nir: remove dead code from copy_prop_vars

When copy_prop_vars also took care of dead write handling, intrin was
used as part of store_to_entry.  Now it isn't, so this assignment
isn't used really used.  Add a comment clarifying what happens to
intrin.

Fixes: 4dfa7adc100 "nir: Remove handling of dead writes from copy_prop_vars"
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

diff --git a/src/compiler/nir/nir_opt_copy_prop_vars.c b/src/compiler/nir/nir_opt_copy_prop_vars.c
index 771f125650e884eab646329b1d82f11454c0ecb5..e109814abcd9d332c434dfda797237384c20e78c 100644 (file)
--- a/src/compiler/nir/nir_opt_copy_prop_vars.c
+++ b/src/compiler/nir/nir_opt_copy_prop_vars.c
@@ -742,9 +742,9 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
             lookup_entry_for_deref(copies, src, nir_derefs_a_contains_b_bit);
          struct value value;
          if (try_load_from_entry(state, src_entry, b, intrin, src, &value)) {
+            /* If load works, intrin (the copy_deref) is removed. */
             if (value.is_ssa) {
                nir_store_deref(b, dst, value.ssa[0], 0xf);
-               intrin = nir_instr_as_intrinsic(nir_builder_last_instr(b));
             } else {
                /* If this would be a no-op self-copy, don't bother. */
                if (nir_compare_derefs(value.deref, dst) & nir_derefs_equal_bit)