This will be useful for cleaning up phis when unrolling loops.
---
src/compiler/nir/nir.h | 1 +
src/compiler/nir/nir_opt_remove_phis.c | 94 +++++++++++++++++++---------------
2 files changed, 53 insertions(+), 42 deletions(-)
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 60aeb8f..0ab3ebc 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2676,6 +2676,7 @@ void nir_opt_gcm(nir_shader *shader);
bool nir_opt_peephole_select(nir_shader *shader);
bool nir_opt_remove_phis(nir_shader *shader);
+bool nir_opt_remove_phi(nir_phi_instr *phi);
bool nir_opt_undef(nir_shader *shader);
diff --git a/src/compiler/nir/nir_opt_remove_phis.c
b/src/compiler/nir/nir_opt_remove_phis.c
index 6d9e0ff..7dea9c7 100644
--- a/src/compiler/nir/nir_opt_remove_phis.c
+++ b/src/compiler/nir/nir_opt_remove_phis.c
@@ -47,6 +47,57 @@ matching_mov(nir_alu_instr *mov1, nir_ssa_def *ssa)
return mov2 && nir_alu_srcs_equal(mov1, mov2, 0, 0);
}
+bool
+nir_opt_remove_phi(nir_phi_instr *phi)
+{
+ nir_ssa_def *def = NULL;
+ nir_alu_instr *mov = NULL;
+ bool srcs_same = true;
+
+ nir_foreach_phi_src(src, phi) {
+ assert(src->src.is_ssa);
+
+ /* For phi nodes at the beginning of loops, we may encounter some
+ * sources from backedges that point back to the destination of the
+ * same phi, i.e. something like:
+ *
+ * a = phi(a, b, ...)
+ *
+ * We can safely ignore these sources, since if all of the normal
+ * sources point to the same definition, then that definition must
+ * still dominate the phi node, and the phi will still always take
+ * the value of that definition.
+ */
+ if (src->src.ssa == &phi->dest.ssa)
+ continue;
+
+ if (def == NULL) {
+ def = src->src.ssa;
+ mov = get_parent_mov(def);
+ } else {
+ if (src->src.ssa != def && !matching_mov(mov, src->src.ssa)) {
+ srcs_same = false;
+ break;
+ }
+ }
+ }
+
+ if (!srcs_same)
+ return false;
+
+ /* We must have found at least one definition, since there must be at
+ * least one forward edge.
+ */
+ assert(def != NULL);
+
+
+ assert(phi->dest.is_ssa);
+ nir_ssa_def_rewrite_uses(&phi->dest.ssa, nir_src_for_ssa(def));
+ nir_instr_remove(&phi->instr);
+
+ return true;
+}
+
/*
* This is a pass for removing phi nodes that look like:
* a = phi(b, b, b, ...)
@@ -74,50 +125,9 @@ remove_phis_block(nir_block *block)
nir_phi_instr *phi = nir_instr_as_phi(instr);
bool is_lcssa_phi = phi->is_lcssa_phi;
- nir_ssa_def *def = NULL;
- nir_alu_instr *mov = NULL;
- bool srcs_same = true;
-
- nir_foreach_phi_src(src, phi) {
- assert(src->src.is_ssa);
-
- /* For phi nodes at the beginning of loops, we may encounter some
- * sources from backedges that point back to the destination of the
- * same phi, i.e. something like:
- *
- * a = phi(a, b, ...)
- *
- * We can safely ignore these sources, since if all of the normal
- * sources point to the same definition, then that definition must
- * still dominate the phi node, and the phi will still always take
- * the value of that definition.
- */
- if (src->src.ssa == &phi->dest.ssa)
- continue;
-
- if (def == NULL) {
- def = src->src.ssa;
- mov = get_parent_mov(def);
- } else {
- if (src->src.ssa != def && !matching_mov(mov, src->src.ssa)) {
- srcs_same = false;
- break;
- }
- }
- }
-
- if (!srcs_same)
+ if (!nir_opt_remove_phi(phi))
continue;
- /* We must have found at least one definition, since there must be at
- * least one forward edge.
- */
- assert(def != NULL);
-
- assert(phi->dest.is_ssa);
- nir_ssa_def_rewrite_uses(&phi->dest.ssa, nir_src_for_ssa(def));
- nir_instr_remove(instr);
-
if (!is_lcssa_phi)
progress = true;
}
--
2.7.4
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
