src/compiler/nir/nir_divergence_analysis.c
+++ b/src/compiler/nir/nir_divergence_analysis.c
@@ -615,6 +615,31 @@
}
static bool
+update_instr_divergence(nir_shader *shader, nir_instr *instr)
+{
+ switch (instr->type) {
+ case nir_instr_type_alu:
+ return visit_alu(nir_instr_as_alu(instr));
+ case nir_instr_type_intrinsic:
+ return visit_intrinsic(shader, nir_instr_as_intrinsic(instr));
+ case nir_instr_type_tex:
+ return visit_tex(nir_instr_as_tex(instr));
+ case nir_instr_type_load_const:
+ return visit_load_const(nir_instr_as_load_const(instr));
+ case nir_instr_type_ssa_undef:
+ return visit_ssa_undef(nir_instr_as_ssa_undef(instr));
+ case nir_instr_type_deref:
+ return visit_deref(shader, nir_instr_as_deref(instr));
+ case nir_instr_type_jump:
+ case nir_instr_type_phi:
+ case nir_instr_type_call:
+ case nir_instr_type_parallel_copy:
+ default:
+ unreachable("NIR divergence analysis: Unsupported instruction type.");
+ }
+}
+
+static bool
visit_block(nir_block *block, struct divergence_state *state)
{
bool has_changed = false;
@@ -627,33 +652,10 @@
if (state->first_visit)
nir_foreach_ssa_def(instr, set_ssa_def_not_divergent, NULL);
- switch (instr->type) {
- case nir_instr_type_alu:
- has_changed |= visit_alu(nir_instr_as_alu(instr));
- break;
- case nir_instr_type_intrinsic:
- has_changed |= visit_intrinsic(state->shader, nir_instr_as_intrinsic(instr));
- break;
- case nir_instr_type_tex:
- has_changed |= visit_tex(nir_instr_as_tex(instr));
- break;
- case nir_instr_type_load_const:
- has_changed |= visit_load_const(nir_instr_as_load_const(instr));
- break;
- case nir_instr_type_ssa_undef:
- has_changed |= visit_ssa_undef(nir_instr_as_ssa_undef(instr));
- break;
- case nir_instr_type_deref:
- has_changed |= visit_deref(state->shader, nir_instr_as_deref(instr));
- break;
- case nir_instr_type_jump:
+ if (instr->type == nir_instr_type_jump)
has_changed |= visit_jump(nir_instr_as_jump(instr), state);
- break;
- case nir_instr_type_phi:
- case nir_instr_type_call:
- case nir_instr_type_parallel_copy:
- unreachable("NIR divergence analysis: Unsupported instruction type.");
- }
+ else
+ has_changed |= update_instr_divergence(state->shader, instr);
}
return has_changed;
@@ -903,3 +905,23 @@
visit_cf_list(&nir_shader_get_entrypoint(shader)->body, &state);
}
+bool nir_update_instr_divergence(nir_shader *shader, nir_instr *instr)
+{
+ nir_foreach_ssa_def(instr, set_ssa_def_not_divergent, NULL);
+
+ if (instr->type == nir_instr_type_phi) {
+ nir_cf_node *prev = nir_cf_node_prev(&instr->block->cf_node);
+ /* can only update gamma/if phis */
+ if (!prev || prev->type != nir_cf_node_if)
+ return false;
+
+ nir_if *nif = nir_cf_node_as_if(prev);
+
+ visit_if_merge_phi(nir_instr_as_phi(instr), nir_src_is_divergent(nif->condition));
+ return true;
+ }
+
+ update_instr_divergence(shader, instr);
+ return true;
+}
+
