nir/copy_prop_vars: Ignore volatile accesses

The spec explicitly says that volatile writes can't be removed and
volatile reads do not guarantee that the same value will still be around
after the read, as if there were a barrier after each read/write. Just
ignore them.

Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>

src/compiler/nir/nir_opt_copy_prop_vars.c

@@ -812,6 +812,9 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
       case nir_intrinsic_load_deref: {
          if (debug) dump_instr(instr);
 
+         if (nir_intrinsic_access(intrin) & ACCESS_VOLATILE)
+            break;
+
          nir_deref_instr *src = nir_src_as_deref(intrin->src[0]);
 
          /* Direct array_derefs of vectors operate on the vectors (the parent
@@ -892,6 +895,9 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
       case nir_intrinsic_store_deref: {
          if (debug) dump_instr(instr);
 
+         if (nir_intrinsic_access(intrin) & ACCESS_VOLATILE)
+            break;
+
          nir_deref_instr *dst = nir_src_as_deref(intrin->src[0]);
          assert(glsl_type_is_vector_or_scalar(dst->type));
 
@@ -936,6 +942,10 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
       case nir_intrinsic_copy_deref: {
          if (debug) dump_instr(instr);
 
+         if ((nir_intrinsic_src_access(intrin) & ACCESS_VOLATILE) ||
+             (nir_intrinsic_dst_access(intrin) & ACCESS_VOLATILE))
+            break;
+
          nir_deref_instr *dst = nir_src_as_deref(intrin->src[0]);
          nir_deref_instr *src = nir_src_as_deref(intrin->src[1]);
 
@@ -1005,6 +1015,9 @@ copy_prop_vars_block(struct copy_prop_var_state *state,
       case nir_intrinsic_deref_atomic_comp_swap:
          if (debug) dump_instr(instr);
 
+         if (nir_intrinsic_access(intrin) & ACCESS_VOLATILE)
+            break;
+
          nir_deref_instr *dst = nir_src_as_deref(intrin->src[0]);
          unsigned num_components = glsl_get_vector_elements(dst->type);
          unsigned full_mask = (1 << num_components) - 1;