Previously, we were just iterating over the program "in order" which
kind-of approximates a DFS, but not really. In particular, we got the
following case wrong:
loop {
a = 3;
if (foo) {
a = 5;
} else {
break;
}
use(a);
}
where use(a) would get 3 instead of 5 because of premature popping of the
SSA def stack. Now, since we do an actaul DFS, we should evaluate use(a)
immediately after a = 5 and we should be ok.
---
src/glsl/nir/nir_lower_variables.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/src/glsl/nir/nir_lower_variables.c
b/src/glsl/nir/nir_lower_variables.c
index eff7d5d..16157b3 100644
--- a/src/glsl/nir/nir_lower_variables.c
+++ b/src/glsl/nir/nir_lower_variables.c
@@ -730,10 +730,8 @@ add_phi_sources(nir_block *block, nir_block *pred,
}
static bool
-lower_deref_to_ssa_block(nir_block *block, void *void_state)
+rename_variables_block(nir_block *block, struct lower_variables_state *state)
{
- struct lower_variables_state *state = void_state;
-
nir_foreach_instr_safe(block, instr) {
if (instr->type == nir_instr_type_phi) {
nir_phi_instr *phi = nir_instr_as_phi(instr);
@@ -862,6 +860,9 @@ lower_deref_to_ssa_block(nir_block *block, void *void_state)
if (block->successors[1])
add_phi_sources(block->successors[1], block, state);
+ for (unsigned i = 0; i < block->num_dom_children; ++i)
+ rename_variables_block(block->dom_children[i], state);
+
return true;
}
@@ -1001,7 +1002,7 @@ nir_lower_variables_impl(nir_function_impl *impl)
nir_metadata_require(impl, nir_metadata_dominance);
insert_phi_nodes(&state);
- nir_foreach_block(impl, lower_deref_to_ssa_block, &state);
+ rename_variables_block(impl->start_block, &state);
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
--
2.2.0
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