nir: Add a lowering pass to split 64bit phis
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6313>
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 8371ae9..3bfc2d1 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -4611,6 +4611,7 @@
bool nir_lower_bit_size(nir_shader *shader,
nir_lower_bit_size_callback callback,
void *callback_data);
+bool nir_lower_64bit_phis(nir_shader *shader);
nir_lower_int64_options nir_lower_int64_op_to_options_mask(nir_op opcode);
bool nir_lower_int64(nir_shader *shader);
diff --git a/src/compiler/nir/nir_lower_bit_size.c b/src/compiler/nir/nir_lower_bit_size.c
index 6e7d57e..71a0f6f 100644
--- a/src/compiler/nir/nir_lower_bit_size.c
+++ b/src/compiler/nir/nir_lower_bit_size.c
@@ -127,3 +127,93 @@
return progress;
}
+
+static void
+split_phi(nir_builder *b, nir_phi_instr *phi)
+{
+ nir_phi_instr *lowered[2] = {
+ nir_phi_instr_create(b->shader),
+ nir_phi_instr_create(b->shader)
+ };
+ int num_components = phi->dest.ssa.num_components;
+ assert(phi->dest.ssa.bit_size == 64);
+
+ nir_foreach_phi_src(src, phi) {
+ assert(num_components == src->src.ssa->num_components);
+
+ b->cursor = nir_before_src(&src->src, false);
+
+ nir_ssa_def *x = nir_unpack_64_2x32_split_x(b, src->src.ssa);
+ nir_ssa_def *y = nir_unpack_64_2x32_split_y(b, src->src.ssa);
+
+ nir_phi_src *xsrc = rzalloc(lowered[0], nir_phi_src);
+ xsrc->pred = src->pred;
+ xsrc->src = nir_src_for_ssa(x);
+ exec_list_push_tail(&lowered[0]->srcs, &xsrc->node);
+
+ nir_phi_src *ysrc = rzalloc(lowered[1], nir_phi_src);
+ ysrc->pred = src->pred;
+ ysrc->src = nir_src_for_ssa(y);
+ exec_list_push_tail(&lowered[1]->srcs, &ysrc->node);
+ }
+
+ nir_ssa_dest_init(&lowered[0]->instr, &lowered[0]->dest,
+ num_components, 32, NULL);
+ nir_ssa_dest_init(&lowered[1]->instr, &lowered[1]->dest,
+ num_components, 32, NULL);
+
+ b->cursor = nir_before_instr(&phi->instr);
+ nir_builder_instr_insert(b, &lowered[0]->instr);
+ nir_builder_instr_insert(b, &lowered[1]->instr);
+
+ b->cursor = nir_after_phis(nir_cursor_current_block(b->cursor));
+ nir_ssa_def *merged = nir_pack_64_2x32_split(b, &lowered[0]->dest.ssa, &lowered[1]->dest.ssa);
+ nir_ssa_def_rewrite_uses(&phi->dest.ssa, nir_src_for_ssa(merged));
+ nir_instr_remove(&phi->instr);
+}
+
+static bool
+lower_64bit_phi_impl(nir_function_impl *impl)
+{
+ nir_builder b;
+ nir_builder_init(&b, impl);
+ bool progress = false;
+
+ nir_foreach_block(block, impl) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type != nir_instr_type_phi)
+ break;
+
+ nir_phi_instr *phi = nir_instr_as_phi(instr);
+ assert(phi->dest.is_ssa);
+
+ if (phi->dest.ssa.bit_size <= 32)
+ continue;
+
+ split_phi(&b, phi);
+ progress = true;
+ }
+ }
+
+ if (progress) {
+ nir_metadata_preserve(impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+ } else {
+ nir_metadata_preserve(impl, nir_metadata_all);
+ }
+
+ return progress;
+}
+
+bool
+nir_lower_64bit_phis(nir_shader *shader)
+{
+ bool progress = false;
+
+ nir_foreach_function(function, shader) {
+ if (function->impl)
+ progress |= lower_64bit_phi_impl(function->impl);
+ }
+
+ return progress;
+}
